ProlactinConcentrationsin Serum UnchangedIn TransientGlobai Amnesia

Transient global amnesia (TGA) has been defined as the abrupt onset of the inability to store new memories, assodated with transient or permanent retrograde amnesia without other neurological signs and symptoms. Although its etiology is uncertain, the two theories proposed most often are epileptogenic and ischemic causes. The abruptness of onset and the reversibility of the episodes, coupled with the occasional abnormalities in the electroencephalogram, led to suspicions that it is a form of epilepsy (1-3). Prolactin concentrations in serum increase after electroconvulsive, generalized tonic-clonic, or complex partial seizures. Modulation of hypothalamic function by epileptic discharges has been postulated (4-8). We know of no previous reports concerning the concentrations of prolactin in serum in episodes of TGA. We determined serum prolactin in three women who were suffering episodes of TGA. All criteria for TGA (9) were present at the time of the episode: (a) transient amnesia attack with no direct relation to cranial trauma, (b) evidence given by a witness of the inability to store new memories, (c) repetitive queries, (d) apparently normal behavior and orientation, (e) evidence given by a witness of normal long-term memory, and (/) presence of retrograde amnesia at least during the episode. We used a double-antibody RIA kit (Travenol Labs., Morton Grove, IL), with which the normal mean value for prolactin measured in our laboratory (n = 95) is 12.3 ig/L (SD 3.7 1zg/L). Three serial determinations were made at 10-mm intervals: during the episode, immediately after the episode, and within 15 days of the episode. One of us re-evaluated the patients at 15rain intervals during the episode. We considered that the episode was finished when no short-memory disturbances were demonstrated on two serial evaluations. Table 1 summarizes the prolactin values of the patients. We found no increased values for serum prolactin in any of these patients. Although a normal post-ictal value does not totally exclude epileptic seizure, an increased value for serum prolactin is considered to be a sensitive indicator of recent epileptic seizure (8). Thus our results make epilepsy a less appealing possibility for the etiology of TGA. References