Spinal Cord Tumors

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53 Spinal Cord Tumors

The most common spinal cord tumors are metastatic extradural lesions usually but not always occurring in patients with already identified malignancies, either cancers or lymphomas. Their presentation is often relatively acute, usually associated with focal back and/or radicular pain. On occasion, these lesions are the initial clinical manifestation of a heretofore unsuspected systemic malignancy. In contrast, primary intradural spinal cord tumors occur infrequently; typically their presentation is a relatively subtle one, ingravescent in temporal profile. Spinal cord and spinal column tumors are best classified within two categories: extradural, occurring outside of the dura, and intradural, contained within the dura mater (Table 53-1; Fig. 53-1).

Table 53-1 Classification of MRI Abnormalities *

Extradural Extramedullary	Intradural Extramedullary	Intradural Intramedullary
Disc disease	Neurinoma	Syringomyelia
Metastatic carcinoma	Meningioma	Tumor
Lymphoma	Intracranial tumor seeding	Ependymoma
Sarcoma	Ependymoma	Glioma
Plasmacytoma	Medulloblastoma	Hemangioblastoma
Primary bone tumor	Glioma	Myelitis
Scar	Cauda equina lesions	Edema
Abscess	Scarring	Lipoma
Hemangioma	Hypertrophic neuropathy	Rare lesions
Rare lesions	Rare lesions	Abscess
Hemorrhage	Lymphoma	Hematoma
Neurilemmoma	Metastasis	Varix with AVM
Meningioma	Hemangioblastoma	Lymphoma
Chordoma	Lipoma	Neuroblastoma
	Dermoid	Metastasis
	Epidermoid
	Cyst
	Clot

* Dermoid or epidermoid, teratoma, lipoma, and cysts are often associated with spinal dysraphism. In this setting, many tumors are intradural, although they may involve all three areas.

Figure 53-1 Classification of Spinal Tumors.

Intradural tumors are further categorized as extramedullary or intramedullary, depending on their relationship to the spinal cord. Intradural extramedullary tumors, usually meningiomas or schwannomas, generally arise outside of the spinal cord parenchyma. These are initially clinically silent; however, with time these tumors surreptitiously enlarge. Once a critical mass is reached, spinal cord compression occurs and symptoms develop. In contrast, intradural intramedullary tumors, such as gliomas and ependymomas, originate within parenchyma of the spinal cord. As these intramedullary malignancies primarily expand, important neurologic pathways and cell populations are subsequently compromised and eventually destroyed.

Extradural tumors generally are derived from metastatic lesions to vertebral bodies with extension into the epidural space, causing external compression of the thecal sac and its contents. Primary bony vertebral tumors also occur, both malignant, such as myeloma, and benign, including hemangiomas and osteoid osteomas.

Extradural Spinal Tumors

Clinical Vignette

A 62-year-old postal carrier presented with midthoracic pain and rapidly progressive weakness and numbness in both legs and difficulty initiating his urine stream. During the preceding 6 weeks, he intermittently awakened with midthoracic vertebral pain that increasingly radiated to his epigastrium. This was particularly precipitated by lifting, bending, or straining at stool. An initial gastrointestinal evaluation was normal. Twenty-four hours before admission, he began to experience progressive difficulty standing, walking, and voiding. The morning of this evaluation, he was unable to get out of bed on his own and was totally unable to void. During the past 3 months, he had noted an increasingly irritating cough; he was a 60-pack-year smoker.

Neurologic examination demonstrated a T9 “cord level” to both pinprick and temperature. Muscle stretch reflexes were absent at the knees and ankles, and plantar stimulation was flexor. There was mild tenderness to palpation over the lower thoracic spine. He became incontinent of urine. Rectal sphincter tone was lax.

Spinal radiographs revealed destruction of the T9 vertebral body. Magnetic resonance imaging (MRI) demonstrated a soft tissue mass involving most of the T9 vertebral body, extending into the pedicle, with epidural extension of the tumor into the spinal canal leading to marked compression of the spinal cord. Immediate dexamethasone and subsequent radiation therapy was unsuccessful in reversing his clinical course. Chest radiograph (Fig. 53-2) demonstrated a left main stem bronchus tumor that on biopsy proved to be a primary small cell lung cancer.

Figure 53-2 Extradural Metastatic Spinal Tumors.

Spinal neoplasms are predominantly secondary to metastatic cancer. This occurs in up to one third of cancer patients. Lung, breast, prostate, and lymphoma are the most common metastatic lesions leading to spinal cord compression.

