It is a slow-moving spinal cord disease, which is affected by many pathogenic factors and is characterized by the formation of tubular cavities in the spinal cord and a series of clinical manifestations.

2. What is the reason?

It can be divided into congenital dysplasia and secondary syringomyelia. The former is often complicated with cerebellar tonsillar hernia deformity, while the latter is often caused by trauma, tumor and inflammation. The latter is rare and refers to spinal cord compression secondary to spinal cord tumor's disease, trauma, inflammation, cervical spondylosis and spinal stenosis.

There are several theories about congenital dysplasia.

A, congenital spinal neural tube atresia:

This disease is often accompanied by congenital anomalies such as spina bifida, cervical rib, scoliosis and occipital malformation to support this view.

Second, the proliferation of embryonic cells:

The remaining embryonic cell mass in the gray matter of spinal cord slowly proliferated, and the center was necrotic and liquefied to form a cavity.

Third, mechanical factors:

Due to congenital factors, the outlet of the fourth ventricle is blocked, cerebrospinal fluid flows from the fourth ventricle to the subarachnoid space, and the pulsating wave of cerebrospinal fluid impacts the central spinal canal, which expands the ethnic minorities in the central canal and breaks through the central canal wall to form a cavity.

3. How is syringomyelia formed?

① Cerebrospinal fluid pulsation transmission theory when there are lesions leading to occipital foramen obstruction (such as chronic cerebellar tonsillar hernia, craniocervical malformation, arachnoiditis and adhesion of skull base, etc.). ), the increase of intracranial pressure will make the cerebellar tonsil of inferior hernia compress the subarachnoid space of spinal canal from the rear, hinder the craniotomy of cerebrospinal fluid, and further increase the intracranial pressure. When it reaches a certain level, the beating and impact of cerebrospinal fluid in the fourth ventricle enlarges the opening of the Swiss central canal on the spinal cord, and cerebrospinal fluid enters the degenerated central canal of the spinal cord. If the central spinal canal simply forms a linearly expanding cavity, it is called myelohydronephrosis. If the ependyma is damaged or torn, the spinal cord tissue under the ependyma will be compressed and edema, and the perivascular space near the ependyma will be forced to expand. On the one hand, the liquid in the central tube will pulsate outward to expand the central tube and form a central cavity, and at the same time, it will enter the perivascular space below it and the adjacent intercellular space along the ruptured ependyma (E68A 847A 696416F36438+03637373

② Compression theory: The posterior cranial fossa and foramen magnum are squeezed to compress the lower brain stem and upper cervical spinal cord, resulting in the separation of cerebrospinal fluid. Because of the effect of intracranial pressure, the ball valve effect is formed, which makes cerebrospinal fluid flow to the cranial side and prevents its reverse flow. When sitting up or Valsalva exercises (holding his breath hard), the instantaneous pressure increases, and the ventricular fluid is sucked into the central tube, forming a cavity. After the cavity is formed, the venous pressure around the dura mater changes to centrifuge the cavity fluid and create a new cavity.

(3) adhesion theory Dall Dayan thinks that when Valsalva exercises, the venous pressure increases and is transmitted to the epidural venous plexus of the spinal cord. However, due to the blockage of the foramen magnum, the cerebrospinal fluid can not flow to the cranial side, but enters the spinal parenchyma through the Virochow-Robin space, so the cavity may not communicate with the fourth ventricle or the central tube, and the water-soluble contrast agent Amipak can delay entering the cavity to support the conclusion that the cavity communicates with the subarachnoid space. Centrifugal cavity may be caused by some undetermined anatomical factors, such as adhesion between spinal cord components.

4. Lesions

The appearance of spinal cord in the cavity can be normal, or spindle-shaped expansion, or obvious atrophy. The cavity is filled with liquid and usually communicates with the central tube. The cavity wall is composed of glial cells and glial fibers. The cavity is usually located at the junction of the anterior and posterior gray matter of the lower cervical segment and the upper thoracic segment of the spinal cord, and at the base of one or two posterior horns. The cavity can be limited to several segments, or it can extend to the medulla oblongata and the whole spinal cord. The cavities on the cross section are different in size and irregular in shape. In the development of glial hyperplasia around the lacuna, the anterior horn, lateral horn, posterior horn and anterior commissure of gray matter are first damaged, and then the long bundles in white matter are affected, resulting in degeneration, necrosis and loss of corresponding nerve tissue.

