Perimesencephalic nonaneurysmal subarachnoid hemorrhage with unilateral third cranial nerve palsy: two case reports.

Perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSAH) is a benign form of subarachnoid hemorrhage and is usually not associated with any focal deficit. We describe two rare cases of PNSAH with unilateral third cranial nerve palsy. Both patients were treated conservatively. The outcomes of our two cases were excellent. The third cranial nerve palsy resolved gradually in both patients, suggesting that the prognosis for third cranial nerve palsy concomitant with PNSAH is favorable. Unilateral third cranial nerve palsy may occur as the first clinical manifestation of PNSAH.