Intracellular Ca2+ acts as the second messenger in a variety of cells. Many cellular functions are tightly regulated by the intracellular Ca2+ concentrations ([Ca2+]i). Therefore, measurement of the [Ca2+]i is of critical importance. Calcium-sensitive dual excitations, indicators, such as fura-2, are now widely used to measure the [Ca2+]i in living cells. The development of techniques allowing the measurement of [Ca2+]i has contributed noticeably to our understanding of many cellular functions. Digital video microscopy, confocal laser scanning microscopy, and multiphoton microscopy allow accurate spatial analysis of [Ca2+]i at the subcellular level. Fura-2 has been used commonly to measure the [Ca2+]i because of the sensitivity and specificity of the method. It can be loaded into living cells with little disruption of the cellular functions. Fura-2 acetoxymethyl ester (AM) is a lipid-soluble derivative that is often used extracellularly because of its ability to pass through cell membranes, whereas fura-2 by itself cannot be introduced into the cells. For fura-2 measurements, measurements of the fluorescence intensities at two excitation wavelengths can be used to obtain an estimate of the [Ca2+]i, independent of the dye concentration and the thickness of the cell membrane. In this review, I summarize the advantages and pitfalls of using fura-2 and other standard Ca2+ indicators, methods used to measure the [Ca2+]i, including simultaneous measurements of cell movements and the changes in the [Ca2+]i, and procedures used for measuring the cellular and/or subcellular Ca2+ concentrations in living cells from the cochlea, such as the outer and inner hair cells.
The prevalence of BPPV in hemodialysis patients, and whether BPPV in hemodialysis patients is intractable, were examined. The investigation was conducted by a questionnaire survey of 390 hemodialysis patients at three facilities and in 134 patients with BPPV at my clinic. Probable BPPV was diagnosed in the hemodialysis patients when positional vertigo was evoked by lying down, getting up or turning over in bed, and the vertigo decreased within 1 minute. Intractability of BPPV was estimated according to the time taken for remission of the positional vertigo and the frequency of recurrence. Bone mineral density (Z-score) measurements by dual X-ray absorptiometry of the radius bone were performed in 146 hemodialysis patients. The Z-scores were compared between the probable BPPV patients and the patients with no vertigo and/or dizziness. The prevalence of BPPV was about 9% in the hemodialysis patients. There were no significant differences between the groups in terms of the duration of BPPV or the multiple recurrence rates. Bone mineral density was similar in the groups. We conclude that BPPV in hemodialysis patients predominates and occurs often but is not always intractable. It is not clear whether Ca metabolism may play a role in the development of BPPV in hemodialysis patients.
To clarify the mechanism underlying the differences between voluntary saccade and the quick phase of optokinetic and vestibular nystagmus, the characteristics of the adducting and abducting eye movements were verified. During alternating saccades to lateral fixation targets, the adducting eye started behind the abducting eye, but quickly overtook it, reaching the fixation target first. The small delay in the onset of the adducting movement could be attributed to one more neural tract that the lateral fixation cue drives than the abducting eye. The quick-phase movements during optokinetic and caloric nystagmus showed similar characteristics, although during caloric stimulation, the abducting eye sometimes was not overtaken by the adducting eye. This likely reflects the different firing patterns of the burst neurons caused by the different neural circuits.
The percentage of patients with bilateral canal paresis (CP) was 12.9% in the 279 patients suffering from dizziness or vertigo visiting the Laboratory of Equilibrium Function at Kumamoto University hospital from 2002 to 2006 who were enrolled in the study. As the cause of bilateral CP, Meniere's disease and central nervous system diseases were considered to be the most important. We divided patients with bilateral canal paresis into the light CP group and severe CP group and examined the differences in the between the two groups. The body equilibrium was affected to a more severe degree in the severe CP group as compared with that in the light CP group. On the other hand, the result of ADL evaluation showed the absence of any significant difference between the two groups. As long as the semicircular canal function was maintained, the body equilibrium was maintained. We thought that the correspondence that did not let light CP shift to severe CP is necessary.
We performed a demographic analysis of 2293 vertiginous patients seen at our clinic from February 1995 to November 2005. While a definitive diagnosis could be made in 1287 cases (56%), the diagnosis remained tentative in 622 (27%), and the cause diagnosis remained unknown in 384 cases (17%). The most common vertiginous disease was benign paroxysmal positional vertigo (456 cases), followed in prevalence by Meniere's disease (232 cases). Most patients had visited other medical facilities before visiting our clinic. Analysis of the medical facilities visited by the patients suggested that the vertiginous patients visited both physicians and otolaryngologists; while. physicians saw the patients in primary care settings, otolaryngologists examined the patients at general hospitals and university hospitals. This discrepancy may complicate the care of vertiginous patients.
