Oculomotor Dysfunction in Motor Neuron Disease.

INTRODUCTION: Though eye movements are relatively spared in motor neuron disease (MND), recent literature suggests patients may exhibit oculomotor dysfunction (OD). Frontal lobe involvement has been postulated based on oculomotor pathway anatomy and clinical overlap of amyotrophic lateral sclerosis (ALS) with frontotemporal dementia. We examined oculomotor characteristics in patients with MND presenting to an ALS Center, hypothesizing that patients with prominent upper motor neuron involvement or pseudobulbar affect (PBA) may demonstrate greater OD. METHODS: This was a single-center prospective observational study. Patients with diagnosis of MND were examined at bedside. Center for Neurologic Study-Liability Scale (CNS-LS) was administered to screen for pseudobulbar affect. Primary outcome was OD and the secondary outcome was the association between presence of OD in patients with MND experiencing symptoms of PBA or upper motor neuron dysfunction. Wilcoxon rank-sum scores and Fisher's exact tests were used to perform statistical analyses. RESULTS: 53 patients with MND underwent the clinical ophthalmic evaluation. On bedside examination, 34 patients (64.2%) presented with OD. There were no significant associations between locations of MND at presentation and the presence or type of OD. OD was associated with increased disease severity as measured by reduced FVC (p = 0.02). There was no significant association between OD and CNS-LS (p = 0.2). DISCUSSION: Though our study did not find a significant association between OD and upper versus lower MND at presentation, OD may be useful as an additional clinical marker for advanced disease.

Do weather-related ambient atmospheric-pressure changes influence sleep disordered breathing?

OBJECTIVE: High-altitude studies of sleep disordered breathing (SDB) show increases in apnea hypopnea indices with elevation gains. Hypoxic changes, rather than reductions in atmospheric pressure (AP), are thought to be the driving factor. Ambient pressure-related changes in SDB have not been extensively studied at low altitude. We performed a cross-sectional study of weather-related AP effects on measures of SDB at the University of WashingtonMedicine Sleep Institute, a Seattle, Washington-based polysomnography lab located 200 feet above sea level. METHOD: Obstructive, central, and apnea-hypopnea indices from 537 patients were retrospectively correlated to mean 8-hour date-matched overnight AP data. Linear regression analysis and interquartile comparison of AP-related respiratory indices were performed and adjusted for age, sex, and body mass index. RESULTS: The obstructive apnea index increased with lower weather-related APs (p = 0.01 for linear trend), interquartile analysis showed significant worsening with lowered mean, minimum, and maximum nightly APs. Similar changes were not seen with central or apnea-hypopnea indices. CONCLUSIONS: The obstructive apnea index is altered by changes in weather-related AP during diagnostic polysomnography performed at 200 feet above sea level. Small changes in ambient atmospheric pressure due to weather systems may be important in the pathophysiology and diagnosis of obstructive sleep apnea.