The possibility of abstinence seizures in patients who abuse alcohol or use benzodiazepine and related sedative drugs, must be considered when seizures occur for the first time in adult life or in adolescence. Suspicion is raised by the stigmata of alcohol abuse or a history of prolonged anxiety requiring sedative drugs. Also, sleep disturbance, tremulousness, disorientation, illusions, and hallucinations can be associated with the convulsive phase of the withdrawal syndrome. Seizures in this setting may occur singly, but as often, in a brief flurry, the entire convulsive period lasting for several hours and rarely for a day or longer, during which time the patient may display twitchiness or myoclonus and be unduly sensitive to photic stimulation. Chapter 41 discusses alcohol and other drug-related seizures in detail.
An outburst of seizures is also a prominent feature of all varieties of bacterial meningitis, more so in children than in adults. Fever, headache, and stiff neck provide the clues to diagnosis, and lumbar puncture yields the salient data. In endemic areas and in individuals who have traveled from these areas, cysticercosis and tuberculous granulomas of the brain are very common causes of epilepsy. Myoclonic jerking and seizures may appear early in acute herpes simplex encephalitis and other forms of viral, treponemal, and parasitic encephalitis, including those derived from HIV infection, both directly and indirectly such as toxoplasmosis and brain lymphoma; and in subacute sclerosing panencephalitis. Seizure(s) without fever or stiff neck may be the initial manifestation of syphilitic meningitis, a fact worth noting as this process reemerges in AIDS patients.
A variety of autoimmune encephalitides may cause seizures as, for example, with the anti-NMDA receptor antibody that is associated with ovarian and other teratomas and other paraneoplastic conditions such as the antibody syndrome directed at the voltage-gated potassium channel complex (see Chap. 30).
Uremia has a strong tendency to produce convulsions. Of interest is the relation of seizures to the development of acute anuric renal failure, generally from acute tubular necrosis but occasionally due to glomerular disease. Total anuria may be tolerated for several days without the appearance of neurologic signs, and then there is an abrupt onset of twitching, trembling, myoclonic jerks, and brief generalized motor seizures; acute hypertension probably plays a role. The entire motor constellation, one of the most dramatic in medicine, lasts several days until the patient sinks into terminal coma or recovers by dialysis. When this twitch-convulsive syndrome accompanies lupus erythematosus, seizures of undetermined cause, or generalized neoplasia, one should suspect its basis in renal failure.
Other acute metabolic illnesses and electrolytic disorders complicated by generalized and multifocal motor seizures are hyponatremia and its opposite, the hypernatremic, hyperglycemic and other hyperosmolar states, hypoglycemia, thyrotoxicity, porphyria, hypomagnesemia, and hypocalcemia. In all these cases, rapidly evolving electrolyte abnormalities are more likely to cause seizures than those occurring gradually. For this reason it is not possible to assign absolute levels of sodium, blood urea nitrogen (BUN), osmolarity, or glucose concentrations above or below which seizures are likely to occur. Lead (in children) and mercury (in children and adults) are the most frequent of the metallic poisons, still rare as a group, that cause convulsions. The presence of these heavy metals in homeopathic treatments should not be overlooked.