Syringomyelia of the cervical and thoracic spine

Translated from Greek, the term "syringomyelia" literally means "emptiness in the spinal cord." Pathology is a chronic disorder of the central nervous system, which is characterized by the formation of fluid-filled cavities in the spinal cord. Less commonly, the disease also affects the medulla oblongata.

Syringomyelia is caused by damage to glial tissue, or is the result of malformations of the craniovertebral junction. The disease belongs to a number of incurable pathologies, it is diagnosed using magnetic resonance imaging. [1], [2]

Epidemiology

Syringomyelia is referred to as chronic progressive pathologies of the nervous system. This disorder is characterized by the formation of peculiar cavities in the spinal cord (more often in the lower cervical or upper thoracic segment), which entail the loss of certain types of sensitivity in the corresponding zones. The problem can spread to the medulla oblongata. When involved in the process of the bridge of varoli, the patient is diagnosed with syringobulbia. It is extremely rare that there is a lesion of the lumbar spine, as well as complete damage to the spinal column.

Syringomyelia affects most men (approximately 2: 1). Clinical symptoms are usually found at a young age (about 25 years), less often at 35-40 years.

More than half of the cases are associated with Arnold-Chiari syndrome. [3], [4]

True syringomyelia is usually accompanied by congenital deformities and developmental defects of the spinal column, such as curvatures, malformation of the chest, malocclusion, asymmetry of the facial part of the skull and other skeletal segments, ear dysplasia, bifurcation of the tongue, accessory fingers or nipples of the mammary glands, etc. The disease occurs in more than 30% of cases and is familial, and is diagnosed mainly in males. In all other cases, syringomyelia is associated with defects in the craniovertebral junction, which entail an expansion of the spinal cord canal. In the area of maximum expansion, the gray matter undergoes destruction, which causes the appearance of characteristic symptoms. Less common causes are spinal injuries, hemorrhages, and cerebrospinal infarction.

The prevalence of syringomyelia is about 3 cases per hundred thousand people. Some studies have shown that the prevalence of syringomyelia ranges from 8.4 per 100,000 to 0.9 per 10,000, taking into account ethnic and geographic differences. [5],  [6] In about 75% of cases, disability or disability occurs at a young and middle age (20-45 years). [7]

Causes syringomyelia

Syringomyelia can be congenital or acquired:

• The congenital form is a consequence of the abnormal development of the spinal column and spinal cord in the embryonic period. Glial cells, designed to protect nerve structures, mature too slowly, and some of them continue to grow after the completion of the formation of the central nervous system.
• The acquired form becomes the result of tumor processes, spasms, traumatic injuries of the spine, acute infectious and inflammatory diseases.

Any of these forms is accompanied by the formation of an excess number of additional neuroglia. Against the background of their constant death, cavities with an inner lining of glial tissue are formed. Liquid easily penetrates through such a fence, so the voids are quickly filled with cerebrospinal fluid: cystic elements are formed, which gradually increase. The next stage is an increase in pressure on nearby structures, which leads to pain, loss of various types of sensitivity in the limbs and body. [8]

The main reasons for this pathology are the following:

• congenital anomalies of the central nervous system;
• tumors with spread to the spinal structures and the lower part of the brain;
• traumatic injuries and developmental anomalies of the spinal column;
• pathological narrowing of the spinal canal;
• defeat of the zone of transition of the base of the skull to the spinal column;
• excessive physical activity.

To date, experts continue to research risk factors that can lead to the development of syringomyelia.

Risk factors

Among the factors contributing to the development of syringomyelia, the most significant role is played by:

• acute and chronic infectious and inflammatory pathologies of the respiratory system;
• heavy physical activity;
• trauma, inflammatory and tumor processes affecting the spinal column; [9]
• unsatisfactory professional and living conditions.

Additional factors include:

• Smoking - significantly increases the risk of problems with the spinal column, as it reduces the level of oxygen in the blood, which entails the appearance of trophic disorders in the tissues.
• Excess weight puts additional stress on the spine. Sometimes it is possible to alleviate the symptoms of the disease only by eliminating the extra pounds.
• Too tall (for men - more than 180 cm, for women - more than 175 cm).