The medullary cavity mostly extends from the cervical spinal cord, usually located in the nucleus of spinal tract of trigeminal nerve and the nucleus of doubt in the posterolateral part of the medulla oblongata, and then affects the surrounding long tract, making it secondary degeneration.

5.Chiari malformation (cerebellar tonsil hernia malformation)

It is defined as the congenital abnormal development of brain structure in the midline of cranial fossa after embryonic period, and the cerebellar tonsil extends downward or/and the lower part of the medulla oblongata or even the fourth ventricle protrudes into the cervical spinal canal through the foramen magnum. Is the most common cause of syringomyelia.

Classification is divided into three types:

Type ⅰ: The cerebellar tonsil and vermis herniated into the spinal canal, but the fourth ventricle remained on the foramen magnum.

Type ⅱ: the fourth ventricle herniated into the spinal canal.

Type ⅲ: On the basis of type ⅰ and type ⅱ, spina bifida and meningocele are combined.

At present, the generally accepted diagnostic standard is that the lateral or bilateral submandibular hernia scanned by MRI is less than 5mm beyond the edge of the foramen magnum, and it is not difficult to make a diagnosis combined with clinical manifestations (headache, compression of posterior brain structure, spinal cord symptoms, hydrocephalus, etc.). ).

Clinical manifestations may include some or all of the following symptoms:

Symptoms of cranial and cervical nerves include hoarseness, dysphagia, neck pain and limited movement.

Symptoms of brain stem and medulla oblongata include limb dyskinesia, hemiplegia and quadriplegia, limb sensory disturbance and dysuria.

Cerebellar symptoms include ataxia, unsteady walking and nystagmus.

Increased intracranial pressure's symptoms include headache, vomiting, fundus edema and decreased vision.

Syringomyelia is characterized by separation or muscular atrophy of both upper limbs (see 6. What are the common symptoms of syringomyelia? )。

6. What are the common symptoms of syringomyelia?

Most of them occur at the age of 20 ~ 30, and men are about three times as many as women. The onset is hidden and the course of disease is slow. The clinical manifestations are nerve damage symptoms of the involved spinal cord segments, such as dissociative sensory disturbance with pain and temperature perception weakened or disappeared, deep sensory preservation, and motor disorder and neurotrophic disorder caused by long bundle injury of spinal cord.

Clinical symptoms vary with the location and scope of the cavity.

① Sensory disorder

There are two types of sensory disturbance in this disease, namely, segmental dissociative sensory disturbance dominated by spinal cord in the cavity and branching sensory disturbance below the lesion.

Segmental dissociative sensory disturbance (that is, pain and temperature sense's disturbance, while the sense of touch and depth is complete or relatively normal) is the most prominent clinical sign of this disease. Patients often find the disease only after their arms are burned, cut and stabbed, and are often accompanied by spontaneous pain, numbness and ant walking in their hands and arms. During the examination, it can be seen that the pain sensation and temperature sensation on one or both sides of the spinal cord are obviously dull or disappeared, while the tactile sensation remains or is slightly damaged, which usually ranges from the neck down to the chest and is distributed in a shawl or jacket shape. If the cavity spreads to the trigeminal sensory tract of the upper cervical spinal cord, facial pain and temperature sense's disorder may also occur. If the cavity starts from lumbosacral segment, there will be separated superficial sensory disturbance of lower limbs and perineum. If the cavity extends to the posterior root entrance, the depth perception of the damaged segment can be completely lost.

Bundle sensory disturbance. When the cavity expands and damages one or two spinal thalamic tracts, it will produce fascicular surface sensory disturbance and damage the contralateral or bilateral lower body. The posterior cord of spinal cord is often damaged finally, and there is deep sensory disturbance of ipsilateral or bilateral body below the damaged plane.

