[The efficiency of magnetic resonance angiography (MRA) in the diagnosis and vertigo--prediction of vertebrobasilar insufficiency (VBI) and atherosclerosis]

Major causes of vertigo in patients who attend Otolaryngology clinics are peripheral vestibular disorders (PVD) and vertebrobasilar insufficiency (VBI). The purpose of this study was to see whether MRA findings can distinguish VBI from PVD to evaluate the efficiency of MRA in the diagnosis of vertigo. A total of 185 vertigo patients were examined by MRA with the 3D-Phase Contrast method. Three kinds of abnormalities of vessels, that is, (a) disappearance, (b) meandering, and (c) stoppage were found in MRA imaging. Therefore, we classified the MRA patterns into four types with two subtypes: type I; normal, type II-R; right hypoform of the vertebral artery, II-L; left hypoform of the vertebral artery, III; meandering form of the vertebrobasilar artery, IV-1; stoppage form of the basilar artery, IV-2; hypoform of the bilateral vertebral and basilar arteries. Diagnosis of the MRA patterns in each patient was camed out by a radiologist and neurosurgeon with the cooperation of an otolaryngologist. In 185 vertigo patients, 139 patients were clinically diagnosed as having PVD, 41 patients as having VBI, and 5 patients as having cerebellar and brainstem infarctions. The numbers of patients in MRA patterns I, II-R, II-L, III and IV were 140, 17, 12, 8, and 8 cases, respectively. The total number of VBI patients who demonstrated type III or IV patterns in MRA was significantly higher than that of type I, II-R and II-L (P < 0.005). All of the 8 cases with cerebellar and brainstem infarction belonged to type IV. Cerebral angiography was performed in nine cases with type II-R, II-L, III or IV-1, and the number of patients in each group was 3, 3, 1 and 2 cases, respectively. All of the type II-R and II-L cases revealed hypoform of the vertebral artery. The appearance of type III was restricted to type III's view was only meandering and type IV-1 showed severe stenotic changes in the union area. These data show that MRA findings in the diagnosis of vertigo patients are very effective in distinguishing VBI and cerebellar and brainstem infarction from PVD and that some pattern of MRA may correspond to atherosclerosis of the vertebrobasilar artery. We think MRA examination of vertigo patients is useful not only to assist in the diagnosis of the etiology but also to predict the stage of atherosclerosis in each patient.

[A case report of an arachnoid cyst in the craniovertebral junction]

We reported a case of arachnoid cyst in the craniovertebral junction which was extremely rare. A 36-year-old man presented truncal ataxia and dysesthesia in the right upper extremity. CT and MR images revealed a large cyst in the craniovertebral junction. As for findings of MR images, cystic lesion showed similar intensity as cerebrospinal fluid. Intradural arachnoid cyst with thickened dura was opened to communicate with subarachnoid space. Fluid in the cyst was watery clear. Histological finding of the surgical specimen was arachnoid cyst without inflammatory changes. Arachnoid cyst in the craniovertebral junction is discussed with literature.

[Multiple meningioma associated with intraosseous and tentorial meningioma--case report]

We report a case of multiple meningioma associated with intraosseous and tentorial meningioma. A 75-year-old woman was admitted to our hospital with blurred vision and exophthalmos in the left eye. Left lower hemianopsia, deterioration of visual acuity and right cerebellar signs were found on neurological examination. CT and MR image revealed an intraosseous tumor of the left sphenoid bone and a right tentorial mass. Cytogenetic analysis failed to reveal any abnormalities of chromosome 22. The intraosseous tumor which was transitional type meningioma and the tentorial mass, which was a fibroblastic meningioma were successfully excised. Postoperatively, the patient's symptoms and signs improved. Intraosseous meningioma associated with multiple meningioma is extremely rare and the histogenesis of meningioma arising from ectopic arachnoid cells is discussed.

