Seizures Associated with Nonneurologic Medical Conditions

Seizures frequently arise during the course of medical illnesses that do not primarily affect the central nervous system (CNS). A patient’s history, including a review of medications and physical examination, should be informed by a consideration of the seizures as a symptom of CNS dysfunction. The urgency to pursue a diagnosis is related to the time of presentation following the seizure. In a neurologically intact patient without progressive symptoms, quick (within days), but not emergent (within hours), evaluation may be appropriate. Within the first 24 hours, vital signs, level of consciousness, and focality on examination determine urgency. The need for emergent neuroimaging studies and lumbar puncture depends on the likelihood of intracranial lesion, CNS or systemic infection, a patient’s metabolic state, and the possibility of drug or alcohol intoxication. In a patient who presents more than 1 week after an initial seizure, recurrent attacks establish the diagnosis of epilepsy. Several factors predispose a patient to seizures, including (i) changes in blood-brain barrier permeability as a result of infection, hypoxia, dysautoregulation of cerebral blood flow, or microdeposition of hemorrhage or edema secondary to vascular endothelial damage; (ii) alteration of neuronal excitability by exogenous or endogenous substances, such as excitatory and inhibitory neurotransmitters; (iii) inability of glial cells to regulate the neuronal extracellular environment; (iv) electrolyte imbalances; (v) hypoxia–ischemia; and (vi) direct and remote effects of neoplasm. Some patients without epilepsy may be genetically prone to seizures secondary to systemic factors. Understanding the interaction of other organ systems is necessary for the appropriate management of seizures. In patients with hepatic or renal dysfunction, changes in pharmacokinetics induced by metabolic dysfunction alter treatment with antiepileptic drugs (AEDs). In cases of hepatic dysfunction, plasma concentrations must be correlated with serum albumin and protein levels and, if possible, free (unbound) levels. Patients with hepatic and renal failure may have normal serum albumin levels, but altered protein binding, resulting in elevated concentrations of free drug

Keywords:

seizure , medical condition