Toshiki Takemae

Usefulness of ceramic implants in neurosurgery.

The authors have designed various implants made of alumina ceramic for neurosurgical use. They were used for reconstruction of the sellar floor and orbital wall and for cranioplasty to repair bone defects in both the convexity and the suboccipital region. Burr hole and sphenoid buttons were made to prevent postoperative dents in the skin. A ceramic-silicon sponge was developed as a marker prosthesis for neurovascular decompression. There were no untoward side effects such as infection or rejection by recipient tissue in humans or dogs. The advantages and disadvantages of the material are discussed.

Normovolaemic induced hypertension therapy for cerebral vasospasm after subarachnoid haemorrhage

SummaryWe showed that normovolaemic induced hypertension therapy was effective in reducing ischaemic symptoms attributed to cerebral vasospasm in 41 patients after subarachnoid haemorrhage. By inducing hypertension to 25% to 50% above normal systolic arterial blood pressure, we observed that in 17 of 24 cases (71%) neurological deficits improved. In four cases of haemorrhagic infarction, the blood pressure rose to over 50% of systolic arterial pressure, and a low density area was confirmed on computerized tomography (CT) scan prior to vasospasm. Induced hypertension was therefore not considered when a low density area was revealed on CT scan.Restriction of fluid input is usually a factor in producing hypovolaemia after a neurosurgical operation. Intravascular volume expansion has been reported effective in reversing ischaemic deficits. However, according to Poiseuilles equation, increasing blood volume to a state of hypervolaemia can not enhance flow. The cerebral blood flow (CBF) was raised by increasing perfusion pressure, reducing viscosity, or increasing blood vessel diameter. Intravascular volume expansion elevates not only systemic arterial pressure, but also pulmonary artery wedge pressure over 18 mmHg and cardiac index over 2.2. Since pulmonary oedema and congestive heart failure may develop, one should monitor haemodynamic parameters with the Swan-Ganz catheter as a preventive measure.We emphasize that normovolaemic induced hypertension, maintaining haemodynamics subset 1 of the comparable haemodynamic subsets, is effective in raising perfusion pressure of CBF.

Development of the operating computerized tomographic scanner system for neurosurgery

SummaryA computerized tomographic (CT) scanner system for intraoperative imaging is presented. The system consists of the following: 1) CT scanner with a mobile gantry, 2) digitally controlled operating table with central processing unit (CPU) and encoder unit; the table can be controlled by the scanner computer as accurately as the scanner bed, and 3) exclusively designed head fixation devices. It allows us to scan the patient on the operating table in the operating room pre-operatively, intra-operatively and immediately after surgery.

Intraoperative Computed Tomographic Scanning during Transsphenoidal Surgery: Technical Note

Intraoperative computed tomographic scanning during transsphenoidal surgery on pituitary lesions is performed and evaluated. A computed tomographic scanner system exclusively developed for the operating room is used for this purpose during transsphenoidal surgery. Ten consecutive patients with pituitary lesions underwent operations by this method, which used a combination of an ordinary fluoroscopy unit and the computed tomographic scanner.

Intraoperative Computed Tomographic Scanning during Transsphenoidal Surgery

Intraoperative computed tomographic scanning during transsphenoidal surgery on pituitary lesions is performed and evaluated. A computed tomographic scanner system exclusively developed for the operating room is used for this purpose during transsphenoidal surgery. Ten consecutive patients with pituitary lesions underwent operations by this method, which used a combination of an ordinary fluoroscopy unit and the computed tomographic scanner.

