Cortical functional abnormality assessed by auditory-evoked magnetic fields and therapeutic approach in patients with chronic dizziness

A long-lasting dizzy sensation is a common complaint in elderly subjects. The pathogenesis and effective treatment of such chronic dizziness (CD), however, have not yet been fully elucidated because of lack of methods for evaluating this sensation. On the basis of assumption that CD may be attributable partly to cortical functional abnormality, we attempted to estimate the function of auditory cortex by measurements of auditory-evoked magnetic fields (AEFs). Magnetic field signals in the parieto-temporal cortex were evoked by 1000-Hz tone-burst with 90-dB normal hearing level sounds, and the highest-amplitude magnetic waveforms at approximately 100-ms (N100m) were analyzed as electrical current arrows in normal subjects (n=11), patients with CD (n=27) and patients with cerebral infarction but no dizzy sensation (n=9). In the normal subjects, the current arrows pointed to a nearly straight line with small directional distortion as indicated by a rotation-degree parameter, dI(rot) of 1.59+/-0.46. In 17 of 27 CD patients, the directions of current arrows were markedly distorted showing abnormally high dI(rot) values greater than 2.50 (the mean plus two standard deviations of normal values) and disclosed a clockwise or counter-clockwise rotation in either side or both sides of parieto-temporal cortex. In all the patients with cerebral infarction, the current arrows exhibited the similar pattern as the normal subjects. None of them exhibited abnormally high dI(rot) values. We hypothesized that the rotational abnormality may be caused by abnormal neuronal excitation, since non-evoked magnetic fields in temporal lobe epilepsy demonstrated the similar current rotational abnormality as reported previously. Seven CD patients were treated with anticonvulsants, and four showed remarkable amelioration of dizzy sensation. In all the four patients with symptomatic amelioration, the disappearance of rotational abnormality in AEFs or the tendency towards disappearance was observed following symptomatic amelioration. The results of the present study suggest that the auditory center may contribute to the maintenance of equilibrium, and its dysfunction may lead to the development of CD. AEFs measurements may make it possible to evaluate the functional abnormality of auditory center and may be useful for studying the pathophysiology and treatment of CD.     

Severe personality changes after unilateral left paramedian thalamic infarct

Personality changes are not uncommon after paramedian thalamic infarction, but usually bilateral or relatively large lesions, often complicated by other neurological or neuropsychological deficits, are present. 'Pure' cases of unilateral lesions are extremely rare. We report that a right-handed, 48-year-old man, who was hypertensive and diabetic but had no prior psychiatric history, developed severe personality changes and a frontal-like syndrome after recovery from acute-onset impairment of consciousness at the age of 43. Other neurological and neuropsychological disturbances, especially verbal and visual amnesia, were unremarkable. MRI showed a very small infarct in the left paramedian area of the thalamus, mainly involving the dorsomedial nucleus.     

Demyelination associated with HSV-1-induced facial paralysis

In 1995, we developed an animal model of transient homolateral facial nerve paralysis by inoculating Herpes simplex virus type 1 (HSV-1) into the auricle of mice. This study examined the mechanism of facial nerve paralysis in this model histopathologically. Using the immunofluorescence technique with anti-HSV-1 antibody, the time course of viral spread and the site of viral replication were investigated over the entire course of the facial nerve. Furthermore, viral replication and nerve degeneration at the site of viral replication were observed by electron microscopy. On the 7th day after inoculation, facial paralysis was observed in more than 60% of mice. Immunofluorescence study revealed HSV-1 in the geniculate ganglion, the descending root, and the facial nucleus at this stage. On the 9th day, the descending root in the sections stained with osmium looked pale, because prominent demyelination had occurred in this region; electron micrographs showed many degenerated oligodendrocytes and large naked axons. In contrast, the facial nucleus neurons showed no remarkable degeneration, despite HSV-1 particles in their cytoplasm. From these findings, we concluded that facial nerve paralysis in this model is caused mainly by facial nerve demyelination in the descending root.     

Effects of brain-derived neurotrophic factor (BDNF) on compression-induced spinal cord injury: BDNF attenuates down-regulation of superoxide dismutase expression and promotes up-regulation of myelin basic protein expression

Neurotrophins enhance the survival of cells in the nervous system under both physiological and pathological conditions, such as those caused by disease or trauma. We recently demonstrated that expression of brain-derived neurotrophic factor (BDNF) was up-regulated in neurons and glia after compression-induced spinal cord injury (SCI). We show here the effects of BDNF on the oligodendrocyte survival and functional recovery after SCI. The effects of intrathecally administered BDNF on both Cu/Zn superoxide dismutase (CuZnSOD) and myelin basic protein (MBP) expression were examined using rats that had received compression-induced spinal cord injury. CuZnSOD expression in the spinal cord was down-regulated within 24 h of compression-induced injury and then recovered. Continuous infusion of BDNF inhibited the acute down-regulation of CuZnSOD expression. In situ hybridization showed that CuZnSOD was expressed in both neurons and glia. Although MBP expression was greatly reduced after injury, BDNF administration promoted the recovery of MBP expression nearly to a control level after 2 wk. Furthermore, BDNF administration also prompted behavioral recovery. These results suggest BDNF's usefulness in human clinical applications. The attenuation of CuZnSOD down-regulation may be related to a protective effect of BDNF and the promotion of MBP up-regulation may be related to a long-lasting restorative effect.     

