Acute Metabolic Crisis in Maple Syrup Urine Disease, a Rare but Life-Threatening Neurocritical Care Emergency: Case Report

<title>Abstract</title> <p>Background Maple syrup urine disease (MSUD) is a rare, autosomal recessive disorder characterized by a deficiency in the branched-chain alpha-keto acid dehydrogenase enzyme complex necessary for metabolizing the three branched-chain amino acids (BCAAs): leucine, isoleucine, and valine. Periods of stress and illness can cause patients to experience sudden metabolic crises. We present a rare but important case of an adult patient with MSUD in crisis who was admitted to our Neurologic Intensive Care Unit (NeuroICU) with encephalopathy, cerebral edema, and seizures triggered by sepsis. Case presentation A 49-year-old male with MSUD presented to the hospital with encephalopathy, which progressively worsened during his admission. The patient was diagnosed with sepsis, which thereafter triggered an MSUD crisis requiring transfer to the NeuroICU. Continuous EEG revealed focal seizures in the left frontal region, which were suppressed using a midazolam infusion. A head CT revealed cerebral edema, and an MRI demonstrated extensive DWI hyperintensity throughout the bilateral cerebral cortices and deep nuclei with ADC correlate. Despite dietary modifications, the patient continued to have elevated BCAA levels. Therefore, continuous renal replacement therapy (CRRT) was initiated and titrated to control BCAA levels. These BCAA levels were monitored daily while the underlying triggers were corrected. Over four weeks, the patient’s condition improved to his neurological baseline, and he was subsequently discharged home. Conclusion Our case emphasizes the importance of understanding the neurological complications associated with an MSUD crisis--which include seizures, cerebral edema, and coma–as well as highlights CRRT as an effective method for correcting metabolic disturbances in adults with MSUD. Additionally, it highlights that extensive diffusion restriction (DWI hyperintensity) with an ADC correlate is not helpful in neurologic recovery prognostication. Intense multidisciplinary collaboration amongst nutrition, genetics, metabolic, nephrology, pharmacy, and NeuroICU teams aimed at developing effective strategies to reduce BCAA levels and prevent drug interactions was crucial to patient recovery.</p>