Myoclonic status epilepticus in the elderly

Myoclonic status epilepticus (MSE) is a critical neurological condition in elderly patients, characterized by near-continuous myoclonus associated with epileptiform EEG abnormalities. Despite its clinical significance, its features, etiologies, and prognoses are still not well understood in this population. To describe the ictal semiology, polygraphic findings, etiology, and prognosis of elderly patients with MSE and to evaluate the correlation between etiology and prognosis, as well as the relationship between MSE duration and clinical outcomes.

A retrospective study was conducted on patients over 60 years old diagnosed with MSE between 2013 and August 2024. Clinical and electroencephalographic variables were analyzed, and statistical analysis was performed to assess correlations between etiology, MSE duration, and prognosis.

Twenty-seven patients with MSE were included, with a mean age of 77.6 ± 10.5 years, and 51.9% were female. Proximal myoclonus was observed in multiple regions, predominantly in the upper limbs and face. All patients exhibited bilateral frontocentral epileptiform or rhythmic EEG correlates of myoclonus. Etiologically, 9 cases involved hypoxic-ischemic encephalopathy (HIE), 15 were due to toxic-metabolic or infectious causes, and 3 were linked to neurodegenerative processes. Most patients with prolonged MSE (more than 72 h) required ICU admission, and complete recovery was achieved in 66.7% of cases. Mortality was observed in 9 patients, all of whom had refractory, prolonged MSE and were treated in the ICU. Significant correlations were found between etiology and prognosis, and between MSE duration and clinical outcomes (p < .001).

This study highlights two patterns of MSE in a case series of elderly patients: toxic-metabolic MSE, associated with a favorable prognosis, and HIE-associated MSE, which was refractory and linked to high mortality. These findings emphasize the importance of early etiological identification in guiding treatment and defining prognosis in elderly patients with MSE.