Kyouichi Suzuki

Blood flow disturbance in perforating arteries attributable to aneurysm surgery

OBJECT The object of this study was to investigate patients with cerebral infarction in the area of the perforating arteries after aneurysm surgery. METHODS The authors studied the incidence of cerebral infarction in 1043 patients using computed tomography or magnetic resonance imaging and the affected perforating arteries, clinical symptoms, prognosis, and operative maneuvers resulting in blood flow disturbance. RESULTS Among 46 patients (4.4%) with infarction, the affected perforating arteries were the anterior choroidal artery (AChA) in nine patients, lenticulostriate artery (LSA) in nine patients, hypothalamic artery in two patients, posterior thalamoperforating artery in five patients, perforating artery of the vertebral artery (VA) in three patients, anterior thalamoperforating artery in nine patients, and recurrent artery of Heubner in nine patients. Sequelae persisted in 21 (45.7%) of the 46 patients; 13 (28.3%) had transient symptoms and 12 (26.1%) were asymptomatic. Sequelae developed in all patients with infarctions in perforating arteries in the area of the AChA, hypothalamic artery, or perforating artery of the VA; in four of five patients with posterior thalamoperforating artery involvement; and in two of nine with LSA involvement. The symptoms of anterior thalamoperforating artery infarction or recurrent artery of Heubner infarction were mild and/or transient. The operative maneuvers leading to blood flow disturbance in perforating arteries were aneurysmal neck clipping in 21 patients, temporary occlusion of the parent artery in nine patients, direct injury in seven patients, retraction in five patients, and trapping of the parent artery in four patients. CONCLUSIONS The patency of the perforating artery cannot be determined by intraoperative microscopic inspection. Intraoperative motor evoked potential monitoring contributed to the detection of blood flow disturbance in the territory of the AChA and LSA.

Confirmation of blood flow in perforating arteries using fluorescein cerebral angiography during aneurysm surgery

OBJECT The authors performed fluorescein cerebral angiography in patients after aneurysm clip placement to confirm the patency of the parent artery, perforating artery, and other arteries around the aneurysm. METHODS Twenty-three patients who underwent aneurysm surgery were studied. Aneurysms were located in the internal carotid artery in 12 patients, middle cerebral artery in six, anterior cerebral artery in three, basilar artery bifurcation in one, and junction of the vertebral artery (VA) and posterior inferior cerebellar artery in one. After aneurysm clip placement, the target arteries were illuminated using a beam from a blue light-emitting diode atop a 7-mm diameter pencil-type probe. In all patients, after intravenous administration of 5 ml of 10% fluorescein sodium, fluorescence in the vessels was clearly observed through a microscope and recorded on videotape. RESULTS The excellent image quality and spatial resolution of the fluorescein angiography procedure facilitated intraoperative real-time assessment of the patency of the perforating arteries and branches near the aneurysm, including: 12 posterior communicating arteries; 12 anterior choroidal arteries; four lenticulostriate arteries; three recurrent arteries of Heubner; three hypothalamic arteries; one ophthalmic artery; one perforating artery arising from the VA; and one posterior thalamoperforating artery. All 23 patients experienced an uneventful postoperative course without clinical symptoms of perforating artery occlusion. CONCLUSIONS Because the fluorescein angiography procedure described here allows intraoperative confirmation of the patency of perforating arteries located deep inside the surgical field, it can be practically used for preventing unexpected cerebral infarction during aneurysm surgery.

