Takeo Tanishima

Lipid peroxidation as a cause of cerebral vasospasm.

In the present study, the vasocontractile activities of purified oxyhemoglobin, methemoglobin, peroxides of linoleic and arachidonic acid, and hydrogen peroxide were examined in vitro, using the canine basilar artery. It was shown that all of them possess a vasocontractile capacity in a dose-dependent fashion. Fresh canine arterial blood was incubated at 37 degree C for 2 weeks, and the daily change of its vasocontractile capacity and the amount of TBA-reactive substance was studied. This study revealed a gradual and parallel increase in both of them. In a clinical study with 32 SAH patients, the amount of TBA-reactive substance in the CSF was more elevated when angiographically confirmed vasospasm was present. The angiographical and histological responses of the basilar artery to the cisternal injection of 15-HPAA were studied in dogs. The cisternal injection of 15-HPAA (0.2 and 2.0 mg dissolved in bovine serum) caused a mild initial contraction of the basilar artery that lasted about 7 hours. On the third day, a stronger contraction occurred, persisting thereafter until sacrifice. Electronmicroscopy of those arterial samples revealed the disappearance of myofibrils, pyknotic changes of nuclei, and the appearance of vacuoles as well as electron-dense granules in the tunica media. The prolonged arterial contraction was always associated with remarkable destruction of the endothelial cells. These changes were essentially the same as those in experimental and clinical vasospasm. These data strongly indicate that free radical reactions initiated by clot lysis, represented by lipid peroxidation, plays an important role in the genesis of chronic vasospasm in subarachnoid hemorrhage.

Middle cerebral artery dissection causing subarachnoid hemorrhage and cerebral infarction: Trapping with high-flow bypass preserving the lenticulostriate artery.

Background: Spontaneous intracranial arterial dissection (IAD) is an increasingly important cause of stroke, such as subarachnoid hemorrhage (SAH) and hemodynamic or thromboembolic cerebral ischemia. IAD usually occurs in the posterior circulation, and is relatively rare in the anterior circulation including the middle cerebral artery (MCA). Various surgical and endovascular methods to reduce blood flow in the dissected lesion have been proposed, but no optimum treatment has been established. Case Description: An 80-year-old woman with dissection in the M1 portion of the MCA manifesting as SAH presented with repeated hemorrhage and cerebral infarction in the area of the inferior trunk of the MCA. High-flow bypass to the MCA was performed and the dissecting lesion was trapped. Prevention of repeated hemorrhage was achieved, and blood flow was preserved to the lenticulostriate artery as well as the MCA area distal to the lesion. Conclusions: Treatment strategy for IAD of the MCA should be planned for each patient and condition, and surgery should be performed promptly to prevent critical rebleeding given the high recurrence rate. In addition, preventing re-rupture of the IAD, and preserving important perforators around the lesion and blood flow distal to the dissection should be targeted by the treatment strategy.

Giant cavernous carotid aneurysm causing pituitary dysfunction: Pituitary function recovery with high-flow bypass

Background: Giant internal carotid artery (ICA) aneurysms extending into the sellar region, mimicking pituitary tumors, and causing pituitary dysfunction are relatively rare. Open surgery or endovascular treatment can treat these aneurysms, but achieving recovery of endocrine function is difficult. Case Description: A 56-year-old man presented with giant aneurysm of the ICA causing pituitary impairment, leading to disturbance of consciousness due to hyponatremia. High-flow bypass from the cervical external carotid artery to the middle cerebral artery and ligation of the ICA at the cervical portion were performed. One year after the operation, his pituitary function recovered well; he was followed up as an outpatient without hormonal replacement therapy for 8 years after the operation. Conclusion: Giant ICA aneurysm causing pituitary dysfunction is relatively rare, but it is important to consider in the differential diagnosis for hypopituitarism. Treatment with high-flow bypass using radial artery graft can achieve both prevention of aneurysm rupture and recovery of pituitary function.