Severe focal vertebral pain is frequently the presenting symptom of a metastatic spinal cancer (Fig. 53-2). Unfortunately, back pain is such a ubiquitous complaint that the serious nature of a newly occurring pain is often not appreciated even when there is no history of recent trauma. Sometimes, it is difficult to distinguish pain of a metastatic spinal tumor from the much more common mechanical, degenerative, or osteoarthritic musculoskeletal lower back and/or nerve root disorders. However, pain of metastatic spinal cancer origin is often persistent, frequently unrelated to posture, and tends to increase at night. In contrast to more common mechanical back pain, this pain can be of more recent origin.

Progressive neurologic symptoms often vary and are related to the precise level of spinal column involvement; typically the temporal profile is relatively rapid. Tumors at the cervical and thoracic spinal cord levels present with progressive weakness, numbness, and sphincter dysfunction at levels below the tumor. Sphincter difficulties are nonspecific symptoms per se that may develop with tumors at any spinal level. On occasion, bladder and bowel dysfunction per se may be the initial presenting symptom related to a conus medullaris tumor at the distal tip of the spinal cord. The essential message is that whenever sphincter problems develop in a patient with a known cancer, one needs to be alert to the potential of a spinal metastasis. Examination usually reveals hyperreflexia, Babinski signs, and other long tract signs at spinal levels below the tumor involvement.

When evaluating patients with recent-onset sphincter difficulties and suspicion for a metastatic lesion, it is important to recognize that differentiation of conus medullaris lesions, at the spinal cord tip, versus those within the cauda equina may be difficult. Classically when the clinical findings are symmetric and relatively equally involving both lower extremities, the conus medullaris is much more likely the site of the specific pathology. In contrast, cauda equina lesions often lead to an asymmetric distribution of signs and symptoms because not all nerve roots within the cauda equina are equally affected.

Typically, the course of extradural metastatic spinal tumors is more rapid than intradural tumors. It is not unusual for these lesions to have an almost precipitous onset, often producing rapidly evolving motor and sensory deficits within just a few hours to a day or so (Fig. 53-3). A prior diagnosis of either a cancer or a lymphoma will alert the astute clinician to the precise pathophysiologic nature of the spinal lesion. However, occasionally a spinal metastasis may be the initial presentation of a metastatic malignancy.

Figure 53-3 Clinical Profile: Acute Spinal Cord Decompensation with an Epidural Tumor.

Diagnostic Approach

MRI is the standard for evaluating potential metastatic spine lesions, especially those with evolving cord compression. When an MRI is contraindicated, such as with a patient who has a pacemaker, CT myelogram is still a very useful and valid study. An initial preliminary spinal tap is best avoided in these patients as such can change pressure dynamics when there is an obstructing focal cord lesion. If a spinal tap is performed, this study can precipitate a rapid worsening of the patient’s neurologic deficits.

If a primary cancer has not been previously found, a histologic diagnosis becomes mandatory to confirm the nature of the lesion. In some instances, there is a primary bony malignancy such as multiple myeloma originating within the vertebrae per se (Fig. 53-4). Today percutaneous CT-guided needle biopsy is often the most useful procedure if no primary is immediately apparent such as occurred in this chapter’s opening vignette, where a routine chest radiograph led to a diagnostic lung biopsy. When there is no evidence of a primary lesion identified, an open surgical procedure, such as neurosurgical spinal cord decompression with a conjoint biopsy, is very important.

Figure 53-4 Extradural Primary Malignant Spinal Tumors.

Treatment and Prognosis

There are three primary indications for treatment of spinal column metastatic disease: (1) to prevent further spinal cord destruction, (2) to prevent progression of the neurologic deficits, and (3) to control pain. Typically large-dose corticosteroids, that is, 10–20 mg of dexamethasone, followed by 4–6 mg every 4–6 hours, are administered at diagnosis and continued throughout the initial treatment stages for their protective effect on the neural elements.

Focused radiation therapy and/or surgical decompression are the two primary treatment modalities for epidural metastases. When the patient’s neurologic examination demonstrates serious neurologic compromise, radiation therapy may be the initial treatment of choice, particularly depending on the identification of the specific pathology. This is administered locally in multiple fractions that are precisely directed to the involved vertebrae. Pain relief often occurs relatively rapidly within just a few days after commencement of the radiation therapy. Unfortunately some tumors such as renal cell cancer are radiotherapy-resistant tumors. Here the symptoms typically evolve progressively despite radiation therapy. In this setting, surgery is often indicated once the radiotherapy per se is completed.

