I. What is spinal cavernous disease?
It is a slowly progressive spinal cord lesion affected by various pathogenic factors and characterized by the formation of a tubular cavity in the spinal cord, which causes a series of clinical manifestations.
What are the causes?
There are two types of spinal cord cavities: congenital abnormal development and secondary spinal cord cavitation. The former is mostly combined with subungual herniation malformation of the cerebellum, while the latter is often caused by trauma, tumor, inflammation, etc. The latter is rare and refers to spinal cord compression secondary to spinal cord tumors, trauma, inflammation, cervical spondylosis, spinal stenosis, etc.
For those caused by congenital developmental abnormalities, there are several theories as follows
1. Congenital spinal cord neural tube atresia insufficiency.
This disease is often accompanied by other congenital anomalies such as spina bifida, cervical rib, scoliosis, and circumoccipital malformation to support this view.
2. Embryonic cell proliferation.
The residual embryonic cell mass in the spinal gray matter proliferates slowly and the center is necrotic and liquefied to form a cavity.
3, Mechanical factors.
Due to congenital factors causing obstruction of the outlet of the fourth ventricle, the flow of cerebrospinal fluid from the fourth ventricle to the subarachnoid space is obstructed, and the pulsating wave of cerebrospinal fluid impinges downward on the central canal of the spinal cord, causing the minority of the central canal to expand and break through the wall of the central canal to form a cavity.
How is spinal cavitation formed?
1.The theory of cerebrospinal fluid pulsation transmission.
When there are lesions causing obstruction in the foramen magnum area (such as chronic subcerebellar tonsillar herniation, craniocervical malformation and arachnoiditis and adhesions at the base of the skull), the elevated intracranial pressure will cause the subcerebellar tonsillar herniation to posteriorly compress the subarachnoid space of the spinal canal, making the exit of cerebrospinal fluid from the skull obstructed, which makes the intracranial pressure further increase. When a certain level is reached, the pulsating impact of the cerebrospinal fluid within the fourth ventricle enlarges the opening of the central canal of the supraspinal rami, and cerebrospinal fluid enters the originally degenerated central canal of the spinal cord.
If the central canal of the spinal cord is simply made to form a row-like dilated cavity, it is called spinal hydrocele. If the ventricular canal membrane is damaged and torn, the spinal cord tissue under the ventricular canal membrane becomes edematous under pressure, and the perivascular space near the ventricular canal membrane is forced to expand, and the fluid in the central canal pulses outward to expand the central canal and form a central cavity on the one hand, while entering the perivascular space under the ruptured ventricular canal membrane and the adjacent cellular space along the ruptured ventricular canal membrane to form some small pools between the cells, and these small pools penetrate and pool to form a cavity outside the central canal, which is called cavernous hydrocele. This is called spinal cavernous effusion.
2. Compression theory.
The posterior cranial fossa and occipital foramen are crowded and compress the lower brainstem and upper cervical medulla causing cerebrospinal fluid separation. Due to the intracranial pressure, a ball-and-flap effect is formed, which causes cerebrospinal fluid to flow cranially and prevents it from flowing in the opposite direction. When sitting up or Valsalva action (forceful breath-holding), the transient pressure increases, which draws ventricular fluid into the central canal and forms a cavity.
3. Adhesion theory.
Dall Dayan believes that during Valsalva action, venous pressure increases and is transmitted to the peridural venous plexus of the spinal cord, but because the obstruction at the foramen magnum does not allow cerebrospinal fluid to flow cranially, but enters the spinal cord parenchyma through the Virochow-Robin gap, the cavity may not communicate with the fourth ventricle or the central canal, and the water-soluble contrast agent Amipaque may delay entry into the cavity cavity The conclusion that the cavity is connected to the subarachnoid space is supported by the fact that a centrifugal cavity can be caused by some undetermined anatomical factors such as adhesions between spinal cord components.
Pathological changes of spinal cord cavitation
The spinal cord at the site of the cavity may be normal in appearance, pyknotic in expansion, or atrophic in appearance. The cavity cavity is filled with fluid and usually communicates with the central canal, and the cavity wall is composed of glial cells and glial fibers. The cavity is often located in the anterior and posterior gray matter junction of the lower cervical and upper thoracic segments of the spinal cord and at the base of the posterior horn on one or both sides. The cavity may be limited to a few segments, or it may extend up to the medulla oblongata and down to the entire length of the spinal cord, and the cavity may vary in size and shape in cross-section. During the development of the cavity and its surrounding gliosis, the anterior, lateral, and posterior horns of the gray matter and the anterior gray-white matter are first damaged, and then the long tracts of the white matter are affected, causing degeneration, necrosis, and loss of the corresponding neural tissue.
Most of the cervical medullary cavernous syndrome comes from the extension of the cervical medulla, usually located in the posterior lateral part of the medulla in the nucleus of the trigeminal spinalis and the suspected nucleus, and only later affects the surrounding long tracts, causing them to degenerate secondary to each other.
