title: Comparative analysis on the efficiency of the injection laryngoplasty technique using calcium hydroxyapatite (CaHA): the thyrohyoid approach versus the cricothyroid approach.
abstract: OBJECTIVE
  Temporary or permanent vocal paralysis can occur after head and neck surgery for thyroid cancer, esophageal resection, a chest operation that includes lung parenchymal resection due to a vagus or recurrent laryngeal nerve injury, and so forth. These days, the main treatment for vocal fold paralysis is the injection laryngoplasty through the cricothyroid (CT) approach. However, the CT approach is difficult in that an operator cannot see from the tip of the needle to the vocal fold. The aim of this study was to determine the efficacy of the thyrohyoid (TH) approach compared with the CT approach using calcium hydroxyapatite (CaHA) in patients with permanent unilateral vocal fold palsy.
  
  
  METHODS
  From March 2008 to July 2012, 68 consecutive injection laryngoplasties were performed in patients with unilateral glottic insufficiency. Percutaneous injection was performed under local anesthesia into the vocalis muscle, using disposable 25 gauge, 11cm long spinal needles through the CT membrane or TH membrane. Of the 68 patients, videostroboscopic findings and acoustic, perceptual, and subjective evaluations were completed for 64 patients before injection and at 3 months after injection.
  
  
  RESULTS
  In the 64 patients, the CT and TH approaches were used in 30 and 34 patients, respectively. The videostroboscopic findings, acoustic and perceptual parameters (maximum phonation time, jitter, shimmer, and noise-to-harmonic ratio), and Voice Handicap Index significantly improved after the injection in both the CT and TH groups (P<0.05).
  
  
  CONCLUSIONS
  Based on the results of this trial, injection laryngoplasty using the TH approach is an effective alternative to the CT approach, especially for the injection of CaHA in patients with permanent unilateral vocal fold palsy.
authors.affiliation: Department of Otolaryngology, Institute of Health Sciences, Gyeongsang National University, Jinju, Korea. lesaby@hanmail.net
authors.forename: Seung Hoon
authors.initials: SH
authors.lastname: Woo
authors.forename: Young-Ik
authors.initials: YI
authors.lastname: Son
authors.forename: Sang Hyuk
authors.initials: SH
authors.lastname: Lee
authors.forename: Jung Je
authors.initials: JJ
authors.lastname: Park
authors.forename: Jin Pyeong
authors.initials: JP
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004185:Disability Evaluation; D017886:Durapatite / Q000008:administration & dosage* / Q000009:adverse effects; D006801:Humans; D007273:Injections, Intramuscular; D007821:Laryngeal Muscles / Q000187:drug effects* / Q000503:physiopathology; D058753:Laryngoplasty / Q000009:adverse effects / Q000379:methods*; D007828:Laryngoscopy; D008875:Middle Aged; D010699:Phonation; D011446:Prospective Studies; D020127:Recovery of Function; D013061:Speech Acoustics; D049489:Stroboscopy; D013997:Time Factors; D016896:Treatment Outcome; D014741:Video Recording; D014826:Vocal Cord Paralysis / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D014833:Voice Quality; D055815:Young Adult
chemical_list: D017886:Durapatite