Atlanto-axial dislocation: characterized by a smaller in comparison with the atlanto-occipital. Vertebral column Atlanto axial instability in dogs clinical cases

Date: 20.06.2020

Atlas is called the first vertebra of the cervical region, resembling a ring in its appearance and connected to the occipital bone. The atlas is connected to other parts of the spine thanks to a kind of “tooth” located in the axial vertebra, with the help of which a smooth sliding along the surface of the atlas is carried out.

Rotational subluxation of c1 is accompanied by separation of the first and second vertebrae, and the atlas itself is shifted towards the axial element. When the atlas is dislocated, the bone structure remains intact, but the connection between the articular surfaces is lost. In the case of subluxation, the displacement of the first cervical vertebra is fixed, but contact between the vertebral elements is maintained.

Traumatologists distinguish the following types of this traumatic injury:

Subluxation with maximum rotation of the atlas towards the next vertebra. In this case, the head of the victim can lean to the healthy side, the ability of the chin to turn remains.
Atlanto-axial subluxation - instability and asymmetry of the atlanto-axial joint. At the same time, the motor activity of the neck is disturbed, difficulties arise with motor activity and turns.

Atlas subluxation in children is recorded most often in the case of specific, non-typical contractions of muscle groups. According to experts, both in an adult and in a child, the following factors can provoke this injury:

A blow to the head or neck;
Osteochondrosis;
Sharp head movements, neck turns, active sports training;
Falling from height;
Traumatic sports;
Unexpected turning of the head after prolonged rest, with concomitant relaxation of the muscles.

Atlas subluxation in a newborn is caused by weakening of the tendon and ligamentous apparatus with an increased susceptibility to traumatic injuries. Trauma in a child can even be congenital: damage occurs directly during the birth process.

Also, a subluxation of the first cervical vertebra in a child often occurs with careless handling of the baby (for example, in the case of excessively sudden movements during dressing). This injury often occurs if you do not support the baby's head when lifting.

What is the danger?

Atlas dislocation, like subluxation, is a rather serious injury, because when the vertebrae are displaced, as a rule, the vascular bundle is clamped. As a result, in people suffering from this pathology, intracranial pressure increases, which threatens with very dangerous consequences for life and health, up to cerebral edema.

In addition, the displaced vertebra also compresses certain parts of the spinal cord, and this, in turn, leads to disturbances in the functioning of the internal organs, the motor activity of the patient's limbs (both upper and lower).

Among the most common consequences of this type of injury, doctors distinguish the following symptoms:

Headache;
sleep disorders;
Violation of the sensitivity of the upper and lower extremities, numbness;
muscle weakness;
Disorders in the work of the cardiovascular system.

The most dangerous consequences of dislocations and subluxations of the atlas are paralysis, impaired renal and intestinal function, and breathing problems. If you find such signs, you need to immediately call an ambulance for the victim!

It is most difficult to identify possible complications and undesirable consequences in a baby. As a rule, alarming signs appear when the child begins to walk. Traumatologists distinguish the following belated complications of rotational subluxation, which can be detected in young patients:

Scoliosis;
flat feet;
hyperactivity;
memory disorders;
Increased fatigue;
Violations of visual function;
problems concentrating;
Rhinitis occurring in a chronic form.

Therefore, it is very important to be able to identify rotational subluxation of the cervical vertebra and turn to an experienced, professional specialist in time, who will prescribe an effective, competent treatment to the victim.

How is it manifested?

The particular insidiousness of this injury lies in the fact that in some cases it can proceed almost asymptomatically for a long time, without showing itself with specific signs, in addition to headaches caused by a violation of the processes of cerebral blood supply.

However, according to traumatologists, most patients experience the following symptoms:

Violations of the motor activity of the neck;
Attacks of dizziness;
Nausea;
Fainting states;
Specific sensation of tinnitus;
Disorders of visual function;
Muscle spasms, pain localized in the back and shoulder region;
Convulsive syndrome.

Quite often, victims complain that their arms and legs go numb, there is swelling and redness of the cervical skin. In young children with this type of traumatic injury, the following symptoms are usually observed:

Torticollis;
Convulsive syndrome of the lower jaws;
regurgitation after feeding;
puffiness;
Tension of muscle groups;
Delays in mental and physical development, weight gain.

Also, parents should pay attention to the fact that babies begin to act up for no reason, often cry, sleep poorly, and may refuse to eat.

Having found at least some of the symptoms characteristic of atlas subluxation, you should contact the emergency room for professional medical help as soon as possible!

About diagnostics

Diagnosis of rotational subluxation begins with an examination of the victim by a specialist, studying the clinical picture and the results of the collected anamnesis. It is imperative to consult a qualified neurologist. In addition, in order to make an accurate diagnosis, patients are assigned the following types of studies:

X-ray in two projections;
Magnetic resonance imaging;
CT scan.

Only after a full diagnosis, the doctor will be able to prescribe the optimal treatment for the victim!

Treatment Methods

The first thing a specialist should do after making a diagnosis is to adjust the atlas. In no case should you try to perform this manipulation on your own, as this is fraught with serious injuries to the nerve roots and blood vessels!

Repositioning the atlas is a rather painful procedure, so it is usually performed under local anesthesia. Depending on the characteristics of a particular clinical case, the doctor adjusts the vertebra either manually or using the so-called Glisson's loop for this purpose.

In the case of particularly severe injuries, ruptures of the transverse ligaments, it may be necessary to perform surgical intervention. During the operation, the specialist artificially fixes the position of the atlas and axis, using clamp screws specially designed for this purpose. The operation is performed under general anesthesia.

Further treatment of subluxation of the cervical vertebra C1 involves wearing an orthopedic orthosis, massage courses, physiotherapy and exercise therapy.

The structure of the cervical

The structure of the cervical
What are the diseases of the cervical region?
The mechanism of development of cervical arthrosis
Causes of the disease
stages
Symptoms
Diagnostics
Treatment
Conservative treatment
Surgery

In the human axial skeleton, consisting of the skull, vertebral column and chest, there are 34 vertebrae. 7 of them belong to the cervical region. In the diagrams, they are indicated by the letter C and numbers from 1 to 7, the numbering is from top to bottom.

The C1 vertebra, the atlas, has a specific structure, it consists of 2 arches, has no body. Its upper part articulates with the occipital bone of the skull by articular processes, the lower part - with the C2 vertebra (axis). The axis differs from all vertebrae in the presence of an odontoid process with two articular surfaces. A ligament is attached to one, the other articulates with a fossa on the posterior surface of the atlas. In addition to the median anlantoaxial joint, vertebrae 1 and 2 are articulated through a pair of lateral joints with flat, even articular surfaces. The 3 joints of the atlanto-axial joint act as a single combined joint and provide rotational movements of the head.