What are the common symptoms of spinal cord cavitation?
The onset of the disease is mostly in the age of 20-30, and the number of men is about three times that of women. The onset of the disease is insidious and the course of the disease is slow. The clinical manifestations are symptoms of nerve damage in the affected spinal cord segments, characterized by hyperalgesia or loss of pain and temperature sensation and preservation of deep sensation, as well as motor disorders and neurotrophic disorders of damage to the long tracts of the spinal cord.
Clinical symptoms vary depending on the location and extent of the cavity.
1.Sensory disorder
Two types of sensory disorders can be seen in this disease, namely segmental dissociative sensory disorders innervated by the spinal cord at the site of the cavity and bundle sensory disorders below the lesion.
(1) Segmental dissociative sensory disorder.
That is, pain and temperature sensation are impaired, while touch and deep sensation are intact or relatively normal, which is the most prominent clinical sign of this disease. Patients are often found to have the disease only after they are unaware of the pain after being burned, cut or stabbed in the arm, and are often accompanied by spontaneous pain, numbness, ankylosis and other sensory abnormalities in the hand and arm. On examination, the pain and temperature sensations are significantly dulled or absent on one or both sides of the spinal cord segmental distribution, while the sense of touch is preserved or mildly impaired, usually up to the neck and down to the chest, with a shawl or short top-like distribution. If the cavity reaches the trigeminal sensory tract of the upper cervical medulla, pain and temperature sensation may also be impaired in the face. If the cavity starts in the lumbosacral region, the lower extremities and perineum will have a separate superficial sensory disturbance. If the cavity reaches the entrance of the posterior root, all superficial and deep sensations in the damaged segment may be lost.
(2) Bundle sensory disorder.
When the cavity extends to damage the thalamic tract of the spinal cord on one or both sides, it produces fascicular superficial sensory deficits in the contralateral or bilateral trunk below the damage. The posterior cord of the spinal cord is often the last to be damaged, and in this case, deep sensory impairment of the ipsilateral or bilateral soma below the plane of damage occurs.
Since the shape and distribution of the cavity are often irregular, and segmental and fascicular sensory deficits are often mixed, careful examination is required to determine the extent and nature of the cavity.
2.Motor disorders
Lower motor neuron paresis. When the cervical and thoracic cavity of the spinal cord reaches the anterior horn, weakness, atrophy and tremor of the muscles of the forearm and interosseous muscles of the hand appear. If the hand muscles are severely atrophied, the hand may appear as an “eagle’s claw” hand. With the development of the lesion, it may gradually spread to the upper arm, shoulder girdle and some intercostal muscles, causing paralysis. The lumbosacral cavity shows muscle atrophy in the lower extremities and feet.
Upper motor neuron paresis. When the lesion compresses the pyramidal fasciculus, signs of upper motor neuron paresis may appear on one or both sides below the plane of damage.
3.Vegetative nerve dysfunction
Plant nerve dysfunction is often more pronounced, due to the lesion spreading to the lateral horn. It is common to see dystrophy of the upper limbs, thickened skin, burn scars or intractable ulcers, cyanosis and chills, and excessive or little sweating. Horner’s sign can be seen in the lateral horn damage of the lower cervical medulla. About 20% of patients with bone and joint damage, often multiple, upper limbs are common, joint swelling, bone atrophy in the joint area, decalcification, destroyed by wear and tear, but no pain, this neurogenic arthropathy is called Charcot joint.
4.Other symptoms
It is often combined with scoliosis, retroflexion, spina bifida, bowed feet, flat skull base, hydrocephalus and congenital submedullary herniation and other deformities.
5. Medullary cavitation
The cavity often extends from the spinal cord and can also be the first site of the disease. The cavity often invades the nucleus suspensus of the medulla oblongata, the nucleus of the hypoglossal nerve and the nucleus of the trigeminal spinal tract, resulting in dysphagia, dysphonia, atrophy and tremor of the tongue muscles and even inability to extend the tongue. If the cavity affects the vestibulocerebellar pathway, it may cause nystagmus, vertigo, and gait instability. Peripheral facial palsy may occur when the facial nucleus of the pontine brain is damaged.
V. Diagnosis of spinal cord cavitation
The disease mostly develops in young and middle-aged people, and the course of the disease is slow. Segmental dissociative superficial sensory impairment, muscle atrophy and weakness, skin and joint dystrophy, often accompanied by spinal deformity, bowed feet, etc. The pressure and composition of the cerebrospinal fluid are mostly normal, but the cavity can also cause obstruction of the spinal canal and increase the protein content of the cerebrospinal fluid. x-ray radiographs can confirm the accompanying skeletal deformities, and magnetic resonance imaging (MRI) is the best diagnostic method for spinal cord cavitation, which not only shows the location, shape and extent of the cavity, but also clarifies the diagnosis of related pathologies (deformity, tumor, spinal stenosis, etc.).