On occasion, patients who present with specific neurologic symptoms and signs are best treated with surgery. This provides for rapid decompression of the neural elements and preserves previously unaffected neurologic function. Surgical intervention generally requires removal of as much tumor as possible. In many instances, when spinal column destruction has caused significant spinal instability, fusion and/or grafting is initially required followed by subsequent radiotherapy to the area.

Prognosis for patients with metastatic disease to the spine depends on their clinical status upon presentation. Individuals who have presented with a severe neurologic deficit such as paraplegia existing at least 24–36 hours often do not regain significant neurologic function. However, many patients who present with acute deterioration, still retaining some distal neurologic function, who undergo rapid evaluation and treatment often experience improvement.

Very occasionally, one finds a few types of primary benign bony vertebral tumors. Although histologically these are not malignant as are most extradural tumors, these lesions may reach a critical mass, causing vertebral collapse and spinal cord compression (Fig. 53-5). Usually these benign tumors have a less aggressive clinical course; however, once they reach a critical mass, they may portend serious threat to spinal cord function. Uncommonly, surgical decompression is indicated.

Figure 53-5 Extradural Primary Benign Spinal Tumors.

Intradural Extramedullary Tumors

Intradural extra-axial (extramedullary) tumors originate within the dural sleeve of the spinal column but outside of the spinal cord, that is, intradural extramedullary. These lesions primarily arise within the leptomeninges or the nerve roots. Additionally, one may find meningiomas within this age group.

Clinical Vignette

This 41-year-old woman noted the occasional appearance of tingling in her right leg that was particularly prominent when she played tennis. She had no significant back pain. Her initial detailed neurologic examination was perfect. MRI of the lumbosacral spine was normal. A follow-up appointment was scheduled for 2 months. However, within just a few weeks, she noted persistent right leg numbness particularly present when she shaved her leg. On self-testing, she became cognizant of diminished touch sensation in a pre-tibial distribution. Lumbar spine MRI was normal. Subsequently, her walking began to be limited as her left foot seemed to turn in after walking a few blocks.

Repeat neurologic examination demonstrated a slightly spastic gait, subtle weakness of the left iliopsoas, more brisk muscle stretch reflexes on the left, a left Babinski sign, and a subtle cord level to pin and temperature sensation at T6 on the right.

MRI confirmed the presence of a large intradural extramedullary tumor compressing the spinal cord. An encapsulated benign meningioma was surgically removed. She had an excellent recovery with no clinical residua.

There was a seeming paradox here in that even when the patient developed clinical symptoms, her neurologic examination was initially normal. And then as her symptoms became more specific and subtle abnormalities appeared on neurologic examination, her MRI demonstrated very marked spinal cord compression with a very significant-sized tumor. The clinical temporal profile of meningiomas is to gradually enlarge, subtly compressing the spinal cord. This tissue is amazingly resilient when the pathologic process is a very ingravescent one. Here the initial symptoms were relatively benign, with intermittent leg numbness precipitated by exercise and body heat. Such a setting, in the face of a normal lumbar MRI, suggested the possibility of early multiple sclerosis.

Continued observation was therefore important, as were patient instructions to call with any new symptomatology and return for follow-up within a few months. On this occasion, subsequent neurologic examination demonstrated a subtle sensory cord level and contralateral corticospinal dysfunction, typical of a classic Brown–Sequard syndrome indicating a specific level of spinal cord dysfunction (see Chapter 44). Focused spinal MRI at a higher level led to the diagnosis of this treatable lesion.

Intradural extramedullary tumors are most commonly meningiomas (Fig. 53-6A) arising from within the dura per se, or are nerve sheath tumors. The latter are classified into two main groups, schwannomas, about 65% (Fig. 53-6B), and neurofibromas. Both often have a similar gross appearance and require microscopic analysis for differentiation. Neurofibromas have less dense cellular structure (Antoni B pattern) and often contain nerve elements. Usually benign, these lesions occur as a solitary finding or as multiple nodules throughout the body. Type I neurofibromatosis (von Recklinghausen disease) is a familial condition with two or more neurofibromas, associated neurocutaneous findings such as café-au-lait spots, and axillary freckling. Nerve sheath tumors such as schwannomas typically develop in middle-aged women. These lesions are benign, slow-growing tumors that gradually lead to significant clinical symptomatology especially when these originate near the spinal cord. Type I neurofibromatosis (von Recklinghausen disease) is an autosomal dominant disorder often associated with optic gliomas, and Lisch nodules of the iris, along with certain skeletal abnormalities. Type II neurofibromatosis is most frequently associated with bilateral hearing loss due to neurofibromas of the eighth cranial nerve and are not associated with spinal cord compression (see Chapter 52). Schwannomas have a dense pattern on microscopic analysis and may be found at the level of the nerve root.