Post-hypoxic myoclonus: Differentiating benign and malignant etiologies in diagnosis and prognosis

Abstract

HighlightsMyoclonus status epilepticus may be reflected by generalized epileptiform discharges and burst suppression on EEG.Patients with Lance-Adams syndrome often demonstrate focal epileptiform activity at the vertex on EEG.EEG is vital in evaluating post-hypoxic myoclonus; studies are needed to assess its utility in predicting outcomes.

Novel epileptogenic positive rolandic sharp waves in an adult: an unusual case of post-hypoxic myoclonus

“…Though the eventual appearance of generalized epileptiform activity could suggest MSE, a normal background argued against MSE, as did the patient's improved mental status and prognosis. Further, PRS became definitively time-locked to each jerk, which stands in contrast to reports of such time-locking being typically absent in MSE [1]. For these reasons, we believe the generalization of epileptiform activity is attributable to increased PRS prominence rather than compatibility with MSE.…”

“…MSE arises early on, usually in deeply comatose patients with poor prognosis, and correlates to EEG findings of generalized epileptiform activity against a highly abnormal background [4]. LAS produces intention myoclonus, usually arising more slowly (over days to years), with a normal or slow EEG background, and/or demonstrating vertex-specific epileptiform activity [1]. The defining features of both entities are being continuously updated (see Further Reading).…”

“…Post-hypoxic myoclonus (PHM), a common consequence of cardiac arrest and anoxic brain injury, is broadly divided into the entities of myoclonic status epilepticus (MSE) and Lance-Adams syndrome (LAS) [1]. MSE and LAS are differentiated on the grounds of clinical and electroencephalographic (EEG) findings, with distinction between the two entities carrying important prognostic information.…”

Neurologic prognostication after resuscitation from cardiac arrest

“…Survival rates with a good neurologic outcome despite the presence of myoclonus within 72 hours of out‐of‐hospital cardiac arrest have been reported at 9%–16% 19‐22 . It may be that different forms of myoclonus, such as myoclonus status epilepticus, have a worse prognosis than that of more benign forms of myoclonus such as Lance‐Adams syndrome 23 . Continuous electroencephalogram (EEG) testing, discussed below, is essential to make this distinction 23 …”

“…It may be that different forms of myoclonus, such as myoclonus status epilepticus, have a worse prognosis than that of more benign forms of myoclonus such as Lance‐Adams syndrome 23 . Continuous electroencephalogram (EEG) testing, discussed below, is essential to make this distinction 23 …”