Diagnosis
Because of the ipsilateral characteristic of Kernohan's notch, diagnosis is unique. Many clinicians assume a right sided paralysis corresponds with an injury in the left hemisphere of the brain and misdiagnose Kernohan's notch. Despite this complication that ipsilateral paralysis causes, it makes it very easy to diagnose when coupled with imaging techniques. For example, when seeing an MRI of a blood clot on the left side of the brain coupled with left-sided paralysis, it immediately points to Kernohan's notch.
In most head trauma cases, CT scans are the standard diagnostic method; however it is not ideal for imaging small lesions, so MRI is used to identify Kernohan's notch. It is important to distinguish Kernohan's notch from direct brain stem injuries. Case studies have shown that in patients with chronic subdural hematoma, a compressive deformity of the crus cerebri without an abnormal MRI signal may predict a better recovery in patients with Kernohan's notch.
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