Definition
The formation of a tubular cavity in the spinal cord that is affected by a variety of pathogenic factors and causes a series of clinical manifestations is called spinal cavernous disease.
Etiology
There is no uniform understanding of the etiology and pathogenesis of spinal cord cavitation. In clinical work, congenital malformations of the craniocervical junction combined with spinal cord cavitation are common (submicrocephalic tonsillar herniation malformation is the most common), and the cavity is mostly found in the cervical and upper thoracic segments of the spinal cord. It is generally believed that submural herniation of the cerebellar tonsils causes poor cerebrospinal fluid circulation in this area, resulting in damage to the spinal cord and the formation of spinal cord cavities. In addition, spinal cord injuries and tumors can cause the formation of spinal cord cavities.
Clinical manifestations
Spinal cord cavitation usually starts slowly and worsens gradually. Patients often seek medical attention for reasons such as pain, numbness in the upper limbs and trunk, weakness in the upper limbs, especially the hands, muscle atrophy, or inflexible movements.
The clinical manifestations of spinal cavernous disease can be divided into the following three main areas.
1.Sensory abnormalities
Usually, the pain and temperature sensation of one or both upper extremities are reduced or disappeared; or there may be numbness, or in severe cases, the hand is burned or cut without sensation; or there is pain in the neck, shoulder, back or upper extremities. Some patients also have abnormal sensation in the lower limbs.
2.Motor abnormalities
The main manifestations are decreased strength of one or both upper limbs; hand muscle atrophy, in severe cases, the little finger and ring finger cannot be straightened and the hand is claw-shaped; muscle atrophy of the neck, shoulder and arm. Some patients have lower limb movement disorders. Some patients with continuous progression of symptoms or without treatment may be paralyzed in the late stage.
3.Vegetational symptoms
Such as dry and less sweaty skin on one limb and trunk, deformation of upper limb joints, etc.
4.Some patients may have symptoms related to submicrocephalic tonsillar herniation malformation.
Diagnosis
The diagnosis of spinal cord cavitation and occipitocervical junction deformity can be confirmed based on clinical manifestations, combined with magnetic resonance imaging (MRI) and X-ray plain film.
Treatment
1.General treatment
Pay attention to the protection of the affected limbs to avoid burns, heat injuries and other accidental injuries; consciously carry out targeted activities and exercises, and do massage and physical therapy to delay muscle atrophy or promote its recovery and prevent joint contracture; take B vitamins and other neurotrophic drugs.
2.Surgical treatment
Just like the lack of a unified understanding of the cause, the surgical treatment of spinal cavernous disease also lacks a unified approach.
The surgical treatment of spinal cord cavitation can be divided into two parts: one is to decompress the craniocervical junction area to correct the deformity and prevent the disease from developing or deteriorating; the other is cavity shunt, that is, to make a cavity fistula or place a shunt to relieve the compression of the cavity on the spinal cord to relieve the symptoms or prevent the disease from progressing. The first part is usually done for spinal cord cavitation with submicrocephalic tonsillar herniation, and the second part is chosen according to the situation.
Decompression of the craniocervical junction area.
Decompression of the craniocervical junction is usually performed at three levels: the first level is decompression of the bony structures, which usually includes removal of part of the occipital bone, opening of the foramen magnum, and removal of the cervical 1 and 2 vertebral plates; the second level is release of the dura and atlanto-occipital fascia; the third level is decompression of the median foramen of the four ventricles, and some physicians also remove the subherniated cerebellar tonsils. The first of these levels is common access.
Cavity shunt.
Usually refers to the incision of the cavity at the more obvious site of the cavity to allow access to the subarachnoid space. It can be divided into fistulotomy and shunt placement, the former refers to the incision of the cavity only, while the latter refers to the further disposal of silicone shunts to ensure a smooth flow.
3.Other treatment
In the early days, deep X-ray irradiation or radioisotope iodine 131 was used to treat cavernous spinal cord in an attempt to stop the expansion of the cavity, but the effect was not sure, and has been basically eliminated.
Our principles for the surgical treatment of spinal cord cavitation
Principles of surgery.
The causes of spinal cord cavitation combined with congenital malformations such as subungual herniation of the cerebellum are related to congenital malformations that are already organically altered and we cannot restore them to normal, but can only treat them appropriately so that they do not continue to cause damage. The presence of a spinal cord cavity indicates organic damage to the spinal cord, and this damage to the nervous system is usually irreparable; treatment is simply to keep the damage from getting worse.
In summary, the fundamental goal of surgical treatment of spinal cord cavitation is to prevent or delay the progression of the disease. At the same time, it is common in clinical work for spinal cord cavitation to be accompanied by irritating symptoms such as pain and numbness, as well as for those whose limb strength is weakened and whose nerves are not yet completely damaged, and who may see an improvement in their symptoms. Therefore, it is inappropriate to advocate the efficacy of surgical treatment for spinal cord cavitation. If the spinal cord cavity is not tense and the condition is stationary without development, especially in middle-aged or older patients, surgery may be withheld and closely observed; those with progressive disease and irritating symptoms such as pain are recommended for surgical treatment.
Surgical methods.
The surgical removal of the cerebellar tonsils in the lower herniation is not favored, because although its role is not very important and is already in a deformed state, it is still fundamentally part of the normal nervous system, and the so-called “subperitoneal resection” is often said to be difficult to do strictly, and the process of resection is bound to cause greater interference with the nervous system.
We are not in favor of unblocking the median foramen of the four ventricles as a routine for spinal cord cavity surgery, because any operation into the subarachnoid space itself may cause adhesions, and when the subarachnoid space is connected to the wound, blood entering it may also cause adhesions, and may also cause fluid accumulation in the wound and aggravate postoperative symptoms.
We believe that the key to successful surgery is to improve the patency of the subarachnoid space. Therefore, we advocate that
1. in the absence of clear evidence of arachnoid adhesions, keep the arachnoid intact and do not enter the subarachnoid space in order to avoid damaging the central nervous system and artificially causing adhesions as much as possible.
2. avoiding cerebellar tonsillectomy whenever possible.
3, when it is necessary to open the arachnoid membrane, minimize its destruction, for example, when performing cavity placement shunt, we only need a small arachnoid opening of about 0.5 cm in length, which is tightly sutured after the placement is completed.
4. The dura is cut as much as possible during the surgery to fully release the bony, dural and fascial compression, while keeping the arachnoid membrane intact, which is elastic and ductile and can provide sufficient space for decompression and expansion, while ensuring the neurological system is isolated from the outside world.
5. The minimally invasive concept is implemented during surgery: minimize the damage to the soft tissue and bone structure of the wound; minimize the interference with the central nervous system. This is essential to maintain the stability of the cervical spine and to reduce postoperative subarachnoid adhesions.
Perspectives on future surgical approaches
For the surgical treatment of subungual herniation of the cerebellum combined with spinal cavitation, we have developed our ideas based on the experience of a large number of cases in the past to now advocate minimally invasive, limited, and adequate decompression, which is contrary to the expanded decompression advocated by some current scholars, but I believe our advocacy is in line with the modern surgical development trend. Now, we have made progress in limited resection of the occipital bone and subtle decompression of the cardinal plate, etc. Our next step will be to compensate and design the necessary special instruments for atlantoaxial enlargement and minimally invasive cavity shunting.