REM Sleep Components Predict the Response to Initial Treatment of Infantile Spasms

Abstract

Summary:Purpose: The phasic inhibition index (PII) is the rate of the simultaneous occurrence of rapid eye movement bursts (RBs) and phasic chin muscle activity (PCMA) during rapid eye movement sleep (REMS). PI1 is low insofar as physiologically occurring REM-related phasic inhibition acts on chin muscles. Previously we found that PI1 was significantly higher in patients with infantile spasms (1%) who had a recurrence of convulsions than in patients with ISs who exhibited no recurrence. We aimed to predict the response of patients with ISs to conventional anticonvulsants (AEDs) by means of REMS components including PII, expecting to facilitate avoidance of potentially hazardous hormonal therapy.Methods: REMS, recorded before the beginning of any medication, was retrospectively examined in 15 patients with ISs. The patients were classified into two groups according to the response to initial treatment with conventional AEDs. Conventional AEDs were enough to control the spasms in six good responders (GRs), whereas further hormonal therapy was required in nine poor responders (PRs) to control the spasms.Results: The amount of REMS was significantly lower in patients with ISs than in controls. GRs had less REMS than did PRs, although no significant difference was observed. Although the frequencies of RB and PCMA showed no significant differences among GRs, PRs, and controls, the average PI1 value in PRs (12.6 +-3.4; mean f SD) was significantly (p < 0,001) higher than that in GRs (6.1 ? 1.7).Conclusions: PI1 is a useful parameter for differentiating GRs from PRs. Key Words: REM sleep-Phasic inhibition index-Infantile spasms-Brainstem-ACTH.Rapid eye movement (REM)-related phasic inhibition (1,2) acts on human chin muscles (3) during REM sleep (REMS). To determine the degree of this inhibition, we introduced the phasic inhibition index (PII) (4-6). PI1 is the rate of the simultaneous occurrence of bursts of rapid eye movements (RBs) and phasic chin muscle activity (PCMA) during REMS. PI1 is low insofar as physiologically occurring REM-related phasic inhibition acts on chin muscles. Because RB, PCMA, and PI1 (7-1 1 ) are all free of the first-night effect, PI1 can be assessed with a single (-night) polysomnography (6).Infantile spasms (ISs) are a unique form of seizure disorder limited almost entirely to infants during the first year of life. In general, the prognosis is believed to de-