Namio Kodama

Rebleeding from ruptured intracranial aneurysms in North Eastern Province of Japan. A cooperative study

OBJECTnRebleeding from ruptured intracranial aneurysms is a major cause of death and disability. With regard to the factors that precipitate the rebleeding and influence the time course after initial bleeding, previous reports differ in their results, and the number of patients investigated was not sufficient for valid conclusions. This study was thus designed to clarify the factors related to rebleeding from ruptured intracranial aneurysms in a large group of patients of the North Eastern Province of Japan.nnnMETHODSnWe found 181 patients with rebleeding after hospitalization among 5612 cases of ruptured intracranial aneurysms from January 1997 to December 2001 in 33 major hospitals in the North Eastern Province of Japan. We analyzed the data with respect to the time course after bleeding and rebleeding, the arterial blood pressure, the situation when rebleeding occurred, the methods of neuroimaging, the level of consciousness, the treatment and the outcome.nnnRESULTSnOf 181 patients who were hospitalized, rebleeding occurred in 65 (35.9%) within 3 h and 88 (48.6%) within 6 h after the initial subarachnoid hemorrhage (SAH). The consciousness level before the rebleeding varied widely in distribution, but belonged to the drowsiness or less [Japan coma scale (JCS) single-digit] in 83 patients (45.8%), but after rebleeding, JCS triple-digits (semicoma to coma) included 152 patients (84.0%). Systolic arterial blood pressure prior to rebleeding was most commonly between 120 and 140 mmHg. Rebleeding did occur more frequently during angiography (totally 29 patients, 20%) and much less frequently during 3D-CTA and MRA procedures (a single case). Treatment consisted of aneurysm neck clipping in 72 patients (40.0%), endovascular therapy with coils in 4 patients (2.2%) and conservative ones in 103 patients (56.9%). As to outcome, 109 patients with rebleeding (60.2%) died in 3 months following initial SAH.nnnCONCLUSIONnRebleeding occurs more frequently in the earlier period after the initial SAH than previously believed. Thus, more aggressive pharmacologically induced systemic arterial hypotension appears to be important for preventing rebleeding but ultimate outcome of more aggressive hypotension is yet to be determined. If feasible, in order to avoid catheter-angiography related rebleeding, evaluations solely with 3D-CTA and MRA should be in consideration and earlier surgical intervention seems essential as rebleeding does occur often within the first 3 h of onset.

Perinidal dilated capillary networks in cerebral arteriovenous malformations.

OBJECTIVEThe perinidal vascular structures of cerebral arteriovenous malformations were examined, to clarify their pathomorphological features. METHODSTwenty-two resected specimens of human brain structures adjacent to the nidus were examined. The vessels surrounding the nidus were three-dimensionally reconstructed with a computer graphics system. RESULTSIn all cases, the analysis of serial sections revealed that perinidal dilated capillaries were located in brain tissue 1 to 7 mm from the nidal border. The vessels surrounding the nidus demonstrated markedly dilated capillary networks (perinidal dilated capillary network [PDCN]). The diameters of the vessels forming the PDCN were 10 to 25 times those of normal capillaries. The PDCN connected not only to the nidus, feeding arteries, and draining veins, via arterioles and venules, but also to the normal capillary network, arterioles, and venules. CONCLUSIONWithout exception, each nidus was accompanied by a PDCN, which connected not only to the nidus, feeding arteries, and draining veins, via arterioles and venules, but also to normal capillaries, arterioles, and venules. The PDCN should be considered in studies aimed at gaining an understanding of the mechanisms underlying the intraoperative and postoperative bleeding, growth, and recurrence of surgically treated cerebral arteriovenous malformations.

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.

Glossopharyngeal Nerve Evoked Potentials after Stimulation of the Posterior Part of the Tongue in Dogs

