Correlating voice handicap index and quantitative videostroboscopy following injection laryngoplasty for unilateral...

1) Determine the correlation between voice handicap index and quantitative videostroboscopy for patients undergoing injection laryngoplasty for unilateral vocal paralysis; 2) assess which videostroboscopy measurements correlate best with voice handicap index in patients demonstrating progressive improvement beyond six months following injection laryngoplasty.

Case series with chart review.

Patients undergoing outpatient injection laryngoplasty with hyaluronic acid between 2005 and 2007.

Twenty-eight patients were assessed preoperatively and postoperatively using voice handicap index and videostroboscopy. Various videostroboscopy measurements were quantified: glottic open area (ratio of open to total glottic area during closed phase of phonation), glottic closed phase (frame ratio of closed phase to total glottic cycle), supraglottic compression (percent encroachment of supraglottis onto best-fit ellipse around glottis), wave amplitude (difference in glottic open area between open and closed phases), and wave duration (number of frames per glottic cycle). Correlation coefficients were calculated using Spearman's r.

One hundred seventeen separate recordings were analyzed. Correlation coefficients between voice handicap index (normalized to preoperative values) and glottic closed phase showed moderate-strong correlation (r = -0.733, P < 0.001), while glottic open area and wave duration showed weak-moderate correlation (r = 0.465, P < 0.001 and r = -0.404, P < 0.001 respectively). Other parameters showed poor correlation. A subset of 25 recordings from eight patients with progressive voice handicap index improvement beyond six months showed highest correlation with supraglottic compression (r = 0.504, P < 0.05).

Voice handicap index correlates best with glottic closed phase, suggesting duration of vocal fold closure during the glottic cycle best represents patients' subjective outcome post-procedure. Progressive improvement in voice handicap index beyond six months may relate to gradual reduction in compensatory supraglottic compression, with moderate correlation.