The bodies of the next 5 vertebrae, C3-C7, have elongated edges - uncinate processes. They articulate with the lower lateral part of the body of the upper vertebra, forming the uncovertebral joints (Lusch's joints). In fact, this is neoarthrosis, that is, false joints, some researchers consider their formation to be the result of thinning of the intervertebral discs in osteochondrosis. Others see these joints as an adaptive mechanism that is not present at birth but can form after age 20 to increase spinal mobility. In itself, the formation of Luschka joints is not a disease, but these joints are often affected by arthrosis of the uncovertebral joints.

Also, the cervical vertebrae have paired facet (intervertebral) joints connecting the articular processes. The vertebral bodies are separated by intervertebral discs, these are fibrocartilaginous formations, which are similar in their functions to articular cartilage. The vertebrae are supported in the correct position by the system of ligaments, with wear of the facet, uncovertebral joints and intervertebral discs, the load on the ligaments increases, they hypertrophy. Blood vessels and nerves pass through the openings in the transverse processes of the vertebral arches. The spine is surrounded by muscles, which normally provide its stability.

What are the diseases of the cervical region?

Let's get acquainted with spondylarthrosis of the cervical spine: what it is, what diseases it is associated with, for what reasons it develops and what complications it threatens. Spondylarthrosis is a collective name for diseases of the joints of the spine, in which degenerative and dystrophic changes occur in cartilage and bone tissue. Cervical spondyloarthrosis, in which facet (facet) joints are affected, is usually called cervicoarthrosis. What is uncovertebral arthrosis of the cervical spine? So called arthrosis of the uncovertebral joints of the cervical region, abbreviated as uncoarthrosis.

In addition to spondylarthrosis and its particular manifestation - uncoarthrosis, other diseases can develop in the cervical region:

osteochondrosis is a degenerative-dystrophic lesion of the vertebral joints and intervertebral discs. First, the structure of the disc changes, it becomes less elastic, then it bulges beyond the intervertebral fissure (protrusion), a hernia is formed;
Deforming spondylosis is often considered as the 4th stage of osteochondrosis, in which degeneration of the fibrous ring of the disc and the growth of osteophytes on the vertebral bodies occur. Sometimes adjacent vertebrae are completely fused. In MBC-10, arthrosis of the spine is classified as a particular manifestation of spondylosis, that is, osteochondrosis, spondylosis, spondyloarthrosis are closely related;
spondylolisthesis - displacement of the vertebrae. Degenerative spondylolisthesis develops as a complication of arthrosis, osteochondrosis, but the disease can also be the result of trauma, dysplasia, bone tumors;
cervical-brachial sciatica - compression of the roots of the spinal nerves, often develops as a complication of osteochondrosis or spondyloarthrosis of the cervical spine;
arthritis is an inflammatory disease of the joints.

The mechanism of development of cervical arthrosis

What is spondylarthrosis of the cervical spine and how does it develop? The disease begins with the fact that in the articular cartilage, the processes of degeneration outweigh the processes of recovery. This may be due to nutritional deficiencies, mechanical trauma, metabolic disorders, and other factors. The thinning and destruction of the cartilage lining leads to the exposure of the articular areas, the friction of the bones against each other is accompanied by painful sensations. Bone tissue at the articulation sites is compacted, and osteophytes - bone spikes - are formed along the edges of the articular processes. Due to their growth, the joint is deformed, so the disease is also called deforming arthrosis.

In parallel with the destruction of cartilage and the growth of osteophytes, calcification (calcification) of the cervical ligaments occurs. Under the influence of osteophytes, the joint capsule is stretched and provokes muscle spasm. Deforming spondylosis, spondylarthrosis is aggravated by vascular and neurological disorders, the risk of which is higher with simultaneous damage to the joints and intervertebral discs. Osteophytes irritate and injure blood vessels and nerve fibers, and displaced vertebrae compress them.

Causes of the disease

uneven distribution of the load on the spine due to incorrect posture, flat feet, dislocations of the hip joint;
polio;
past injuries, hypothermia and frostbite of the cervical region;
destruction of cartilage under the influence of an infection or inflammatory process, including on the background of arthritis;
endocrine disorders leading to metabolic disorders;
excessive load on the spine (hard physical work, professional sports, overweight);
sedentary lifestyle;
age-related changes, natural aging of the body.

Sometimes spondylolisthesis, associated with abnormal mobility of the vertebrae or due to other causes, leads to the development of vertebral arthrosis of the cervical spine. Conversely, arthrosis, spondylosis lead to displacement of the vertebrae. Spondylarthrosis and osteochondrosis also go hand in hand. Sometimes, due to the destruction of articular cartilage, the load on the intervertebral discs increases. Sometimes, on the contrary, a decrease in the height of the discs against the background of osteochondrosis provokes arthrosis of the vertebral joints, in particular, uncovertebral osteoarthritis of the cervical spine.

stages

Arthrosis of the cervical vertebrae takes place in the development of 4 stages:

1 - degenerative-dystrophic changes in the cartilage have already begun, it loses fluid, becomes less elastic, brittle, the ligaments and joint capsule are affected. But there are no clinical signs of cervical spondyloarthrosis, and only a specialist during a physical examination can suspect that the patient develops arthrosis;
2 - degenerative processes affect the fibrous tissue of the joints. Arthrosis of the 2nd degree is manifested by moderate pain, increased fatigue, difficult movements of the spine in the cervical region;
3 - bone tissue is involved in the process, its compaction (osteosclerosis) begins and osteophytes appear, signs of inflammation are often noted, ligaments lose elasticity;
4 - large osteophytes are formed, severely limiting the mobility of the spine, the patient cannot turn his head, he is forced to turn his whole body. Muscles, nerves, blood vessels are involved in the process.

loading…

With the defeat of the facet joints, the appearance of osteophytes is combined with the phenomena of osteosclerosis. Uncoarthrosis can develop in a deforming or sclerotizing type. In the first case, the uncinate processes are lengthened and sharpened due to the growth of osteophytes along their edge. In the second, osteosclerosis develops in the processes, their tissue thickens, they themselves become thicker, more massive, and osteophytes grow on the vertebral body.

Symptoms

Pain syndrome is one of the main manifestations of cervical arthrosis. First, pain occurs in response to neck movements, prolonged static load (staying in one position) and quickly disappear. Over time, they become more and more long, for their appearance, an insignificant load is enough. If in the early stages the pain is caused by friction of the bones into the joint, then in the later stages it is one of the manifestations of the radicular syndrome, that is, a consequence of pinched nerve endings. In this case, the pain is constant, aching, from time to time there is a sharp sharp pain. Another cause of pain in the neck is muscle spasm, which often accompanies spondyloarthrosis, uncoarthrosis and osteochondrosis.

