Comparison of techniques for identification of peripheral vestibular nystagmus.

OBJECTIVE: To determine the best clinical method for identifying peripheral vestibular nystagmus, by comparing eye movement examination with optic fixation, and with fixation removed using Frenzel's glasses, infra-red video-Frenzel's goggles or an ophthalmoscope, with results of electronystagmography. METHOD: One hundred patients referred for electronystagmography from the audiovestibular medicine clinic at Queen Alexandra Hospital, Portsmouth, were examined immediately before undergoing electronystagmography. RESULTS: Video-Frenzel's goggles were highly effective at detecting peripheral vestibular nystagmus, with a sensitivity of 85 per cent (95 per cent confidence interval, 62.1-96.8 per cent) and a specificity of 65 per cent (53.5-75.3 per cent), compared with electronystagmography. Ophthalmoscopy had comparable sensitivity to Frenzel's glasses (used in the dark), i.e. 26.3 per cent (9.1-51.2 per cent) compared with 31.6 per cent (12.6-56.6 per cent), respectively. Frenzel's glasses as normally used in ENT clinics (i.e. in dim lighting) were ineffective, with a sensitivity of just 10 per cent (1.2-31.7 per cent). CONCLUSION: Video-Frenzel's goggles should be used in all clinics with substantial numbers of balance-impaired patients. Traditional Frenzel's glasses have no place in clinical practice unless formal black-out facilities are available.

Orthopaedic theatre noise: a potential hazard to patients.

Potentially hazardous noise levels are generated in the course of major orthopaedic surgery. The risk to staff is probably real but very small. We used a sound level meter to record maximum and mean levels and found peak values which exceeded 100 dB(A). If sustained, there is a possibility of significant inner ear damage and perhaps permanent troublesome tinnitus, especially among elderly and already hearing-impaired patients. This could be eliminated by the use of ear defenders or disposable earplugs.

Effect of the class III antiarrhythmic agent E-4031 on the ATP-sensitive potassium channel in rabbit ventricular myocytes.

The class III antiarrhythmic drug E-4031, a known blocker of the delayed rectifier potassium channel (IK), might also be capable of blocking the ATP-sensitive potassium channel (IKATP). We examined this possibility by studying the effect of E-4031 on single IKATP channels in membrane patches excised from ventricular myocytes that were obtained by standard enzymatic dissociation techniques from New Zealand white rabbits. In inside-out patches, E-4031 caused a dose-dependent block of IKATP with an EC50 of 31 +/- 1 microM, Hill coefficient of 0.89 +/- 0.24 and no effect on channel conductance. Open dwell-time kinetics were fitted by two exponential components, with E-4031 causing reduction of the longer time constant. In outside-out patches, the concentration of E-4031 required to produce blockade was much higher. We conclude that E-4031 blocks the ATP-sensitive potassium channel and that it does so from within the cytoplasm, with one-to-one channel binding stoichiometry. Single channel conductance is unchanged, but the longer time constant for the open state is reduced, which suggests that E-4031 may be an open channel blocker of intermediate to slow time course.

Inhibition of ATP-sensitive potassium channels in cardiac myocytes by the novel class III antiarrhythmic agent MS-551.

The novel class III antiarrhythmic agent, MS-551, has recently been shown to attenuate the decrease in ventricular effective refractory period and to prevent the subsequent ventricular fibrillation induced by pinacidil and hypoxia in isolated perfused rabbit hearts (Friedrichs et al. 1994). We studied the effects of MS-551 on single ATP-sensitive potassium channels in isolated rabbit ventricular myocytes using standard patch-clamp methods. MS-551 in the range from 1 microM to 100 microM produced a concentration-dependent reduction of the open probability of the ATP-sensitive potassium channel, with an apparent ED50 of 30 microM. This reduced channel activity was due to a smaller number of channel openings per unit time, and the average duration of each opening of the channel was unaffected. This property of MS-551 is likely to be of most significance in ischaemic tissue, where the ATP-sensitive channels are thought to carry the predominant current that shortens the duration of the action potential.

Effect of captopril on functional mitral regurgitation in dilated heart failure: a randomised double blind placebo controlled trial.