Pathogenesis

Syringomyelia develops due to a disorder that occurs in the spinal structures. Microscopic cavities form in the spinal cord of patients. Connective tissue (instead of nerve tissue) grows around them, which leads to squeezing and disruption of the sensitive channels through which pain and temperature sensitivity is carried out. [10]

Even with a congenital etiology of the disease, the appearance and further development of pathological changes in the spinal cord are mainly due to external stimuli. Exposure from the outside contributes to the manifestation of an internal disorder, which entails the development of syringomyelia. [11]

Scientists have noticed that in most patients, the disease appears in persons who systematically face heavy physical exertion. This was confirmed by the fact that the introduction of labor mechanization into production led to a decrease in the incidence of syringomyelia. [12]

Currently, more and more often in patients diagnosed with syringomyelia, the following factors are noted as the cause of the disease:

• trauma, back bruises;
• hypothermia, prolonged exposure to cold conditions;
• smoking, alcohol abuse;
• lack of attention to one's own health, ignoring the first signs of pathology, self-medication, untimely access to a doctor.

In medicine, the following types of pathogenesis of the disease are distinguished:

• violation of the circulation of cerebrospinal fluid in the area of the posterior cranial fossa and spinal cord, which occurred as a result of a failure at the embryonic stage of development;
• improper closure of the medullary tube with the formation of a posterior suture, which occurs as a result of bone defects and gliomatosis, followed by disintegration and the formation of cavity and gap changes.

Genetic-constitutional disorders are found in the form of specific dysraphic signs, which are transmitted in an autosomal dominant way and are a predisposition to pathology. Defects in the formation of the medullary tube and craniovertebral junction provide only favorable conditions for the development of pathology. [13]

The pathogenetic role is played by injuries of the spinal column and spinal cord, physical microtrauma. The problem most often affects the cervical and upper thoracic spinal cord, less often the lower thoracic and lumbosacral spine. [14]

In some patients, the pathological process extends to the region of the medulla oblongata (in the form of syringobulbia), less often to the region of the bridge and the inner capsule. [15]

Symptoms syringomyelia

In most patients with syringomyelia, cavities are formed in the posterior horns of the spinal cord. It is there that the sensitive nerve cells responsible for pain and temperature sensations are located. On the skin of a sick person, it is possible to determine whole zones on which sensitivity is not determined. Most often they are found on the arms and body - like "half-jacket" and "jacket", which corresponds to unilateral and bilateral lesions.

Read more about the symptoms and types of syringomyelia here .

Complications and consequences

Complications of syringomyelia can be:

• muscle atrophy, contractures;
• secondary infection, development of pneumonia, bronchopneumonia, cystitis, pyelonephritis;
• infection in wounds and damage to the skin, the development of purulent processes, up to septic complications;
• development of bulbar paralysis, which may result in respiratory arrest and death of the patient.

Experts note that syringomyelia most often takes on a sluggish character and rarely leads to the development of severe conditions. The exception is the aggressive progressive form of the disease, in which the formation of spinal cavities continues. Such a pathology already poses a danger not only to health, but also to the patient's life: urgent surgical treatment is required.

In general, the course of syringomyelia is difficult to predict: the disease proceeds with alternating periods of stable and progressive dynamics. Progression can be observed over a period of several weeks to several years, with sharp deterioration and equally sharp slowdowns in development. Under the influence of provoking factors (severe cough, intense head movement, etc.), an acute clinical picture may develop in a previously asymptomatic patient.

The quality of life of patients is comparable to that of those with heart failure or malignant neoplastic processes.

Possible postoperative complications are:

• the outflow of cerebrospinal fluid (liquorrhea);
• pseudomeningocele;
• shunt displacement;
• transient neurological failure.

The incidence of such complications after surgery is relatively low.

The main consequence of syringomyelia is myelopathy, which can progress to paraplegia and tetraplegia, cause spasms, the formation of pressure ulcers, ulcers, relapses of pneumonia, and also lead to disorders of the intestinal and urogenital functions. [16]

Diagnostics syringomyelia

Diagnostic measures begin with a patient survey. At the same time, it is important for the doctor to pay attention to the signs that characterize such symptomatic groups as spinal cord injury and craniovertebral pathology. Suspicious signs are:

• sensitive disorders (paresthesia, pain, analgesia, dysesthesia, decrease in temperature sensations);
• aching pains in the arms, neck, back of the head, chest;
• a feeling of coldness or chilliness in some areas, numbness;
• persistent headache, otoneurological and visual disturbances (eye pain, photophobia, diplopia, loss of vision clarity, dizziness, vestibular disorders, pressure and tinnitus, hearing impairment, vertigo).

