Abstracts

Rationale: To present a case of myoclonic status epilepticus associated with hyperammonemia in whom ICU EEG changes are representative of ammonia level. Myoclonic status epilepticus (MSE) is defined as prolonged continuous or discontinuous clusters of epileptic myoclonus, with or without impairment of consciousness. Myoclonic status epilepticus has been described in generalized epilepsy syndromes, neurodegenerative diseases, infectious or inflammatory neurologic diseases, toxic-metabolic states, and anoxic brain injury. Though hyperammonemia is known to be associated with diffuse periodic discharges on EEG, often with triphasic morphology, it is rarely implicated as a cause for refractory myoclonic status epilepticus.

Methods: We present a case of myoclonic status with EEG changes correlating with ammonia level.

Results: A 47-year-old woman with PMH of CKD-3, Lupus, and gastric bypass presented to an outside facility with altered mental status. CT head without contrast showed no abnormalities. Labs were significant for elevated ammonia level (256 uMol/L) and elevated liver enzymes, AP 129, AST/ALT387/127, Total bilirubin of 2.2. The patient was hypotensive, requiring pressors, and intubated for airway protection. Ammonia trended down from 256 to 76 uMol/L. VEEG initially showed abundant, diffuse, periodic discharges with triphasic sharp-wave morphology at 1.5-2 Hz in long runs that worsened during arousal. Keppra was initiated. MRI brain and LP were unremarkable. The next day, EEG showed improvement with only occasional epileptiform discharges. On day 3, the patient was found to have facial, head and left arm jerking with EEG correlate of high amplitude diffuse polyspike and wave discharges in very long runs consistent with myoclonic status epilepticus. Ammonia was rechecked and was found to be 659. She was started on benzodiazepines, and the AED dose was increased. She continued to worsen, requiring midazolam, propofol drips, and AED’s Vimpat, Keppra. Ammonia continued to increase to 676. CRRT was started. The patient developed severe cerebral edema with herniation. Her family changed goals of care to comfort care and she later passed away.

Conclusions: High ammonia levels are thought to increase glutamate excitotoxicity even though the exact pathogenesis needs to be determined. At high levels, ammonia can cross the blood-brain barrier and is converted into glutamine which acts as an osmolyte and increases cerebral volume. Myoclonic status epilepticus is a rare complication of hyperammonemia with a poor prognosis due to complications like cerebral edema and multisystem failure. High vigilance for seizures with continuous EEG monitoring and prompt treatment of hyperammonemia and epileptiform EEG activity is of paramount importance to minimize the risk of fatal outcomes.

Funding: Please list any funding that was received in support of this abstract.: None.