The blink reflex recovery cycle differs between essential and presumed psychogenic XXXX .

@entity1 @entity2473 @entity12440 @entity9663
BACKGROUND: Psychogenic @entity9663 is difficult to distinguish clinically from benign essential @entity9663 (BEB). The blink reflex recovery cycle measures the excitability of @entity1 brainstem interneurons and is abnormal in BEB. We wished to study the blink reflex recovery cycle in @entity1 with atypical (presumed psychogenic) @entity9663 ( @entity12440 ). METHODS: This was a prospective data collection study investigating the R2 blink reflex recovery cycle at interstimulus intervals (ISI) of 200, 300, 500, 1,000, and 3,000 msec in 10 @entity1 with BEB, 9 @entity1 with @entity12440 , and 9 healthy controls. All @entity1 had @entity2473 of the orbicularis oculi muscles. To compare individual @entity1 , an R2 recovery index was calculated as average of the recovery values at ISIs of 200, 300, and 500 msec, with the upper limit of normal defined as mean (control group) + 2 SD. RESULTS: The R2 recovery cycle was significantly disinhibited in @entity1 with BEB, whereas @entity1 with @entity12440 did not differ from controls on a group level. The upper limit of normal for the R2 recovery index was 61%. The R2 index was abnormal in 9 out of 10 @entity1 with BEB and in none of the @entity1 with @entity12440 . CONCLUSIONS: A normal blink reflex recovery cycle indicates normal brainstem interneuron excitability. Assessment of the R2 recovery cycle may provide a useful diagnostic tool to distinguish @entity1 with psychogenic @entity9663 from BEB and is worthy of further study.
