title: Diagnosis and prognosis of iatrogenic injury of the recurrent laryngeal nerve.
abstract: OBJECTIVE
  Following perioperative injury to a macroscopically intact recurrent laryngeal nerve (RLN), there are two possible intraneural injury types: 1) axonal injury, including disruption of axons, and 2) conduction block, only affecting the Schwann cells and the nodes of Ranvier. In this study, it was hypothesized that the functional outcome after RLN injury may depend on the type of nerve injury.
  
  
  METHODS
  Fifteen patients with acute postoperative unilateral RLN paralysis were prospectively studied. Electrophysiological examination (laryngeal electromyography) was used to differentiate between the two types of nerve injury. Vocal fold motions were monitored by repeated laryngoscopy during the study period (up to 6 months). Three of the patients with axonal injury were treated with the regeneration-promoting agent nimodipine.
  
  
  RESULTS
  The patients with conduction block all recovered normal vocal fold motion, whereas patients with axonal injury within the nerve had a significantly worse outcome. The 3 patients who were treated with nimodipine all recovered normal or near-normal vocal fold mobility despite the more severe axonal injury.
  
  
  CONCLUSIONS
  In contrast to previous reports, our results show that laryngeal electromyography is a reliable tool for diagnosing the type of injury within the injured RLN, making it possible to predict the functional outcome in these patients. On the basis of the results, a future randomized study on nimodipine treatment for RLN axonal injury is suggested.
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Hydman
authors.forename: Gunnar
authors.initials: G
authors.lastname: Björck
authors.forename: Jonas K E
authors.initials: JK
authors.lastname: Persson
authors.forename: Jan
authors.initials: J
authors.lastname: Zedenius
authors.forename: Per
authors.initials: P
authors.lastname: Mattsson
mesh_terms: D002121:Calcium Channel Blockers / Q000627:therapeutic use; D015331:Cohort Studies; D004576:Electromyography; D006801:Humans; D007049:Iatrogenic Disease; D007828:Laryngoscopy; D009416:Nerve Regeneration / Q000502:physiology*; D009553:Nimodipine / Q000627:therapeutic use; D010865:Pilot Projects; D011379:Prognosis; D020127:Recovery of Function / Q000502:physiology; D061226:Recurrent Laryngeal Nerve Injuries; D013965:Thyroidectomy / Q000009:adverse effects*; D014826:Vocal Cord Paralysis / Q000175:diagnosis* / Q000209:etiology* / Q000628:therapy
chemical_list: D002121:Calcium Channel Blockers; D009553:Nimodipine