Dyspnea after subthalamic deep brain stimulation in Parkinson's disease: a case-control study.

OBJECTIVE: Dyspnea can be present as non-motor symptom in patients with Parkinson's disease (PD). Deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves motor and non-motor symptoms in PD. However, new-onset dyspnea has been reported after DBS surgery. We have studied respiratory characteristics of PD patients with bilateral STN-DBS to assess the impact of DBS on pulmonary function. METHODS: STN-DBS PD patients with dyspnea after surgery (cases) were matched with STN-DBS PD patients without dyspnea (controls). Motor and pulmonary function were assessed with stimulation and without medication (on stim/off med), and without stimulation and medication (off stim/off med). Pulmonary function was investigated with spirometry and dyspnea with the Medical Research Council Dyspnea Scale (MRCDS) and the Borg Scale (BS). RESULTS: Seven cases (five men, 58.30 ± 6.70 years of age) and seven controls (six men, 61.10 ± 6.30 years of age) were enrolled. MRCDS and BS revealed the presence of dyspnea in both groups. No significant changes in pulmonary function were found in both cases and controls in on stim/off med vs. off stim/off med condition (p < 0.05), and in cases vs. controls in on stim/ off med condition (p < 0.05). CONCLUSIONS: No impact of STN-DBS on pulmonary function was found in cases. Impaired perception of dyspnea and spread of stimulation surrounding the STN might account for new-onset dyspnea after DBS surgery. Dyspnea was detected also in controls using ad hoc questionnaires. Our findings suggest further investigation of this non-motor symptom in PD patients.

Ask a neurologist: What primary care providers ask, and reducing referrals through eConsults.

BACKGROUND: Access to neurology consultation is limited by high demand and urgency of the presentation. Champlain BASETM (Building Access to Specialists through eConsultation) (eConsult service) aims to increase access through direct communication between primary care providers (PCPs) and specialists. Rapid responses to PCP questions can guide management and sometimes relieve the need for a formal consultation. We reviewed which topics were frequently addressed, the types of questions asked, and the effect on primary care for the patient. METHODS: This is a retrospective review of 387 consecutive questions submitted to the Champlain BASETM service between May 2011 and January 2015 and the data generated from routine use and PCP exit surveys. Questions were categorized by topic and type and analyzed quantitatively. This included time required to answer each question and effect on plans for traditional referral and clinical course of action. RESULTS: The top 5 topics were headache (17%), incidental imaging findings (11%), numbness/tingling (11%), seizure (9%), and cerebrovascular disease (CVD) (9%). Fifty-one percent were related to diagnosis (choice of test, imaging interpretation, symptom interpretation), 23% to drug treatment (choice, adverse effects, prescribing instructions), and 17% to management (general, need for referral). Eighty-eight percent of questions took less than 10 minutes of specialist time to answer, and 80% were answered within 1 day. eConsults decreased face-to-face referrals by 50%. In 54% of cases, the PCP received information for a new course of action. CONCLUSIONS: We found that an eConsult service provides timely access to neurologists and can divert half of intended face-to-face consultations. The most common questions posed by PCPs regarded diagnosis and drug therapy for headaches, seizures, altered sensation, and CVD. eConsult services could provide guidance for continuing medical education planning in neurology.

Alpha-1 antitrypsin deficiency in Canada: regional disparities in diagnosis and management.

BACKGROUND: Since 1999, as part of the Alpha1 International Registry (AIR), the Canadian Alpha-1 Antitrypsin Deficiency (AATD) Registry has maintained demographic and medical information volunteered by AATD individuals. METHODS: We undertook a retrospective chart review to describe the characteristics of registry participants. Inclusion criteria were ZZ phenotype or other severe deficiency and written consent. We reviewed baseline medical records and annual follow-ups, conducted by mail. RESULTS: The number of registrants ranged from 8.7 per million in British Columbia and Ontario to 1.3 per million in Quebec. Similarly, the rate of augmentation therapy use ranged from 7.7 per million in British Columbia to 0.1 per million in Quebec. 290 patients (146 males), most PiZZ, were enrolled by 2013. Patients with lung disease reported symptoms onset at (mean ± SD) 40 ± 11 years but were diagnosed as AATD at 47 ± 10 years. Typical patients were ex-smokers with respiratory symptoms, severely reduced FEV1, an accelerated rate of FEV1 decline, and minimal bronchodilator response. A subgroup diagnosed by liver disease or familial screening was younger and had better preserved lung function but a similar rate of FEV1 decline. There were 63 deaths, of which 29 were lung-related and 6 were liver-related. Average age at death was 60.5 ± 11.2 years. DISCUSSION: Most patients experience a diagnostic delay of seven years after symptom onset, a period during which lung health may deteriorate further. There is marked regional variation in the rate of diagnosis and specific therapy usage for AAT in Canada.

