Tonic electromyographic activity following bilateral tonic–clonic seizures is associated with periictal respiratory dysfunction and postictal generalized EEG suppression

Abstract

Summary Objective No biomarkers reliably predict risk for sudden unexpected death in epilepsy (SUDEP). Postictal generalized electroencephalography (EEG) suppression (PGES) is a possible biomarker for SUDEP risk. However, its utility in predicting SUDEP remains uncertain. We had observed that postictal tonic electromyography (PTEMG) activity follows some generalized convulsive seizures (GCS). PTEMG activity and PGES may have a common pathophysiologic basis. PGES is associated with periictal respiratory distress. There is evidence that tonic EMG occurs with brain hypoxia. Thus PTEMG activity may be related to seizure‐associated hypoxemia. Pronounced variation occurs among expert clinicians in identifying PGES, thereby limiting its utility as a biomarker. Characteristics of PTEMG activity and its relationship to preceding GCS have not been explored. We studied PTEMG activity characteristics, its relationship to the preceding seizure and associated respiratory dysfunction. Methods We reviewed 145 GCS in 66 patients undergoing video‐EEG telemetry (VET). The presence of PTEMG activity was defined when tonic EMG occurred for at least 3 seconds following seizure termination and was identified with filter settings at 5‐200 Hz. Duration of PTEMG activity, the seizure, PGES, seizure‐associated peripheral capillary oxygen saturation (SpO2) change, and end‐tidal CO2 were analyzed. We compared data from GCS with and without PTEMG activity. Results Ninety of 145 seizures with GCS had PTEMG activity. The remainder had postictal slowing without PTEMG activity, and cessation of activity was followed by EEG slowing. Duration of the initial PTEMG discharge was 39.1 (mean) ± (standard deviation) 17.9 seconds. SpO2 nadir was lower (P = 0.005) in seizures with PTEMG activity than in those without (72% vs 77%). End‐tidal CO2 was higher (P = 0.05) in seizures with PTEMG activity than in those without (63 vs 56 mm Hg). PGES duration was 35.6 ± 22.2 seconds and associated with duration of PTEMG activity (P < 0.001). Significance The novel finding is that PTEMG activity occurs following 62% of GCS and that seizures with PTEMG activity have greater severity of respiratory dysfunction than seizures without. PTEMG activity is readily discerned by visual analysis of VET at appropriate filter settings and has the potential of being a complementary or surrogate biomarker of PGES for assessing SUDEP risk.

Postictal generalized EEG suppression and postictal immobility: what do we know?

“…Contradictory results have been obtained by other studies where the occurrence of PGES was associated with the presence and a nearly doubled duration of the tonic phase (Semmelroch et al, 2012;Freitas et al, 2013;Tao et al, 2013) as well as with a bilateral symmetrical tonic extension of the limbs (Alexandre et al, 2015;Marchi et al, 2019) and oral tonicity (wide mouth opening and vocalization) (Marchi et al, 2019). Tonic muscle contraction, PGES and their association with brain hypoxia have also been highlighted in a recent paper, where postictal tonic electromyography activity following some generalized convulsive seizures was associated with PGES and with a greater severity of respiratory dysfunction (Park and Seyal, 2019). PGES has also been considered a possible marker of postictal autonomic dysregulation.…”

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“…A metodologia a ser utilizada na realização do exame deverá ser específica para determinação de ME e o laudo deverá ser elaborado por escrito e assinado por profissional com comprovada experiência e capacitado no exame nessa situação clínica (Park, Seyal, 2019). Em geral, exames que detectam a presença de perfusão cerebral, como angiografia cerebral e doppler transcraniano, não são afetados pelo uso de drogas depressoras do sistema nervoso central ou distúrbios metabólicos, sendo os mais indicados quando essas sit uações estão presentes.…”

Biomarkers of seizure severity derived from wearable devices

“…27 In a recent study, seizures with postictal tonic EMG activity (measured at the EEG electrodes) were associated with longer durations of PGES, as well as a greater severity of respiratory dysfunction, thus being another potential biomarker for SUDEP. 28 Tonic EMG activity following bilateral tonic-clonic seizures is associated with peri-ictal respiratory dysfunction and PGES. 28…”

“…28 Tonic EMG activity following bilateral tonic-clonic seizures is associated with peri-ictal respiratory dysfunction and PGES. 28…”