First, pain is localized in the area of the affected joint. So, if a patient has C4 arthrosis, then pain is felt in the area of the projection of this vertebra, approximately in the middle of the cervical region. When nerves are pinched, pain can radiate to different areas of the cervical-collar zone, shoulder girdle, and hands. Radicular syndrome, in addition to pain, is manifested by numbness and / or paresthesia (tingling, goosebumps) in the area of \u200b\u200binnervation. Perhaps cold extremities or hot flashes, increased sweating. The manifestations of the vertebral artery syndrome are even more diverse. When it is squeezed, the blood supply to the brain is disturbed, which can be suspected by the following signs:

frequent headaches, including sharp ones, such as lumbago, unbearable migraines, pains in one half of the head;
increased blood pressure, which is not amenable to drug correction;
dizziness, up to fainting;
nausea against the background of high blood pressure;
spots, dots, sparks before the eyes, noise in the ears;
deterioration of memory, weakening of attention;
unsteadiness of gait, loss of balance, cases of falling are noted, although the patient remains conscious.

Patients with vertebral artery syndrome have a high risk of stroke. Deforming uncovertebral arthrosis c5 c6 is especially dangerous. The spinal canal at the level of these small vertebrae is narrow, the holes in the transverse processes are also small, and therefore the likelihood of squeezing the spinal cord, nerve endings and blood vessels increases. And the sharp, elongated edges of the uncinate processes can injure nearby formations.

Diagnostics

With osteoarthritis of the neck, the symptoms do not always clearly indicate this particular disease. To make a complete objective picture, the doctor needs to listen to the patient's complaints, study his medical history, examine and feel the spine, perform a series of tests, send the patient for x-rays and other examinations. Arthrosis of the cervical region is usually manifested by muscle tension. When trying to turn the head, throw it back or press the chin to the chest, the patient feels pain, a crunch is often heard, the range of motion is limited. On palpation, hard, compacted muscles, growths on the vertebrae are felt. If an increase in the vertebrae is visible to the naked eye, this means that the disease has entered stage 3-4.

X-ray allows you to determine at the level of which vertebrae the disease is localized, which structures are affected (facet, uncovertebral joints, intervertebral discs), how far the degenerative-dystrophic process has gone. Pictures have to be taken in at least 2 projections in order to see the affected area.

In addition to radiography, CT and MRI are performed, which provide information about the state of articular cartilage, intervertebral discs, muscles, and ligaments. The best way to study blood vessels is angiography. For differential diagnosis, laboratory tests are prescribed. With arthritis of the cervical spine, the symptoms of the inflammatory process are pronounced, swelling of the joints, redness of the skin, and local fever are noticeable. With arthrosis, moderate signs of inflammation are detected by laboratory methods. With a complicated course of spondyloarthrosis, the patient can be referred to other narrow specialists - a neurosurgeon, an oculist, a cardiologist.

Treatment

Deforming spondylarthrosis of the cervical spine requires complex treatment, mainly treated with conservative methods.

Conservative treatment

Drug therapy begins with pain relief with NSAIDs, with intense pain, blockades are performed with anesthetics and hormones. Also shown is the restoration of cartilage tissue with the help of chondroprotectors, the removal of muscle spasms with the help of muscle relaxants, the use of drugs to improve cerebral circulation, vitamins of group B.

Non-drug therapy:

physiotherapy - electrophoresis, ultrasound and phonophoresis, magnetotherapy, laser therapy and other procedures;
orthopedic treatment - sleeping on an orthopedic mattress with a pillow, in the acute phase - wearing a Shants collar;
acupressure and segmental massage, according to indications - manual therapy, reflexology;

A good effect is given by sanatorium treatment in specialized complexes. The patient can undergo a course of mud therapy, healing baths, computer spinal traction, a number of physiotherapy procedures. The procedures are complemented by therapeutic exercises and physical education, diet. Proper nutrition for arthrosis is no less important than drug and non-drug therapy. The patient requires animal and vegetable proteins, fiber, collagen, vitamins and trace elements. But the use of fats and carbohydrates should be limited, refractory fats and sweets should be excluded from the diet, preservatives, fast food, and alcohol will also have to be abandoned.

In folk medicine, you can find many recipes for cervical arthrosis, these are infusions, decoctions for oral administration, and rubbing, compositions for compresses. But arthrosis of the cervical region is too serious a disease, and it is unacceptable to treat it exclusively with folk remedies, ignoring the doctor's prescriptions.

Causes of the disease

Mechanical damage:
- car accident;
Bone diseases:
- osteoporosis;
- rheumatoid arthritis;

Cervical arthrosis can be congenital, associated with an abnormal structure of the vertebrae, usually the atlas, or acquired. Acquired arthrosis or deforming spondylosis is due to various reasons:

Mechanical damage:
- car accident;
- blows, falls, careless movements of the head and neck;
- the action of various mechanisms, including work injuries;
Bone diseases:
- osteoporosis;
- rheumatoid arthritis;
- ankylosing spondylitis.

Symptoms of dislocation and fracture of the joint

The dislocation is accompanied by acute pain in the neck.

Chronic pain:

Intensity:
- severe to extremely severe.
Duration:
- continuous chronic;
Character:
- burning;
- stabbing;
- strong cutting.

Headache:

occipital;
tension type.

Range of motion of the neck:

limited flexion, extension and rotation of the neck.

Spinal cord compression caused by joint injury:

Intensity:
- severe to extremely severe.
Duration:
- continuous chronic;
- the pain lasts more than 6 months, even after the fracture and dislocation have healed.
Character:
- burning;
- stabbing;
- strong cutting.
Spread from the site of injury:
- upper limbs, neck and chest.

Damage to the spinal cord limits the mobility of the upper limbs.

Conservative treatment

Julia asks:

Hello! My son is 13 years old. We consulted a neurologist for frequent headaches. They did an MRI of the brain. Conclusion: MRI picture of cysts of the perivascular spaces of the right hemisphere of the brain, Arnold-Chiari I, asymmetry of the atlanto-axial joint. Please explain what this means, how dangerous it is for the child.

Doctor Pogrebnoy Stanislav Leonidovich answers

Hello dear Julia!