Because the shape and distribution of cavities are often irregular, and segmental and branched sensory disorders are mixed together, it is necessary to check carefully before determining their scope and nature.

② Dyskinesia

Paralysis of lower motor neurons. When the cervical spinal cord and thoracic cavity spread to the anterior horn, muscle weakness, atrophy and muscle bundle tremor occurred in thenar muscle, interosseous muscle and forearm. People with severely atrophied hand muscles can have "eagle claw" hands. With the development of the disease, it can gradually spread to the upper arm, shoulder strap and some intercostal muscles, causing paralysis. Lumbosacral cavity is characterized by muscle atrophy of lower limbs and feet.

Paralysis of upper motor neurons. When the lesion compresses the pyramidal tract, there may be signs of upper motor neuron paralysis on one or both sides below the injury plane.

③ Autonomic nerve dysfunction

Vegetative nerve dysfunction is often obvious, which is caused by the spread of lesions to the lateral corner, such as upper limb malnutrition, skin thickening, burn scars or intractable ulcer, cyanosis, hyperhidrosis or hypohidrosis. Horner's sign can be seen in the damage of lateral horn of lower cervical spinal cord. About 20% patients have multiple bone and joint injuries, mostly swelling of upper limbs and joints, bone atrophy, decalcification and joint wear, but there is no pain. This neurogenic arthropathy is called Charcot joint.

④ Other symptoms

Often associated with scoliosis, kyphosis, spina bifida, arch of foot, flat skull base, hydrocephalus and congenital subdural hernia.

⑤ medullary cavity

Its cavity usually extends from the spinal cord and can also be the first site of the disease. Dysphagia, unclear pronunciation, frequent invasion of nucleus accumbens of medulla oblongata, hypoglossal nucleus and spinal tract nucleus of trigeminal nerve, muscle atrophy, tongue tremor and even inability to extend the tongue, facial pain, decreased temperature but tactile sensation. If the cavity spreads to the vestibulo-cerebellar pathway, it can cause nystagmus, dizziness and gait instability. Peripheral facial paralysis may occur when the nucleus of the bridge deck is damaged.

7. Diagnosis of syringomyelia

The disease is easy to occur in young adults and the course of disease is slow. Segmental dissociative superficial sensory disturbance, muscle atrophy and weakness, skin and joint malnutrition, often accompanied by spinal deformity, arch of foot and so on. The pressure and composition of cerebrospinal fluid are mostly normal. When the cavity is large, it can also cause spinal canal obstruction and increase the protein content of cerebrospinal fluid. X-ray can confirm the accompanying skeletal malformation, and magnetic resonance is the best diagnostic method for syringomyelia, which can not only show the position, shape and scope of the cavity, but also confirm the diagnosis of related diseases (malformation, tumor, spinal stenosis, etc.). ).

8. Should syringomyelia be treated with drugs or surgery?

In clinical work, we often divide the treatment of diseases into surgical treatment and drug conservative treatment. For some diseases (such as gastric ulcer), medical treatment should be carried out first, and if it fails, surgery should be considered; For other diseases (such as various malformations), surgical treatment should be considered first, and appropriate medication should be used after operation. Syringomyelia (combined with cerebellar tonsillar hernia malformation) belongs to the latter. In view of the pathological basis of this disease (combined with cerebellar tonsillar hernia deformity) and its slow progress, drug treatment can not correct the deformity, and the curative effect is not reliable. Surgical decompression to correct deformity is the basis of all treatments, otherwise the nerve injury will continue to deteriorate slowly or quickly. For patients who do not need surgery for the time being, have surgical contraindications or are unwilling to accept surgical treatment, appropriate drug treatment is beneficial.

9. Under what circumstances do syringomyelia and cerebellar tonsillar hernia need surgical treatment?

Surgical treatment is required in the following cases:

1. Obstructive hydrocephalus and increased intracranial pressure occurred in cerebellar tonsillar hernia malformation;

2. Patients with cerebellar tonsillar hernia have obvious symptoms of compressing medulla oblongata, spinal cord and occipitocervical nerve roots;

3. Patients with intractable pain and dizziness in cerebellar tonsillar hernia can try surgical decompression;

4. Cerebellar tonsillar hernia with syringomyelia, especially when the cavity is growing or the symptoms are developing;

5. syringomyelia complicated with other deformities of occipital and neck needs surgical solution;

6. Simple syringomyelia has obvious spinal cord compression, and the cavity is gradually enlarged or symptoms are gradually aggravated;

7. There are other conditions leading to syringomyelia that need to be solved by surgery, such as intraspinal tumors and tethered spinal cord.