Cranio-nasal median splitting for radical resection of craniopharyngioma

A new surgical approach for radical resection of craniopharyngioma is presented. This approach (cranio-nasal median splitting) involves craniotomy in the centre of the frontal bone, removal of the median portion of the supraorbital bar that incorporates the nasal bone, and detachment of the medial canthal ligaments. The frontal lobes, the cribriform plates, the planum sphenoidale, and the upper nasal cavities are split in the midline. The extraventricular surface of the hypothalamus, the pituitary stalk, and the posterior portion of the Willis' arterial ring are well visualized through the midline infrachiasmatic route. The intraventricular surface of the hypothalamus is also visible in the same operative field through the lamina terminalis and/or the anterior portion of the corpus callosum. This excellent visualization is quite helpful for minimizing operative injury to the hypothalamus and the pituitary stalk whichever surface of the third ventricular floor the tumour is situated upon. Three cases of craniopharyngioma operated upon by this approach are presented. Discussions are focused not only on the indication, but on the advantages and disadvantages of this approach. The surgical techniques for reconstruction of the cranial base are also described, together with some precautions that should be taken to prevent possible postoperative complications.

Telecanthal approach for meningiomas in the ethmoid and sphenoid sinuses

In three cases involving meningiomas in the ethmoid and sphenoid sinuses, transbasal spreading of the interocular distance (telecanthal approach) was used for tumor removal and reconstruction of the skull base. This telecanthal approach involves 1) bilateral en bloc removal of the superior lateral rim of the orbit, the nasal bone, and the posterior lateral wall of the orbit; 2) detachment of the medial canthal ligaments; and 3) spreading of the interocular distance. This approach provides a wide working space beneath the anterior half of the midline skull base, and needs neither a facial incision nor significant retraction of the brain. The surgical technique and its modification are described. The discussion focuses not only on comparisons with other techniques, but on the indications for this approach. Meningiomas originating in the paranasal sinuses are rare; a brief review of the literature concerning the clinicopathological features and pathogenesis is also given.

[Posterior fossa hemorrhage 11 years after the use of silastic dural substitute: case report]

A case of posterior fossa hemorrhage is reported. The hemorrhage occurred 11 years after posterior fossa craniotomy with closure using a graft of silastic dural substitute. This 14 year-old girl underwent suboccipital craniotomy at the age of 3 years because of traumatic posterior fossa hemorrhage. The dura mater was repaired with a piece of dural substitute. Eleven years later, she developed severe headache and vomiting. Computerized tomography scanning revealed a high density area in the right posterior fossa. At exploration, a fresh clot was evacuated between the dural graft and the fibrous scar tissue. The resected fibrous scar tissue was 1cm thick, and was adhering to the duro glial scar tissue. Her postoperative course was uneventful, and she was discharged 2 weeks after surgery. Microscopic examination of the fibrous scar tissue revealed an outer layer of loose connective tissue with numerous capillaries. The inner layer consisted of dense connective tissue. It was speculated that fragile capillaries of fibrous scar tissue caused this hemorrhage. Surgeons should not forget this complication although silastic dural substitute is less used than it used to be.

[Comparison of five modes of dialysis in neurosurgical patients with renal failure]

In neurosurgical patients with renal failure, dialysis entails specific problems, chief of which is increased intracranial pressure and progressive brain edema as a result of rapid lowering of the serum osmolality. Another major problem is a tendency to hemorrhage, in response to either systemic heparinization or insufficient dialysis. The authors describe the results obtained with hemodialysis (HD), continuous arteriovenous hemofiltration (CAVH), continuous ambulatory peritoneal dialysis (CAPD), continuous peritoneal dialysis (CPD), and intermittent peritoneal dialysis (IPD). Nine patients were treated with HD, one with CAVH, five with CAPD or CPD, and two with IPD. Three of the six patients treated with continuous dialysis (CAVH, CAPD, and CPD) died, whereas intermittent dialysis (HD and IPD) carried an 82% mortality rate (nine of 11 patients). The causes of death were progressive brain edema in three cases, intracranial hemorrhage in three, gastrointestinal bleeding in three, overhydration due to insufficient dialysis in one, septicemia in one, and rupture of a cerebral aneurysm in one. Continuous dialysis appeared to be superior to intermittent dialysis in these neurosurgical patients in that it produced less brain edema and was less often associated with hemorrhage due to insufficient dialysis. In HD and CAVH, systemic heparinization was also thought to account for the high incidence of hemorrhage. However, CAVH with short half-life anticoagulants may be useful in patients who have abdominal complications and are therefore not suitable candidates for peritoneal dialysis.

