Kenichiro Sugita

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.

Reconstruction of the sellar floor during transsphenoidal operations using alumina ceramic

Abstract Our clinical experience with repair of the sellar floor during transsphenoidal surgery using alumina ceramic is reported. The sellar floor was reconstructed with the use of this material, a known tissue-compatible substance. We consider this technique easy, safe, and useful in rhinoseptoplastic surgery.

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.

Subdural fluid collection following craniotomy

The occurrence of subdural fluid collection following craniotomy for intracranial aneurysms was studied with regard to the patients age, preoperative grade, external decompression, incidence of the craniotomy, external drainage, and ventriculoperitoneal shunt. The following results and conclusions were obtained: Enlargement of the subdural space was observed in 76 of 147 patients (51.7%). The patients age was the most likely causative factor in producing the lesion. Six patients required surgical management for the collection: three were for subdural hygroma and three were for chronic subdural hematoma. It is estimated that two factors, multiple craniotomy and younger age, accelerated the formation of symptomatic subdural hygromas. When the patient complains of headache or motor weakness 1 or 2 months after undergoing a craniotomy, one should suspect chronic subdural hematoma, especially in an elderly patient with ruptured aneurysm.

Chronic meningitis with marked unilateral tentorial pachymeningitis

Two cases of chronic meningitis with marked granulomatous thickening of the cerebellar tentorium are presented. The clinical features of both cases were those of chronic meningitis, namely, incessant chronic headache, long-lasting moderate increase of intracranial pressure, multiple cranial nerve involvement, slight lymphocytosis, and increased protein in cerebrospinal fluid. The characteristic finding on computed tomography scan was slight, high density of the unilateral cerebellar tentorium with marked contrast enhancement. Both patients died of complications, and necropsy revealed marked granulomatous thickening of the unilateral cerebellar tentorium. Although noninfectious disease was strongly suspected, the etiology could not be specified either clinically or by necropsy.

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.

Fixation System for Cervical Spinal Operation: Application of the Head Fixation System and Multipurpose Cervical Frame

We have designed a multipurpose cervical frame to use with our operative head fixation system and have used it in 60 cervical spinal operations including anterior, posterior, lateral, and transoral approaches, with satisfactory results. We emphasize the following advantages of this system: (a) Both stability and an exact position of the cervical spine can be maintained during operation. (b) Positioning of patients for operation, including those with a halo vest, is efficiently carried out with safety and ease. (c) Our newly designed cervical frame enables exact and refined intraoperative retraction with various kinds of retractors. (d) When microsurgery is performed, the surgeon can sit at the patients head in an operating chair.

Removal of an arteriovenous malformation in the optic chiasm: A case of bonnet-dechaume-blanc syndrome without retinal involvement

A rare case of an arteriovenous malformation involving the optic chiasm associated with vascular anomaly in the left maxillary region is presented. The angiogram demonstrated an arteriovenous malformation arising from the anterior circle of Willis (internal carotid, posterior communicating, and proximal anterior cerebral arteries), and located in the region of the optic chiasm and hypothalamus. The case was diagnosed as the Bonnet-Dechaume-Blanc syndrome without intraorbital and retinal arteriovenous malformations. The suprasellar arteriovenous malformation was removed, except for a small portion in the hypothalamus, with satisfactory results.

An improved neurosurgical system: New operating table, chair, microscope and other instrumentation

SummaryWe have developed what we call the instrument trio in the neurosurgical operating theatre: a remotecontrolled operating microscope with magnetic lock, an operating table with remote-controlled X-Y shifter, and a floating operating chair. In addition other important improvements in instrumentation have been made; they include a quick sterilization system for the operating microscope, a multipurpose head frame and an improved retractor system. The instruments and their characteristics are described in detail.