Status epilepticus with prominent motor symptoms clusters into distinct electroclinical phenotypes

Status epilepticus (SE) is a heterogeneous condition and considerable variability exists in its etiology, semiology, electroencephalographic correlates, and response to treatment. The aim of the present study was to explore whether distinct phenotypes may be identified within SE with prominent motor symptoms.

Consecutive episodes of SE with prominent motor symptoms in patients aged ≥14 years were included. Etiology of SE was defined as symptomatic (acute, remote, progressive) or unknown. Electroencephalogram (EEG) recordings were searched for lateralized periodic discharges (LPDs), generalized sharply and/or triphasic periodic potentials (GPDs), and spontaneous burst suppression (BS). According to treatment response, SE was classified into responsive, refractory and super-refractory. Average linkage hierarchical cluster analysis was performed with Pearson's correlation as a similarity measure.

A total of 240 episodes of SE were identified. Three major clusters were found. The first cluster linked focal motor SE evolving into non-convulsive SE (NCSE), presence of LPDs/GPDs on EEG, unknown etiology and treatment refractoriness. The second cluster linked convulsive and myoclonic SE evolving into NCSE, presence of spontaneous BS on EEG, progressive symptomatic etiology and super-refractoriness. The third cluster linked convulsive and myoclonic SE not evolving into other semiologies, absence of LPDs/GPDs/spontaneous BS on EEG, acute symptomatic etiology and treatment responsiveness.

Distinct electroclinical phenotypes characterized by different response to pharmacological intervention can be identified within the heterogeneity of SE with prominent motor phenomena.