Tsutomu Yagishita

Size of cerebral aneurysms and related factors in patients with subarachnoid hemorrhage

BACKGROUND As the indication for surgical treatment of incidentally discovered small aneurysms remains controversial. METHODS We retrospectively investigated the characteristics of small ruptured aneurysms and examined the relationship between the size and location of ruptured intracranial aneurysms and the sex, age, lifestyle, and medical history of 280 patients with ruptured aneurysm treated at our institute. RESULTS The mean diameter of ruptured aneurysms in this series was 7.6 mm. In diameter, 135 (48.2%) ranged between 5 and 10 mm; 73 (26.1%) were smaller than 5 mm. The size of the ruptured aneurysms was significantly smaller (mean 6.5 mm) in patients with non- or poorly controlled hypertension than in normotensive patients (mean 8.3 mm) (p < 0.05). Ruptured aneurysms in the anterior communicating artery (AcomA) and anterior cerebral artery (ACA) were significantly smaller (p < 0.01) than those in the internal carotid artery or middle cerebral artery. Among 58 patients with multiple aneurysms, only 7 (12%) suffered rupture of aneurysms smaller than 5 mm (p < 0.01). Patients younger than 40 years and patients with a family history of subarachnoid hemorrhage appeared to predispose to the rupture of small-sized aneurysms, although those did not affect the statistical significance. CONCLUSIONS This study shows that even aneurysms smaller than 10 mm may rupture. However, treatment decisions for unruptured aneurysm should not be based solely on the size of the unruptured aneurysms. Our data implies that even small aneurysms in the AcomA and ACA had an increased tendency for rupture, and that hypertensive patients were at higher risk for the rupture of small aneurysms.

Surgical management of aneurysms of the bifurcation of the internal carotid artery

Internal carotid artery (ICA) bifurcation aneurysms are rare and easily bleed in younger patients, but are difficult to treat surgically, due to perforators surrounding and adherent to the aneurysm. A series of 25 patients treated by clipping under the operating microscope are analyzed and compared with previous cases. Twenty-five patients, 11 men and 14 women (mean age 51 years), were treated by the same neurosurgeon. Seventeen patients presented with subarachnoid hemorrhage (Hunt & Kosnik Grade I in three, II in five, III in two, IV in seven), five with unruptured ICA bifurcation aneurysms, and three with unruptured ICA bifurcation aneurysms but another ruptured aneurysm. There were 23 small, one large, and one giant ICA bifurcation aneurysms. The projection was superior in 12, anterior in seven, and posterior in six cases. Pterional approach was employed for all cases. Outcomes were evaluated at discharge with the Glasgow Outcome Scale. Favorable outcomes (good recovery (GR) and moderate disability (MD)) were obtained in ten of 17 patients with ruptured ICA bifurcation aneurysm. Favorable outcomes were significantly greater in Grades I and II (three in I, four in II) than in Grades III and IV (one in III, two in IV; P=0.0498). Seven of eight patients with unruptured ICA bifurcation aneurysm had favorable outcomes. Temporary clipping and projection of the aneurysm did not affect the outcome. Causative factors of unfavorable outcomes were primary brain damage in cases of small and large aneurysms and perforator damage in the case of giant aneurysm. Poor clinical grade and vasospasm are the causative factors of poor outcome in patients with ruptured ICA bifurcation aneurysm. Preservation of perforators is crucial in cases of giant aneurysm. Clipping of unruptured ICA bifurcation aneurysms is recommended since they tend to bleed at a lower age than other aneurysms.

Oculomotor nerve palsy after surgery for upper basilar artery aneurysms.

