Occipital-posterior cerebral artery bypass via the occipital interhemispheric approach
A 70-year-old male with a previous history of bilateral MCA occlusion treated with STA-MCA bypass 20 years ago presented to the emergency room with 3 days of vertigo and nausea. Significant neurological examination findings on admission included horizontal nystagmus and right extremity ataxia. Magnetic resonance imaging (MRI) revealed infarction on the right middle cerebellar peduncle on diffusion-weighted imaging (DWI) as well as poor visualization of the basilar artery. Angiography revealed right VA occlusion and a left VA terminating in a PICA []. Collateral circulation was identified in the distal basilar artery via the diminutive posterior communicating artery of the stenotic right internal carotid artery []. The patient’s level of consciousness decreased to semicoma, and the area of infarction in the cerebellar peduncle and left occipital lobe was noted to have increased. There was a reduction in regional cerebral blood flow (rCBF) in the posterior fossa on N-isopropyl-123I-p-iodoamphetamine (IMP) and single photon emission computed tomography (SPECT). The patient underwent right OA-PCA bypass at 26 days after hospital admission []. His consciousness improved postoperatively, and no further deterioration was observed either in clinical status or on imaging studies. Postoperative angiography revealed patency of the bypass []. He was transferred to a rehabilitation hospital 2 months later with a modified Rankin Scale (mRS) score of 3.