Evaluation of maximal respiratory pressures in myasthenia gravis. Prognostic value.
We assess the prognosis of mild forms of myasthenia gravis (MG) by maximal respiratory pressures (MRP) and single fiber electromyography (SFEMG). Fifty MG patients (12 form I, 21 form IIa and 17 form IIb) are valued by MRP [maximal expiratory pressure (MEP) and maximal inspiratory pressure (MIP)] and SFEMG, and are followed-up clinically. We have found in form I patients developing form IIa and form IIa worsening to form IIb, MEP and MIP mean relative values significantly lower than the rest. Inversely, IIb form patients improving to IIa form display MIP mean relative values higher than the rest; no difference appears with MEP. A reduction under 50% of fifth-percentile implies clinical deterioration in forms I and IIa, while its surpassing in IIb form suggests a tendency to improvement. No evident differences are found by SFEMG. MRP allow the follow-up of MG patients and could warn us of a clinical prognosis.
Department of Neurology, La Paz University Hospital, Universidad Autónoma de Madrid, Madrid, Spain. cumunfer@gobiernodecanarias.org
Carmen
C
Muñoz  Fernández
Exuperio
E
Díez Tejedor
Ana
A
Frank Garcia
Jose María
JM
Pino
Concepción
C
Pérez Conde
Pablo
P
Barreiro Tella
D004576:Electromyography / Q000379:methods; D006801:Humans; D008451:Maximal Voluntary Ventilation / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D009157:Myasthenia Gravis / Q000145:classification / Q000503:physiopathology*; D011312:Pressure; D012119:Respiration; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000294:innervation / Q000503:physiopathology*; D012720:Severity of Illness Index