Neuropsychological findings in a patient with Kernohan's notch

This case report describes the use of neuropsychological testing to Iocalize and diagnose lesions The testing was instrumental in disentangling contradictory symptoms to reveal a Kernohan's notch (later confirmed by MRI), thus ruling out incorrect diagnoses We describe the case of a 36-year-old right-handed man who developed a left epidural hematoma after suffering head trauma from a blunt instrument Sequelae 2 months post-injury included left hemiparesis (ipsilateral to the lesion), dysphonic speech, severe naming/word-finding deficits, and severe memory impairment This patient's symptom pattern presented somewhat of a mystery as his cognitive deficits appeared consistent with left hemisphere damage, while his left motor symptoms suggested right hemisphere damage Medical records were inconsistent Deficits on neuropsychological testing at 3 months post-injury included impairment in verbal and visual memory, confrontation naming, and left-sided motor function Attention, visual-spatial skills, nonverbal problem solving, and right motor speed and coordination were intact A herniation syndrome, Kernohan's notch, was considered to be the most likely explanation This phenomenon occurs when a mass occupying lesion causes significant midline shift of the midbrain, pressing the contralateral cerebral peduncle against the tentorium This pressure produces an ischemic infact in the region of the corticospinal (motor) pathways Subsequent MRI confirmed a lesion in the right cerebral crus The pattern of neuropsychological finding in this patient is discussed.