Nontuberculous mycobacterial infection as a cause of difficult-to-control asthma: a case-control study.

BACKGROUND: Symptomatic disease due to nontuberculous mycobacteria (NTM) is known to occur commonly in the presence of structural lung disease, but is not described in association with asthma. METHODS: This was a case-control study nested in a cohort. We identified 22 patients with difficult asthma referred to a tertiary academic referral center and subsequently found to have infection with NTM. We matched each case with two control subjects (next two consecutive patients referred for asthma management). RESULTS: It took on average 2.1 years from the onset of new or worsening symptoms to NTM diagnosis. The most common symptoms were worsening cough (77%), sputum production (40.9%), and frequent exacerbations (31.8%). Mycobacterium avium complex accounted for 63.6% of the infections, Mycobacterium xenopi the balance. Case subjects were older (59.8 ± 8.9 vs 42.6 ± 18 years; P < .001) and had more severe airflow obstruction (FEV(1), 57% [40%-74%] vs 89.5% [80%-98%]; P < .001). There was no difference between case and control subjects in the proportion using inhaled corticosteroids (ICS) or the average daily dose at the time of presentation, but case subjects had used ICS for a longer period (17 [6.2-20] vs 4 [0.75-6.0] years; P=.002). Six subjects with NTM were being treated with daily oral steroids, whereas none of the control subjects was. Of the 22 cases, 10 were treated with antibiotics for NTM, seven demonstrating clinical improvement or resolution of the presenting symptoms. CONCLUSIONS: NTM infection can be associated with asthma and should be considered in difficult-to-treat disease, especially in older individuals with more severe airflow obstruction and greater exposure to inhaled or systemic corticosteroids.

Predicting the need for supplemental oxygen during airline flight in patients with chronic pulmonary disease: a comparison of predictive equations and altitude simulation.

BACKGROUND: Patients with chronic pulmonary diseases are at increased risk of hypoxemia when travelling by air. Screening guidelines, predictive equations based on ground level measurements and altitude simulation laboratory procedures have been recommended for determining risk but have not been rigorously evaluated and compared. OBJECTIVES: To determine the adequacy of screening recommendations that identify patients at risk of hypoxemia at altitude, to evaluate the specificity and sensitivity of published predictive equations, and to analyze other possible predictors of the need for in-flight oxygen. METHODS: The charts of 27 consecutive eligible patients referred for hypoxia altitude simulation testing before flight were reviewed. Patients breathed a fraction of inspired oxygen of 0.15 for 20 min. This patient population was compared with the screening recommendations made by six official bodies and compared the partial pressure of arterial oxygen (PaO(2)) obtained during altitude simulation with the PaO(2) predicted by 16 published predictive equations. RESULTS: Of the 27 subjects, 25% to 33% who were predicted to maintain adequate oxygenation in flight by the British Thoracic Society, Aerospace Medical Association or American Thoracic Society guidelines became hypoxemic during altitude simulation. The 16 predictive equations were markedly inaccurate in predicting the PaO(2) measured during altitude simulation; only one had a positive predictive value of greater than 30%. Regression analysis identified PaO(2) at ground level (r=0.50; P=0.009), diffusion capacity (r=0.56; P=0.05) and per cent forced expiratory volume in 1 s (r=0.57; P=0.009) as having predictive value for hypoxia at altitude. CONCLUSIONS: Current screening recommendations for determining which patients require formal assessment of oxygen during flight are inadequate. Predictive equations based on sea level variables provide poor estimates of PaO(2) measured during altitude simulation.

Modulating Fitts's Law: the effect of disappearing allocentric information.

A modulation of Fitts's Law occurs when rapid pointing movements are made to targets within a placeholder array. Although Fitts's Law predicts increasing movement times with larger movement amplitudes, with the placeholder array the furthest target is reached faster than the second furthest. This study analyzed the timing of this effect by removing placeholders at either target onset or movement onset. Placeholders shown during movement planning were sufficient to cause the violation of Fitts's Law. Placeholders removed at the target onset did not produce the last position advantage, a result which was confirmed in an independent data set. Together, these results converge with recent proposals that pinpoint the contribution of allocentric information to visuo-motor control largely to the movement planning stage.