Diffusion Tensor Imaging Findings in Two Cases of Internal Capsular Genu Infarction

Internal capsular genu infarcts infrequently cause cognitive impairment and behavioral changes, and little is known about the underlying mechanism. Using diffusion-tensor imaging (DTI) and the fractional anisotropy (FA) index in the region of interest (ROI) and ipsilesional frontal cortex, we evaluated two patients with internal capsular genu infarction who presented with frontal dysfunction and cognitive impairment. The reported findings help to elucidate the mechanism underlying cognitive deterioration in internal capsular genu infarction.

Temporary Spontaneous Remission in Primary CNS Lymphoma

Spontaneous remission in untreated primary central nervous system lymphoma is rare. A 66-year-old man was admitted with dizziness and gait disturbance. Initial fluid-attenuated inversion-recovery images revealed hyperintensities in the upper brainstem, left temporal lobe, and right occipital lobe. The patient's symptoms and lesions disappeared spontaneously after 1 month. However, he was readmitted after 4 months with right hemiparesis. Magnetic resonance imaging revealed a homogenous enhanced lesion in the left basal ganglia with a vasogenic pattern. This disease warranted biopsy, which revealed large B-cell lymphoma.

Inhibitory Effect of Tyrphostin AG126 on Brain Synaptosomal Dysfunction Induced by Cholesterol Oxidation Products

BACKGROUND: Formation of cholesterol oxidation products is a suggested mechanism of neurodegenerative disorders. Neuronal cell death is mediated by an increased release of excitotoxic glutamate from the presynaptic nerve endings. Tyrosine-specific protein kinases modulate neurotransmitter release at the nerve terminals. Tyrphostin AG126 has anti-inflammatory and cytoprotective effects. However, it remains uncertain whether tyrphostin AG126 has a preventive effect on the alteration of nerve terminal function induced by cholesterol oxidation products. METHODS: The present study was performed to assess the effect of cholesterol oxidation products against nerve terminal function using synaptosomes isolated from rat cerebrum. We determined the preventive effect of tyrphostin AG126 against oxysterol toxicity by measuring the effects on the glutamate release, depolarization of the membrane potential, changes in Ca2+ levels, and Na+/K+-ATPase activity. RESULTS: Synaptosomes treated with 7-ketocholesterol or 25-hydroxycholesterol exhibited a sustained release of glutamate, depolarization of membrane potential, early rapid increase in cellular Ca2+ levels and decrease in Na+/K+-ATPase activity. Those responses were concentration-dependent. Treatment of tyrphostin AG126 interfered with alteration of synaptosomal functions and decrease in Na+/K+-ATPase activity induced by 7-ketocholesterol or 25-hydroxycholesterol. CONCLUSIONS: The results show that 7-ketocholesterol and 25-hydroxycholesterol seem to cause the release of glutamate by inducing depolarization of the membrane potential and early rapid increase in cellular Ca2+ levels and by inactivating Na+/K+-ATPase in the cerebral synaptosomes. Treatment of tyrphostin AG126 may prevent the oxysterol-induced nerve terminal dysfunction.

Electrophysiological Changes in Lambert-Eaton Myasthenic Syndrome With Intravenous Immunoglobulin Therapy

No abstract available.

Inhibition of Oxidative Tissue Damage and Mitochondrial Dysfunction by Glycyrrhizin in the 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine Mouse Model of Parkinson's Disease

BACKGROUND: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) produces an irreversible and severe parkinsonian-like syndrome. A licorice compound glycyrrhizin exerts a cytoprotective or anti-oxidant effect in various disease conditions, but its effect against the MPTP-induced brain tissue damage remains uncertain. The present study elucidates the protective effects of glycyrrhizin against brain tissue damage in the MPTP mouse model of Parkinson's disease. METHODS: We measured the activities of antioxidant enzymes and formation of tissue peroxidation products in the brains of MPTP-treated mice. We also performed an in vitro assay to examine the effects of 1-methyl-4-phenylpyridinium (MPP+) on the mitochondrial respiratory electron flow, membrane potential and cytochrome c release and measured the scavenging action of glycyrrhizin against reactive oxygen species. RESULTS: The MPTP treatment increased activities of total superoxide dismutase, catalase, and glutathione peroxidase and levels of malondialdehyde and carbonyls in the basal ganglia, diencephalon plus midbrain compared to the control mouse brain. Co-administration of glycyrrhizin (16.8 mg/kg = 20 micrometer) attenuated the MPTP effect on the enzyme activities and formation of tissue peroxidation products. Glycyrrhizin attenuated the 500 micrometer MPP+ -induced inhibition of electron flow, changes in the membrane potential and cytochrome c release in isolated brain mitochondria. Glycyrrhizin (1-50 micrometer) showed a scavenging action against superoxide radicals, hydrogen peroxide and hydroxyl radicals. CONCLUSIONS: Glycyrrhizin may prevent the toxicity of MPTP against brain tissue by suppressing mitochondrial damage and oxidative tissue damage. Glycyrrhizin seems to attenuate oxidative brain tissue damage occurring in Parkinson's disease through antioxidant action and prevention of mitochondrial dysfunction.

Mild Encephalopathy with Reversible Lesion in the Splenium of the Corpus Callosum and Bilateral Frontal White Matter

A 59-year-old man visited an emergency room due to the sudden onset of severe dysarthria with a drowsy mental status. MRI demonstrated T2 prolongation and restricted diffusion involving the splenium of the corpus callosum and bilateral frontal white matter neurological signs and symptoms were mild, and the recovery was complete within a week. Follow-up MRI performed one month later revealed complete resolution of the lesions. The clinical and radiological courses were consistent with previously reported reversible isolated splenial lesions in mild encephalitis/encephalopathy except for the presence of frontal lesions. This case suggests that such reversible lesions can occur outside the splenium.

Two Cases of Cerebral Venous Thrombosis with High Signal Intensity of Intravascular Clots on Diffusion Weighted Image

High signal intensity on diffusion-weighted image (DWI) at the site of venous occlusion has previously been reported in cerebral venous thrombosis (CVT). The frequency and diagnostic value of these signal changes in CVT were unknown. Some authors suggest that the presence of high signal intensity on DWI in occluded veins might help diagnose CVT and suggest low rate of recanalization. We experienced two cases of CVT with high signal intensity at the site of intravascular clot on DWI.