OBJECTIVE The goals of this study were to evaluate the relationship between postoperative oculomotor nerve palsy and other clinical factors and to improve preoperative estimations of the risk. Such an evaluation has not been previously described in the literature. METHODS Patient records for 77 basilar tip aneurysm cases and 28 basilar superior cerebellar artery aneurysm cases treated between 1981 and 1997 were reviewed. Clinical and radiological parameters were separately analyzed using the chi2 test, and then multiple-regression analysis was used. RESULTS Postoperative oculomotor palsy occurred in 25 (32%) patients with basilar tip aneurysms and 11 (39%) patients with basilar superior cerebellar artery aneurysms, in addition to 2 patients with basilar tip aneurysms and 3 patients with basilar superior cerebellar artery aneurysms who exhibited oculomotor palsy before surgery. For both type of aneurysms, the size and direction of the aneurysms were closely related to oculomotor nerve palsy. The complication also tended to occur in early surgery cases, in younger patients, and in patients of poor-clinical grade status. CONCLUSION In this study, some clinical and radiological factors were found to be associated with postoperative oculomotor nerve palsy.

Intraoperative Monitoring of the Motor Function: Experimental and Clinical Study

Manipulation of the lesions adjacent to the primary motor area or the motor pathway is troublesome for neurosurgeons because they lack an effective method to determine the primary motor area or to monitor motor function in the operative room. It will be of great value to establish a monitoring method of the corticospinal tract under general anaesthesia. We recorded the motor evoked potential (MEP) from direct motor cortex stimulation in cats and showed that it derives almost purely from the corticospinal tract. Then we used this technique during the operation of the resection of tumours near the primary motor area or the motor pathway. 1. Experimental study: Twenty adult cats were used in this study. Recording electrodes were flexible bipolar catheter electrodes inserted into the spinal epidural space. Stimulating electrodes were silver ball electrode on the cortex (anode) and needle electrode in the temporal muscle (cathode). Stimulation of 4-24 V, 5-10 Hz and 0.2 msec in duration were done and evoked potentials signals were averaged 60 to 512 times. MEP with multiple peaks was obtained that had a 112 msec conduction velocity in the spinal cord. We found the same signals from the stimulation of ipsilateral cerebral peduncle. Radiofrequency lesioning of ipsilateral cerebral peduncle produced a loss of MEP. These results show that MEP derives from the corticospinal tract. Significant wave form change, with components of short latency, was noted by the excessively intense stimuli. We supposed that superimposition of the signals from the extrapyramidal pathways, excited in the brain stem, results in this change.(ABSTRACT TRUNCATED AT 250 WORDS)

Surgical outcomes in elderly patients with aneurysmal subarachnoid hemorrhage

The optimum management for elderly patients with aneurysmal subarachnoid hemorrhage (SAH) remains controversial. The surgical indications for aneurysmal SAH in elderly patients were investigated. Materials and methods: This study retrospectively reviewed 148 elderly patients over 70 years old among 1019 patients surgically treated for SAH. The patients were divided into three groups: group A, 93 patients aged 70–74 years; group B, 33 patients aged 75–79 years; and group C, 22 patients aged over 80 years. The outcomes were evaluated using the Glasgow Outcome Scale, with good recovery and moderate disability considered as favorable. The surgical outcome was analyzed compared with the preoperative Hunt and Kosnik grade, location of the aneurysm and causes of complication. Results: A favorable outcome for patients in preoperative Hunt and Kosnik grades I and II was achieved in 84.8% of group A, 63.8% of group B and 57.1% of group C, and for patients in grades III–V, 40.4% of group A, 15.4% of group B and 12.5% of group C. The rate of favorable outcome decreased with age and worse preoperative clinical grade. In patients remaining conscious before operation, the differences in recovery rates were not statistically significant by advancing age. For those patients with disturbance of consciousness, however, the recovery rate was significantly worse in groups B and C as compared with group A. The causes of poor outcome were primary brain damage, vasospasm and muscle weakness due to extended bed rest. In addition, more than half of the patients in a severely disabled or vegetative state at the time of discharge resulted in death within 5 years. Conclusion: Surgery should be considered for elderly patients with aneurysmal SAH leading a normal life before onset and without severe systemic disease, even in those over 80 years, but not in patients with disturbance of consciousness due to primary brain damage.

