SHM Converge Scientific Abstract ePoster Gallery-A Rare Flashback to Med School Biochemistry: An Adult Case of Leucine Encephalopathy in Maple Syrup Urine Disease

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This case report describes a 23-year-old man with classic maple syrup urine disease (MSUD) who presented with 3 days of vivid nightmares and hallucinations. MSUD is a rare inborn error of metabolism caused by deficiency of the enzyme that breaks down the branched-chain amino acids leucine, isoleucine, and valine. When untreated, accumulation of these amino acids can lead to severe neurotoxicity, including cerebral edema, brain herniation, and death. Acute decompensation is typically managed with glucose infusion and temporary protein restriction.<br /><br />Although the patient denied abdominal pain, vomiting, imbalance, or other neurologic deficits, his symptoms raised concern for leucine encephalopathy. Pediatric Genetics was consulted immediately. Because confirmatory plasma amino acid testing would take 24–36 hours, the team began empiric MSUD metabolic intoxication treatment right away.<br /><br />The treatment protocol included IV 10% dextrose in normal saline, insulin or rescue glucose to maintain serum glucose in target range, IV lipids, complete protein restriction for 24 hours followed by a low-protein diet, daily plasma amino acids, frequent urine ketone checks, neurologic monitoring, and continuation of his home MSUD supplement.<br /><br />Throughout hospitalization, beta-hydroxybutyrate and urine ketones remained normal, and the patient’s hallucinations and nightmares resolved after treatment began. His neurologic exam remained normal, with no ataxia or focal deficits. Plasma leucine levels decreased steadily from 463 nmol/mL on admission to 353 at 24 hours, 205 at 48 hours, and 72 at 72 hours. He was discharged after 72 hours once symptoms resolved and leucine normalized.<br /><br />The case emphasizes that in MSUD patients with neurologic symptoms suggestive of leucine intoxication, urgent expert consultation and immediate treatment are critical to prevent permanent neurologic injury or death.

Asset Subtitle

Brad L. Manning

Meta Tag

Author List Brad L. Manning

Category Clinical Vignettes

Concept Maple Syrup Urine Disease

Concept Branched-Chain Amino Acid Catabolism

Concept Metabolic Decompensation

Concept Leucine

Concept Leucine Encephalopathy

Distinguished Non-Finalist

Presenter Organization University of Iowa Hospitals and Clinics

Presenting Author Brad L. Manning

Track Adult

Keywords

maple syrup urine disease

MSUD

leucine encephalopathy

hallucinations

nightmares

branched-chain amino acids

metabolic decompensation

protein restriction

plasma amino acids

neurologic toxicity

Maple Syrup Urine Disease

Branched-Chain Amino Acid Catabolism

Metabolic Decompensation

Leucine

Leucine Encephalopathy