VI. Should spinal cavernous disease be treated medically or surgically?
In clinical work, we often divide the treatment of the disease into surgical treatment and conservative drug treatment. For some diseases (such as gastric ulcer), we advocate drug treatment first, and then consider surgery if it is ineffective; for other diseases (such as various deformities), we advocate surgery first, and then use appropriate drugs after surgery. Spinal cord cavitation (combined with submicrocephalic tonsillar herniation malformation) belongs to the latter category.
In view of the pathological basis of the disease (combined submicrocephalic herniation malformation) and its slowly progressive nature, drug therapy is unable to correct the malformation and its efficacy is not very reliable. Surgical decompression of the deformity is the basis of all treatment, otherwise the neurological damage will continue to increase slowly or rapidly. For those who do not need surgery for the time being, have contraindications to surgery or are unwilling to undergo surgery, appropriate medication is beneficial.
Under what circumstances do spinal cord cavitation and subungual herniation require surgery?
Surgery is required in the following cases.
1. subcerebellar tonsillar herniation malformations presenting with obstructive hydrocephalus and increased intracranial pressure
2. subungual herniation of the cerebellum with obvious symptoms of compression of the medulla oblongata, spinal cord and occipital and cervical nerve roots
3. those with subcerebellar tonsillar herniation presenting with intractable pain and vertigo may be treated by trial surgical decompression
4, subcerebellar tonsillar herniation combined with spinal cord cavitation, especially if the cavity is increasing in size or the symptoms are developing
5, spinal cord cavitation combined with other deformities of the occipital neck that require surgical solution.
6, simple spinal cord cavitation with significant spinal cord compression, progressive cavity enlargement or progressive symptom aggravation
7, the presence of other conditions leading to spinal cord cavitation need surgery, such as intraspinal tumors, spinal cord embolism, etc.
VIII. How to treat surgically?
In the past, surgery was complicated, but recently the mainstream surgery has been recognized. The basic principles of surgery are
1.To decompress the craniocervical junction area. The basic principles of surgery are: 1) Decompression of the craniocervical junction area, and treatment of possible deformities and other pathological factors in the area to eliminate the cause and prevent the development and deterioration of the lesion.
2.Reconstruct the structure that meets the physiological needs and improve the cerebrospinal fluid circulation.
3.Make cavity aspiration or shunt to reduce the size of the cavity and release the intrinsic compression to relieve the symptoms.
Through scientific and reasonable design and meticulous and precise surgical procedures, satisfactory clinical results are obtained.
(1) Posterior cranial fossa and craniocervical junction incision and decompression surgery: the usual posterior cranial fossa decompression surgery is performed, with emphasis on releasing the subhypophyseal herniation and arachnoid adhesions in the greater occipital foramen, so that the cerebrospinal fluid flow from the middle foramen of the four ventricles is unobstructed. If tumors, cysts, and other pathological factors are found, they will be treated as well. If decompression is not sufficient, the C2 lamina can be removed.
(2) Expanded dural repair: to reconstruct a smooth cerebrospinal fluid circulation channel.
(3) Spinal cord cavity aspiration, dissection or shunt: In the same way as spinal cord tumor surgery, the cervical and thoracic vertebral plates are dissected, the dura mater is cut, and the spinal cord at the site of the cavity is explored. -In general, spinal cord bulge can be found. The most distended part of the spinal cord is found in the dorsal midline. Along the posterior median fissure. The spinal cord is selected as a non-vascular area and a longitudinal incision is made to reach the cavity. A silicone tube is placed inside the cavity for spinal subarachnoid shunt, or the catheter is sent to the cerebellar medullary pool or pontine pool for shunt.
(4) Filling of the upper spinal cord cavity: according to the posterior cranial fossa decompression procedure, open the posterior cranial fossa and probe below the four ventricles to find out whether there is central canal enlargement, if it exists. A small piece of muscle is taken to fill the opening with cold. The above procedures can be performed simultaneously. After surgery, the cavity shrinks or disappears in most cases. Comparisons can be checked periodically with MRI scans to observe changes in the cavity and the condition of the spinal cord. However, the surgery is not radical. The recent efficacy is obvious. In advanced cases, those with huge spinal cord cavities and obvious atrophy and degeneration of neural tissue, the surgical efficacy is not significant.
What are the risks of surgical treatment of spinal cord cavitation?
In general, surgical treatment of spinal cord cavitation is a relatively safe procedure, and it is safer if the subarachnoid space is not opened, the median foramen of the four ventricles is not explored, and the cerebellar tonsillectomy is not performed.
Possible complications: incisional effusion, infection, and bloody cerebrospinal fluid. All of these complications have a low or mild incidence.