OBJECTIVE: To determine the efficacy and dose requirements of captopril to reduce functional mitral regurgitation in patients with dilated heart failure. DESIGN: A randomised double blind placebo controlled parallel arm trial. Incremental daily doses of 25 mg, 50 mg and 100 mg captopril used for a four week period each for a total of 12 weeks preceded by a two week placebo washout. Twenty eight ambulatory patients (mean age 72) New York Heart Association (NYHA) class II or III with apparently controlled ischaemic dilated heart failure (ejection fraction 29% (0.04%)) on digoxin, diuretics, and nitrates were randomised. All had at least grade 2/4 functional mitral regurgitation (> 5 cm2 regurgitant area on colour flow Doppler). RESULTS: Twenty three patients completed the study (13 on placebo and 10 on captopril). Significant improvements were confined to the captopril group. Compared with placebo the following improvements were noted in the captopril treated group: mitral regurgitant area decreased from a threshold at 50 mg/day (p < 0.05, mean (95% confidence interval (95% CI)) 3.1 (0.2 to 6.0) cm2), with a further decrease at 100 mg/day (p < 0.01, mean (95% CI) 5.3 (3.1 to 7.5) cm2). Significant improvements in all the other measurements were noted only after 100 mg/day. Stroke volume increased (p < 0.01, mean (95% CI) 11, (1.4 to 21) ml), systemic vascular resistance decreased (p < 0.05, mean (95% CI) 414 (35 to 793) dyn s cm5), left atrial area decreased (p < 0.05, mean (95% CI) 4.3 (0.03 to 8.6) cm2), and deceleration time increased (p < 0.01, mean (95% CI) 52 ms (7 to 98) ms). Left ventricular diameter decreased marginally (p = 0.06, mean (95% CI) 4 (-0.05 to 9 mm). Duke activity index score increased (p < 0.001, median (95% CI) 6.8 (4.5 to 12) points). Heart rate, mean arterial blood pressure, serum creatinine, and serum potassium did not change with either placebo or captopril. No patient was withdrawn directly due to the side effects of captopril. In an open phase nine placebo patients given captopril in rapid increments reaching 100 mg/day in the fourth week showed similar improvements. CONCLUSION: Captopril is efficacious in reducing functional mitral regurgitation in dilated heart failure. Patients require and must tolerate high doses (50-100 mg/day) for additive effects over supervised conventional treatment to occur.

TENS in refractory angina pectoris. Three case reports.

OBJECTIVE: To demonstrate the use of transcutaneous electrical nerve stimulation (TENS) in the treatment of refractory angina pectoris. CLINICAL FEATURES: Three cases are presented. Patient 1 was a 56-year-old man with a 20-year history of angina pectoris. Angiography revealed extensive stenoses of coronary arteries. He was deemed unsuitable for coronary bypass surgery due to significant distal coronary disease. Patient 2 was an 81-year-old woman with angina that responded poorly to increasing drug therapy: she also had extensive stenoses but was judged unsuitable for surgery. Patient 3 was a 69-year-old man who had previously undergone two coronary bypass procedures and presented with unstable rest angina. The patient was deemed unsuitable for a third coronary artery bypass operation due to distal disease and the small calibre of the intermediate artery. INTERVENTION AND OUTCOME: Each patient had TENS added to their treatment regimen (one hour twice a day for Patient 1; one hour three times a day for Patients 2 and 3). Patient 1 experienced a marked reduction in pain which lasted for over a year before symptoms of angina again worsened. Patient 2 has experienced no further pain of angina except on occasions when her TENS unit was not working or she neglected to use it as prescribed. Patient 3 had been free of angina from commencement of TENS therapy on review three months later. CONCLUSION: TENS may be useful in the treatment of angina pectoris which is refractory to medical therapy when the patient is not suitable for revascularisation procedures or revascularisation has failed. The mechanism of action is probably a combination of analgesia per se and inhibition of sympathetic nervous stimulation of the heart.

Assessment of the relationship of cerebral hemisphere arousal asymmetry to perceptual asymmetry.

