Spinal Cord Tumours

Spinal Cord Tumours

A wide variety of tumors affect the spine. Approximately 20% of CNS tumors occur in the spine. The majority of spinal tumors are histologically benign, unlike cranial tumors. Understanding the two major spinal concepts facilitates understanding of the effects of spinal tumors. The two concepts are spinal stability and neural compression. Destruction of bones or ligaments can cause spinal instability, and lead to deformities such as kyphosis or subluxation and possible subsequent neural compression. Tumor growth in the spinal canal or neural foramina can cause direct compression of the spinal cord or nerve roots and cause loss of function. Anatomic cat­egorization provides the most logical approach to these tumors. The various tumors present in characteristic locations. An understanding of the anatomy leads to an understanding of the clinical presentation and possible therapeutic options

Extradural Tumors

Extradural tumors comprise 55% of spinal tumors. This category  includes tumors arising within the bony structures of the vertebrae and in the epidural space. Destruction of the bone can lead to in­stability and fractures, leading to pain and/or deformity. Epidural expansion can lead to spinal cord or nerve root compression with radiculopathy or myelopathy, respectively.

Metastatic Tumors, Metastatic tumors are the most common extradural tumors. Spinal metastases most commonly occur in the thoracic and lumbar vertebral bodies because the greatest volume of red bone marrow is found there in. The most common primary tumors are lymphoma. lung. breast, and prostate. Other sources include renal, colon. thyroid, sarcoma. and melanoma Most spinal metastases create osteolytic lesions. Osteoblastic, sclerotic lesions suggest prostate cancer in men and breast cancer In women. Patients with progressing neurologic dysfunction or debilitating pain should undergo urgent surgery or radiation therapy. Preoperative neurologic function correlates with postoperative function. Patients may lose function over hours These patients should be given high-dose intra­ venous dexamethasone, taken immediately to MRI, and then to the operating room or radiation therapy suite. Indication. for surgery

include failure of radiation therapy, spinal instability, recurrence after radiation therapy, and the need for diagnosis in cases of un­known primary tumors. Most cases with significant bone involve­ment require both decompression and fusion. Bony fusion usually takes 2 to 3 months. Prognosis governs operative decisions. Surgery is unlikely to improve quality of life for patients with a life ex­pectancy of 3 months or less, but is likely to improve quality of life for patients with life expectancy of 6 months or more. Benefit for patients With 3 to 6 months life expectancy is unclear and re­quires frank discussion with the patient and family. Patients who are unlikely to tolerate general anesthesia, are already completely paralyzed, or who have very radiosensitive tumors such as myeloma and lymphoma, should generally not be offered surgery,

Primary Tumors. Hemangiomas are benign tumors found in10% of people at autopsy. They occur in the vertebral bodies of the thoracolumbar spine and are frequently asymptomatic. They are often vascular and may hemorrhage, causing pain or neuro­logic deficit. Large hemangiomas can destabilize the body and pre­dispose to fracture. Osteoblatic lesions include osteoid osteoma and osteoblastoma, The latter tends to be larger and more destruc­tive. Aneurysmal bone cysts are non neoplastic, expansile. lytic le­sions containing thin-walled blood cavities which usually occur in the lamina or spinous processes of the cervicothoracic spine. They may cause pain or sufficiently weaken the bone to lead to fracture
Cancers arising primarily in the bony spine include Ewing's sar­
coma, osteosarcoma, chondrosarcoma, and plasmacytoma.

Intradural Extramedullary Tumors

Intradural extramedullary tumors compnse 40% of spinal tumors
.and arise from the meninges or nerve root elements. They may com­press the spinal cord, causing myelopathy, or the nerve roots, causing radiculopathy. All of the most common intradural-extramedullary tumors are typically benign, slow growing, and well circumscribed. Rare benign epidural masses include arachnoid cysts, dermoids, and epidermoids. Rare malignant epidural tumors include metastases and high-grade gliomas.

Meningioma. Meningiomas arise from the arachnoid mater. They appear to be dural based and enhance on MRl. An enhancing (dural tail) may be seen. They occur most commonly in the tho­racic spine , but also arise in the cervical and lumbar regions. Some spinal meningiomas grow into the epidural space. Growth causes cord compression and progressive myelopathy with hyperreflexia, spasticity, and gait difficulties. Surgical excision is the treatment of choice. The surgeon often finds a clean margin be­tween the tumor and dura, and between the tumor and spinal cord, allowing enbloc resection without damage to the cord
Scbwannoma. Schwannomas are derived from peripheral nerve sheath Schwann cells. They are benign, encapsulated tumors that almost never undergo malignant degeneration. Two-thirds are entirely intradural, one-sixth are entirely extradural, and one-sixth have the classic dumbbell shape from intradural and extradural com­ponents. Symptoms result from radiculopathy, often presenting as pain, or myelopathy. Symptomatic lesions should be surgically re­sected. The parent nerve root can usually be preserved. Patients with multiple schwannomas likely have neurofibromatosis type 2 (NF-2). Resect symptomatic lesions in NF2 patients
Neurofibroma. Neurofibromas tend to be more fusiform and grow within the parent nerve, rather than forming an encapsulated mass off the nerve, as with schwannomas. They are benign but not encapsulated. They present similarly to schwaonomas and the two may be difficult to differentiate on imaging. Salvage of the par­ent nerve is more challenging with neurofibromas. Thoracic and high cervical nerve roots may be sacrificed with minimal deficit, to improve likelihood of total resection. Patients with multiple neu­rofibromas likely have neurofibromatosis type I, also known as von Recklinghausen's neurofibromatosis. Resection for symptomatic le­sions should be offered

Intramedullary tumors comprise 5% of spinal tumors. they arise within the parenchyma of the spinal cord. Common presenting symptoms are local or radicular pain, sensory loss, weakness, or sphincter dysfunction. Patients with such symptoms should undergo MRI of the entire spine with and without enhancement

Ependymoma. Ependymomas are the most common intra­ medullary tumors in adults. There are several histologic variants. The myxopapillary type occurs in the conus medullaris or the filum terminale in the lumbar region and has the best prognosis after resec­tion. The cellular type occurs 

more frequently in the cervical cord. Many spinal 
ependymomas have cystic areas and may contain hem­orrhage. Surgical removal can improve function. A distinct tumor margin often exists, allowing safer excision. Postoperative radiation therapy after subtotal resection may prolong disease control.

Astrocytoma. Astrocytomas are the most common intra­ medullary tumors in children, although they also occur in adults . They may occur at all levels, although more often in the cervical cord. The tumor may interfere with the CSF-containing central canal of the spinal cord, leading to a dilated central canal, referred to as sy­ringomyelia, or simply syrinx, Spinal astrocytomas are usually low grade, but complete excision is rarely possible due to the non en­capsulated, infiltrative nature of the tumor. As such, patients with astrocytomas fare worse overall than patients with ependymomas.

Other Tumors, Other types of rare tumors include high-grade astrocytomas, dermoids, epidermoids, teratomas, hemangiomas, he­mangioblastomas. and metastases. Patients usually present with pain. Prognosis depends generally on preoperative function and the histologic characteristics of the lesion


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