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

A Romigi; M Caccamo; F Testa; D Ticconi; S Cappellano; B Di Gioia; G Vitrani; I Rosenzweig; D Centonze

doi:10.1016/j.clinph.2023.01.019

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

Clin Neurophysiol. 2023 May:149:25-31. doi: 10.1016/j.clinph.2023.01.019. Epub 2023 Feb 13.

Authors

A Romigi¹, M Caccamo², F Testa², D Ticconi², S Cappellano², B Di Gioia², G Vitrani², I Rosenzweig³, D Centonze²

Affiliations

¹ IRCCS Neuromed Istituto Neurologico Mediterraneo, Sleep Medicine Center, Via Atinense 18, Pozzilli, IS, Italy. Electronic address: andrea.romigi@gmail.com.
² IRCCS Neuromed Istituto Neurologico Mediterraneo, Sleep Medicine Center, Via Atinense 18, Pozzilli, IS, Italy.
³ Sleep Disorders Centre, Guy's and St Thomas' NHS Foundation Trust, London, UK; Sleep and Brain Plasticity Centre, Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London, UK.

PMID: 36870217
DOI: 10.1016/j.clinph.2023.01.019

Abstract

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 34.9 years, SD 16.8) and sixteen with NT2 (10 M 6F, mean age 39 years, SD 11.8) and 20 controls with other hypersomnias (10 M, 10F mean age 45.1 years, SD 15.1) were recruited. AI was evaluated at different levels of vigilance (Wake and REM sleep) in each nap and throughout the MSLT of each group. The validity of AI in identifying patients with narcolepsy (NT1 and NT2) was analyzed using receiver operating characteristic (ROC) curves.

Results: AI during wakefulness (WAI) was significantly higher in the narcolepsy groups (NT1 and NT2 p < 0.001) compared to the hypersomniac group. AI during REM sleep (RAI) (p = 0.03) and WAI in nap with sudden onsets of REM sleep periods (SOREMP) (p = 0.001) were lower in NT1 than in NT2. The ROC curves showed high AUC values for WAI (NT1 0.88; Best Cut-off > 0.57, Sensitivity 79.3 % Specificity 90 %; NT2 0.89 Best Cut-off > 0.67 Sensitivity 87.5 % Specificity 95 %; NT1 and NT2 0.88 Best Cut-off > 0.57 Sensitivity 82.2 % Specificity 90 %) in discriminating subjects suffering from other hypersomnias. RAI and WAI in nap with SOREMP showed a poor AUC value (RAI AUC: 0.7 Best cutoff 0.7 Sensitivity 50 % Specificity 87.5 %; WAI in nap before SOREMP AUC: 0.66, Best cut-off < 0.82 sensitivity 61.9 % and specificity 67.35 %) differentiating NT1 and NT2.

Conclusions: WAI may represent an encouraging electrophysiological marker of narcolepsy and suggests a vulnerable tendency to dissociative wake / sleep dysregulation lacking in other forms of hypersomnia.

Significance: AI during wakefulness may help distinguish between narcolepsy and other hypersomnias.

Keywords: Atonia index; Hypersomnia; Multiple sleep latency test; Narcolepsy type 1; Narcolepsy type 2.

MeSH terms

Adult
Disorders of Excessive Somnolence*
Humans
Middle Aged
Muscles
Narcolepsy* / diagnosis
Polysomnography / methods
Sleep Latency / physiology