During the survey, it is imperative to clarify with the patient about the hereditary factor, about previous pathologies and injuries, about the degree of physical activity. Since the acute onset of syringomyelia is very rare, and the disease is predominantly slow and protracted, it is necessary to try to determine the approximate period of onset of the development of the disorder.

When examining a patient, one should pay attention to the presence of a typical clinical picture of syringomyelia: paresis, sensitivity disorders, vegetative-trophic changes.

Laboratory tests are nonspecific and are prescribed as part of general clinical research:

• general analysis of blood and urine;
• blood chemistry.

Instrumental diagnostics, first of all, is represented by MRI. It is this procedure that makes it possible to evaluate the parameters of cavity formations, to describe the size and configuration. It is optimal to use the sagittal projection in the T1 mode, which is due to its lower degree of sensitivity to fluid movement. Typical MRI signs of syringomyelia are as follows:

• alteration of the spinal cord signal, such as a longitudinal, central or paracentral region, the intensity of which is similar to that of cerebrospinal fluid;
• the volume of the spinal cord in diameter may be increased;
• the more frequent location of the pathological cavity is the cervicothoracic region;
• the distribution of the cavity - from 2 segments to the entire length of the spinal cord;
• cavity diameter - 2-23 mm;
• when the size of the cavities is more than 8 mm, spinal expansion is noted.

It is recommended to perform MRI along the entire length of the spinal column.

The shape of the cavities is of the following types:

• symmetrical, with central localization, rounded-oval;
• irregular in shape, localized in the central or paracentral spinal regions.

The second variant of the cavity, located in the area between the anterior and posterior spinal arteries, without connection to the subarachnoid space, is most often associated with external damage - for example, with trauma.

Magnetic resonance imaging is performed not only at the diagnostic stage, but also in the process of dynamic monitoring of the effectiveness of therapy:

• MRI signs of incomplete cavity formation (the so-called "presyrinx"): spinal expansion without neoplasm associated with the presence of interstitial edema;
• MRI signs of collapse of the cavities: a vertically flattened cavity, stretched horizontally, with atrophy of the spinal cord.

The repeated procedure of magnetic resonance imaging is carried out according to indications. If the pathology is relatively stable, then repeated studies can be performed once every 2 years.

• Radiography of the skull, cranio-vertebral zone, spinal column, upper limbs, joints is performed depending on the location of the pathology and its clinical characteristics. With syringomyelia, it is possible to identify defects in the development of the skeleton, neurodystrophic processes, foci of osteoporosis, arthropathies, bone anomalies, etc. The severity of pathological changes makes it possible to assess the severity and prognosis of the disorder.
• Computed tomography is not as informative as MRI or radiography. The appearance of a pathological cavity can be detected only in conjunction with myelography and water-soluble contrast. [17]
• Electromyography helps to clarify the presence of damage to the motor neurons of the anterior spinal horns, to identify the problem even in the preclinical period of the anterior spinal process.
• Electroneuromyography allows consideration of the initial pyramidal disorders and axonal degeneration.
• Electroencephalography is necessary to determine the impaired function of the brain stem structures and the first signs of syringobulbia.
• Echo-encephalography is used to detect syringoencephaly, helps to determine the expanded system of the ventricles of the brain.
• Esthesiometric diagnostics is used to clarify the location and intensity of sensitivity disorders.

Differential diagnosis

Differential diagnosis is carried out with the following pathologies and conditions:

• Intramedullary tumor (especially with damage to the cervical spine) and tumors of the medulla oblongata - are determined by the results of magnetic resonance imaging.
• Hematomyelia is characterized by an acute onset of symptoms immediately after injury, with a further regressive course. Diagnosis is difficult with hemorrhage into the syringomyelitis cavity.
• Amyotrophic lateral sclerosis is characterized by a rapid rate of development and features of pathological changes that are noted during imaging of the spinal cord.
• Cervical ischemic myelopathy - has a specific etiology of development, is characterized by impaired sensitivity according to the dynamic principle and characteristic features in spondylography and MRI.
• Spinal cord cysts, tumors, post-traumatic or cystic myelopathy, spinal arachnoiditis, tuberculous spondylitis.
• Cranio-vertebral defects (hypoplastic processes in the atlas and axis, platybasia, basilar impression, etc.) are accompanied by neurological symptoms, without the formation of cystic formations. The main differentiation method is MRI.
• Raynaud's disease, angiotropopathy.
• Compression-ischemic neuropathies (carpal or cubital canal syndromes). [18]

