Karl E. Misulis, MD, PhD
CHAPTER CONTENTS
•Spinal and Leptomeningeal Tumors
•Remote Manifestations of Cancer
◦Lambert-Eaton Myasthenic Syndrome
◦Paraneoplastic Cerebellar Degeneration
•Neurologic Effects of Cancer Treatment
◦Radiation Injury to the Brain
◦Radiation Effects on the Brain
OVERVIEW
Cancer and other tumors can affect the nervous system by local effect of a primary or metastatic lesion; by remote effect due to metabolic, vascular, or autoimmune effects of the cancer; or by side effects from the cancer therapy. Most common is the local effect of the tumor, whether primary or metastatic.
PRIMARY BRAIN TUMORS
Primary brain tumors are not as common as metastatic tumors to the brain but they are an occasional reason for neurology consultation in the hospital. Half of primary brain tumors are gliomas. Many are meningioma and are benign. Causes of primary brain tumors are unknown, and although there is an increased incidence in relation to radiation exposure, associations with cell phones are unsubstantiated.
PRESENTATION is with headache in 80% of patients, and many will have seizures, cognitive changes, weakness, numbness, or speech changes.
DIAGNOSIS is best with magnetic resonance imaging (MRI) with and without contrast because computed tomography (CT) imaging is not very sensitive or specific. Biopsy is needed to make a diagnosis.
The World Health Organization (WHO) has a comprehensive classification scheme for tumors in general and brain tumors specifically. This was summarized best in the article by Louis,1 the full text of which is freely available from PMC. In general, primary brain tumors are described by grades, with grade I representing well-differentiated, generally benign tumors and grade IV representing the most malignant tumors.
Primary brain tumor types are summarized here:
◦Highly malignant glial tumor; most common of the glial tumors
◦Presents with focal deficit or seizures appropriate to the location of the tumor or headache; on MRI, a thick, ringlike enhancement with surrounding edema
•Anaplastic astrocytoma/Anaplastic oligodendroglioma
◦Common glial tumors that are less aggressive than GBM, with distinct histopathology and molecular markers. Presents with focal deficit or seizures appropriate to the location. Anaplastic astrocytoma may progress to GBM; may not enhance on MRI.
◦Anaplastic oligodendroglioma has the better prognosis.
•Astrocytoma/Oligodendroglioma
◦Common low-grade glial tumors, with distinct histopathology and molecular markers; often progress to a higher grade. These lesions rarely enhance on MRI; usually present due to seizure.
◦Oligodendroglioma has the better prognosis.
◦Tumors arising from the meninges, from the arachnoid layer. In the brain, they are typically over the convexity, midline interhemispheric, or skull-based.
◦Produces focal symptoms depending on location from dysfunction of the adjacent parenchyma
◦More than 90% are grade I with an excellent prognosis.
◦Includes craniopharyngioma, pituitary adenoma, usually histologically benign but invasive. Common symptoms are headache, visual disturbance, and endocrine dysfunction. Visual disturbance is due to compression of the optic chiasm resulting in bitemporal hemianopia. Occasionally, rare glial tumors or brain metastasis can develop here.
◦Tumor of embryonal origin located in the cerebellum and 4th ventricle; commonly seeds CSF
◦Presents with headache, diplopia, ataxia, mental status changes, nausea, vomiting
◦Less common glial tumor of ependymal origin; can be intraventricular or spinal arising in the central canal.
◦Presents with symptoms depending on location. Intracranial tumor usually produces lethargy, nausea, headache, brainstem, and/or cerebellar dysfunction. Spinal tumor produces regional pain with myelopathy appropriate to the location.
◦Lymphoma that is isolated to the brain or spinal cord. Secondary involvement of the CNS is necessary to rule out by looking for systemic lymphoma. Typically, a B-cell lymphoma with a distinct appearance on MRI.
Initial management in the ED involves stabilization. If there is symptomatic edema or mass effect, high-dose corticosteroids may be necessary, using a one-time IV dose of 10 mg of dexamethasone followed by 4 mg three to four times a day. Antiepileptic medication is indicated only if a seizure has occurred.
Further management depends on grade, stage, and host factors such as age and comorbid conditions.
METASTATIC BRAIN TUMORS
Metastatic brain tumors are the most common CNS tumors. Increased survival from systemic cancers has resulted in increased prevalence of brain metastases.2 The most common sources are lung, breast, melanoma, renal cell, and colon cancers. Metastatic tumors with the highest propensity to cause intracerebral hemorrhage include melanoma, renal cell carcinoma, thyroid cancer, and choriocarcinoma
PRESENTATION is similar to primary brain tumors with headache, focal symptoms, seizure, and/or mental status changes.
DIAGNOSIS begins with imaging in any patient with symptoms of brain tumor whether there is known cancer or not. Diagnosis is generally confirmed by MRI brain with and without contrast, which is the most sensitive. Positron emission tomography (PET) with CT is less sensitive, but preferable to PET alone.3 Patients without a history of cancer will need body imaging because brain metastasis can be the initial presentation of systemic cancer. A small percentage of patients diagnosed with brain metastases have no identified systemic cancer. Occasionally, biopsy is necessary to confirm diagnosis or help guide therapy.
MANAGEMENT of metastatic tumors depends on the primary site, number of metastases, and prior treatment. Corticosteroids are indicated for symptomatic edema. A solitary or single brain metastasis can be treated by resection if systemic cancer is controlled. Additionally, a brain metastasis that is large and symptomatic can be resected. With a few small brain metastases, stereotactic radiosurgery is commonly used, while whole brain radiation therapy is used for numerous or large brain metastasis. Systemic chemotherapy is generally not effective for brain metastases of most cancers but may be indicated in select patients.
SPINAL AND LEPTOMENINGEAL TUMORS
Spinal tumors are most commonly metastatic but can be primary. Metastases from remote tumors are most common; however, tumors affecting the brain and upper spine can seed the spinal fluid and produce drop metastases.
PRESENTATION of spinal tumors is with back pain and focal symptoms in the extremities, with weakness, numbness, or radiating pain. Evaluation with MRI of the spine is recommended. Urgent consultation with neurosurgery or radiation oncology is recommended.
PRESENTATION of leptomeningeal metastases may be with a myriad of symptoms but should be suspected with multifocal involvement (e.g., radiculopathies, cranial neuropathies).
DIAGNOSIS: MRI spine with contrast often shows meningeal disease. Lumbar puncture (LP) with at least 10 mL of spinal fluid should be sent for cytology. Opening pressure is usually elevated. Protein is increased. Glucose may be reduced. Leptomeningeal metastasis represents an end-stage involvement of cancer and portends a poor prognosis, with most patients living just weeks after diagnosis. However, young, healthy patients can do well with aggressive treatment.
Spinal cord tumors, their locations, and common etiologies include:
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