BACKGROUND Posterior cerebral artery (PCA) dissecting aneurysms commonly occur in the proximal PCA and are considered rare. The treatment of proximal PCA dissecting aneurysms is challenging because of the existence of perforators supplying the vital neural structures. Recently, endovascular intervention has been used; however, concerns for ischemic or hemorrhagic complications exist. OBSERVATIONS A 54-year-old woman presented with subarachnoid hemorrhage due to dissecting aneurysm rupture at the P1-P2 junction of the PCA. The thalamoperforating artery (TPA) and medial posterior choroidal artery (MPchA) originated from the proximal end and the distal end of the aneurysm, respectively. Additionally, the posterior communicating artery (PcomA) connected with the dissected segment. To preserve these perforators, we performed surgical trapping combined with superficial temporal artery (STA) PCA anastomosis. Clips were applied for trapping the proximal and distal end of the aneurysm, with preservation of the TPA and MPchA origin. PcomA was left open for blood flow preservation to the perforators directly arising from the aneurysm. The postoperative course was uneventful, and the patient was discharged. LESSONS Surgical trapping using STA-PCA bypass could be a treatment of choice for proximal PCA dissecting aneurysms, considering its potential for cure and prevention of ischemic complications.

A method of designing a digital hearing aid for speech signal suitable for sensorineural hearing loss with a narrow audible range is proposed. First, the input signal is divided into short time blocks (8 ms) and its spectrum is analyzed using short-time FFT. Then the frequency-gain characteristic of the digital filter for the block is determined using loudness compensation functions that describe the relation between the loudness of normal listeners and that of impaired listeners, so that the input signal within the block is projected on to the dynamic range of the subject. This algorithm is realized using a digital signal processor (DSP). The results of monosyllabic intelligibility tests to evaluate the performance of the system for six sensorineural impaired listeners are also shown. [Work supported by Grant-in-Aid for Scientific Research from the Ministry of Education and the Ministry of Public Welfare.]