Saccular aneurysms arising at locations other than at arterial divisions are extremely rare. The authors describe eight such aneurysms that protruded from the dorsal wall of the internal carotid artery (ICA) and were unrelated to any arterial junction. Radical surgery was performed in all eight cases. The aneurysms were saccular with a fragile wide or semifusiform neck. Intraoperative rupture occurred in three cases. From this experience, it is emphasized that these unusual protruding aneurysms of the dorsal ICA should be clipped with the clip blade parallel to the parent artery. In addition to clipping, complete wrapping with fascia or Bemsheet (cellulose fabric) is often advisable to prevent slippage of clips or postoperative rupture of residual aneurysm.

To investigate the feasibility of a newly developed, near-infrared optical spectroscopy device, we analysed measurements of the infrared tracer indocyanine green (ICG) using sensors with a single near infrared light source and multiple light detectors. Two ml of ICG dye, 1.0 mg ml-1 in concentration, were injected into the internal carotid artery during cerebral angiography in 14 adult patients. The resultant washout curves were measured bilaterally using sensors with 4 detectors spaced at 10, 20, 30 and 40 mm from the infrared light source on the right side, and 15, 25, 35 and 45 mm from the source for the left side, respectively. Washout curves were analysed to determine the relative amplitude of the ICG absorption signal and deduce each detector's penetration distance. When ICG was injected into the internal carotid artery, relative absorption increased with detector distance from the light source. No substantial difference in attenuation was observed in any of the detectors during external carotid injection of ICG. The resultant information related depth of penetration of the light with source-detector separation distances. The feasibility of the system for measuring cerebral oxygen saturation and haemodynamics noninvasively or monitoring at bedside is discussed.

Direct surgery for intra-axial lesions of the brain stem is considered a hazardous procedure, and morbidity of varying degrees cannot be avoided even with partial removal or biopsy. The main causes of morbidity relate to direct damage during removal of the lesion, selection of an entry route into the brain stem, and the direction of brain stem retraction. The authors examined the possibility of making a medullary incision and retracting the brain stem, taking into account the symptomatology and surgical anatomy, and found two safe entry zones into the brain stem through a suboccipital approach via the floor of the fourth ventricle. These safe entry zones are areas where important neural structures are less prominent. One is the "suprafacial triangle," which is bordered medially by the medial longitudinal fascicle, caudally by the facial nerve (which runs in the brain-stem parenchyma), and laterally by the cerebellar peduncle. The second is the "infrafacial triangle," which is bordered medially by the medial longitudinal fascicle, caudally by the striae medullares, and laterally by the facial nerve. In order to minimize the retraction-related damage to important brain-stem structures, the brain stem should be retracted either laterally or rostrally in the suprafacial triangle approach and only laterally in the infrafacial triangle approach. Three localized intra-axial brain-stem lesions were treated surgically via the safe entry zones using the suprafacial approach in two and the infrafacial approach in one. The cases are described and the approaches delineated. Both approaches are indicated for focal intra-axial lesions located unilaterally and dorsal to the medial lemniscus in the lower midbrain to the pons. Magnetic resonance imaging is useful in selecting these approaches, and intraoperative ultrasonography is helpful to confirm the exact location of a lesion before a medullary incision is made. These approaches can also be used as routes for aspiration of brain-stem hemorrhage as well as for tumor biopsy.

The tumor growth rate of residual NFPAs is strongly influenced by the patient's age. The TVDT in elderly patients is much longer than that previously reported. Treatment strategies that take into consideration the natural history of residual adenomas should be established especially in the elderly population.

This review summarizes the presentation and outcome of a large series of 24 patients with 27 distal PICA aneurysms, and we conclude that distal PICA aneurysms are benign entities compared with vertebral artery-PICA aneurysms. Characteristics that should be considered in the treatment of distal PICA aneurysms are discussed.