Involuntary movements in patients with impaired awareness: A comparative study of phenomenology and neurophysiological evaluation

Introduction

Subtle involuntary movements in patients with impaired awareness may suggest non-convulsive status epilepticus (NCSE), but their diagnostic accuracy is unclear. Since electroencephalography (EEG) is not always available, clinicians often rely on motor signs for early diagnosis. We aimed to characterize these movements and evaluate interrater agreement and diagnostic accuracy among specialists.

Methods

We conducted a retrospective observational study of 98 patients with suspected NCSE who underwent video-EEG between 2014 and 2019. Video samples of involuntary movements were reviewed by two epileptologists and two movement disorder specialists, blinded to clinical data. Movements were classified phenomenologically and categorized as epileptic or non-epileptic. Final NCSE diagnosis was determined using modified Salzburg Consensus Criteria. Interrater agreement and diagnostic metrics were calculated.

Results

NCSE was confirmed in 37 patients (37.8 %). Myoclonus (43.3 %), tremor (26.8 %), and clonus (19.6 %) were the most frequent phenomena. No significant differences in movement types were observed between NCSE and non-NCSE groups. Interrater agreement was fair overall (κ = 0.26), moderate only for tremor (κ = 0.577). Diagnostic sensitivity and specificity based on video alone were 54.1 % and 68.9 %, respectively. Movement disorder specialists were more sensitive (68.2 %) but less specific (62.2 %) than epileptologists (42.3 % sensitivity; 77.5 % specificity).

Conclusion

Motor phenomena alone do not reliably distinguish NCSE from other causes of impaired consciousness. Despite frequent use, these signs show limited diagnostic accuracy and low interrater reliability. Video-EEG remains essential, and future studies should refine clinical tools for early NCSE recognition.