A preliminary study of the prognostic role of electromyography in laryngeal paralysis.
Confidence in the reliability of laryngeal electromyography to predict recovery is critical if this tool is to be used to select the type and timing of surgical intervention. The characteristics of electromyography of 14 patients with unilateral vocal fold paralysis were assessed to determine which factor or combination of factors would be most useful in determining prognosis. We examined the duration, amplitude, waveform morphology, root-mean-square, and time interval from onset to electromyography recording. The results supported the concept that electromyography recordings are valuable in determining prognosis if performed before 6 months and preferably within 6 weeks of onset of laryngeal paralysis. A positive prognosis for laryngeal recovery was indicated when the following electromyography features were present in the immobile vocal fold: (1) normal motor unit waveform morphology, (2) overall electromyography activity characterized by a root-mean-square value greater than 40 microV in any one task, and (3) no electrical silence during voluntary tasks. On the basis of this criteria our overall correct prognostic rate was 89%.
Min
Y B
YB
Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City 52242.
Finnegan
E M
EM
Hoffman
H T
HT
Luschei
E S
ES
McCulloch
T M
TM
D004576:Electromyography / Q000379:methods; D005500:Follow-Up Studies; D005544:Forecasting; D006801:Humans; D007821:Laryngeal Muscles / Q000503:physiopathology; D009046:Motor Neurons / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D009126:Muscle Relaxation / Q000502:physiology; D010700:Phonetics; D011379:Prognosis; D011930:Reaction Time / Q000502:physiology; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors; D014636:Valsalva Maneuver; D014826:Vocal Cord Paralysis / Q000503:physiopathology* / Q000601:surgery*