Kernohan-Woltman notch phenomenon: an unusual cause of ipsilateral motor deficit

Posttraumatic ipsilateral motor deficits are rare and raise etiologic and prognostic concerns for the rehabilitation team. We present two cases with an unusual central neurologic cause of ipsilateral weakness. The first patient was assaulted, with a resultant severe traumatic brain injury. Initial computed tomography showed a large right subdural hematoma (SDH) with significant mass effect. Following a craniotomy for evacuation of the SDH, the patient was noted to have paradoxical right-sided (ipsilateral) motor deficits. Postoperative magnetic resonance imaging (MRI) showed compression of the contralateral (left) cerebral peduncle against the tentorium, thus resulting in ipsilateral (right-sided) motor weakness (the Kernohan-Woltman notch phenomenon). Prior limited reports carried a grave prognosis for these patients. On discharge from inpatient rehabilitation, the patient was functioning at a Rancho Los Amigos Scale VI. The second patient was involved in a motor vehicle accident and was found to have a large left frontotemporal subdural hematoma with shift. A dense left hemiplegia was noted after hematoma evacuation. MRI also showed a right cerebral peduncle hypointensity. At discharge, the patient was rated a Rancho Los Amigos Scale VI. Physiatrists need to be aware of the causes of ipsilateral motor weakness as well as the limitations of prognostic data.