Arnold-Chiari anomaly is a congenital anomaly in which the skull is, as it were, small for the structures of the cerebellum and medulla oblongata. Because of this, the pons, medulla oblongata, and cerebellar tonsils descend down to the foramen magnum. With an anomaly of type 1, which exists in your case, there is a descent into the spinal canal of the caudal parts of the brain, below the plane of the foramen magnum. Sometimes this is asymptomatic, but in the event of an increase in intracranial pressure, a situation may arise when these structures begin to shift even lower, and there may be a real threat of their infringement. In this case, Arnold-Chiari syndrome may occur. It manifests itself with the following symptoms:

Various headaches in the back of the head, which increase with sneezing and coughing, in the hands, pain and temperature sensitivity, as well as strength, may decrease. There may be increased muscle tone in the legs, dizziness and fainting often occur, and visual acuity also decreases.

Atlanto-axial instability or atlanto-axial dislocation in dogs causes a symptom complex of disorders characterized by neurological problems.

The dog may be forced to keep his head up, weakness of the pelvic and thoracic limbs, impaired coordination and a sharp decrease in appetite appear. The severity of disorders directly depends on the degree of instability and underlying causes.

Atlanto-axial instability in dogs can be acute or chronic.

What's happening?

The normal anatomical relationship between the first (C1) and the second cervical vertebra (C2) is disrupted, resulting in their displacement relative to each other and compression of the spinal cord structures (Fig. 1a, b).

The main causes that can cause C1-C2 instability are the following: hypoplasia, aplasia of the odontoid process, malformations, articular fracture, rupture of the dorsal ligament, or a combination of them.

The true traumatic factor is rare and mostly in large dogs.

Who is sick?

Basically, this disease affects dwarf breeds of dogs, such as Yorkies, Spitz, toy terriers. The hereditary factor is determined.

Diagnosis of atlanto-axial instability

When examining these patients, the specialist must be very careful in manipulating the head so as not to cause possible secondary damage. The main and accessible diagnostic method is X-ray examination.

On the radiograph in the lateral projection, the ventral displacement of C1 relative to C2 is determined. A displacement of 2-4 mm indicates the presence of pathology (photo 1).

To assess the condition of the odontoid process, a direct projection is performed with forced rotation of the head.

Often in patients aged 4 months with atlanto-axial instability, a wide-open fontanel remains, evidence of increased intracranial pressure. Here, it will be valuable to conduct an ultrasound examination of the brain (photo 2) and evaluate the cerebrospinal fluid to exclude associated problems. Accompanying problems can be inflammatory processes in the form of meningoencephalitis.

Treatment of atlano-axial instability

There is a conservative and surgical method for the treatment of atlanto-axial instability.

First of all, it is necessary to make a corset around the neck to limit the rotation of the head and neck. Anti-inflammatory drugs are also used.

The purpose of conservative therapy is to provide temporary anatomical stability for the formation of scar-connective tissue in the area of the vertebral joints.

The surgical method will be the main one, since it has a higher percentage of favorable outcome and good results immediately after the operation.

The main goal of surgical treatment is to fix the vertebrae in an anatomically correct position by various methods and designs.

There is a method of dorsal and ventral stabilization.

Each method has its own advantages and disadvantages.

With dorsal stabilization, it is difficult to make a fixation structure that will respond to displacement loading forces (photo 3). However, even with a slight postoperative displacement, these patients may feel well.

To date, the method of ventral stabilization is considered the most effective (photo 4). Full fixation of the articular surfaces of the atlanto-axial articulation is carried out with knitting needles, screws, etc. depending on the size of the dog.

Forecast

If conservative treatment is not successful within 50-80 days, then it is necessary to focus on surgical correction.

If, after the start of conservative treatment, neurological signs do not go away or worsen, then surgical treatment is urgently needed.

Surgical treatment of atlanto-axial instability in dogs under 7 months of age and weighing up to 1.5 kg should be performed by an experienced surgeon, since the bone tissue is not yet “mature” and complications of structural failure can be fatal. If in the early postoperative period there was a relapse of the disease, then the prognosis will be cautious.

Atlanto-axial instability is a pathological condition associated with an unstable connection of the first (atlas) and second (axis or epistrophy) cervical vertebrae. This is primarily due to the underdevelopment of the ligamentous apparatus of the epistrophy tooth (the second cervical vertebra). As a result, the tooth is more unstable. This becomes especially relevant when moving the head up and down. The fact is that this tooth is located in the spinal canal and is located in close proximity to the spinal cord (Figure 1). Therefore, with every movement in the neck, there is a risk of damage to the latter. As a result of atlanto-axial instability, spinal compression (squeezing) occurs, which causes deterioration of blood circulation in the area of the pathological focus and, as a result, dysfunction of the nerve conduction of the spinal cord. Simplistically, this can be imagined as a watering hose (spinal cord), on which a stone (an epistrophy tooth) was placed. The larger the stone, the stronger the pressure on the hose, the worse the water (nerve impulses) flows through the hose.

As a rule, this disease is observed in decorative dwarf dogs.

Clinical signs

Atlanto-axial instability is a congenital pathology. However, this does not mean that clinical signs develop from the first days of life. In the vast majority of cases, the manifestation of the disease occurs in the first year. Less often, the disease manifests itself at a later date. And most often, the owners simply do not notice the clinical manifestations, if they are not of a global nature.

Chihuahuas, toy terriers, and Yorkshire terriers mostly suffer from this disease. It is also found in King Charles Spaniels, Miniature Pinschers, Papillons, Pomeranians and many other Toy breeds.

As a result of atlanto-axial instability, a number of neurological signs can be observed:

The first thing you should pay attention to is pain in the neck, which can be manifested by shortening and thickening of the latter, tension in this area, stiffness of movement not only of the head and neck, but also of the dog as a whole (especially the forelimbs). Sometimes the pain comes to light only at rise on hands or a touch to a neck.
Often such dogs walk with their heads down, as if they were guilty of something (the “Guilty Dog” pose).
In more severe cases, there is a violation of the coordination of the movements of the limbs, which can manifest itself as a prancing gait of the forelegs (dysmetria), and more severe disorders (unsteadiness, falling to one side, incorrect setting of the limbs, as if the dog was drunk).
Not infrequently, the owners note the instability of the head, which is expressed by the rolling (unsteadiness) of the head from left to right, like a puppet.
In extreme situations, paralysis of all four legs is possible.

If you find any of the listed signs in your pet, immediately contact our clinic for consultation, urgent diagnosis and assistance. Sometimes a delay of more than 12 hours from the moment the first symptoms appear leads to the development of irreversible processes that are detrimental to the animal.

