What Is a Spinal Schwannoma?

Spinal canal schwannomas are also called Schwann cell tumors in the spinal canal, accounting for about 25% of intradural spinal tumors. They can occur in all segments of the spinal canal, most of them are single, with a peak incidence of 40 There is no significant difference between men and women between the ages of 60 and 60. Spinal schwannomas originate from the dorsal spinal nerve roots, and can also produce subchondral infiltration when they grow concentrically. This situation is more common in rhomboid neurofibromas. Brachial plexus or lumbar plexus schwannomas can grow into the dura mater along multiple nerve roots. In contrast, Schwann cell tumors next to the spine are usually located outside the spinal cord when they expand into the spinal canal. About 2.5% of intradural schwannomas are malignant, and at least half of them occur in patients with multiple neurofibromatosis.

Basic Information

nickname: Schwann cell tumor in spinal canal
Visiting department: Neurosurgery, Oncology
Multiple groups: 40 to 60 years old

Common locations: Spinal canal
Common causes: Unclear, some people think that it is mainly caused by molecular changes at the gene level
Common symptoms: Pain, paresthesia, dyskinesia, sphincter dysfunction

Causes of spinal schwannoma

The exact cause of tumor formation is still unclear, and quite a lot of views believe that the occurrence and growth of tumors are mainly caused by molecular changes at the gene level.

Most spinal schwannomas in the spinal canal are completely located in the dura mater, and 10% to 15% grow out of the spinal canal through the dorsal nerve root sleeve to form a dumbbell shape; about 10% of schwannomas are located in the dura mater. Outer or paravertebral; about 1% of schwannoma grows in the medulla, most of which are considered to grow along the nerve sheath around the blood vessels that enter the spinal cord.

Clinical manifestations of spinal schwannoma

Spinal canal schwannomas mostly have a longer course, with the shortest history in the thoracic segment, and longer in the cervical and lumbar segments. Sometimes the course can exceed 5 years. When the tumor is cystic or bleeding, it is an acute process.

The main clinical symptoms and signs of spinal schwannomas are pain, paresthesia, dyskinesia, and sphincter dysfunction. The incidence of paresthesia is about 85%, and the incidence of pain is nearly 80%.

The most common first symptoms were radicular pain, followed by paresthesia and dyskinesia. The pain of the upper neck tumor is mainly in the neck, and it is occasionally radiated to the shoulder and upper arm. The tumor pain of the neck and chest is mostly located at the back of the neck or upper back, and radiates to one or both shoulders, upper limbs and chest. Tumors in the segment often manifest as back pain and radiate to the shoulders or chest; pain in thoracic tumors is mostly located in the thoracolumbar region and can radiate to the abdomen, groin, and lower limbs. Pain in thoracolumbar tumors is located in the waist and can radiate to the groin, arms, thighs and calves. Pain in lumbosacral tumors is located in the lumbosacral, hip, perineal, and lower limbs.

20% of the first symptoms are paresthesia, which can be divided into two categories: hypersensitivity and hypothyroidism. The former manifests as antagonism, numbness, chills, soreness, and burning; the latter is mostly a combination of pain, mildness, and touch. The sensory disturbance usually starts from the distal end and gradually develops upwards. The patient's subjective paresthesia is abnormal in the early stage. No special findings are found in the examination, followed by hypothyroidism, and finally all sensations are accompanied by loss of motor function. The cone and pony tail no longer have spinal cord parenchyma, so the paresthesia is distributed in a peripheral nerve type. Typically, the skin of the anus and perineum is numb in the saddle area.

Dyskinesia was the third most common symptom. Depending on the location of the tumor, dyskinesia caused by nerve root or bundle damage can occur. As the symptoms progress, dysfunction of the pyramidal bundle can occur, so the scope and degree of paralysis vary. Most patients have different degrees of mobility difficulties when they come to the hospital, and half of them have limb paralysis. The timing of dyskinesia varies depending on the location of the tumor. Tumors in the cone or pony tail will show significant dyskinesia in the later stages, and thoracic tumors will appear earlier. Sphincter dysfunction is often a late symptom, indicating partial or complete compression of the spinal cord.

The main clinical symptoms and signs of spinal schwannomas are pain, paresthesia, dyskinesia, and sphincter dysfunction.

Spinal canal schwannoma

Spinal plain film

The direct signs are the shadows of calcified plaques of the schwannoma, which are rare. The indirect signs refer to the corresponding changes caused by the tumor compressing the spinal canal and its adjacent bone structure, including vertebral arch destruction, widening of the distance between pedicles, and even Root destruction disappears, vertebral body depression or foramen enlargement.

Spinal angiography

The subarachnoid occlusion rate is about 95%, and the cup-shaped filling defect is typical.

3.CT and MRI examination

CT scans make it difficult to make a definitive diagnosis. Tumors showed extramedullary low-signal tumors on MMRI _1- weighted images and high-signal tumors on T2-weighted images; enhanced scans: solid tumors were uniformly enhanced, cystic tumors were circularly enhanced, and few tumors were unevenly enhanced . Depending on the anatomical level of the tumor, the corresponding spinal cord displacement occurs.

4. Lumbar puncture

Neck compression tests are mostly manifested in different degrees of subarachnoid space obstruction; cerebrospinal fluid circulation failure below the tumor site, and tumor cell shedding, resulting in increased cerebrospinal fluid protein content. In addition, because the tumor is generally free in the spinal canal, the symptoms can be aggravated after lumbar puncture and release of cerebrospinal fluid. This is due to the spinal cord compression caused by tumor changes in the spinal canal dynamics.

Diagnosis of spinal schwannoma

There is obvious radicular pain, motor and sensory disorders develop from the bottom up, there is a skin allergy zone at the tumor segment level, especially the presence of spinal cord hemisection syndrome (expressed below the lesion segment, ipsilateral motor neuron motor movement Paralysis and loss of touch and deep sensation, pain on the opposite side, loss of temperature sensation) and cerebrospinal fluid dynamic changes cause increased pain, all suggest the possibility of extramedullary schwannomas of the spinal cord, and necessary auxiliary examinations should be made to confirm the diagnosis.

Spinal schwannoma treatment

The treatment of benign schwannoma is mainly surgical resection. The vast majority of cases can be cured by standard posterior laminotomy, and the tumor is completely resected, and rarely relapses. Adjuvant radiotherapy should be performed after surgical removal of malignant schwannoma.

Prognosis of spinal schwannoma

Malignant schwannoma has a poor prognosis and rarely survives more than 1 year. These tumors must be distinguished from a small number of Schwann cell tumors that show aggressive histological characteristics. Schwann cell tumors with a malignant tendency have a relatively good prognosis.