Clinical Features of Brain Tumors and Complications of Their Treatment

Overview of Symptoms

Patients with both primary and metastatic brain tumors can present with a variety of clinical symptoms and neurological signs. These manifestations are not specific for individual tumor subtypes or brain tumors, and symptoms can easily be mistaken for a number of other neurological conditions. In general, symptoms and signs are influenced by the underlying tumor’s location, size, and growth rate. Some symptoms are focal, allowing clinical localization of the underlying tumor, while others are generalized and nonlocalizing. At the same time, it is important to note that brain tumor patients may have very few, if any, symptoms at the time of diagnosis.

Focal brain tumor symptoms are typically caused by tumor invasion into brain parenchyma, or by local compression from tumor, associated edema, or hemorrhage. In contrast, most generalized symptoms are the result of an increase in intracranial pressure that results from mass effect of the tumor, malignant edema, or hydrocephalus from cerebrospinal fluid (CSF) outflow obstruction. Brain tumors rarely cause constitutional symptoms associated with other advanced systemic cancers such as fevers, night sweats, anorexia, or weight loss. Symptoms produced by brain tumors are typically subacute and progressive, developing over days to weeks. However, because initial symptoms are often subtle, delayed recognition can make their eventual appearance seem acute. Obvious exceptions include symptoms from seizures, hemorrhages, and herniation, which can appear suddenly. Often even large brain tumors produce surprisingly few symptoms, which speaks to the nervous system’s ability to accommodate gradual tumor growth. In fact, radiographic evidence of midline shift or herniation caused by a brain tumor may have minimal clinical consequences, in stark contrast to more acute neuropathology ( Fig. 73.1 ). Unfortunately, as a result, even a seemingly normal neurological examination cannot completely rule out the presence of an underlying brain tumor.

Patient age can influence presentation, as in the case of elderly patients where cerebral atrophy may mitigate mass effect, or infants who may present with increasing head circumference. Patient comorbidities can also affect the recognition of brain tumor symptoms, as with headaches in a patient with a history of migraines or cognitive changes in the elderly. In the end, the presentation of a patient with a brain tumor can be quite variable, and there are no symptoms or signs specific to the diagnosis. Instead, a thorough history and neurological examination are required together with a high level of suspicion, particularly in at-risk populations such as those with a history of systemic cancer, prior brain radiation, or tumor predisposition syndromes. Understanding the ways in which brain tumors can present and some of the “red flags” to look for will help clinicians know when to suspect the diagnosis.

Specific Symptoms and Signs

Focal Symptoms

Focal motor symptoms

The frontal lobe is a common location for both primary and metastatic brain tumors, which frequently cause motor weakness in the contralateral face or limbs ( Fig. 73.2 ). Weakness can result from tumors invading or compressing motor tracts in the cortex, subcortical white matter, internal capsule, or brainstem. Symptoms generally begin as subtle incoordination or loss of fine motor control and progress gradually, so that patients may not initially recognize weakness, though signs may be found on neurological examination. This gradual development of weakness is unlike the sudden weakness seen in stroke, though acute weakness can develop after a seizure or in the setting of intratumoral hemorrhage. Because hemorrhage is common, particularly in pilocytic astrocytoma, in high-grade glioma, and in metastases from melanoma and thyroid and renal cell carcinoma, it is important to obtain a 1- to 2-month follow-up magnetic resonance imaging (MRI) in any patient presenting with an otherwise unexplained intracranial hemorrhage ( ).

Brain tumors rarely present with extrapyramidal motor manifestations, and though there are reports of patients with thalamic or basal ganglia tumors presenting with tremors or parkinsonism ( ), these symptoms rarely occur in isolation.

Ataxia

Tumors of the cerebellum and brainstem tumors infiltrating the cerebellar peduncles can frequently produce symptoms and signs of ataxia. Cerebellar hemispheric tumors can cause ipsilateral limb ataxia, though many produce few symptoms. In contrast, involvement of the cerebellar vermis tends to be more symptomatic, producing truncal ataxia, often with nystagmus, scanning dysarthria, and ataxic gait. Less well localizing is a more general gait unsteadiness frequently experienced by brain tumor patients. This may be due to subtle limb weakness, disequilibrium, or sensory disturbances, and a detailed neurological examination is necessary to distinguish these causes from ataxia. In addition to symptoms of ataxia, large cerebellar tumors can cause CSF outflow obstruction (with symptoms of increased intracranial pressure) or compressed brainstem structures. Ataxia can, therefore, be an important initial clue to a tumor with the potential for acute neurological decline. Ataxia and associated symptoms from cerebellar tumors are much more common in children, where more than half of primary brain tumors arise in the posterior fossa ( ). In contrast to children, ataxia is relatively uncommon in adults, as fewer than 20% of adult brain tumors arise in the posterior fossa.

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