The clinical value of serum prolactin measurement in the differential diagnosis of complex partial seizures.

The time course of changes in serum prolactin after complex partial seizures has been determined and compared to similar changes after other types of seizure and non-epileptic attacks. Seizures in 33 subjects were recorded on video EEG telemetry. Peak serum prolactin concentrations occurred 15-20 min after tonic-clonic seizures, 10 min after complex partial seizures, and were highest after generalised tonic-clonic seizures. Serum prolactin concentrations remained less than 1000 mU/l after absences and non-epileptic attacks. Application of Bayes' theorem showed that where serum prolactin was greater than 1000 mU/l 5-10 min post event this would identify genuine tonic-clonic or complex partial seizures. The false negative rate of this test was 9% for tonic-clonic seizures and 38% for complex partial seizures. Failure of serum prolactin to rise after an attack is of little value in distinguishing complex partial seizures from non-epileptic attacks.