Muscle atonia index during multiple sleep latency test: A possible marker to differentiate narcolepsy from other hypersomnias.

Objective: The complexity and delay of the diagnosis of narcolepsy require several diagnostic tests and invasive procedures such as lumbar puncture. Our study aimed to determine the changes in muscle tone (atonia index, AI) at different levels of vigilance during the entire multiple sleep latency test (MSLT) and each nap in people with narcolepsy type 1 (NT1) and 2 (NT2) compared with other hypersomnias and its potential diagnostic value.

Methods: Twenty-nine patients with NT1 (11 M 18F, mean age 34.