Diagnostics

When patients with suspected atlanto-axial instability appear at the AVERS veterinary clinic, the severity of the disease is assessed. Further, during the examination by a neurologist, the ability to move and reflexes are checked, which is very important for making an accurate diagnosis. In particular, they evaluate:

Mental status (level of consciousness of the patient)
Reflexes of the cranial nerves to exclude brain pathologies (for example, craniocervical malformation). Since the symptoms of these diseases are often similar.
Staging reflexes (postural reflexes, proprioception)
Own reflexes of the spinal cord (reflexes of the lower motor neuron), such as the withdrawal reflex of the thoracic and pelvic limbs, knee reflex, anal reflex.

It is also worth excluding banal weakness, which may be associated with diseases of other organ systems. For example, with a viral or often recorded failure or severe weakness of the pelvic limbs.

Of the additional research methods in our clinic, we often use:

X-ray of the cervical spine in lateral projection. Including using stress shots, when the patient's head is pressed tightly against the chest (Figure 2), which is often more indicative of the described problem.
If the situation does not require emergency treatment, an MRI (magnetic resonance imaging) or CT (computed tomography) may be needed to confirm the diagnosis. Also, these studies make it possible to exclude concomitant pathologies of the brain, cervical spine and spinal cord, which can radically change the tactics of treatment.
If the situation is urgent, and there is no MRI or CT at hand, then myelography (a series of radiographs with the introduction of a contrast agent into the spinal canal) can be performed to confirm the diagnosis and exclude concomitant pathologies of the cervical spine.

Pathologies associated with atlanto-axial instability

Not infrequently, along with atlanto-axial instability, other pathologies of the nervous system and surrounding tissues are recorded. They can be divided into 2 groups:

Diseases that are a consequence of the underlying problem
Diseases that develop independently of atlanto-axial instability.

The first group includes such problems as hydrocephalus and syringomyelia. These are diseases in which there is stagnation of cerebrospinal fluid (cerebrospinal fluid) in the natural cavities of the brain and spinal cord, respectively. The fact is that the compression caused by the instability we are talking about partially or completely blocks the flow of cerebrospinal fluid along the liquor-conducting paths, just like platinum blocks the flow of a river. Which in turn leads to the accumulation of cerebrospinal fluid in the cerebral ventricles and spinal canal. If during the diagnosis hydrocephalus or syringomyelia is detected, the prognosis of the disease deteriorates sharply.

The diseases of the second group include cranio-cervical malformation, degenerative diseases of the intervertebral discs ("herniated discs") of the first and second types, otitis media, meningoencephalitis. In all these ailments, the symptoms are very similar to those of atlanto-axial instability. It should also be noted that all of the above problems are characteristic of the same dwarf dog breeds.

Therefore, it is very important to carry out a full diagnosis of such patients. Since the identification of a particular comorbidity can lead to fundamental changes in the tactics of treating such a patient. Conversely, the lack of information about an additional problem leads not only to the absence of the result of therapy, but can also be fatal for your pet.

Treatment

To develop a tactic for the treatment of atlanto-axial instability, first of all, it is necessary to assess the severity of the manifestation of clinical symptoms. If necessary, your pet will be provided with emergency neurological care, which includes decongestant therapy and elimination of the consequences caused by the disease. Such therapy, not infrequently, gives time for a full diagnosis of the patient, since quite often this disease requires the use of emergency therapeutic and diagnostic measures. However, this is not a complete treatment, but only temporary support for the patient.

Treatment of atlanto-axial instability is carried out only surgically. There are several ways to fix this issue. But the essence of all operations is to stabilize the first two cervical vertebrae in an anatomically correct position. If you do not go into the nuances, then all methods can be divided into two types:

Dorsal stabilization (stabilization from the upper side of the spine)
Ventral stabilization (from the bottom side)

Dorsal stabilization (Figure 3) is easier to perform but older and often more dangerous. The danger lies in the rather frequent relapses (resumption) of the disease and the risk of damage to the cerebellum with comorbidities (eg, cranio-cervical malformation), which often go hand in hand with atlanto-axial instability. The essence of the method is the fixed connection of the epistrophy ridge with the bow of the atlas with a circling (medical) wire.

The second, more advanced, method is ventral stabilization (Figure 4). There are several types of this type of treatment. But they all come down to fixing the bodies of the first two vertebrae with screws in a stationary state. This method is more reliable, but requires more training of surgeons, since it is more difficult in technical execution. In our clinic, we usually use this method for the treatment of atlanto-axial instability.

The cost of diagnosis and treatment of atlanto-axial instability in the AVERS veterinary clinic

The veterinary clinic "AVERS" treats neurological patients, including those with atlanto-axial instability. This is a rather complex pathology that requires an integrated treatment and diagnostic approach, which includes:

Neurologist examination
Laboratory and instrumental research
Surgery.

Seeing a neurologist is worth it ) .

In a planned situation, 2-3 x-rays will be performed: a standard x-ray of the cervical spine in a lateral projection and a stress image in the same projection, an x-ray of this area in a direct projection may also be required. The cost of one x-ray is ) .

If the situation is urgent, then in such cases we perform myelography of the cervical spine. This is a specialized neurological examination, which consists in a series of radiographs of the spine with a preliminary injection of a contrast agent into it. Naturally, such manipulation is performed under general anesthesia (narcosis). The cost of this study is ) + anesthesia cost () + cost of consumables.

As a rule, such an examination algorithm is sufficient to make a final diagnosis and exclude pathologies associated with atlanto-axial instability.

If the diagnosis is confirmed, then in the vast majority of cases, the patient is waiting for an operation to stabilize the atlanto-axial joint, the cost of which is () + cost of anesthesia ) + the cost of drugs and consumables.

Despite the tangible budget of all activities related to the diagnosis and treatment of this pathology, the prices of our clinic are average for Moscow, for veterinary institutions that have the appropriate specialists and equipment.

For more information on cost, call our clinic.

Neurosurgeon-traumatologist VK "AVERS"

PhD in Biology

Among congenital anomalies of the spinal column, the most common in small dogs is the incorrect formation of the first two cervical vertebrae. In dwarf breeds, such as the Pekingese, Japanese Chin, Toy Terrier, Chihuahua, Yorkshire Terrier and some others, because of this, not only rotational, but also non-physiological angular displacement of the second cervical vertebra relative to the first is possible, that is, subluxation. As a result, compression of the spinal cord occurs, leading to very serious consequences.

Among congenital anomalies of the spinal column, the most common in small dogs is the incorrect formation of the first two cervical vertebrae. Anatomically, the first cervical vertebra, the atlas, is a ring with wings extending to the sides, planted, as if on an axis, on the protruding odontoid process of the second cervical vertebra - the epistrophy. From above, the structure is additionally reinforced with ligaments that attach a special crest of the second cervical vertebra to the occipital bone and atlas (Fig. 1). Such a connection allows the animal to make rotational movements of the head (for example, shake its ears), while the spinal cord passing through these vertebrae is not deformed or compressed.

