UMEM Educational Pearls

Category: Neurology

Title: What's the cause of this patient's hemiplegia?

Keywords: Uncal herniation, ipsilateral hemiplegia, Kernohan's notch, Kernohan's sign (PubMed Search)

Posted: 8/10/2016 by WanTsu Wendy Chang, MD
Click here to contact WanTsu Wendy Chang, MD

Question

Patient presents after a fall confused, not moving his right side, but moving his left side spontaneously. What's the diagnosis?

Answer

The patient has a right subdural hematoma (SDH) with midline shift and right uncal herniation.
The classic presentation of a cerebral lesion with uncal herniation is ipsilateral mydriasis, contralateral hemiparesis, and abnormal extensor posturing.
In this patient’s case, there is compression of the contralateral cerebral peduncle of the midbrain by the edge of the tentorium cerebelli producing an ipsilateral hemiplegia (see attachment for Figure 2).
This false localizing sign is named Kernohan’s notch syndrome, Kernohan’s notch phenomenon, or Kernohan’s sign.

References

Diagram modified from "Localised Neurological Disease and Its Management A Intracranial". clinicalgate.com/localised-neurological-disease-and-its-management-a-intracranial/. Accessed 10 Aug 2016.

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Attachments

1608101928_20160810_Figure_2.jpg (38 Kb)