Ted Mau1, Hao-Min Pan1, Lesley F Childs1. 1. Clinical Center for Voice Care, Department of Otolaryngology-Head and Neck Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, U.S.A.
Abstract
OBJECTIVES/HYPOTHESIS: Patients with unilateral vocal fold paralysis (UVFP) are commonly told to wait 12 months for spontaneous recovery. This study aims to 1) determine the time to vocal recovery in UVFP, 2) use that data to develop a neurophysiologically plausible model for recovery, and 3) use the model to generate meaningful predictions for patient counseling. STUDY DESIGN: Case series with de novo mathematical modeling. METHODS: Patients with UVFP who could pinpoint a discrete onset of vocal improvement were identified. The time-to-recovery data were modeled by assuming an "early" recovery group with neuropraxia and a "late" recovery group with more severe nerve injury. For the late group, a two-stage model was developed to explain the time to recovery: regenerating axons must cross the site of injury in stage 1 (probabilistic), followed by unimpeded regrowth to the larynx in stage 2 (deterministic). RESULTS: Of 727 cases of UVFP over a 7-year period, 44 reported spontaneous recovery with a discrete onset of vocal improvement. A hybrid distribution incorporating the two stages (exponentially modified Gaussian) accurately modeled the time-to-recovery data (R2 = 0.918). The model predicts 86% of patients with recoverable UVFP will recover within 6 months, with 96% recovering within 9 months. Earlier vocal recovery is associated with recovery of vocal fold motion and younger age. CONCLUSIONS: Waiting 12 months for spontaneous recovery is probably too conservative. Repair across the site of injury, and not regrowth to larynx, is likely the rate-determining step in reinnervation, consistent with other works on peripheral nerve regeneration. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:2585-2590, 2017.
OBJECTIVES/HYPOTHESIS: Patients with unilateral vocal fold paralysis (UVFP) are commonly told to wait 12 months for spontaneous recovery. This study aims to 1) determine the time to vocal recovery in UVFP, 2) use that data to develop a neurophysiologically plausible model for recovery, and 3) use the model to generate meaningful predictions for patient counseling. STUDY DESIGN: Case series with de novo mathematical modeling. METHODS:Patients with UVFP who could pinpoint a discrete onset of vocal improvement were identified. The time-to-recovery data were modeled by assuming an "early" recovery group with neuropraxia and a "late" recovery group with more severe nerve injury. For the late group, a two-stage model was developed to explain the time to recovery: regenerating axons must cross the site of injury in stage 1 (probabilistic), followed by unimpeded regrowth to the larynx in stage 2 (deterministic). RESULTS: Of 727 cases of UVFP over a 7-year period, 44 reported spontaneous recovery with a discrete onset of vocal improvement. A hybrid distribution incorporating the two stages (exponentially modified Gaussian) accurately modeled the time-to-recovery data (R2 = 0.918). The model predicts 86% of patients with recoverable UVFP will recover within 6 months, with 96% recovering within 9 months. Earlier vocal recovery is associated with recovery of vocal fold motion and younger age. CONCLUSIONS: Waiting 12 months for spontaneous recovery is probably too conservative. Repair across the site of injury, and not regrowth to larynx, is likely the rate-determining step in reinnervation, consistent with other works on peripheral nerve regeneration. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:2585-2590, 2017.
Authors: Chang Hwan Ryu; Seung Jin Lee; Jae-Gu Cho; Ik Joon Choi; Yoon Seok Choi; Yong Tae Hong; Soo Yeon Jung; Ji Won Kim; Doh Young Lee; Dong Kun Lee; GIljoon Lee; Sang Joon Lee; Young Chan Lee; Yong Sang Lee; Inn Chul Nam; Ki Nam Park; Young Min Park; Eui-Suk Sung; Hee Young Son; In Hyo Seo; Byung-Joo Lee; Jae-Yol Lim Journal: Clin Exp Otorhinolaryngol Date: 2021-06-01 Impact factor: 3.372