DYSPNEA IN DYSTONIA - A FUNCTIONAL-EVALUATION

Background: Dystonia consists of action-triggered sustained focal musc le contractions, worsened by effort, and resulting in voice changes, a bnormal posturing, and dyspnea, The cause of dyspnea, previously unexp lained, is the basis of this report. Methods: Since the maximal effort s required to perform pulmonary function testing (PFT) could worsen th e muscular contractions in dystonic patients, we used several tests to identify possible causes of dyspnea. These included spirometry with f low volume loops (FVL), tidal volume breathing, maximum voluntary vent ilation (MVV), and inspiratory and expiratory muscle pressures (PImax, PEmax), sitting and supine, We used cycle ergometry with arterial blo od gas (ABG) values to detect cardiac/pulmonary limitations and respir atory inductive plethysmography (RIP) to assess chest wall/abdominal m ovements for synchrony, Dynamic videofluoroscopy (VF) assessed and rec orded the action-triggered muscle activity of the upper airways and th e diaphragm during quiet breathing, speech, swallowing, and maximal re spiratory maneuvers similar to the efforts required during PFT. Result s: Twenty-six dystonic patients, 12 women and 14 men, ages 14 to 70 ye ars (mean age, 52.3 years) were evaluated. Their neurologic classifica tion included 22 primary (idiopathic) and 4 secondary (2 postneurolept ic use, 2 posttraumatic). Four patients originally classified as havin g focal dystonia had dyspnea and were found to have diaphragmatic and/ or upper airway dysfunction too. The PFTs showed abnormal FVL and/or t idal volume breathing patterns, with intermittent interruptions of air now during inspiration or expiration in 20 of 24 patients. The VF was abnormal in 24 of 26 patients: 19 patients had combined upper airway (UA) and diaphragmatic dysfunction (DD); 1 patient had UA dysfunction alone, and 4 patients had DD alone. Except for poor effort and/or dyst onic movements, cycle ergometry was normal in 18 of 21 patients. The A BG values and/or pulse oximetry were normal in 19 of 22 patients. Conc lusion: Dyspnea in dystonia appears to be due to excessive and/or dysy nchronized contractions of the upper airways and/or diaphragm, with us ually normal gas exchange, These spasmodic and irregular muscular cont ractions during speech and daily activities are associated with the se nsation of excessive effort to overcome the spasms, Excessive spasms c an be triggered during PFT and are best detected on FVL patterns coupl ed with dynamic VF.