Traumatic intraventricular hemorrhage: report of twenty-six cases and consideration of the pathogenic mechanism

A series of 26 patients suffering traumatic intraventricular hemorrhage (IVH) after closed head injury is reviewed, and the pathogenic mechanism of the traumatic IVH is discussed considering the site of origin of the IVH. Computed tomographic detection of the origin of the IVH was possible in 15 patients (Group 1): 6 had frontal or temporal contusional intracerebral hemorrhage spreading into the ventricle (Subgroup A), 5 had the original hemorrhage in the caudate nucleus (Subgroup B), and 4 originally bled in the thalamus (Subgroup C). The origin of the IVH was not determined in 11 patients (Group 2): 6 had concomitant hemorrhage around the brain stem (Subgroup D), and 5 had small IVH with or without small intracerebral hemorrhage (Subgroup E). The site of impact was not uniform in Subgroup A, whereas the other four subgroups usually had frontal or occipital impact. In Subgroup A, the IVH was discovered more than several hours after trauma. In the other four subgroups, however, the IVH was detected in as short a time as 0.5 to 1.5 hours after trauma. In Subgroups B and C, the impact along the long axis of the skull and the early occurrence of hemorrhage in the basal ganglia suggest that shear injury between the perforating vessels and the basal ganglia may be the responsible mechanism. The several other possible mechanisms in Subgroups D and E are reviewed and discussed in relation to diffuse brain injury.

Computed tomography of intracranial chondroma with emphasis on delayed contrast enhancement

Intracranial chondroma is an unusual cartilaginous tumor originating from the base of the skull. We report on two cases of intracranial chondroma that showed delayed contrast enhancement on CT after high-dose administration of contrast medium. This CT feature may be useful to differentiate chondromas from other tumors of the skull base such as meningiomas and neurinomas.

[Surgical approach for jugular foramen neurinoma--combined suboccipital and infralabyrinthine approach using a rotatable head holder]

A 36-year-old male with jugular foramen neurinoma was operated upon using a rotatable head holder, which enables the surgeon to rotate the patient's head at any time during the procedure and to gain access in multiple directions to the tumor. The tumor was situated primarily in the jugular foramen and showed partial extension into intracranial as well as into extracranial space. The patient was placed in the lateral position with a rotatable head holder, which allows rotation of the patient's head with the range of 10 degrees face up to 80 degrees face down from the horizontal plane. A linear skin incision was made, beginning behind the auricle and extending along the anterior margin of the sternocleidomastoid muscle, and the sternocleidomastoid muscle was divided just below the tip of the mastoid process. During mastoidectomy and suboccipital craniectomy, the patient's head was rotated 15 degrees face down and sigmoid sinus was exposed toward the jugular foramen, meanwhile the posterior fossa dura mater was opened and the intracranial portion of the tumor was removed with the head positioned 45 degrees-60 degrees face down. The patient's head is then turned 30 degrees face down and the facial canal was opened to displace the facial nerve forward. This oblique posterior approach minimized facial nerve displacement and provided excellent exposure of the large tumor rest which was situated mainly in the jugular foramen and partly extended extracranially. The rotatable head holder allows excellent access in multiple directions and is very helpful in approaching to jugular foramen neurinomas which grow primarily in the jugular foramen and extend both into intra- and extracranially.