Brain metastasis is a common complication of cancer. Recent population-based data suggest that up to 20% of adults with cancer will develop symptomatic brain metastases during life (1). Autopsy studies indicate that another 25%–30% of patients with disseminated cancer have asymptomatic brain metastases at the time of death. The incidence of brain metastasis varies by primary cancer type, being highest for lung (20%) followed by melanoma (7%), renal (6.5%), breast (5%), and colorectal (1.8%). Prostate, gynecologic, head and neck, and non-melanomatous skin cancers involve the brain parenchyma infrequently. The prevalence of brain metastases has increased in the past three decades. Contributing factors may include more sensitive imaging techniques (gadolinium enhanced MRI), lengthened survival due to more effective systemic therapies, and poor central nervous system (CNS) penetration of many chemotherapeutic and antibody-based agents.
Common signs and symptoms of metastatic brain tumors can be classified as either focal or generalized (Table 64-1) (2). Focal symptoms, such as hemiparesis, aphasia, and visual field defects, vary according to location of the tumor. Generalized symptoms, such as headache, confusion, lethargy, nausea, and vomiting, result from increased ICP or hydrocephalus. Metastatic deposits near the ventricular system can cause obstructive hydrocephalus by interruption of normal cerebrospinal fluid (CSF) outflow pathways through the third and fourth ventricles. Obstructive hydrocephalus is of particular concern with posterior fossa tumors. Headaches caused by increased ICP and/or hydrocephalus may have the following characteristics:
TABLE 64-1SYMPTOMS AND SIGNS OF BRAIN METASTASIS ||Download (.pdf) TABLE 64-1 SYMPTOMS AND SIGNS OF BRAIN METASTASIS
|Symptoms ||% ||Signs ||% |
|Headache ||49 ||Mental status change ||58 |
|Focal weakness ||30 ||Hemiparesis ||59 |
|Mental disturbance ||32 ||Sensory loss ||21 |
|Gait ataxia ||21 ||Papilledema ||20 |
|Speech difficulty ||12 ||Gait ataxia ||19 |
|Visual disturbance ||6 ||Aphasia ||18 |
|Sensory disturbance ||6 ||Visual field cut ||7 |
|Limb ataxia ||6 ||Limb ataxia ||6 |
| || ||Depressed consciousness ||4 |
Worse in the morning and with recumbency
Associated with nausea and vomiting
Exacerbated by coughing or straining
Accompanied by confusion or lethargy
The presence of papilledema is very suggestive of increased ICP, although its absence does not exclude it.
Contrast-enhanced MRI has replaced CT as the study of choice for patients with suspected brain metastasis (Figure 64-1). MRI is more sensitive than CT for small lesions, particularly in the brain stem and posterior fossa (Figure 64-2). In addition, MRI is better able to distinguish metastatic lesions from alternative diagnoses such as abscess or stroke. All cancer patients with new neurological symptoms ...