Yutaka Kuru

Middle Fossa Arachnoid Cyst: Clinical, Neuroradiological, and Surgical Features

16 patients and 4 adult cases of small-or medium-sized middle fossa arachnoid cyst were subjected to various neuroradiological investigations and their results were analyzed in terms of possible mechanisms of cyst expansion. Based on the results of the investigations which strongly suggested that the cyst is an expanding lesion, all cases were surgically treated by the same techniques of craniotomy, excision of the outer cyst membrane, followed by a cystoperitoneal shunt, resulting in complete disappearance of the cyst concomitant with reexpansion of the surrounding brain and marked improvement in the clinical pictures of the patients.

MRI findings in the mild type of mucopolysaccharidosis II (Hunter's syndrome)

SummaryNeuroradiological findings in a 44-year-old male with the typical mild type of Hunters disease are reported. Cranial MRI revealed patchy areas of increased and decreased signals in T1- and T2-weighted images in the thalamus and the basal ganglia giving rise to a honey comb-like appearance as a whole. The deep white matter showed high signals in the T2-weighted image. To our knowledge, the honey comb-like appearance has never been reported in this disorder. Deposition of mucopolysaccharides and/or glycolipids and increase in fluid content seem to be responsible for these changes.

Surgically confirmed myelographic classification of congenital intraspinal lipoma in the lumbosacral region

Twenty-four cases of histologically confirmed congenital intraspinal lipoma of the lumbosacral region were studied by means of myelography with metrizamide. The findings were compared with intraoperative observations. Myelography with metrizamide clearly revealed the detailed intrathecal structures and allowed a classification of intraspinal lipomas into four types, in terms of their insertion into the conus medullaris: (1) dorsal type, either with direct or indirect (via an intrathecal stalk) insertion of the extrathecal lipoma into the dorsal aspect of the conus medullaris; (2) caudal type; (3) combined type; and (4) filar lipoma. Based on our surgical experience in untethering and decompression of the lesions, the classification was found to be useful in designing a safe and effective surgical procedure which minimized all possible trauma to the intrathecal neural structures.

Serial neuroradiological studies in focal cerebritis

We report serial neuroradiological studies in a patient with focal cerebritis in the head of the left caudate nucleus. On the day after the onset of symptoms, CT showed an ill-defined low density lesion. The lack of contrast enhancement appeared to be the most important finding for differentiating focal cerebritis from an encapsulated brain abscess or a tumour. MRI two days later revealed the centre of the lesion to be of slightly low intensity on T1-weighted inversion recovery (IR) images and very low intensity on T2-weighted spin echo images, which appeared to correspond to the early cerebritis stage of experimentally induced cerebritis and brain abscess. Ten days after the onset of symptoms, CT revealed a thin ring of enhancement in the head of the caudate nucleus, and a similar small ring was seen in the hypothalamus 16 days after the onset, corresponding to the late cerebritis stage. MRI nine days later revealed ill-defined high signal lesions within the involved area on the T1-weighted IR images. To our knowledge, this is the first published MRI documentation of the early cerebritis stage developing into an encapsulated brain abscess. The mechanisms underlying of these radiographic changes are discussed.

Acoustic Neurinoma with Early Venous Drainage and Caput Medusae-like Vasculature on Angiogram

It has been considered that acoustic neurinomas are hypovascular tumors on angiogram. Recent angiographical analysis, however, revealed that some of them showed tumor stain, capsular stain, and even arteriovenous shunt. The problem with operation on the acoustic neurinoma with a peculiar vasculature on angiogram has not been discussed in previous reports. In this paper, the neuroradiological findings of a unique case are described, in conjunction with the operative problem. A case of huge acoustic neurinoma with early venous drainage and caput medusae-like vasculature on angiogram is presented. The patient was a 46-year-old woman suffering from dizziness and gait disturbance. On admission, she had bilateral choked disc, left fifth and seventh nerve palsy, and left cerebellar signs. The audiogram showed scale out on the left, carolic test and auditory brain stem response were nil on the left side. On computed tomography, a huge, heterogeneously enhanced mass was detected in the left cerebellopontine angle. Vertebral angiography revealed that the tumor was supplied by the anterior inferior cerebellar artery and ascending pharyngeal artery. Caput medusae-like vasculature was visualized in arterial and capillary phases, and abnormal draining veins were also opacified in these phases. They were considered to be an arteriovenous fistula. At operation, the abnormal vasculature looked like an arteriovenous malformation on the tumor capsule, which made the surgical procedure of dissecting the tumor from the pons extremely difficult.

Ammon’s Horn Sclerosis on Pneumoencephalotomography

Fourteen cases with psychomotor seizure were examined by pneumoencephalotomographic technique. In all cases uni- or bilateral changes of the inferior horn were found: diverticular dilatation of subiculum, lowering and irregularity of the floor, reduction of width, and deformation of digitation. These findings correlated well with the autopsy reports. In most cases, EEG findings also correlated.

Basiparallel Cut by Pneumoencephalotomography and Cerebellar Atrophy

The basiparallel cut is a nearly horizontal slice of the posterior fossa used in air study and the structures are observed on a plane parallel to the clivus. Total shrinkage of the cerebellum, with or without fourth ventricle dilatation, was found in cases of olivopontocerebellar atrophy, some intoxications, and a few senile subjects. Some atrophy of paleocerebellar portions was seen in Holmes-type degeneration. Another pattern was symmetric shrinkage of neocerebellar lobules and relatively specific for the cases of ‘multiple system atrophy’ such as progressive supranuclear palsy, striatonigral degeneration, Marie’s ataxia, etc. Loss of the superior cerebellar peduncle was clearly demonstrated in this view.