Airway limitation and exercise intolerance in well-regulated myasthenia gravis patients.
OBJECTIVE
Myasthenia gravis (MG) is an autoimmune disease of neuromuscular synapses, characterized by muscular weakness and reduced endurance. Remission can be obtained in many patients. However, some of these patients complain of fatigue. The aim of this study was to assess exercise capacity and lung function in well-regulated MG patients.


METHODS
Ten otherwise healthy MG patients and 10 matched controls underwent dynamic spirometry, and a ramped symptom-limited bicycle exercise test. Spirometric variables included forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and maximum voluntary ventilation (MVV). Exercise variables included maximal oxygen uptake (VO(2) max), anaerobic threshold (VO(2) AT) maximum work load (W), maximum ventilation (VE max), and limiting symptom.


RESULTS
Myasthenia gravis patients had significantly lower FEV1/FVC ratio than controls. This was more marked in patients on acetylcholine esterase inhibitors. On the contrary, patients not using acetylcholine esterase inhibitors had a significantly lower exercise endurance time.


CONCLUSIONS
Well-regulated MG patients, especially those using pyridostigmine, tend to have an airway obstruction. The modest airway limitation might be a contributing factor to their fatigue. Patients who are not using acetylcholinesterase inhibitor seem to have diminished exercise endurance in spite of their clinically complete remission.
Elsais
A
A
Department of Neurology, Oslo University Hospital, Oslo, Norway. ahmed.elsais@medisin.uio.no
Johansen
B
B
Kerty
E
E
D000328:Adult; D017079:Exercise Tolerance / Q000187:drug effects / Q000502:physiology*; D015673:Fatigue Syndrome, Chronic / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D009157:Myasthenia Gravis / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology*; D010809:Physical Fitness / Q000502:physiology*; D012131:Respiratory Insufficiency / Q000139:chemically induced / Q000175:diagnosis / Q000503:physiopathology*