10, how to operate?

In the past, the surgical methods were complicated, but recently the mainstream surgical methods have been recognized. The basic principle of operation is: 1, decompression of craniocervical junction, treatment of possible deformities and other pathological factors in this area, elimination of etiology, and prevention of lesion development and deterioration. 2. Reconstruct the structure that meets the physiological needs and improve the circulation of cerebrospinal fluid. 3, cavity suction or shunt, so that the cavity shrinks, relieve internal oppression to relieve symptoms. Through scientific and reasonable design and meticulous and accurate operation, satisfactory clinical results have been achieved.

1) Incision and decompression of posterior cranial fossa and craniocervical junction: according to the usual decompression method of posterior cranial fossa. The key point is to relieve cerebellar tonsillar hernia and arachnoid adhesion in foramen magnum, so that cerebrospinal fluid in the middle of the fourth ventricle can flow out smoothly. If there are pathological factors such as tumors and cysts, deal with them. If decompression is insufficient, C2 laminectomy can be performed.

2) Extended repair of dura mater: reconstruction of unobstructed cerebrospinal fluid circulation channel.

3) Syringomyelia aspiration, incision or shunt: According to the surgical method of myeloma, cervical and thoracic laminectomy, dural incision and exploration of spinal cord in the cavity can be selected. In the most prominent part of the spinal cord, in the dorsal midline. Along the posterior median fissure. Select-avascular zone. Cut the spinal cord vertically to reach the cavity. Leave the silicone tube in a series of holes for spinal subarachnoid shunt, or send the catheter to cerebellomedullary cistern or pons cistern for shunt.

4) syringomyelia occlusion; Open the posterior cranial fossa according to the decompression method of the posterior cranial fossa. Explore the lower part of the fourth ventricle to see if there is central canal enlargement. If there is. Take a small piece of muscle and fill the opening with cold compress. The above operations can be carried out simultaneously. After the operation, the cavity shrank or disappeared in most cases. By comparing MRI scanning with routine examination, we can observe the changes of cavity and the situation of spinal cord. But the operation is not radical. The short-term curative effect is obvious. In advanced cases, patients with giant syringomyelia and obvious atrophy and degeneration of nerve tissue have no significant effect.

The literature reported that the operative effect was 80%.

Some thoughts on surgical methods for syringomyelia.

We advocate the idea that:

1, keep the arachnoid intact, and irregularly dredge the median hole of the fourth ventricle to avoid damaging the central nervous system, allowing blood to enter the subarachnoid space and artificially causing adhesion.

2. The cerebellar tonsil of the inferior hernia is not removed because it is in a deformed state, but it is still a part of the nervous system and has its own function; The so-called "subdural resection" is actually very difficult to do. The process of resection is bound to open the subarachnoid space and cause brain tissue trauma.

3. The dura mater should be cut and expanded to fully relieve the compression on bone, dura mater and fascia, so as to ensure that the nervous system is isolated from the outside world.

4. Advocate the concept of minimally invasive to minimize the damage to soft tissue and bone structure; Minimize the interference to the central nervous system. This is very important for maintaining the stability of cervical spine and reducing postoperative subarachnoid adhesion.

5. The correction of congenital malformation only stops the disease from getting worse, but the damage to the nervous system is usually irreversible. Olfactory sheath cell transplantation may be beneficial to the repair of spinal cord injury.

What are the risks of surgical treatment of syringomyelia?

Generally speaking, surgical treatment of syringomyelia is a relatively safe operation, and it is safer not to open the subarachnoid space, explore the median foramen of the fourth ventricle and remove the cerebellar tonsils.

Possible complications: wound effusion, infection, bloody cerebrospinal fluid. The incidence of the above complications is very low or slight.