Objective: To investigate the interrater variability in clinical assessment of acute post-hypoxic myoclonus (PHM) after cardiopulmonary resuscitation.

Background: PHM is a clinical symptom that can occur after anoxic brain injury. Based on its clinical presentation, it can be divided into generalized and (multi) focal PHM, of which the former has been associated rather with a subcortical dysfunction and very poor prognosis, and the latter with a cortical dysfunction and a relatively better prognosis. However, these anatomic associations are derived from conscious patients and indirect neurophysiological measurements. In clinical practice, the subtypes of PHM could potentially support prognostication and guide treatment. However, it is not known if and to which extent a variation exists in clinical assessment of PHM by different physicians.

Methods: A standardized video protocol for examination of acute PHM was conducted. Ten patients with PHM were included (8 male, median age 62, IQR=27, 1 patient survived). Videos were scored by three experienced neurologists, blinded for patient outcome. Raters classified the PHM into semiology (generalized or (multi) focal), localization (proximal, distal or both), stimulus sensitivity (present or absent), severity (Clinical Global Impression of Severity scale (CGI-S); range 1-7) and the second part of the Unified Myoclonus Rating Scale (UMRS) score (range 0-128). Interrater variability was calculated by the intraclass correlation coefficient (ICC) and Kappa statistics.

Results: Poor interrater agreement was found for semiology (κ -0.05, 30% consensus), moderate agreement for localization (κ 0.46, 60% consensus) and poor agreement for stimulus sensitivity of PHM (κ -0.05, 30% consensus). Good agreement was obtained for the CGI-S score (ICC 0.64) and very good agreement for the UMRS score (ICC 0.82).

Conclusions: Although assessments were from video recordings, our data suggest that clinical assessment of PHM etiology, i.e. cortical versus subcortical, is not reliable among different physicians, and therefore should not be used in prognostication or guiding treatment. Conversely, the CGI-S and UMRS scales appear to be reliable in assessment of PHM severity. However, the relation between PHM severity and outcome is unknown. Further, larger and more quantitative studies on PHM and the relation with outcome are needed to address this knowledge gap.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-interrater-variability-in-clinical-assessment-of-post-hypoxic-myoclonus/