Intraoperative monitoring of visual evoked potential: introduction of a clinically useful method

OBJECT To obtain a clinically useful method of intraoperative monitoring of visual evoked potentials (VEPs), the authors developed a new light-stimulating device and introduced electroretinography (ERG) to ascertain retinal light stimulation after induction of venous anesthesia. METHODS The new stimulating device consists of 16 red light-emitting diodes embedded in a soft silicone disc to avoid deviation of the light axis after frontal scalp-flap reflection. After induction of venous anesthesia with propofol, the authors performed ERG and VEP recording in 100 patients (200 eyes) who were at intraoperative risk for visual impairment. RESULTS Stable ERG and VEP recordings were obtained in 187 eyes. In 12 eyes, stable ERG data were recorded but VEPs could not be obtained, probably because all 12 eyes manifested severe preoperative visual dysfunction. The disappearance of ERG data and VEPs in the 13th eye after frontal scalp-flap reflection suggested technical failure attributable to deviation of the light axis. The criterion for amplitude changes was defined as a 50% increase or decrease in amplitude compared with the control level. In 1 of 187 eyes the authors observed an increase in intraoperative amplitude and postoperative visual function improvement. Of 169 eyes without amplitude changes, 17 manifested improved visual function postoperatively, 150 showed no change, and 2 worsened (1 patient with a temporal tumor developed a slight visual field defect in both eyes). Of 3 eyes with intraoperative VEP deterioration and subsequent recovery upon changing the operative maneuver, 1 improved and 2 exhibited no change. The VEP amplitude decreased without subsequent recovery to 50% of the control level in 14 eyes, and all of these developed various degrees of postoperative deterioration of visual function. CONCLUSIONS With the strategy introduced here it is possible to record intraoperative VEPs in almost all patients except in those with severe visual dysfunction. In some patients, postoperative visual deterioration can be avoided or minimized by intraoperative VEP recording. All patients without an intraoperative decrease in the VEP amplitude were without severe postoperative deterioration in visual function, suggesting that intraoperative VEP monitoring may contribute to prevent postoperative visual dysfunction.

Prevention of vasospasm—cisternal irrigation therapy with urokinase and ascorbic acid

Cisternal irrigation therapy with urokinase and ascorbic acid was applied in 118 cases for preventing vasospasm after aneurysmal subarachnoid hemorrhage (SAH); in other 28 cases only urokinase was used. All of the patients were in Group 3 according to the CT classification by Fisher, and the CT number (Hounsfield number) of the thickest clot was over 60. These CT findings suggested a high chance for occurrence of symptomatic vasospasm. All patients underwent surgery within 72 hours. After clipping the aneurysm, irrigation tubes were placed in the Sylvian fissure (inlet), either on one side or bilaterally, and also in the prechiasmal or prepontine cistern (outlet). Lactated-Ringer’s solution with urokinase (60, 120 IU/ml) and ascorbic acid (2, 4 mg/ml) was infused at the rate of 20–60 ml/hours for about 10 days. In the former group with urokinase and ascorbic acid, symptomatic vasospasm was observed in 3 cases (2.5%) and only one of them (0.8%) showed neurological sequelae. In the latter group with only urokinase (30–120 IU/ml), symptomatic vasospasm occurred in three cases (10.7%), transiently. We compared these results with those of 111 control cases without the irrigation therapy, which had the same degree of SAH on the preoperative CT scans. In the control group, symptomatic vaso-spasm occurred in 38 cases (34.2%).

Utility and the limit of motor evoked potential monitoring for preventing complications in surgery for cerebral arteriovenous malformation.

OBJECTIVE To evaluate the usefulness of motor evoked potential (MEP) monitoring and mapping in arteriovenous malformation surgery. METHODS Intraoperative MEP monitoring was performed in 21 patients whose AVMs were located near the motor area or fed by arteries related to the corticospinal tract to detect blood flow insufficiency and/or direct injury to the corticospinal tract and/or to map the motor area. RESULTS In 4 of 16 patients monitored for blood flow insufficiency, the MEP changed intraoperatively. In 2 patients, the changes were attributable to temporary occlusion of the feeding artery (anterior choroidal or lenticulostriate artery): 1 patient had a venous infarction around the internal capsule caused by thrombosis of the draining vein and the other bled intraoperatively from the nidus. In 17 patients, the MEP was monitored to rule out direct injury. In 1 patient, the MEP changed on coagulation of fragile vessels around the nidus in the precentral gyrus; it recovered after coagulation was discontinued. In 1 of 5 patients with MEP changes, the MEP did not recover; permanent hemiparesis developed in this patient because of venous infarction. In 1 of 11 patients subjected to MEP mapping of the motor area, we found translocation to the postcentral sulcus. CONCLUSION In arteriovenous malformation surgery, MEP monitoring facilitates the detection of blood flow insufficiency and/or direct injury of the corticospinal tract and mapping of the motor area. It contributes to reducing the incidence of postoperative motor paresis.

