Short paperEarly Lance–Adams syndrome after cardiac arrest: Prevalence, time to return to awareness, and outcome in a large cohort
Introduction
Nearly one fifth of patients resuscitated from cardiac arrest (CA) may develop myoclonus [1], [2]. However, clinical and electroencephalographic (EEG) differences exist between “status myoclonus”, a condition strongly related to poor prognosis [3], and myoclonus that is amenable to improvement, including awakening with awareness, which may represent early-appearing Lance–Adams syndrome (LAS) [2], [4], [5]. The latter has been defined as generalized action myoclonus appearing within a few days to weeks after CA and coma, mostly (but not exclusively) of hypoxic origin [6]. It is often accompanied by dysmetria, dysarthria and ataxia, with relative preservation of cognition [7]. This syndrome can become chronic, and patients usually need long-term antiepileptic treatment. Specific EEG features in patients with early myoclonus have been recently outlined [4]: suppression-burst background with high-amplitude, diffuse polyspikes correlate with dismal prognosis (“status myoclonus”), whereas continuous background with narrow, midline centered spike-waves correspond to LAS, and a relatively good outcome.
Clinically, it is of paramount importance to recognize early LAS patients in order to offer them a chance of regaining awareness. Our aim was to describe our experience, focusing on pharmacologic management in the ICU, time to awakening, and long-term prognosis.
Section snippets
Patients
From our prospective CA registry including consecutive adults admitted for CA from June 2006 to November 2016, we retrospectively identified subjects with early LAS defined as follows: survivors at discharge, having presented generalized myoclonus within 96 h after CA (considering the masking effect of acute sedation) together with an epileptiform EEG on a continuous background within 48 h [4].
Until July 2014, patients were managed at 33° during the first 24 h, then increasingly at 36 °C.
Patient characteristics
Among the 458 CA patients, seven survivors (1.5%) developed early LAS as previously defined.
Median age was 57 years, most common CA etiology was cardiac, while first cardiac rhythms were evenly distributed. Median time to ROSC was 22 min. Their clinical characteristics are summarized in Table 1.
Neurological and neurophysiological assessments
Within 72 h after CA, in normothermia and off sedation, all seven patients had preserved brainstem reflexes and localized pain; only two showed spontaneous eye opening (without interaction with the
Discussion
This series shows that early LAS, occurring in only 1.5% of our cohort, represents a rare diagnosis in patients after a CA. A combination of high dosed, relatively broad spectrum AED was used promptly, but the first signs of awareness were relatively delayed (up to 3 weeks); almost half of patients had a complete recovery.
In a previous assessment of our group, including 1 patient described here, 24.8% of the cohort developed a postanoxic status epilepticus, 2 of whom had LAS (3.1% of total) [5]
Conflict of interest statement
The authors declare that they have no conflict of interest.
Acknowledgment
The authors thank Christine Stähli, RN, for help in data acquisition.
References (20)
- et al.
EEG reactivity to pain in comatose patients: importance of the stimulus type
Resuscitation
(2015) - et al.
Neurologic recovery after therapeutic hypothermia in patients with post-cardiac arrest myoclonus
Resuscitation
(2012) - et al.
Neurological prognostication of outcome in patients in coma after cardiac arrest
Lancet Neurol
(2016) - et al.
Early multimodal outcome prediction after cardiac arrest in patients treated with hypothermia
Critical Care Med
(2014) - et al.
Neurologic outcomes and postresuscitation care of patients with myoclonus following cardiac arrest
Crit Care Med
(2015) - et al.
Outcome from coma after cardiopulmonary resuscitation: relation to seizures and myoclonus
Neurology
(1988) - et al.
Clinically disctinct electroencephalographic phenotypes of early myoclonus after cardiac arrest
Ann Neurol
(2016) - et al.
Predictors of awakening from postanoxic status epilepticus after therapeutic hypothermia
Neurology
(2009) - et al.
The syndrome of intention or action myoclonus as a sequel to hypoxic encephalopathy
Brain
(1963) - et al.
Good functional outcome after prolonged postanoxic comatose myoclonic status epilepticus in a patient who had undergone bone marrow transplantation
Case Rep Neurol Med
(2013)