In dwarf breeds, such as the Pekingese, Japanese Chin, Toy Terrier, Chihuahua, Yorkshire Terrier and some others, due to insufficient development of processes and fixing ligaments, not only rotational, but also non-physiological angular displacement of the second cervical vertebra relative to the first is possible, that is subluxation (Fig. 2). As a result, compression of the spinal cord occurs, leading to very serious consequences.

Puppies born with an anomaly of the first cervical vertebrae do not show any signs in the first months of life. They develop normally, are active and mobile. Usually not earlier than 6 months, owners notice a decrease in the dog's mobility. Sometimes the appearance of the first signs is preceded by an unsuccessful jump, fall or head injury on the run. Unfortunately, as a rule, only obvious movement disorders make you see a doctor.

A typical symptom is weakness of the forelimbs. At first, the dog periodically cannot properly place its front paws on the pillows and leans on a bent hand. Then he cannot rise on his forelimbs above the floor and crawls on his stomach. Motor disorders of the hind limbs appear later and are not so pronounced. No deformation of the neck during external examination is not detected. Pain is absent in most cases.

The described signs are clearly visible in Toy Terriers and Chihuahuas, less pronounced in Chins and at first difficult to distinguish in Pekingese due to the large amount of wool and breed deformity of the paws in this breed. Accordingly, with dogs of some breeds, they go to the doctor at the initial stage of the disease, while with others they come when the animal cannot walk at all.

Rice. 2 Since the outward displacement of the second cervical vertebra is not noticeable, the only possible way to reliably recognize this disease is an X-ray examination. Take two pictures in lateral projection. On the first, the head of the animal should be extended along the length of the spine, on the other, the head is bent to the handle of the sternum. In restless animals, short-term sedation should be used, since forcible flexion of the neck is dangerous for them.

In healthy animals, flexion of the neck does not change the position of the atlas and epistrophy. The process of the second cervical vertebra in any position of the head is located above the arch of the atlas. In the case of subluxation, there is a noticeable departure of the process from the arch and the presence of an angle between the first and second cervical vertebrae. Special radiological techniques for epistropheal subluxation are usually not required and the risk of their use is unreasonably high.

Since the displacement of the vertebrae, leading to dysfunction of the spinal cord, is due to anatomical causes, the treatment of epistropheal subluxation should be surgical. Fixing the head and neck of the animal with a wide collar, prescribing various medications gives only a temporary effect and often only aggravates the situation, since the restoration of the mobility of a sick animal leads to further destabilization of the vertebrae. Sometimes it can be used to prove to the owners of the animal that the problem is not in the paws and the effect of conservative treatment will only be temporary.

There are several ways to stabilize the overly mobile connection of the atlas and epistrophy. Foreign literature describes methods aimed at obtaining a fixed fusion between the lower surfaces of the vertebrae. These methods probably have their advantages, but the lack of special plates and screws, as well as the high risk of spinal cord injury if they are incorrectly located on the tiny vertebrae of small dogs, make these methods inapplicable in practice.

In addition to these methods, it is proposed to attach the process of the second cervical vertebra to the arch of the atlas with wire or non-absorbable cords. Moreover, the second approach is considered insufficiently reliable due to the possibility of secondary displacement of the vertebrae.

In recent years, our clinic has been using fixation of the vertebrae with lavsan cords according to the original method. To gain access to the problem area of the spine, the skin is dissected from the occipital crest to the third cervical vertebra. Muscles along the midline, focusing on a well-defined crest of the epistrophy, partly sharply, partly bluntly, move apart to the vertebrae. The crest of the second cervical vertebra is carefully released from the soft tissues throughout. Then, very carefully, the muscles are separated from the arch of the first cervical vertebra. Due to the insufficient development of the first and second cervical vertebrae and their displacement, the spaces between them gape widely, which makes it possible to damage the spinal cord at this moment.

Having widely spread the muscles, the dura mater is dissected along the anterior and posterior edges of the arch of the atlas. This moment of the operation is also very dangerous. Since the use of a single loop around the bow of the atlas is reputedly not reliable enough, we use two cords that are passed independently of each other. The result is a more reliable system that allows movement between the vertebrae within physiological limits, but prevents renewed pressure on the spinal cord.

Threading should be as careful as possible, the angular displacement of the vertebrae, inevitable at this moment, should be minimized. Since all manipulations are performed in the area of the location of vital centers and it is quite possible to have a violation of breathing, before the start of the operation, intubation and artificial ventilation of the lungs are performed throughout the intervention.

Careful preoperative preparation, maintenance of vital functions during surgery, careful manipulation of the wound, anti-shock measures at the exit from anesthesia allow minimizing the risk of surgical treatment of epistropheal subluxation, but it still remains, and dog owners should be warned about this. Since they make the final decision on the operation, the decision must be balanced and considered. The owners of the animal must understand that there is no other way out, and part of the responsibility for the fate of the dog lies with them.

With rare exceptions, the results of surgical treatment are good or excellent. This is facilitated not only by the technique of the operation, but also by the correct postoperative rehabilitation of the animal. There is a complete recovery of motor ability, we observed relapses only when we used the traditional technique with a wire loop. We consider external neck fixators unnecessary.

Thus, the timely recognition of this congenital anomaly, which should be facilitated by the neurological alertness of the doctor performing the initial examination of dogs of breeds susceptible to this problem, allows for the correct treatment and a quick recovery of the affected animal.

Atlanto-axial instability usually occurs in small breed dogs and begins clinically in young animals, although it can occur at any age. This disease can be inherited or result from injury. With atlanto-axial instability, subluxation, or displacement, of the second cervical vertebra (epistrophy) relative to the first (atlas) occurs, followed by compression of the spinal cord, which leads to severe neurological symptoms: tetraparesis, paralysis, and proprioceptive deficit. The disease may be accompanied by hydroencephaly and syringohydromyelia. Among the main causes of atlanto-axial instability are the following:

Abnormal shape of the odontoid process or its absence
Underdevelopment of the ligaments of the odontoid process
Post-traumatic rupture of the atlanto-axial ligaments
Fracture of the odontoid process as a result of trauma (strong flexion of the neck)

Anatomically, there are no intervertebral discs between the occipital bone, atlas, and epistrophy, and these vertebrae form a flexible segment of the cervical spine, providing good neck mobility. The interaction between the first and second cervical vertebrae is carried out due to the articular surfaces, ligaments and the odontoid process of the epistrophy, which enters the fossa of the atlas tooth. The odontoid process, in turn, is fixed by the longitudinal and alar ligaments, as well as the transverse ligament of the atlas. The crest of the epistrophy is attached to the dorsal arch of the atlas by the dorsal atlantoaxial ligament.

