Treatment outcomes of benign paroxysmal positional vertigo.

OBJECTIVE: The purpose of this study was to examine the efficacy of the particle repositioning manoeuvre (PRM) in the treatment of benign paroxysmal positional vertigo (BPPV). DESIGN: A randomized prospective study of patients with BPPV. METHODS: Seventy-one patients were randomized to one of three groups at their first clinic visit. These groups included the PRM, a sham PRM, and a control group. Patients were followed up in clinic at 2 weeks and 3 months. The mean long-term follow-up was 12 months. A telephone questionnaire was also conducted. RESULTS: At 2-week follow-up, 81.8% of patients in the PRM group had a resolution of symptoms and a negative Dix-Hallpike test compared with 15.3% in the sham PRM group and 60% in the control group. This difference was statistically significant between the treatment (PRM) and sham PRM groups and between the sham and control groups. It nearly reached significance between the treatment and control groups (p = .06). The sham treatment group had by far the worst outcome at the 2-week interval. There was no statistically significant difference between the groups after 2 weeks. CONCLUSION: The PRM is side specific. It may help induce remission of the vertiginous symptoms of BPPV in the short term. This cannot be attributable to a placebo effect. The PRM does not seem to affect the natural history of the disorder in the long term. The sham treatment causes a delay in spontaneous recovery, possibly by preventing the particles from falling into the utricle. This study has not compared the frequency or severity of symptoms.

Effect of triamcinolone acetonide on the development of the pulmonary airways in the fetal rat.

Triamcinolone acetonide (TAC) has a potent teratogenic effect on various mammalian fetal tissues as well as a steroid effect on the lung. Less well documented is the fact that it produces profound oligohydramnios. We wished to determine what effect TAC would have on branching morphogenesis and other aspects of lung development, using an in vivo model described previously. Thirty rats were randomized to receive 0.6 mg/kg of TAC or saline on days 12, 13, and 14 of gestation. At gestational days 15, 17, 18, and 21, the left lungs of 365 fetuses were studied by dissecting microscopy, histology, and morphometry. TAC produced profound pulmonary hypoplasia (dry Jung weight/body weight 0.025, compared with 0.06 in controls) on day 21. TAC decreased maternal weight gain, fetal weight, placental weight, aminiotic fluid, and pole to pole length (PTP), while it increased the peripheral airway count (PAC). The number of central and intermediate airway branches was reduced, and they were dilated. Growth of peripheral airways was enhanced. In treated fetuses epithelial cells lining these airspaces were histologically more mature and the mesenchyme thinner than in controls. These findings were confirmed by the morphometric measurements. We conclude that when TAC is administered in the early phase of fetal rat lung development, the lungs become hypoplastic, with hypoplasia of the intermediate airways, an increase in the number of peripheral airways, and increased differentiation. We speculate that these effects are primarily due to the steroid action of TAC and that the mechanisms of monopodial branching are different from those of dichotomous branching.

Post-treatment instructions in the nonsurgical management of benign paroxysmal positional vertigo.

Benign paroxysmal positional vertigo (BPPV) is the commonest peripheral vestibular disorder seen in dizziness clinics. It was long believed that the condition was caused by inorganic particles in the cupula of the posterior semicircular canal (PSC). More recently it has been suggested that BPPV may result from free-floating densities in the endolymph of the long arm of the PSC. Among the various treatment modalities used, two maneuvers, each based on a different theory of pathogenesis, have reported equally high success in the control of this disorder. These maneuvers are customarily followed by strict post-treatment instructions. We studied patients with BPPV prospectively by comparing the therapeutic effectiveness of these two modalities and studying the importance of post-treatment instructions in affecting the final outcome in each modality. We showed that both maneuvers were equally successful in controlling the symptoms and that post-treatment instructions were not necessary.

Development of the pulmonary airways in the fetal rat and its relation to the prenatal environment.