We report two young patients of Wallenberg syndrome who presented with acute vertigo as the initial symptom. Neither Case 1, an 8-year-old girl, nor Case 2, a 29-year-old man, showed any abnormal findings on the initial magnetic resonance imaging (MRI) on day 1. In addition to nystagmus, several neurological signs became positive during the clinical course. Finally, the diagnosis of Wallenberg syndrome was made in both cases based on the detection of a lateral medullary infarction in a follow-up MRI conducted on day 4. Stroke should be considered in the differential diagnosis of acute vertigo, even in young patients without risk factors for cerebrovascular disorders, such as hypertension, diabetes and/or hyperlipidemia. Since MRI may show no abnormalities in the very early stages of stroke, neurological examinations are useful to establish the diagnosis in cases presenting with vertigo induced by brain stem or cerebellar infarction.
Brainstem disorders are often characterized by abnormal eye movements, however, the type of abnormal movements vary depending on the localization and severity of the damage. Here, we report a case of pontine hemorrhage who exhibited horizontal conjugate gaze palsy and disorder of speech discrimination. The 34-year-old man presented with eye pain and dull feeling malaise?, disorder of speech articulation and torpor paralysis ?? of the left side of the body of sudden onset, that developed while he was driving a car. Clinical examination revealed horizontal conjugate gaze palsy, both rightward and leftward, while vertical gaze and convergence were normal. Although the pure-tone audiogram and DPOAE were within normal range, ABR showed prolongation of latency, and reduction of speech discrimination was recognized. MRI revealed evidence of hematoma and edema extending from the mid-dorsal aspect to the right side of the pons. Based on the findings, the patient was diagnosed to have pontine hemorrhage due to hypertension affecting the right facial nerve nucleus, right pyramidal tract, bilateral abducens nuclei, MLF, PPRF and the auditory neural pathway. Although the symptoms of pyramidal tract and auditory disorder resolved by day 19 when he was?? moved to another hospital, the other neurological symptoms were persistent.
The effects of menopause on equilibrium disorders were studied in 315 women aged 12-89 yr old in Japan. The patients were divided into 3 groups; premenopausal women aged 12-44 yr old (Group 1; n=103), menopausal women aged 45-55 yr old (Group 2; n=64), and postmenopausal women aged 56-83 yrs (Group 3; n=148). As corresponding controls, 178 men aged 14-80 yrs with equilibrium disorders were enrolled. The percentages of each disease were compared among Groups 1, 2 and 3. Furthermore, the percentages were also compared between the women and the men. The percentage of patients with Meniere's disease differed among the women of Groups 1, 2 and 3 (p<0.10). The percentage of patients with Meniere's disease was higher in Group 1 than in Group 3 women (p<0.10). The percentage of patients with sudden deafness was higher in Group 3 women than in the corresponding group 3 of men (p<0.05). The percentage of patients with vertebrobasilar insufficiency differed among the women of Groups 1, 2 and 3 (p<0.05), was higher in the Group 3 than the Group 1 women (p<0.05). The percentage of patients with vertigo/dizziness due to unstable blood pressure differed among the women of Groups 1, 2and 3 (p<0.05), was higher in the Group 2 than in the Group 1 (p<0.10) and Group 3 (p<0.10) women. The percentage of patients with Meniere's disease, sudden deafness, vertebrobasilar insufficiency, and vertigo/dizziness due to unstable blood pressure in men did not differ significantly among the corresponding three control groups of men. The results of the comparative study between women and men suggests that menopause might have an effect on the incidence of Meniere's disaese, sudden deafness, vertebrobasilar insufficiency and vertigo/dizziness due to unstable blood pressure.
The clinical picture and course of vestibular neuronitis (VN) were investigated in 53 cases encountered over the last 8 years and 9 months. Lesions of the vestibular nerve were evaluated by the caloric test and vestibular evoked myogenic potentials (VEMP); canal paresis (CP) with normal VEMP indicated superior VN, while CP with impaired VEMP indicated both superior and inferior VN. Among the 53 cases of VN evaluated, 37 had superior VN, 13 had superior and inferior VN, and the remaining 3 cases were labeled as undetermined. No case of inferior VN was found in our series. Functional recovery of the vestibular nerve was confirmed in half of the cases in whom the caloric test was repeated around 3 months later. The average duration of gaze nystagmus observed was 11.5 days, and that of positional nystagmus observed using a CCD camera was 6 months. On the other hand, the duration for which gaze nystagmus was observed in 50% of the cases (50% positive period) was 9.5 days, and the corresponding duration for positional nystagmus was 62 days. The difference in the average duration and 50% positive period is discussed.