Soluble adhesion molecules in muscular dystrophy

To determine whether soluble adhesion molecules are affected in muscular dystrophy, we measured serum levels of creatine kinase (CK), soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1), soluble (s) E-selectin, and fibrin and fibrinogen degradation products (FDP) in 25 patients with Duchenne muscular dystrophy (DMD), 7 with Becker muscular dystrophy, 7 with Fukuyama type congenital muscular dystrophy, 6 with myotonic dystrophy (MyD), and 5 with spinal muscular atrophy (SMA) type 2, and also serum sVCAM-1, sICAM-1, and sE-selectin in 9 healthy controls. The levels of sVCAM-1 in the patients with DMD were 367.0-852.0 ng/ml (552.8 +/- 23.1) and significantly elevated than those in the patients with MyD, SMA type 2, and controls. The levels of sICAM-1 and sE-selectin in the patients with muscular dystrophy were 0.2-376.0 ng/ml and 17.9-119.0 ng/ml, respectively. They were also elevated than those in the patients with SMA type 2 and controls, but not significantly. The levels of sVCAM-1 and sE-selectin in the patients with DMD significantly correlated with age. There was no correlation between the levels of soluble adhesion molecules and those of CK or FDP in any groups. These changes of soluble adhesion molecules may reflect the process of muscle destruction and endothelial cell activation in muscular dystrophy.     

Delayed effects of the microvascular decompression on hemifacial spasm: a retrospective study of 131 consecutive operated cases

We reviewed 131 consecutive cases operated for hemifacial spasm (HFS) by the same surgeon between January 1983 and April 1999. Microvascular decompression (MVD) was performed via lateral suboccipital approach. Post-operative follow-up ranged from 1.5 to 10 years (average 34 months). The final outcome divided into three categories, excellent (total recovery) in 120 cases (91.6%), partial (> 75% recovery) in 4 cases (3.1%), and unchanged or recurrent in 7 cases (5.3%). Only 2 cases were re-operated, and final outcome of both was excellent. Based on these data, we aimed to determine a period of the final judgement of MVD effect and the causative factors of delayed effects on HFS retrospectively. There were 102 complete recovered cases without hemifacial paralysis; immediate recovery from HFS was observed in 78 cases (76.5%), after 1 month in nine cases, 1-3 months in 5 cases, 3-6 months in 3 cases, 6-10 months in 2 cases, and 10-12 months in 5 cases. Thus, most cases were completely recovered within one year of observation. On the other hand, there was no statistically significant difference between immediate and delayed relief cases in clinical histories or operative observations. Therefore, our results suggest that the final judgement of the MVD effect could be made at least one year after surgery.     

Pseudoxanthoma elasticum: report of a case without any mutations in 5 exons of the MRP6 gene

Pseudoxanthoma elasticum (PXE) is an inherited systemic disorder of connective tissue. We describe a patient with PXE who does not have mutations in exons 16, 24, 27, 28, and 30 of the MRP6 gene.     

Synchronous firing dynamics in a heterogeneous neurosecretory-cell population in an insect

Five pairs of neurosecretory cells in the subesophageal ganglion of the silkmoth Bombyx mori discharge action potentials in (near) synchrony to release a pheromone biosynthesis-activating neuropeptide (PBAN). Waveforms of compound action potentials recorded extracellularly from axonal tracts were analyzed to determine the firing activity, timing of spikes and the combination of active cells. Analyses revealed a heterogeneous cellular organization of the neurosecretory cell system. There was a gradient in the firing activity among the cells and the activity of a cell was closely related to relative timing of firing: the most active cell was usually the first to fire and participated in about 90% of all synchronous firing events, while the least active unit was mostly the last to fire and contributed to only 40% of all firing events. A cell with a higher firing activity had a higher potential to mediate propagation of synchronous firing in the cell system. Firing activities of right and left cell groups usually differed and the difference increased in case of a low temperature. Synchronous firings occurred more frequently among the same subgroup of cells rather than different subgroups. Heterogeneous cellular organization and coupling may be important for producing a graded pattern of active cell numbers, which seems to be suitable for maintaining a stable firing (secretory) activity of the cell system for a long period of time.     

Optical imaging of glycinergic inhibition in the vestibular and cochlear nuclei

Using multiple-site optical recording techniques, the spatiotemporal activity was observed in both the cochlear and vestibular nucleus in newborn mice. The optical responses were obviously enhanced by bath-applied strychnine. A quantitative analysis showed higher enhancements to occur in the cochlear nucleus than in the vestibular nucleus. Optical imaging enables us to visualize the spatiotemporal extent of the inhibitory receptive field after the application of strychnine.     

Comparison of the morphological changes of restenosis after the implantation of various types of stents in a swine model

BACKGROUND: Stent design causes the differences of restenosis rate, but the morphological differences after the various types of stent implantation have not been clarified. DESIGN: Seven types of stents were implanted in pig coronary arteries to clarify how the mechanism of restenosis differs with coil stents and tube stents. METHODS: The left anterior descending coronary arteries (LADs) of pigs were injured using coronary angioplasty balloons (diameter: 3.0 mm; length: 20 mm; balloon/artery ratio: 1 : 2). Fourteen days after the injury, four types of coil stents (Cordis, Wiktor, GR-I, and GR-II) and three types of tube stents (Palmaz-Schatz, gfx, and Multilink) were implanted, and the LADs were extracted 28 days after the implantation. RESULTS: The proliferated neointima was eccentric in the coil stents and concentric in the tube stents. Although there was no significant difference in the area of neointima, the area of the lumen was significantly larger in the tube stents than in the coil stents ( < 0.01) because of the larger area of stent. Cells positive for anti-proliferating cell nuclear antigen antibody were mainly observed around the stent struts, and most of these cells were also positive for either anti-macrophage or anti-smooth muscle actin antibodies. CONCLUSIONS: Compared to the coil stents, the tube stents induce less negative remodelling including stent recoil, resulting in a wider luminal area. In order to prevent restenosis, it is crucial to implant a stent that will cause less negative remodelling.