Functional Staging for Vocal Cord Paralysis

Abstract

Phonatory function can be reliably tested after vocal paralysis. After a review of 116 cases, 55 patients underwent objective testing. The clinical history of vocal ability and aspiration were found to be significantly correlated with measurements of phonatory mean flow rate (MFR), maximum phonation time (MPT), and maximum decibel output (SPL). A four-stage classification system, based on clinical and objective measurements, has been formulated. In stage I, measures of vocal parameters approached those of normals with MFR = 155 cc/sec, MPT = 12 sec, and SPL = 92 dB. Patients with stage IV disability have high MFR (480 cc/sec), but low MPTs (less than 3 sec) and low SPL values (76 dB). Factors such as sex, age, weight loss, and the presence of malignancy affect the degree of vocal function deficit. Post-therapy recordings indicated an improvement in vocal function by an increase in MPT and SPL, with a decrease in MFR. Measurements of MFR, PT, and SPL are good objective indicators available to the clinician. Functional staging can be applied to assessment and treatment of vocal cord paralysis.