Acute, reversible axonal energy failure during stroke-like episodes in MELAS.

The pathophysiology of stroke-like episodes in MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) remains unresolved. Possible mechanisms include mitochondrial angiopathy, cytopathy, or both, collectively resulting in cellular energy depletion. To clarify disease mechanisms, axonal excitability properties were investigated in a 10-year-old child with MELAS. Serial assessments during a stroke-like episode revealed reversible depolarization of the axonal membrane consistent with disruption of energy-dependent processes. Axonal parameters correlated with the clinical assessment of central dysfunction and biochemical measures of acidosis. Novel axonal excitability techniques have established acute, reversible ischemic-like depolarization that may serve as a surrogate marker of central events that develop during stroke-like episodes in MELAS.