This study examined the hypothesis that characteristic individual differences in cerebral hemisphere arousal asymmetry are related to individual differences in perceptual asymmetry observed in verbally based visual half-field tasks. The study used electrophysiological measures of arousal asymmetry rather than behaviorally derived measures (Levy, Heller, Banich, & Burton, 1983). Measures of alpha asymmetry were obtained from 20 right-handed males during a baseline relaxation condition and during a visual half-field version of the lexical decision task. Reaction time measures of perceptual asymmetry were obtained during this task. The results indicated that a basal arousal asymmetry measured at the temporal recording location during the baseline condition was significantly related to individual perceptual asymmetry during the subsequent lexical decision task. This basal arousal asymmetry was relatively stable across different task conditions. A task-related arousal asymmetry measured at the parietal location during the lexical decision task also made a significant contribution in predicting individual perceptual asymmetry. These two measures of individual arousal asymmetry were able to predict 50% of the variance in perceptual asymmetry. The implications of the results for explaining more wide-ranging individual differences in behavioral style and personality are discussed.

Optic disc oedema and diabetes mellitus: a case report with review.

Optic disc oedema is a neurological complication of diabetes mellitus. Typically, the patient is a young diabetic with minimal symptomatology but severe bilateral optic disc oedema discovered on routine eye examination. It is a relatively benign condition which on occasion can result in a residual visual deficit, but requires no specific intervention and represents a subgroup of anterior ischaemic optic neuropathy (AION). We present a patient with insulin dependent diabetes and asymptomatic bilateral optic disc oedema, with a brief review of the syndrome and its pathogenesis.

Early detection of hearing damage in young listeners resulting from exposure to amplified music.

Sixty young subjects in the 15-23 age range, selected on the basis of a questionnaire on the degree of exposure to amplified music, underwent 'high resolution' (4 min per octave) sweep-frequency Békésy tracking audiometry, and measurement of auditory frequency resolution at 4 kHz using the psychophysical comb-filtered noise masking technique. The more exposed groups had 10-15% wider bandwidths than the least exposed, and this difference achieved significance when subjects having audiometric notches were excluded, or when a subset of exposed subjects was taken in whom subjective evidence was obtained of Temporary Threshold Shift or post-exposure tinnitus. While the most exposed groups did not show significantly greater averaged thresholds, there was in the older age group, a significantly increased prevalence of notches in the audiograms in the 3.5-6 kHz range. We conclude that exposure to amplified music can be harmful, the earliest sign being decrease in frequency resolution, and that early elevation of thresholds is better detected by high-resolution Békésy tracking (extending over the range 2-8 kHz) than by conventional fixed-frequency audiometry.

Wildervanck's syndrome--unilateral Mondini dysplasia identified by computed tomography.

We present a case of the Wildervanck (cervico-oculo-acoustic) syndrome exhibiting congenital deafness. Klippel-Feil anomaly and lateral rectus palsy with enophthalmos. Audiometry indicated a predominantly conductive loss which, because of masking difficulties, was assumed to be bilateral: an erroneous assumption supported by results of conventional petrous bone tomography which failed to demonstrate any abnormality of the inner ears. Computed tomography (CT), however, revealed a severe Mondini dysplasia of one ear, a condition which must be assumed to be associated with severe sensorineural hearing loss. Reconstructive middle ear surgery for the conductive loss on the other side was therefore contraindicated.

Is my child normal yet? Correlates of vulnerability.

There are some children whose parents believe them to be unusually susceptible to medical or developmental problems--"vulnerable"--despite a lack of objective evidence of any difficulty. The "vulnerable child syndrome" refers to a constellation of behaviors that are thought to develop as a result of this excessive parental anxiety and subsequent difficulties in limit setting. In this study, the sense of vulnerability expressed by mothers concerning their healthy 3-year-old children is explored; children born prematurely and with considerable neonatal morbidity are compared with children born at full-term. Sense of vulnerability is assessed through the use of a simple instrument, the use and validity of which are described. Mothers of premature infants described a significantly greater sense of vulnerability concerning their children than did mothers of full-term infants. Mothers with more education described a greater sense of vulnerability than did less well-educated mothers, although mothers who claimed greater well-being and marital satisfaction described a lesser sense of vulnerability. Mothers with a greater sense of vulnerability concerning their children also reported more behavior problems, especially in the sphere of discipline, peer relationships and self-control, and in internalizing and somatic symptoms. Pediatricians can intervene in the development of the vulnerable child syndrome by recognizing those children at special risk and helping their parents to nurture their health and independence.