We report the case of a 67-year-old man who developed acute HE due to alcohol-related cirrhosis, who was admitted in a comatose state with hyperammonaemia (peak level, 321 μmol/L). The patient was sedated (propofol 100 mg/hr), intubated, and transferred to the intensive care unit (ICU). Shortly after admission to the ICU, the patient experienced episodes of left brachiofacial myoclonus. Electroencephalogram (EEG) revealed progressive epileptiform activity culminating in refractory MSE with persistent seizures despite treatment with benzodiazepines (midazolam 10 mg, lorazepam 4 mg twice) and intravenous levetiracetam (initial dose of 2,000 mg, followed by 1,500 mg twice daily). According to the American Clinical Neurophysiology Society guidelines, the initial EEG revealed a background slowing and brief potentially ictal rhythmic discharges in the right posterior region, which on day 3 progressed to lateralized periodic discharges fluctuating between 1.5 and 3 Hz, consistent with an ictal-interictal continuum and suggestive of nonconvulsive status epilepticus without motor manifestations at that time. Sedation (propofol 100 mg/hr and midazolam 5 mg/hr) was subsequently increased. On day 4, continuous EEG monitoring revealed a burst suppression pattern coupled with epileptiform discharges time-locked with myoclonus, consistent with MSE featuring a seizure suppression pattern. MRI revealed diffuse and symmetrical cortical lesions (Fig. 1). Following lactulose therapy, hyperammonaemia was almost completely resolved by day 4 (71.2 µmol/L) and fully normalised by day 6 (44.9 µmol/L). On day 5, intravenous lacosamide was initiated (400 mg, followed by 100 mg twice daily), and sedation was tapered to minimise hepatic drug accumulation. The persistence of refractory MSE raised concerns for poor prognosis. The patient achieved marked and sustained electroclinical improvement with a lag of 9 days following hyperammonaemia correction. The imaging abnormalities regressed progressively. A summary of the timeline is illustrated in Fig. 2. Although diffuse cortical lesions are generally considered as markers of disease severity, their reversibility has been documented [1]. The observed bioclinical lag may result from the delayed resolution of neurotransmitter imbalance and cerebral oedema, although a definitive cause-and-effect relationship between cerebral oedema and HE-associated seizures has not been established [1].

This case highlights that in the context of HE, the initial clinical severity marked by refractory MSE and diffuse cortical lesions should not preclude supportive management. Prognostication must be approached with caution given the potential for a substantial lag between ammonia level correction and clinical recovery.