Surgical Treatment of Multiple Aneurysms

The authors reviewed surgical results of 618 surgically treated patients with intracranial aneurysms. Multiple aneurysms were observed in 106 (20%) patients. In cases of multiple aneurysms, their policy has been to treat all aneurysms, ruptured and unruptured, in a one-stage operation whenever possible. All aneurysms of 92 patients were treated in one-stage operations. Eighty three (90%) patients improved or remained stationary, 6 (7%) deteriorated, 3 (3%) died postoperatively. The cause of deterioration or death were due to cerebral vasospasm, primary brain damage or surgical procedure for ruptured aneurysms. No significant difference was found in comparing the rupture site of the aneurysm or the timing of the operation in each preoperative clinical grade. Furthermore, all patients were classified into three groups according to the location of the aneurysms. Sixty-two patients had unilateral aneurysms including aneurysms in the midline, i.e. anterior communicating artery aneurysms, distal basilar artery aneurysms and/or bilateral pericallosal artery aneurysms (unilateral group), and 30 patients had bilateral aneurysms (bilateral group). Morbidity and mortality in unilateral group was 6% and 3%, while in bilateral group, 7%, 3% respectively. No significant difference was observed in the bilateral group compared with the unilateral group, and surgical results of each group appeared to be satisfactory. Neither death nor deterioration was found attributable to operative procedure when unruptured aneurysms were added to the surgery for ruptured aneurysms in a one-stage operation. These surgical results for 92 cases were similar to the results in the rest of the 526 cases. Based on these results, the one-stage operation is recommended, whenever possible, for patients with multiple aneurysms, even if bilateral craniotomy is needed.

Surgical Procedures in Cases with Ruptured Anterior Communicating Aneurysms

In general, the results of surgery on anterior communicating aneurysms (ACom AN) is worse than that on internal carotid and middle cerebral aneurysms (IC and MC AN), because of technical difficulty due to the deep location and complex anatomical relationships . Some attempts were made in our hospital to reduce the technical difficulty and improve the surgical results of operation for ACom AN. In this paper, the effect of these attempts was analysed in 208 cases . The timing of the operation and clinical grade were as followes: within 3 days: 67 cases , 4-14 days: 41 cases, over 14 days: 100 cases, I-II: 154 cases, III: 38 cases , IV-V: 15 cases. The operation was carried out by the unilateral pterional approach in all cases . In each case, the side of the approach was determined by angiographic findings except for cases with additional AN and significant hematoma . Craniotomy was performed at the side of the dominant Al in cases where the AN projected forward-downward. In the other cases, the operation was carried out at the side of the deep-seated A2. Use of a temporary clip for a short time and partial removal of gyrus rectus were positively carried out. Craniotomy was performed at the right side in 93 cases (45%) and at the left side in 115 cases (55%). A temporary clip was used in 106 cases (51%) and was significantly frequent in grade II, III cases and in cases operated on within 14 days after SAH. Partial removal of the gyrus rectus was performed in 61 cases (29%) and was significantly frequent in cases where the AN projected upward, grade III, IV cases and cases operated on within 14 days after SAH. Clipping of the AN was performed in all cases. Operatve mortality plus morbidity rate was as follow; I-II: 7%, III: 20%, IVV: 25%. The side of the craniotomy, use of a temporary clip and partial removal of the gyrus rectus caused no significant difference in these rates . The results in cases with AN were almost the same as the results with IC and MC AN. From these results , we can conclude that the side of the craniotomy should be determined by angiographic findings in each case , and use of a temporary clip and partial removal of the gyrus rectus should be carried out actively at the time of the operation for ACom AN.

Venous cerebral infarctions in an infant with chronic subdural hematoma

An infant with multiple cerebral infarctions and chronic subdural hematoma is reported. The infarctions were found after repeated tappings of the hematoma. Angiography did not demonstrate any occlusion of the main arteries. The infarctions were thought to be caused by thrombosis of the hanging cerebral veins. The pathogenesis and significance of the venous infarctions in an infantile subdural hematoma are discussed.