Do Arnold Chiari malformation and syringomyelia require differentiation? These two pathologies often accompany each other: the formation of spinal cord cavities is combined with the displacement of the cerebellar tonsils and sometimes the trunk and IV ventricle below the level of the foramen magnum. Often the genetic factor becomes the "culprit" of the pathology, and treatment is possible only with the help of surgery. [19]

Syringomyelia and hydromyelia require mandatory differentiation. The so-called dropsy of the spinal cord is characterized by a significant increase in cerebrospinal fluid volume and an increase in its pressure. Hydromyelia often coexists with syringomyelia, but it is important to know that these two terms are not identical and mean two different pathologies. The diagnosis is made on the basis of clinical, radiological and tomographic data. [20]

Syringomyelia and syringobulbia are not quite synonymous. They say about syringobulbia if the pathological process in syringomyelia extends to the region of the brainstem, which is accompanied by characteristic symptoms: nystagmus, bulbar disorders and dissociated anesthesia of a part of the face.

Treatment syringomyelia

However, surgery is considered the most effective treatment for syringomyelia . The operation is unconditionally prescribed for the progression of neurological failure - in particular, with the development of central paresis of the lower extremities or peripheral paresis of the upper extremities. The intervention consists in dissecting the central spinal canal, followed by drainage. The operation is really effective: in most patients, the development of pathology stops and neurological disorders decrease. Post-traumatic and post-infectious linear syringomyelia is corrected by performing a bypass between the cavity and the subarachnoid space. If an intramedullary tumor has become the root cause of the pathology, then the neoplasm is removed. Cerebellar implantation is an indication for decompression of the posterior fossa.

Prevention

The main preventive action to prevent the development of syringomyelia is to exclude actions that can disrupt the dynamics of the cerebrospinal fluid. It is important to minimize the likelihood of an increase in intra-abdominal and intracranial pressure: do not lift weights, avoid excessive physical exertion (including strong static stress), intense coughing and sneezing, straining, etc. You should also avoid injuries of the spine and head, maintain a healthy and moderately active image life. Physical inactivity is not encouraged.

If the diagnosis of syringomyelia has already been made, then prevention of worsening of the disease should be performed. Obligatory are:

• dispensary neurological accounting;
• systematic diagnostic procedures to track the dynamics of pathology (magnetic resonance imaging - once every 2 years or more often, depending on the indications);
• regular examinations by a neuropathologist (1-2 times a year).

Syringomyelia is considered a dynamic pathology, and constant clinical observation and diagnostic measures will help determine the deterioration of the pathological process in time and take appropriate therapeutic measures. This is necessary, in particular, for syringomyelia in childhood, when it is important to correctly assess the indications for surgical treatment: there are cases of spontaneous cure of such a disorder, if its development was associated with the rapid growth of the skeletal system.

Forecast

With syringomyelia, as a result of damage to the spinal structures, motor capabilities and sensitivity in the body and limbs deteriorate. Loss of pain and temperature sensation can result in serious injury and burns. Motor dysfunction is accompanied by muscle weakness and atrophy.

In turn, syringomyelia can cause the appearance and aggravation of deformities of the spinal column: often patients develop scoliosis. Rarely, but it happens that the pathology is not accompanied by any symptoms and is discovered by chance when performing an MRI.

The prognosis for syringomyelia is determined by the severity and scale of clinical manifestations, the duration of the disease and its cause. For most patients, the only effective treatment is surgery to stabilize the CSF circulation. The type of surgery is determined by the neurosurgeon.

Approximately every second patient, with competent treatment tactics, has only mild pathological changes. There is information about spontaneous recovery, but such an outcome was noted only in isolated cases - mainly in pediatrics. Such cases were due to intense bone growth and natural spatial expansion for brain structures. More often, syringomyelia becomes the cause of disability.

In the majority of patients, against the background of a prolonged course of pathology, irreversible spinal disorders appear, which worsens the postoperative prognosis: many symptoms remain even after surgery. However, this does not mean that the operation is pointless and inappropriate: thanks to such treatment, it is possible to stop the further progression of the disease.