This is the case of a 75-year-old man treated with scheduled surgical clipping of a giant aneurysm at left internal carotid artery level. After surgery, a cranial CT scan performed revealed the presence of an image consistent with acute ischemia in the left frontal region. Twenty-four hours later, right side mydriasis was reported. This new finding prompted a new cranial CT scan that revealed the progression of ischemic phenomena with damage to the left middle and posterior cerebral artery territories (Fig. 1) with signs of intracranial hypertension and compression at brainstem level against the contralateral tentorium (Fig. 2), which would explain the midriasis of the right side. This is know as the Kernohan-Woltman notch phenomenon. Despite medical treatment, the option of decompressive craniectomy was ruled out, and the patient progressed to brain death.

Figure 1.

Progression ischemia at MCA territory.

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Figure 2.

Compression at brainstem against contralateral tentorium.

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