Diagnosis and prognosis of iatrogenic injury of the recurrent laryngeal nerve.
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.
Hydman
Jonas
J
Department of Clinical Neuroscience, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
Björck
Gunnar
G
Persson
Jonas K E
JK
Zedenius
Jan
J
Mattsson
Per
P
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
D002121:Calcium Channel Blockers; D009553:Nimodipine