We studied the left lung using multi-focus microphotography in 378 rat fetuses, assessing airway branching from day 13 to day 19 of gestation, and lung growth variables from day 13 to day 21. Longitudinal growth, and monopodial and dichotomous branching brought about a consistent airway pattern with variations within each day of gestation and a small overlap between adjacent days. Amniotic fluid weight and pole to pole (PTP) distance of the lung increased quadratically with age, while fetal weight and the peripheral airway count (PAC) increased exponentially. The location of the fetus within the uterus had no effect on fetal variables, but correlations were found between maternal weight gain and both fetal weight and PTP. Fetal weight was the best predictor of PAC from gestational ages 15 to 19 days (P < 0.008). The method described allows for observations that are reproducible within the environmental variations present in normal gestation and can be used to study the effect of external factors on lung development.

Adult-acquired laryngeal stenosis: a study of prognostic factors.

We reviewed cases of adult-acquired laryngeal stenosis treated at the Health Sciences Centre in Winnipeg, Manitoba, over a 15-year period. We studied the influence of various factors on the final outcome including age, sex, etiology, associated conditions, length and diameter of the stenotic segment, as well as its anatomic site. We found a total of 32 patients ranging in age from 16 to 73 years. Fifty-five percent were caused by intubation and 16% by external trauma. Other causes included inflammatory diseases, irradiation, and burns. The subglottis was involved in 82% of the total number of cases reviewed. We studied the probability of decanulation over time by using the Kaplan-Meier survival curves. We then identified the independent factors affecting the probability and time of decanulation by using the Cox Proportional Hazards model. External trauma was found to have the best outcome when compared to other etiologies. The anatomic site of stenosis and its length were independent determinants of outcome, while its diameter was not. Involvement of the glottis in subglottic stenosis led to a significantly poorer outcome. We recommend the use of the length and site of stenosis as primary prognostic factors in the assessment of acquired laryngeal stenosis in the adult population.

In vitro branching morphogenesis of the fetal rat lung.

We studied the pattern of airways branching in the fetal rat lung in vitro. Lung primordia of gestational ages 13, 14, and 15 days were allowed to grow in culture to a gestational age equivalent to 21 days. The first generation airways appear by a single new bud (monopodial budding) from the left main airway (lateral appearing before the medial). They elongate to form branches and then bud dichotomously (2 buds occurring simultaneously and adjacent to each other) at their tips. Then monopodial branching takes place along their sides. The same cycle of budding and branching seems to be repeated for the following generation of the airways. The total number of the peripheral (subpleural) buds was greatest in the day 15 explants and least in day 13 explants throughout the whole culture period, but the statistical model used indicated faster budding in the 13 day explants. Morphometric assessment showed no difference in the ratios between the lung components in the 3 age groups and that the peripheral epithelial measurements were the same in the 3 groups at an equivalent gestational age of 21 days. We have also shown that lobes do not form in the right lung, although appropriate airways do. This may indicate the importance of mesothelial covering of the lung in the process of lobe formation. The method is useful for studying the control of lung morphogenesis.

The in vitro effect of triamcinolone acetonide on branching morphogenesis in the fetal rat lung.

We have studied the effect of triamcinolone acetonide (TAC) on airway morphogenesis of the Sprague-Dawley fetal rat in whole organ lung cultures from day 15 to day 21 of equivalent gestational age (6 days in culture). TAC produced an increased number of peripheral buds from day 18 onward and the airway and airspaces had larger lumens. Airway branching was increased compared to controls, and there was a higher proportion of airway epithelium and a lower proportion of mesenchyme. Cell height was significantly lower in TAC treated lungs except on day 17. This was due to accumulation of glycogen prior to the increased branching activity. In both controls and TAC-treated lungs, peripheral bud number and volume proportion of epithelium increased with time in culture, whereas volume proportion of mesenchyme, mean chord length of airways and airspaces, and epithelial cell height decreased. These changes were more pronounced in the TAC-treated group and were significant. However, TAC-treated lungs were morphologically irregular. We conclude that TAC has a direct effect on airway morphogenesis and it promotes growth of morphologically abnormal lungs. TAC also appears to enhance airway branching and morphologic changes interpreted as increased epithelial maturation.