Intra-Arterial Fluorescence Angiography with Injection of Fluorescein Sodium from the Superficial Temporal Artery during Aneurysm Surgery: Technical Notes

Intra-arterial fluorescence angiography from a catheter inserted into the external carotid artery (ECA) via the superficial temporal artery (STA) allowed us to satisfactorily evaluate cerebral arterial and venous blood flow. We report this novel method that allowed for repeated angiography within minutes with a low risk of complications due to catheter placement from the STA. The STA was secured at the edge of the standard skin incision during cerebral aneurysm surgery. A 3 Fr catheter was inserted approximately 5 cm to 10 cm into the STA. After manual injection of 5 ml of 20 times diluted 10% fluorescein sodium (fluorescein), fluorescein reached the intracranial internal carotid artery (ICA) through the common carotid artery or anastomoses between the ECA and ICA. Fluorescence emission from the cerebral arteries, capillaries, and veins was clearly observed through the microscope and results were recorded. Quick dye clearance makes it possible to reexamine within 1 minute. In addition, we made a graph of the fluorescence emission intensity in the arteries, capillaries, and veins using fluorescence analysis software. With intravenous fluorescence angiography, dye remains in the vessels for a long time. When repeated examinations are necessary, intervals of approximately 10 minutes are required. There were some cases we could not correctly evaluate with intravenous injection due to weak fluorescence emission. Fluorescence angiography with intra-arterial injection from a catheter inserted into the carotid artery or another major vessel, like conventional angiography, has a risk of procedure-related complications. We report our new method since it solved these problems and is useful.

Development of and Clinical Experience with a Simple Device for Performing Intraoperative Fluorescein Fluorescence Cerebral Angiography: Technical Notes

To perform intraoperative fluorescence angiography (FAG) under a microscope without an integrated FAG function with reasonable cost and sufficient quality for evaluation, we made a small and easy to use device for fluorescein FAG (FAG filter). We investigated the practical use of this FAG filter during aneurysm surgery, revascularization surgery, and brain tumor surgery. The FAG filter consists of two types of filters: an excitatory filter and a barrier filter. The excitatory filter excludes all wavelengths except for blue light and the barrier filter passes long waves except for blue light. By adding this FAG filter to a microscope without an integrated FAG function, light from the microscope illuminating the surgical field becomes blue, which is blocked by the barrier filter. We put the FAG filter on the objective lens of the operating microscope correctly and fluorescein sodium was injected intravenously or intra-arterially. Fluorescence (green light) from vessels in the surgical field and the dyed tumor were clearly observed through the microscope and recorded by a memory device. This method was easy and could be performed in a short time (about 10 seconds). Blood flow of small vessels deep in the surgical field could be observed. Blood flow stagnation could be evaluated. However, images from this method were inferior to those obtained by currently commercially available microscopes with an integrated FAG function. In brain tumor surgery, a stained tumor on the brain surface could be observed using this method. FAG could be performed with a microscope without an integrated FAG function easily with only this FAG filter.

