2026 American Academy of Neurology Abstract Website

Objective:

This case report discusses an adult patient without developmental delay who developed acute-onset quadriparesis (proximal > distal) with dysarthria and postural instability, representing an atypical late-adolescent presentation that expands the recognized age spectrum of Pyruvate Dehydrogenase Complex Deficiency (PDCD).

Background:

PDCD is a rare mitochondrial disorder with presentations ranging from fatal neonatal lactic acidosis and severe neurodegeneration to milder chronic neurological deficits later in life. The condition results from impaired oxidative decarboxylation of pyruvate, leading to lactic acidemia. Mutations in PDHB gene account for a minority of PDCD cases and usually manifest in infancy with developmental delay, hypotonia, and characteristic neuroimaging abnormalities. This case reviews an 18-year-old male born to a second-degree consanguineous marriage with no prior neurological deficits or developmental delay, who presented with acute-onset generalized weakness, dysarthria and postural instability following a febrile illness. This demonstrates a late atypical manifestation of PDHB-related PDCD.

Design/Methods:

N/A

Results:

Examination revealed cerebellar dysarthria, proximal weakness, hypotonia, areflexia, and bilateral hammer toes. Complete blood count was remarkable for mild leukocytosis. Infectious, autoimmune, and neuromuscular workups were unremarkable. MRI Brain demonstrated bilateral dentate nucleus signal changes with acute-on-chronic hypertrophic olivary degeneration, suggestive of a mitochondrial etiology. Whole-exome sequencing identified compound heterozygous PDHB variants in trans, consistent with PDHB-related PDCD. Mitochondrial genome sequencing was negative for large deletions. The patient was treated with a mitochondrial cocktail and a modified ketogenic diet.The patient improved clinically over 3–4 days. Residual proximal weakness persisted at discharge, but continued to improve with dietary management and physical therapy. One month follow-up MRI Brain showed resolution of dentate changes and olivary degeneration.

Conclusions:

This case emphasizes the need to consider PDCD as a differential diagnosis for neurological presentations not only during infancy and early childhood, but also during adolescence and adulthood. Further investigation can be done regarding causes of late presentation of this condition.