OBJECTIVE Lower cranial nerve palsy is one of the most critical complications after posterior fossa surgery. However, no established monitoring procedures exist for glossopharyngeal nerve function. Therefore, glossopharyngeal nerve evoked potentials after stimulation of the posterior part of the tongue in dogs was studied to analyze whether glossopharyngeal nerve compound action potentials and evoked potentials are useful in the intraoperative monitoring of patients undergoing brainstem and cerebellopontine angle surgery. METHODS Glossopharyngeal nerve action potentials and cortical potentials were evoked by stimulating the posterior part of the tongue in mongrel dogs. The potentials were evoked by supramaximal constant current electrical stimuli delivered with bipolar stainless steel needle electrodes and recorded with silver ball electrodes. RESULTS Compound nerve action potentials were recorded from the exposed intracranial portion of the glossopharyngeal nerve. The latency of the initial negative peak of the action potentials was 2.8 ± 0.6 milliseconds (mean ± standard deviation; n = 17). Evoked cortical potentials were recorded on the coronal gyrus by stimulating the contralateral side. The latencies of the initial positive peak and negative peak were 20.1 ± 3.7 and 35.7 ± 8.2 milliseconds, respectively (n = 6). Ipsilateral tongue stimulation elicited biphasic evoked potentials on the coronal gyrus, which had small amplitudes and delayed latencies. Both compound nerve action potentials and cortical evoked potentials disappeared after sectioning of the glossopharyngeal nerve. CONCLUSION The glossopharyngeal nerve action potentials and cortical potentials elicited by the stimulation of the posterior one-third of the tongue can be recorded. These evoked potentials represent a new means for intraoperative monitoring of patients undergoing surgery in the brainstem via the cerebellopontine angle, which involves the lower cranial nerves.

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.

BACKGROUNDnIn 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.nnnMETHODSnThe 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.nnnRESULTSnThe 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).nnnCONCLUSIONSnReproducible 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.

Surgery of acutely ruptured cerebral aneurysms aided by three-dimensional computerized tomography angiography without conventional angiography

Abstract In our previous study, 60 cases of subarachnoid hemorrhage (SAH) from ruptured aneurysms were prospectively evaluated both by three-dimensional computerized tomography angiography (3D-CTA) and conventional catheter angiography (CCA), which resulted in a 100% accuracy for 3D-CTA in the diagnosis of ruptured aneurysms. Based on the results, we assessed whether the aneurysm surgery can be performed on patients with ruptured cerebral aneurysms using 3D-CTA without CCA. 3D-CTA was performed with a helical CT scanner. A total of 123 consequent patients with SAH who had undergone surgery in the acute stage on the basis of 3D-CTA findings were studied. One hundred and twenty-three ruptured aneurysms, including 49 associated unruptured aneurysms, were detected using 3D-CTA. In 7 of 123 ruptured aneurysms, 3D-CTA was followed by CCA to acquire the diagnostic confirmation or the information of the vein. All of the ruptured aneurysms were confirmed at the surgery and treated successfully. One hundred and sixteen patients who underwent the operation with the use of 3D-CTA only had no complications related to the lack of CCA information. 3D-CTA provided us with aneurysm location as well as the surgically important information on the configuration of its sac and neck, and its relationship to adjacent vessels and bone structures. 3D-CTA can replace CCA in the diagnosis of ruptured aneurysms and acute surgery can be performed in almost all acutely ruptured aneurysms by using only 3D-CTA without CCA.

Glutamine synthetase protects the spinal cord against hypoxia-induced and GABAA receptor–activated axonal depressions

BACKGROUNDnWe investigated the effects of exogenous GS on hypoxia- and GABA(A) receptor-induced axonal depression in neonatal rats.nnnMETHODSnTo assess the effects of GS on spinal cord axons, CAPs were recorded. Hemicords were exposed to hypoxia by 30-minute superfusion with Ringers solution saturated with 95% N(2) and 5% CO(2) followed by 60-minute exposure to 95% N(2) and 5% CO(2) gassing (N(2) gassing phase) and then 90 minutes of resuperfusion with oxygenated Ringers solution (resuperfusion phase). Exogenous high GS (15 U) or low GS (1.5 U) was delivered during the N(2) gassing phase. The effects of GS on GABA(A) receptor-induced axonal depression were analyzed with oxygenated isolated dorsal columns.nnnRESULTSnThe high GS significantly reduced the decline in the CAP amplitudes during the N(2) gassing and resuperfusion phases (P = .0185) compared to the hypoxia control. The low GS treatment showed a trend toward recovery during the N(2) gassing and resuperfusion phases, but the effect was not significant (P = .3953). In isolated dorsal columns, GS significantly reduced the CAP amplitude depression induced by GABA(A) receptor agonist.nnnCONCLUSIONSnOur findings suggest that GS had dose-dependent protective effects on the spinal cord against hypoxia-induced axonal depression. It may inhibit the depression of CAP amplitudes by blocking GABA(A) receptors.

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.