Hyperammonemic Encephalopathy Associated with Perampanel: Case Report and Discussion
Bibliographic record
Abstract
Hyperammonemic encephalopathy (HE) can manifest with variable symptoms ranging from mild to severe such as lethargy, fatigue, seizure exacerbation, altered behavior, insomnia, impaired consciousness, gait instability, and flapping tremor.1,2,3 Valproate-induced HE has long been described, but can be under-recognized, as mild symptoms can mimic side effects of antiepileptic drugs (AEDs).Hyperammonemia may occur even if serum valproic acid (VPA) levels are within the reference range with normal or slightly elevated liver enzymes serum levels.2,3 Other AEDs have rarely been associated with HE.Adding Levetiracetam (LEV), Phenobarbital (PB), or Topiramate (TPM) to a patient already taking VPA has been reported to trigger HE. 1,4,5 TPM, in particular, may increase that risk 10-fold 5 Moreover, there are case reports describing HE in patients taking Carbamazepine (CBZ) either as monotherapy or in combination with other AEDs, 6 and with TPM monotherapy.7 We report a case of HE associated with Perampanel (PER).The patient is a 27-year-old male with a history of autism, microcephaly, developmental delay, and seizures associated with an 11 Mb pathogenic 8p23.3p23.1 deletion, involving CLN8, ARHGEF10, MCPH1, and RP1L1 genes.There was no family history of epilepsy, autism, or developmental delay.He was the product of a normal pregnancy and uncomplicated delivery at 36 weeks.His seizures began at the age of 8 years, consisting of focal onset with impaired awareness, evolving to bilateral tonicclonic convulsions.The focal symptoms were characterized by staring, cyanosis of the lips, frothing, and eye fluttering.He had several hospital admissions due to status epilepticus.At the age of 15 years, his seizures stopped on a combination of TPM 500 mg/ day and CBZ 800 mg/day.After 12 years of seizure freedom, antiepileptic drug tapering was attempted.CBZ was successfully weaned, but after reducing TPM his seizures recurred.CBZ was reintroduced, TPM was increased and lastly, phenytoin was added after one emergency room visit.As seizures did not abate, 8 months after adding phenytoin, PER was added and titrated up to 4 mg/day.One month after adding PER, his mother reported he was drowsy, fatigued, and began to have events described as "collapsing" episodes where he would lose consciousness and fall, with few associated jerks.His mother described these events as clearly different from his previous seizures.He was admitted to the hospital where blood work showed increased levels of ammonia: 139 umol/L (11-35) and slightly elevated liver enzymes (AST: 69 U/L [7-40], ALP: 92 U/L [40-150]).He was then transferred to the Epilepsy Monitoring Unit (EMU).During video EEG monitoring, two of his typical focal onset seizures with impaired awareness were recorded, without clear localization or lateralization on EEG.He also experienced one "collapsing" episode in the EMU, witnessed by a nurse, and
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.002 | 0.002 |
| Bibliometrics | 0.004 | 0.003 |
| Science and technology studies | 0.004 | 0.003 |
| Scholarly communication | 0.003 | 0.005 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.012 | 0.007 |
| Insufficient payload (model declined to judge) | 0.005 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".