We report a patient with disabling tinnitus that responded dramatically to microvascular decompression of the 8th cranial nerve. The most annoying, episodic, high pitched tinnitus disappeared immediately after the operation. Two types of constant tinnitus either persisted or recurred after the procedure. Nevertheless, the remaining tinnitus is much reduced compared to the preoperative level. The patient was able to return to his previous work 2 months after operation.

We report serial CT and MRI findings in a biopsy-proven case of cerebral amyloid angiopathy (CAA) with isolated angiitis of the central nervous system (CNS). A 69-year-old man had developed dizziness, dementia, and generalized seizure during the preceding 4 years. An initial examination by brain CT and MRI showed bilateral symmetrical periventricular lesions closely resembling those of Binswanger's disease. Subsequently, the lesions expanded slowly, involving a large area of the right cerebral hemisphere with an obvious mass effect. Since a primary brain tumor was suspected, a brain biopsy was performed, and histopathological examination revealed amyloid beta protein CAA within the meningocortical vessels associated with perivascular monocytic cuffing, indicating the presence of isolated angiitis of the CNS. Multinucleated giant cells containing intracytoplasmic beta protein amyloid around a heavily amyloid-laden cortical vessel were also observed. This is the first case report to show sequential radiographical studies of the leukoencephalopathy associated with CAA and isolated angiitis of the CNS.

There had been a smoking case in which dimethylamphetamine (DMA) and its metabolite DMA-N-oxide (DMAO) in addition to methamphetamine (MA) and amphetamine (AM), were detected in the abuser's urine. The analytical results of the confiscated leftover drug enabled us to consider that DMA detected in the abuser's urine would be the pyrolysis product formed by smoking MA. In this study, we carried out a smoking experiment based on this smoking case, and then gave the case full consideration. We heated MA hydrochloride in the range of 250°C to 350°C, in which demethylation and methylation reactions occurred mainly, with a smoke collection apparatus and a gas lighter, and trapped the generating vapor with an adsorption cartridge. AM and DMA were produced via the demethylation and methylation reactions of a methylamino group of MA. Allylbenzene, benzaldehyde, cis-␤-methylstyrene, benzyl chloride and trans-␤-methylstyrene were also formed as pyrolysis products. The sum of the formation ratio of DMA to the starting MA in the cartridge eluate and that in the residual materials inside the smoke collection apparatus was 4.98%. The adsorption of some pyrolyzates containing DMA on the cartridge means that these pyrolyzates can be taken into an abuser's body. The ratios of DMA to AM in the smoking experiments and the smoking case were 52.3% and 50.3%, respectively, and they were nearly equal. There will be no inconsistencies in considering that AM and DMA have been formed as pyrolysis products of MA in the smoking case, and DMA and its metabolite DMAO have been detected in the urine of this smoking abuser.

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