The natural history of idiopathic unilateral vocal fold paralysis: evidence and problems.

OBJECTIVES/HYPOTHESIS: To identify clinical evidence regarding outcome and duration of unilateral idiopathic vocal fold paralysis (IVFP). STUDY
DESIGN: Literature review.
METHODS: Medline search using the terms "vocal fold paralysis," "laryngeal paralysis," "vagal paralysis," and "recurrent nerve paralysis" was performed. Results were cross-checked by substituting "palsy" and "paresis" in place of "paralysis," "cord" in place of "fold," and adding "idiopathic" to each term. Furthermore, papers antedating the period of time covered by Medline were identified in references of publications. Case series identified by means of these searches were examined for information regarding duration and outcome of IVFP.
RESULTS: Seven hundred seventeen cases are reported. Complete recovery of motion occurred in 36 +/- 22% (range, 13-83%) of individuals. Some recovery of motion (complete and partial) occurred in 39 +/- 20% (range, 19-83%). Complete recovery of voice occurred in 52 +/- 17% (range, 25-87%) of cases, some degree of recovery in 61 +/- 22% (range, 25-87%). Most cases appear to recover in well under a year, with rare instances of markedly delayed recovery.
CONCLUSIONS: Review of available evidence reveals a highly variable rate of return of motion in IVFP. The rate of return of normal voice is consistently higher, although similarly variable. The marked differences in rates of recovery among reports appears to be the result of variable definitions of recovery, oversimplified all-or-none notions of paralysis and recovery, and inconsistent reporting of time elapsed from onset of paralysis to evaluation. All of these factors should be addressed in future prospective studies to shed further light on the natural history of vocal fold paralysis.