Ataxia after severe head injury: the pathological substrate.

Ataxia is a common finding in patients who have recovered from severe head injury. This report delineates the clinical and pathological findings in a patient who recovered from a head injury but was left with ataxia of gait. A lesion of the superior cerebellar peduncle, demonstrated post mortem 2 1/2 years after injury, was the only explanation for the ataxia. This lesion is part of the spectrum of changes seen in diffuse axonal injury thought to be due to shearing forces which tear white matter at the time of the initial injury.