Hindawi Publishing Corporation Case Reports in Medicine Volume 2013, Article ID 296874, 3 pages http://dx.doi.org/10.1155/2013/296874 Case Report Kernohan’s Notch: A Forgotten Cause of Hemiplegia—CT Scans Are Useful in This Diagnosis Ragesh Panikkath, Deepa Panikkath, Sian Yik Lim, and Kenneth Nugent Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA Correspondence should be addressed to Ragesh Panikkath; drrageshp@gmail.com Received 19 April 2013; Revised 2 July 2013; Accepted 8 October 2013 Academic Editor: John Kortbeek Copyright © 2013 Ragesh Panikkath et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Hemiparesis ipsilateral to a cerebral lesion can be a false localizing sign. his is due to midline shit of the midbrain resulting in compression of the contralateral pyramidal ibers on the tough dural relection tentorium cerebelli. his may result in partial or complete damage to these ibers. Since these ibers are destined to cross in the medulla and innervate the opposite side of the body, this causes hemiparesis ipsilateral to the site of cerebral lesion. Computed tomography (CT) scans have not been used to support the diagnosis of this entity until now. We report a 68-year-old woman with a subdural hematoma who developed ipsilateral hemiparesis without any other explanation (Kernohan’s notch). he CT of the head showed evidence of compression of the midbrain contralateral to the hematoma and was useful in the diagnosis. he purpose of this report is to increase the awareness of this presentation and to emphasize the utility of CT scans to support the diagnosis. 1. Introduction Hemiparesis ipsilateral to the site of a cerebral lesion has been called Kernohan’s notch. his sign (originally described at autopsy) has been reported with cerebral tumors, subdural hematomas (SDH), and extradural hematomas with midline shit. Recently magnetic resonance imaging (MRI) has been used for this diagnosis in appropriate clinical situations; indirect supportive evidence for this sign has not been described utilizing the more commonly available computed tomography (CT) imaging. 2. A Case Report We report a 69-year-old woman with Alzheimer’s disease and recurrent falls who presented in a comatose state. A CT scan of the head showed a large right subdural hematoma with a midline shit of 18 mm. She underwent urgent neurosurgical evacuation of the subdural hematoma. Her consciousness gradually recovered, but she had right hemiplegia. An MRI did not show any let-sided infarcts which would explain this. Since her hemiplegia was ipsilateral to the side of the subdural hematoma, the possibility of Kernohan’s notch was considered. Gross deviation of the crura of the midbrain to the let side was noted on detailed review of the CT scan of the head done prior to the evacuation of the hematoma (Figure 1). A CT of head ater craniotomy and evacuation of subdural hematoma showed persistent deformity of the midbrain (Figure 2). he MRI images also showed evidence of a shit of the midbrain to the let with hyperintensity in the midbrain in the region of compression. he clinical picture of ipsilateral weakness in a patient with a subdural hematoma, evidence of compression of the midbrain in the CT and MRI of the brain, and the absence of any infarcts on the contralateral side in difusion weighted T1 and T2 sequences of MRI conirmed our suspicion of Kernohan’s notch. 3. Discussion he corticospinal tracts originate in the motor cortex in the frontal lobes and descend through the internal capsules and subsequently through the midbrain and pons, before the majority of the ibers (80%) decussate in the medulla. Due to this decussation, the let cerebral motor cortex controls the movements of the right-side of the body and vice versa. In the midbrain, the pyramidal tract courses anteriorly in the