Masanobu Hokama

Noninvasive cerebral optical spectroscopy: Depth-resolved measurements of cerebral haemodynamics using indocyanine green

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 detectors 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.

Transradial approach for selective cerebral angiography: technical note.

Abstract Selective cerebral angiography is currently being performed using transfemoral and transbrachial approaches. However, these techniques require patients to tolerate a prolonged focal compression and sometimes cause serious complications such as pulmonary embolism. The authors describe a technique of transradial approach as a safer selective cerebral angiography. Between July 1997 and November 1998, 70 patients underwent selective cerebral angiography with a transradial approach using a 4-F catheter. The collateral blood supply to the hand from the ulnar artery was confirmed using Allen’s test prior to the procedure. To prevent the mechanical spasm of the radial artery, an arterial introducer 20 cm long was used. The radial artery was successfully punctured and cannulated in all patients. Selective catheterization of the intended vessels was obtained In over 98% of the carotid angiography and over 95% of the vertebral angiography. No major vascular complications such as cerebral infarction, upper limb ischemia, significant local hematoma or pseudoaneurysm were experienced. The transradial approach is a less invasive and safer technique for selective cerebral angiography, and could be an alternative to transfemoral and transbrachial approaches. [Neurol Res 2000; 22: 605-608]

Surgical approaches to the anterior communicating artery aneurysm and their results.

In the past 12 years, 102 cases of anterior communicating artery aneurysm have been operated upon in our institution. Two basic microsurgical approaches (pterional and interhemispheric) were used. The combined pterional and interhemispheric approach was performed in a few cases. The rational for each surgical approach is discussed in relation to anatomical factors such as the height of the aneurysm neck, the side of dominance of A1, the relationship between the bilateral proximal parts of A2s, and the projection of the aneurysm. The final outcome was correlated to the preoperative clinical grading and timing of surgery. The overall results were as follows; 82.4% good, 5.9% fair, 4.9% poor, and 6.8% mortality rate. The operative results for pterional and interhemispheric approach were comparable with each other. In the combined approach, we got poorer results which could be related to excessive brain retraction and unfavourable clinical grading.

Microsurgical anatomy of the ophthalmic artery and the distal dural ring for the juxta–dural ring aneurysms via the pterional approach

Abstract Microsurgical anatomy for the pterional approach was studied regarding the origin and the course of the ophthalmic artery and the distal dural ring using human cadaveric specimens, with special reference to the surrounding bony structures. In 50 human adult formalin-fixed cadaveric cerebral hemispheres and 10 block specimens of the skull base region including the ophthalmic artery and the carotid dural ring were examined under magnification using an operating microscope. The ophthalmic artery originated from the intradural portion of the internal carotid artery (ICA), except in 5% where the ophthalmic artery originated extradurally. The extradural origin had two patterns: one was that the ophthalmic artery penetrated the bony optic strut (trans-optic strut pattern) and the other was that it coursed into the optic canal proximally to the optic strut without bone penetration (supra-optic strut pattern). The origin of the intradural ophthalmic artery was commonly located at the medial third of the superior wall of the ICA (78%). The ophthalmic artery was commonly taking an S-shaped course in the intradural portion and entered the optic canal over the optic strut. The distal dural ring was tightly adherent to the internal carotid artery; circumferential sectioning of the dural ring is required to mobilize the internal carotid artery. When approaching juxta– dural ring ICA aneurysms via the pterional route, it is important to recognize the extradural origin, especially the trans-optic strut type, and to precisely understand the microsurgical anatomy around the dural ring.

A classification of juxta-dural ring aneurysms with reference to surgical anatomy.

We report a subgroup of internal carotid artery (ICA) aneurysms located near the carotid ring which we call juxtadural ring aneurysms. These aneurysms are classified into three types: paraclinoid intradural, carotid cave and infraclinoid extradural aneurysms. The paraclinoid intradural aneurysms arise from the ICA distal to the origin of the ophthalmic artery and are close to the dural ring, which may include some so-called carotid-ophthalmic aneurysms. The carotid cave aneurysms are located in the carotid cave which is seated in the infraclinoid carotid groove and proximal to the origin of the ophthalmic artery. They are located at the angiographical genu and in the intradural space anatomically. The infraclinoid extradural aneurysms are located close to the dural ring extradurally in the infraclinoid carotid groove sinus, a peripheral venous space of the cavernous sinus. The infraclinoid extradural aneurysms should be differentiated from aneurysms in the cavernous sinus, because they are located in the infraclinoid carotid groove sinus.

Remote-control vascular occluder: technical note.

We have designed a new remote-control vascular occluder for the temporary control of arterial blood flow. It is a modification of the biopsy forceps used in stereotactic surgery. The arm of the occluder is flexible and can be set so that it does not disturb the surgeons view. The occluder is positioned with the blades open on the vessel to be occluded. This device, which is held with a self-retaining retractor connected to the head frame, enables an immediate on-off remote control of arterial occlusion by closing and releasing the blades with a closing button and releasing lever, respectively. Partial closure of the blades is also feasible. The device can be set in a narrow operating field, when proximal control of a parent artery is necessary at its segment distant from the exposed operating field. It can be used in a variety of vascular cases, including giant aneurysms and large arteriovenous malformations.