Posterior fossa decompression for syringomyelia

Syringomyelia is a slow-moving formation of the inner cavity of the spinal cord, which is more common in the neck section and less in the chest and lumbar segments. The void often continues for several segments, sometimes involving the medulla. Most of the holes are single and a few are multiple. The etiology of this disease can be divided into congenital and traumatic, tumor, inflammation and other secondary. Congenital people are often accompanied by cerebellar tonsil sputum type I or with a skull base. The mechanism of syringomyelia formation is not the same as that proposed by Willian (1975): when the occipital foramen obstruction, the intracranial pressure and spinal canal pressure difference increase, and the fourth ventricle cerebrospinal fluid ascends along the upper end of the central canal. Oldfield (1994) and Iskandar (1998) believe that the central canal of the spinal cord is not open, and is a cavity formed by the cerebrospinal fluid on the surface of the spinal cord entering the spinal cord along the perivascular space. Due to the degeneration of the spinal cord itself and the gradual enlargement of the syringomyelia, an oppressive effect on the spinal cord tissue occurs, and the corresponding spinal nerve bundle damage syndrome appears. Cervical syringomyelia has peripheral nerve spasm in this segment, upper limb weakness, hand and arm muscle atrophy and sensory separation disorder (ie, pain temperature loss or disappearance, and deep feeling exists). Symptoms of central long-term damage appear below the segment of spinal cord injury, resulting in the formation of incomplete paralysis of the limbs and more severe neurotrophic disorders. Treatment of diseases: cerebellar tonsil Indication Decompression of the posterior fossa of the syringomyelia is applicable to: Spontaneous stenosis in the neck and thoracic segment and complication of cerebellar tonsils. Contraindications 1, advanced syringomyelia, severe spinal cord degeneration caused by paraplegia, and even limb contracture, generally not suitable for surgery. 2, there are severe odontoid kyphosis or sacral-shaft dislocation, the first to do the posterior fossa decompression is very dangerous. Preoperative preparation 1. Prepare the skin. Wash the head with soap and water 1 day before the operation. Shave the hair on the morning of the operation. You can also shave your head on the eve of surgery. 2. Fasting in the morning of surgery. 3, can give phenobarbital 0.1g orally before surgery to ensure a quiet rest. One hour before the operation, 0.1 g of phenobarbital, 0.4 mg of atropine or 0.3 mg of scopolamine were intramuscularly injected. Surgical procedure 1. Incision The median incision of the occipital region begins at 3 cm from the occipital trochanter, and reaches the plane of the fifth cervical vertebrae. The muscles are cut along the midline, including the suboccipital muscles and the paravertebral muscles of the first to third cervical vertebrae, exposing the occipital bone and the first to third Cervical lamina. 2, bone window craniotomy According to the method of suboccipital decompression under the cranial fossa, the occipital bone is removed and the posterior margin of the foramen magnum is carefully bitten. For patients with skull base stagnation, the edge of the foramen magnum is sunken to the skull. The posterior arch of the atlas can be close to or fused with the occipital foramen. Therefore, it is more difficult to cut the posterior margin of the occipital foramen. It can be ground with a high speed micro drill. Because of the small volume of the posterior cranial fossa of patients with this disease, the occipital squamous resection should be extensive, with the posterior margin of the mastoid on both sides, from the top to the lower edge of the transverse sinus, and the posterior margin of the foramen magnum. At the same time, the posterior arch of the atlas and the second cervical vertebrae should be removed. 3, remove thickened soft tissue After the cranial and upper cervical laminectomy, the fascia near the large hole of the occipital bone should be carefully and patiently removed, and some of them are banded and thickened. In severe cases, the dura mater at the posterior margin of the foramen magnum and the posterior arch of the atlas has obvious impression, indicating that the deformed bone compresses the nerve tissue. 4, the hard brain (ridge) membrane incision Under the operating microscope, the dura of the cranial fossa was "Y" shaped and extended to the meninges of the neck 1 to 3, so that the hard brain (ridge) membrane was widely opened and the occipital neck region was explored. 5, treatment of local lesions Separate local adhesions in the occipital region and cut off the fibrous band of the spinal cord and nerve roots. At this time, the swelled hollow spinal cord can be seen. The congenital cerebellar tonsil and medullary mandibular deformity, skull base depression, medullary and arachnoid adhesion around the spinal cord were relieved, and the normal CSF circulation pathway was reconstructed to balance the pressure in the cranial ridge. 6, hollow cut In the uppermost bulging portion of the syringomyelia, a small opening was made with a sharp knife. One end of a silicone membrane tube was implanted into the cavity, and the other end was placed down into the ventral or ventral subarachnoid space of the spinal cord and sutured with silk thread. On the nearby arachnoid, a cavity-spinal subarachnoid drainage was performed. 7, close the incision The muscles and skin are tightly sutured in layers. complication When the hole is cut, the incision should not be too long, and it should not affect the medulla. Otherwise, it can increase the damage of the brain stem and the upper cervical cord and endanger life.