'De novo' absence status of late onset: report of 11 cases.

Absence status (AS) is a heterogenous epileptic syndrome that can occur at any age, usually in a context of prior epilepsy. Eleven cases of AS occurring in middle-aged patients who had no history of epilepsy were retrospectively collected over a 10-year period (10 women and one man; mean age, 58.6 years). Eight patients were receiving high doses of psychotropic drugs. Clinical and EEG presentation was similar to AS occurring in patients with prior epilepsy. Evaluation of precipitating factors revealed that AS coincided with benzodiazepine withdrawal in eight cases. Cofactors included excessive use of other psychotropic drugs, nonpsychotropic treatment, hypocalcemia, hyponatremia, and chronic alcoholism. CT demonstrated mild cerebral atrophy in six cases. There was no recurrence, even without chronic antiepileptic treatment. These data indicate that (1) most cases of "de novo" AS of middle age or late onset result from the addition of various epileptogenic factors; (2) AS can be considered a new and uncommon complication of benzodiazepine withdrawal, and (3) long-term administration of anticonvulsant medication may not be required.