Rice. 1 - ligamentous apparatus of the atlanto-axial joint.

Rice. 2 - congenital absence of the odontoid process, predisposing to rupture of the dorsal atlantoaxial ligament and leading to displacement of the epistrophy dorsally, and the atlas - ventrally.

Rice. 3 - fracture of the odontoid process and rupture of the transverse ligament of the atlas, rupture of the dorsal atlanto-axial ligament (can occur independently of each other).

Normally, the odontoid process is fixed by strong ligaments that securely articulate the first two vertebrae. These ligaments may be weak or underdeveloped and damaged by the slightest impact on the cervical spine. If the odontoid process has an abnormal shape, then the ligaments, as a rule, are torn, and the epistrophy is displaced relative to the atlas. The odontoid process may be completely absent - in this case, the vertebrae are not fixed in any way, which also leads to subluxation of the atlanto-axial joint and compression of the spinal cord. Although atlanto-axial instability is a congenital disorder of small breeds, torn ligaments with subsequent displacement of the vertebrae can occur as a result of trauma in any animal.

Clinically, the disease is manifested by pain in the cervical spine, as well as partial or complete loss of sensation, paresis and paralysis. A proprioceptive deficit resulting from an excessive increase in the amount of cerebrospinal fluid in the cranial cavity (hydroencephaly) is characterized by impaired motor skills and coordination of movement. Congenital atlanto-axial instability is often combined with syringohydromyelia (formation of cysts and cavities in the central canal of the spinal cord).

Portosystemic shunts are also present in some dogs with congenital AO instability, possibly due to the inheritance of genes that influence the development of these two diseases. Thus, when one of them is detected, it is advisable to conduct diagnostic studies aimed at identifying (or excluding) the other.

The disease is diagnosed on the basis of X-ray examination. An X-ray of an animal with AO instability shows a sharp increase in the space between the epistropheal crest and the dorsal arch of the atlas, which indicates a rupture of the dorsal atlanto-axial ligament. In case of a fracture of the odontoid process and its abnormal shape, the lower contour of the epistrophy is displaced dorsally and does not coincide with the lower contour of the atlas (the dorsal AO ligament may be intact, and the divergence of the atlas with the epistrophy may not be observed).

Rice. 4 - radiographs: normal spine (A), AO instability (B). White arrows indicate an increase in the distance between the epistrophy crest and the dorsal arch of the atlas

Pictures are taken in a lateral projection, while the head should be bent in the cervical region, which should be done very carefully, since excessive force directed to the damaged segment of the spine can cause damage to the spinal cord. AP and axial views can also be helpful in assessing the shape of the odontoid process. Myelography is contraindicated because it can lead to excessive compression of the spinal cord and cause seizures.

Computed tomography provides more detailed diagnostic information than x-rays. However, the presence or absence of syringohydromyelia can only be inferred from MRI results. These diagnostic methods are associated with an anesthetic risk, since the animal must be under general anesthesia at the time of the study.

Rice. 5 - computed tomograms: A - normal, B - AO instability. An asterisk indicates an abnormal odontoid process; the displacement of the lower contour of the epistrophy is indicated by the white arrow.

Treatment is mainly surgical, aimed at fixing the vertebrae with wire cerclages or bone cement. With an abnormal shape of the odontoid process, its resection is performed. If cysts are present in the central canal of the spinal cord, they drain.

Conservative treatment is also possible, when the animal is placed in a cage, and the cervical region is immobilized with a bandage. But it is ineffective and is mainly used as a temporary measure for animals that have contraindications for surgery, for example, with deep paresis and too young an individual. Such treatment aims to stabilize the animal prior to surgery and allow young animals to reach a relatively safe age for surgery.

According to D.P. Beaver et al., the prognosis for dogs with congenital AO instability is in most cases favorable if the animal survives the operation and tolerates the postoperative period well. Operational mortality reaches about 10% of cases, and about 5% of animals need a second operation.

(Atlanto-axial instability / C1-C2 instability in toy breeds)

Doctor of Veterinary Sciences Kozlov N.A.

Gorshkov S.S.

Friday S.A.

Abbreviations: AAN - atlanto-axial instability, AAS - atlanto-axial joint, AO ASIF - International Association of Medical Traumatologists and Orthopedists, C1 - first cervical vertebra (atlas), C2 - second cervical vertebra (epistrophy), Malformation - malformation, ZOE – odontoid process of the epistrophy (syn. tooth of the second cervical vertebra), CT – computed tomography MRI – magnetic resonance imaging, PS – spinal column, KPS – dwarf dog breeds OA – general anesthesia, PMM – polymethyl methacrylate

Introduction

Atlanto-axial instability- (syn. atlanto-axial subluxation (subluxation), dislocation (luxation)) - is excessive mobility in the atlanto-axial joint, between C1 - the first and C2 - the second cervical vertebrae, which leads to compression of the spinal cord in this area and how the consequence is manifested by varying degrees of neurological deficit. AAN is one of the anomalies (malformations) of the spinal column. (R.Bagley, 2006) This pathology is typical for dwarf dog breeds (DeLachunta.2009), but also occurs in large breeds (R.Bagley, 2006).

Anatomical features

The atlantoaxial joint provides rotation of the skull. In this case, the vertebra CI rotates around the odontoid process CII. Between CI and CII there is no intervertebral disc, so the interaction between these vertebrae is carried out mainly due to the ligamentous apparatus. In dwarf dog breeds, congenital instability of the connection of the first and second cervical vertebrae is explained by the following reasons (DeLachunta.2009):

- Underdevelopment of the ligaments holding the epistrophy tooth.

- The absence of a tooth of the second cervical vertebra associated with its postnatal degeneration, malformation or aplasia.

According to Dr. DeLachunta and a number of colleagues, the epistrophy tooth undergoes degeneration in the first months of the animal's life. This degeneration process is similar to the mechanism of development of such a pathology as aseptic necrosis of the femoral head (Legg-Calve-Perthes disease), which is also characteristic of dwarf dog breeds (De Lachunta, 2009).

The completion of the process of ossification of the epistrophy tooth occurs at the age of 7-9 months. (DeLachunta. 2009).

The absence of the odontoid process and / or its underdevelopment occurs in 46% of cases. Rupture of the ligamentous apparatus - in 24% of cases (Jeffery N.D, 1996.) These anomalies in the development of the spinal column are congenital, but injuries to this area can force the appearance of clinical symptoms of the disease (Ellison, 1998; Gibson K.L, 1995).

