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Sensory‐motor polyneuropathy occurring in variant maple syrup urine disease
Author(s) -
Harty S.,
King M. D.,
McCoy B.,
Costigan D.,
Treacy E. P.
Publication year - 2008
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1007/s10545-008-0751-y
Subject(s) - maple syrup urine disease , decompensation , medicine , thiamine , endocrinology , biochemistry , leucine , chemistry , amino acid
Summary Maple syrup urine disease (MSUD; OMIM 248600) results from an inherited deficiency of the branched‐chain ketoacid dehydrogenase (BCKD) complex. Approximately 20% of patients with BCKD deficiency are non‐classic variants of MSUD with differing clinical severity. Outcomes for this cohort are generally favourable; episodes of metabolic decompensation do not appear to correlate with adverse events if acute management is promptly provided. A case of predominantly axonal sensory‐motor neuropathy following metabolic decompensation which persisted for a number of months is presented in an adolescent girl with variant (intermediate type) MSUD. EMG and nerve conduction studies suggested a pre‐existent asymptomatic chronic neuropathy, exacerbated by the acute decompensation. Peak leucine concentration at decompensation was 1083 μmol/L. The patient had laboratory signs of secondary mitochondrial respiratory chain dysfunction at presentation. She had been on a moderate dose of thiamine prior to decompensation; thiamine and pyridoxine blood concentrations were normal. This, to our knowledge, is the first report of a neuropathy presenting in a patient with a decompensation of variant MSUD. We propose that this presentation resembles the intermittent neuropathy observed in pyruvate dehydrogenase deficiency and may reflect secondary inhibition of pyruvate dehydrogenase activity by MSUD metabolites.