Metabolic and nutritional nervous system dysfunction in cancer patients
INTRODUCTION Metabolic and nutritional disorders are common in cancer patients and can result from organ damage secondary to tumor metastases (e.g., liver, kidney, bone), drugs used for cancer treatment and symptom control, secretion of tumor-derived substances that impair systemic organ function, malnutrition, and infection (1-4). In a seminal study from Memorial SloanKettering Cancer Center (MSKCC), metabolic and nutritional disorders accounted for over 10% of all diagnoses in a series of 851 patients seen by the neurology consult service (2). The spectrum of disease that can occur in this setting is very broad and may involve dysfunction of the brain, spinal cord, peripheral nerves, muscle, or various combinations (Table 1). The signs and symptoms often develop insidiously and are typically not accompanied by focal signs. For example, patients with metabolic encephalopathy are usually symptomatic for a day or two before they become confused and agitated enough to warrant consultation. Therefore, an extensive work-up is required in most patients to clarify the etiology of the underlying metabolic and/or nutritional disorder.