Predisposition

Yorkshire Terrier, Chihuahua, Miniature Poodle, Toy Terrier, Pomeranian, Pekingese.

Etiology. Pathogenesis

It was proposed to distinguish 2 main forms of AAN (H. Denny, 1998):

— Congenital atlanto-axial dislocation (primary).

Pathology is typical for dwarf dog breeds. It is based on a minor injury, a jump from the hands, a sofa, etc.

— Acquired atlanto-axial luxation(directly traumatic).

Occurs suddenly as a result of a severe injury, for example, in an accident, a fall. Can be in any animal, regardless of breed and age. More often, acquired atlanto-axial dislocations are very difficult, which is associated with sudden simultaneous and massive compression of the spinal cord by the epistrophy tooth and displaced vertebral arches.

Often, animals that have received minor trauma have a more severe degree of neurological deficit than those that have experienced moderate or major trauma.

It depends on how long the transverse ligament of the epistrophy tooth can withstand and resist the dorsal displacement of the tooth of the second cervical vertebra towards the spinal canal directly during injury (DeLachunta.2009).

Also, atlanto-axial dislocation downstream can be acute and chronic.

Acute- often provoked by trauma (falling from hands, jumping off the couch). Chronic- develop imperceptibly, gradually, without obvious motivating reasons, with a minimal degree of neurological deficit. In the event of a relapse, after treatment of AAN with a similar course, the clinical symptoms are more significant, and the treatment is more difficult.

Sometimes, due to chronic dislocation, atrophy of the dorsal (upper) arch of the atlas gradually develops from constant pressure, which is clearly seen on the x-ray as the absence of the dorsal part of the atlas.

Clinical symptoms

Clinical signs in this pathology can vary from a slight pain reaction in the neck to tetraparesis of the extremities. Symptoms may also include:

Pain syndrome in the cervical region. The dog cannot jump on a chair, sofa, keeps his head down, head turns, flexion, extension of the neck are painful and the dog may squeal during an awkward movement. Often, the owners simply notice only soreness of an incomprehensible origin. The dog reacts to touch, pressure on the stomach, lifting on hands. In such cases, with a timely visit to a doctor who does not specialize in neurological diseases, the latter draws wrong conclusions based on the story of the owners, an incorrect diagnosis is made and treatment or further diagnosis is carried out, which leads to loss of time and late diagnosis. (Sotnikov V.V. .2010)
Paresis or paralysis. Motor deficit can manifest itself in both the pelvic and all four limbs. Tetraparesis of the extremities is often observed. Neurological disorders may vary. For a more objective assessment of the severity and prognosis of spinal cord injury, many gradations have been proposed. Most often in veterinary practice, a system for assessing the severity of spinal cord injury according to Griffits, 1989 is used. Usually, with timely treatment, 1, 2, and 3 degrees of neurological deficit are noted. The prognosis for the correct treatment of "fresh" dislocation is rather favorable.
Neurological syndromes that are associated with the manifestation of intracranial hypertension syndrome, resulting from the blockage of the liquor pathways by the tooth of the second vertebra. This manifests itself in the form of many different neurological symptoms. The dog cannot stand on its paws, falls on its side, chaotically beats with its paws, twists its head sharply to the side and turns over 360 degrees after the head and can continue to somersault until it is stopped. Small dog breeds are prone to developing hydrocephalus, which is often asymptomatic, and if a dog has hydrocephalus, it can be aggravated dramatically by blocking the CSF pathways and increasing pressure in the ventricles of the brain. A sharp increase in pressure in the brain leads to the development of intracranial hypertension syndrome.

The most common clinical signs of pathology:

1) acute pain syndrome- which manifests itself when turning or raising the head in the form of a loud "squeal";

2) ventroflexion- forced position of the head and neck not higher than the level of the withers;

3) proprioceptive deficit chest limbs;

4) tetraparesis/tetraplegia.

Symptoms of brain damage may also be seen, which may be due to impaired CSF circulation and the development or progression of hydrocephalus, which is often present in 95% of toy dog breeds (Braun, 1996), but without clinical signs. In an animal, hydrocephalus may also be accompanied by syringo(hydro)myelia.

Compression of the basilar artery by the odontoid process of the epistropheus can cause symptoms such as disorientation, behavioral changes, and vestibular deficits.

Diagnostics

Differential diagnosis of this pathology includes (H. Denny):

Tumors of PS and spinal cord

Herniated discs

Discospondylitis

With a similar clinical picture, the following may occur:

Spinal fractures

Herniated mesovertebral discs type Hansen 1

Hypoglycemia is a common pathological condition in Yorkshire Terrier puppies and other miniature dogs.

Visual diagnostics includes data from the following studies:

X-ray examination of the cervical region of PS in the lateral projection
X-ray contrast study (myelography). To exclude other pathologies - Computed tomography
Magnetic resonance imaging
Ultrasound of the atlanto-axial joint

An X-ray image allows a fairly clear visualization of the AA joint area, mainly in dwarf dog breeds, due to the very small thickness of the vertebrae (the average thickness of the dorsal arch of the atlas in the period from 1-3 months is 1-1.2 mm. (McCarthy RJ, Lewis DD, 1995)) . It is also possible to assess the increase in the distance between the C1 and C2 vertebrae from the X-ray image.

The picture is recommended to be taken without general anesthesia, since relaxation and removal of the pain syndrome (if any) will aggravate damage to the spinal cord, which, due to ascending edema, can lead to paralysis of the respiratory center and death.

However, it is impossible in any way to judge the compression of the spinal cord on the basis of an x-ray. (Sotnikov V.V., 2010.) For this, it is necessary to perform CT or MRI.

These methods are not always and often not available to everyone, due to the insolvency of the financial situation of the owners of the animal, as well as the lack of CT and MRI devices in ordinary veterinary clinics of the Russian Federation.

In this case, ultrasound of the AA joint can be used as an additional method for diagnosing AAN in dwarf dog breeds. This method is possible and used (Sotnikov V.V., Proceedings of the conference: Neurology of small animals // St. Petersburg, 2010.)

MRI data provide more complete information about spinal cord edema, myelomalacia, or syringohydromyelia (Yagnikov, 2008).

Currently, for the surgical solution of the problem, we use the following surgical stabilization techniques(if there are indications for surgery):

Ventral stabilization;
Stabilization with - 2 spokes (2 mini screws);

Rice. 1 and 2. Intraoperative photo

Dorsal stabilization. As a possible solution to the problem, it is possible to use a dorsal screed (Kishigami) as a fixator