PMC6751912_01
Timeline picture of the clinical course of Patient #1(a 30-year-old woman) with hyperammonemic encephalopathy mimicking non-convulsive status epilepticus
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F1
Patient information and clinical findings are shown in Figure 1. In view of the alarmingly rising hyperammonemia (Figures 1 & 3), she was also started on hemodialysis that failed to provide any definite clinical benefits.
EEG obtained during an unresponsive episode (A) in a 30-year-old woman (Patient# 1) showed continuous, frontally dominant, generalized, 2.5 Hz sharp and wave discharges, with a triphasic morphology in some channels (e.g., Fz-Cz). Following intravenous administration of diazepam (B), there was complete resolution of this pattern, with the appearance of diffuse slowing in the theta range and movement artefacts (patient opened her eyes and withdrew her limbs to painful stimuli and then sat up in the bed and attempted to remove the electrodes) indicating arousal. (Low-frequency filter 0.3 Hz, high-frequency filter 50 Hz).
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F2
During the EEG recording (on day 3 of hospitalization), she was in coma with her eyes closed and there were continuous, generalized, 2.5 Hz sharp and slow wave discharges (Figure 2A) and she was transferred to the Neurology service. A diazepam (10 mg) trial resulted in the disappearance of the ictal sharp waves and she responded partially to painful stimuli by opening her eyes and localizing to pain (Figure 2B). On the subsequent day, she was again unresponsive and continuous EEG recording showed similar findings as observed in Figure 2A.
Marked worsening of hyperammonemia in relation to carbohydrate infusion that was provided as part of the standard treatment protocol for episodic hyperammonemic encephalopathy (mimicking non-convulsive status epilepticus) in a previously undiagnosed case (patient#1) of adult-onset citrullinemia. The plasma glucose and lactate values are in mmol/l.
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F3
Based on the finding of mild hyperammonemia (Figure 3) with a normal liver function test, valproate and topiramate were discontinued. In view of the alarmingly rising hyperammonemia (Figures 1 & 3), she was also started on hemodialysis that failed to provide any definite clinical benefits. Although dextrose infusion was discontinued, she died of worsening encephalopathy and refractory cerebral edema 15 days after admission possibly in the context of prior carbohydrate induced biochemical deterioration in citrin deficiency (Figure 3).
PMC6751912_02
Timeline picture of the clinical course of Patient #2 (a 19-year-old man) with hyperammonemic encephalopathy mimicking non-convulsive status epilepticus
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F4
Patient information and clinical findings are shown in Figure 4 for the timeline picture of the clinical course of patient#2. Patient information and clinical findings are shown in Figure 4 for the timeline picture of the clinical course of patient#2.
EEG obtained during an episode of hyperammonemic encephalopathy (A) with a plasma ammonia level of 105 micromol/l in a 19-year-old man (patient# 2) with a known diagnosis of arginase deficiency showed continuous, frontally dominant, generalized, 2.5 Hz sharp and wave discharges, similar to Figure 1A. Twenty hours following the standard treatment protocol for hyperammonemia that included infusion of dextrose and ammonia scavenger (B), he was conscious and alert and the corresponding EEG normalized to a posterior dominant alpha background rhythm without any ictal discharges. (Low-frequency filter 1 Hz, high-frequency filter 70 Hz).
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F5
During an episode of drowsiness triggered by high protein diet, his plasma ammonia was 105 micromol/l and EEG (Figure 5A) showed identical findings as in case#1. Pari passu, his EEG normalized to an alpha rhythm without any epileptiform, periodic or abnormal rhythmic discharges (Figure 5B).