HIGH-FREQUENCY MONOPOLAR ELECTRICAL STIMULATION OF THE RAT CEREBRAL CORTEX

OBJECTIVEIntraoperative monitoring of the motor-evoked potential has been widely used in patients undergoing neurosurgery. Direct stimulation of the brain with high-frequency monopolar stimulation (HFMS) is one of the most common methods to produce motor-evoked potential. We studied the influence of HFMS on the rat cerebral cortex. METHODSWe applied 1.5, 15, 30, 40, or 50 mA of HFMS to the rat sensorimotor cortex by a short sequence of five monopolar, monophasic, anodal rectangular 500-Hz pulses. We delivered one short five-pulse train 100 times every 5 seconds and examined pre- and post-stimulation electroencephalograms and histological changes at the stimulation site. RESULTSWe observed no spike waves after HFMS in any of the rats. There was no change in the power spectrum or frequency content in any of the rats exposed to HFMS. Histologically, there was significant swelling of the dendrites in rats sacrificed immediately after exposure to 40- and 50-mA stimulation; the 50-mA stimulation group also exhibited slight swelling of the mitochondria. These findings were not obtained in any of the rats sacrificed 30 days after stimulation. CONCLUSIONIn rats exposed to a stimulation intensity of 30-mA or less, no morphological or electrophysiological changes were observed. However, the possibility that HFMS may affect neural tissue cannot be ruled out.

Evoked potentials elicited on the cerebellar cortex by electrical stimulation of the rat spinocerebellar tract.

BACKGROUND In the current study, as a first step to develop a monitoring method of cerebellar functions, we tried to record evoked potentials on the cerebellar cortex by electrical stimulation of the rat SCT, which is located in the Inf-CPed. METHODS The experimental study was performed on rats. Unilateral muscular contractions of quadriceps femoris muscle were elicited by electrical stimulation. The evoked potentials were recorded from the surface of the ipsilateral cerebellum and the contralateral primary sensory cortex. RESULTS The highly reproducible potentials obtained from the ipsilateral cerebellar hemisphere were named SCEP. The SCEP exhibited one negative peak with a latency of 11.7 +/- 0.3 milliseconds (N(11)). Short-latency somatosensory evoked potential was recorded from the contralateral primary sensory cortex with a latency of 19.1 +/- 0.6 milliseconds. Coagulation of the ipsilateral Inf-CPed caused disappearance or marked reduction of the SCEP N(11), but it did not change the SSEP. On the other hand, sectioning of the ipsilateral dorsal column resulted in the disappearance of the SSEP, but it did not affect the SCEP N(11). CONCLUSIONS Reproducible SCEP was recorded from the rat cerebellar hemisphere by electrical stimulation of the quadriceps femoris muscle. We posit that the SCEP differs from the SSEP, which ascends via the dorsal column, and that it is conducted by the dorsal SCT located in the Inf-CPed. Our results suggest that it may be possible to detect the dysfunction of the Inf-CPed electrophysiologically by using SCEP.

Evaluation of cervical arteries with 3D-CTA using multi-detector row CT—one-session scanning of the head and neck using single or double injection of contrast medium

Abstract To detect cervical vascular lesions in 90 patients with intracranial cerebrovascular diseases, we performed three-dimensional CT angiography (3D-CTA) of the head and neck using multi-detector row CT (MD-CT) with a single- or double-bolus injection of contrast material. In the single-injection group (n=70), the head and neck were scanned in one session after continuous injection at a rate of 3 ml/s of contrast medium (total 100 ml). In the double-bolus injection group (n=20), the head was scanned first after the delivery of contrast material (3 ml/s, total 70 ml) and the neck was scanned after a boost injection (2 ml/s, total 30 ml). The single-bolus injection method was simple and suitable for screening for vascular lesions at the carotid bifurcations. The double bolus injection method yielded excellent 3D-CTA of the vertebral- and carotid arteries without interference by cervical veins and was suitable for screening the whole length of the carotid arteries, including the origin of the vertebral arteries. The head and neck 3D-CTA using MD-CT provides valuable diagnostic information regarding vascular lesions of the intracranial and cervical arteries.