Dose escalation trial of a novel calcium antagonist, AT877, in patients with aneurysmal subarachnoid haemorrhage

SummaryThe initial dose-escalating clinical trial of a novel calcium antagonist, AT877, in patients with aneurysmal subarachnoid haemorrhage is reported. AT877 is characterized by its strong spasmolytic activity, its inhibition of intracellular calcium ion activity, and the inhibiton of several protein kinases.A total of 113 patients (Hunt and Hess grades I to IV) who had undergone surgery within 3 days of aneurysmal rupture entered the study. Patients were divided into 5 groups according to the total daily dose of AT877: I: 20 mg; II: 40 mg; III: 60 mg; IV: 90 mg; and V: 120–180 mg. AT877 was given by intravenous infusion over 30 min two or three times a day for 14 days after surgery.Although AT877 did not completely abolish angiographic vasospasm, severe vasospasm was seen less frequently in patients given higher doses. Vasospasm was the cause of a poor clinical outcome (Glasgow outcome scale rating 3 or greater) in 19%, 7%, 9%, 8%, and 6% of the patients in groups I to V, respectively. The results indicated a favourable clinical effect of AT877 at doses above 40 mg per day. Only mild hypotension was seen, even when 60 mg of AT877 was infused over 30 min.AT877 appears to be effective in patients with subarachnoid haemorrhage. Part of its effect may be attributable to protection of the brain from ischaemic insults due to chronic cerebral vasospasm. However, the drug still needs to be evaluated in a placebo-controlled double-blind trial (which is currently being carried out).

Subdural fluid collections following transcortical approach to intra- or paraventricular tumours

SummarySubdural fluid collections appeared in 15 cases (39%) after removal of 38 intra- and paraventricular tumours in the third or lateral ventricle through 18 frontal and 20 parietal transcortical approaches. Transient fluid collections which disappeared within 2 weeks occurred in 6 cases (16%) and persistent ones in 9 cases (24%). Four of the 9 cases (11%) of collections required surgical treatment because of positive clinical signs and symptoms. Two cases had expansive fluid collections and the other two contained subdural haematomas at surgery. The risk factors likely to contribute to a persistent collection were preoperative ventriculomegaly (frontal horn index > 0.38) and a frontal transcortical approach. A symptomatic collection should be considered as a potential complication of the transcortical approach to intraventricular tumours and some methods should be devised to prevent it when intra- or paraventricular tumours with ventriculomegaly are removed.

Is Carotid Reconstruction for Advanced Cancer in the Neck a Safe Procedure

Head and neck surgeons hesitate to resect the carotid artery because of the postoperative risk of neurologic sequelae. On the other hand, there is no curative therapeutic option for head and neck cancer involving the carotid artery, except for complete tumor removal. A retrospective review of all published articles in the English literature dealing with carotid reconstruction for head and neck cancer from 1987 to 1998 was performed. There were only 11 articles, including our series, that reported outcomes of this procedure. Among the 148 patients of this series, major neuromorbidity was 4.7%, and mortality occurred in 6.8% of the patients. Combined major neuromorbidity and mortality was 10.1%. Because total removal of the advanced cancer is the only therapy that can offer the patients a chance for cure, head and neck surgeons should aggressively perform carotid resection and reconstruction.

Multiple spinal neurinomas presenting visual disturbance as the initial symptom: Case report

A case of multiple spinal neurinomas with visual disturbance is reported. A 63-year-old man was admitted with a complaint of progressive visual disturbance due to papilledema without spinal symptoms and signs. The neuroimaging studies demonstrated communicating hydrocephalus and two mass lesions in the cauda equina. Both tumors were found to be neurinomas. Intracranial hypertension secondary to spinal tumors is unusual, and multiple spinal neurinomas are rare. In the patient without spinal symptoms and signs, it is difficult to make a diagnosis of spinal tumor. Importance of checking for a spinal cord lesion by magnetic resonance imaging in such a case is stressed.

Introduction of high definition television system to neurosurgical documentation

The high definition television (HDTV) system is introduced to microneurosurgery. Five cases with intracranial lesions: three cerebral aneurysms (giant aneurysms of the anterior communicating artery and internal carotid artery, aneurysm of the basilar artery), one acoustic neurinoma and one skull base meningioma, were operated on under the microscope using the HDTV system. The surgical procedures of each case were relayed and recorded by the system. In two of the five cases, we used two sets of HDTV system to produce stereoscopic projection. The HDTV system provided us with images of superior quality with a distinctly greater resolution than ordinary video systems.