Voice rest after vocal fold polyp surgery: A Swedish register study of 588 patients.

Objective: To evaluate the impact of voice rest on patient-reported voice outcome 4 months after vocal fold polyp surgery. Methods: Preoperative information was collected about age, sex, and smoking habits and the voice handicap index-10 (VHI-10). Four months postoperatively, voice rest (total voice rest, spoke single words, and spoke normally), and pre and postoperative voice therapy were reported. This was correlated to voice satisfaction from a two-category subjective evaluation "satisfied/ not satisfied" and to VHI-10. Logistic regression models with relative risk for NOT being satisfied with voice after surgery were performed. Results: Data from 588 patients were available. The group "spoke normally" showed the highest degree of patient satisfaction (92%). Younger patients (<59 years) were more satisfied than older (90% vs. 81.5%). High age and low VHI-10 scores before surgery were statistically significant for negative voice outcome. Gender or voice rest type did not significantly affect outcome. The largest improvement in VHI-scores was in the group who spoke normally and least in the group who spoke single words. Conclusion: We found no significant difference in the two-category subjective voice outcome depending on voice rest. VHI-10 showed a statistically significant positive effect on self-evaluated voice outcome, with the largest improvement in the group with no voice rest. However, the clinical relevance of the VHI changes is unclear. The present study does not show any advantage of total voice rest as compared to relative voice rest or speaking freely. High age and low preoperative VHI scores were significant risk factors for worse voice outcome. Level of evidence: 4.

New animal model for assessment of functional laryngeal motor innervation.

OBJECTIVES: The functional motor innervation of the larynx is not fully understood because of the complexity of the peripheral neuroanatomy. Since the late 19th century, there has been controversy regarding the role of the superior laryngeal nerve, which may have wider motor projections than are currently acknowledged. The aim of this study was to develop a large animal model to characterize and quantify the functional motor input to the intrinsic laryngeal muscles. METHODS: We performed invasive electrophysiology (evoked electromyography) in normal pigs. RESULTS: The thyroarytenoid, lateral cricoarytenoid, and posterior cricoarytenoid muscles receive dual innervation from both the superior and recurrent laryngeal nerves, whereas the cricothyroid muscle is innervated only by the superior laryngeal nerve. CONCLUSIONS: The dual innervation pattern from both laryngeal nerves supports the concept of a laryngeal nerve plexus. The motor input through the external branch of the superior laryngeal nerve was surprisingly high. The animal model presented here may be used in future investigations of laryngeal reinnervation following nerve injury.

Diagnosis and prognosis of iatrogenic injury of the recurrent laryngeal nerve.

OBJECTIVES: 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.

Nimodipine improves reinnervation and neuromuscular function after injury to the recurrent laryngeal nerve in the rat.

OBJECTIVES: Injury of the recurrent laryngeal nerve (RLN) is associated with a high degree of neuronal survival, but leads to various levels of vocal fold motion impairment or laryngeal synkinesis, which has been attributed to misdirected reinnervation of the target muscles in the larynx or aberrant, competing reinnervation from adjacent nerve fibers. The aim of the present study was to evaluate the impact of the regeneration-promoting agent nimodipine on reinnervation and neuromuscular function following RLN crush injury. METHODS: Sixty adult rats were randomized into nimodipine-treated or untreated groups and then underwent RLN crush injury. Reinnervation of the posterior cricoarytenoid muscle (PCA) was assessed by electrophysiological examination, retrograde tracing of lower motor neurons before and after injury, and quantification of neuromuscular junctions in the PCA muscle. RESULTS: At 6 weeks after injury, the nimodipine-treated animals showed significantly enhanced neuromuscular function and also demonstrated a higher number of motor neurons in the brain stem that had reinnervated the PCA, compared to the untreated animals. The somatotopic organization of ambiguus motor neurons innervating the larynx was similar before injury and after reinnervation. CONCLUSIONS: Nimodipine improves regeneration and neuromuscular function following RLN injury in the adult rat, and could be of use in future strategies following RLN injury.

Laryngeal adduction asymmetries in normal speaking subjects.

To investigate the prevalence of asymmetries at vocal fold adduction, 109 vocally healthy subjects between 22 and 80 years of age were examined. All subjects were examined with a rigid endoscope and video recorded. The recordings were analysed off line by two laryngologists. Seventy percent of the subjects displayed some kind of asymmetry. There was no difference between the sexes. Side differences in antero-posterior position of the corniculate or cuneiform tubercles were the most frequent asymmetries, occurring in 66% of the total material and in 92% of the asymmetrical cases. Asymmetries appeared more common and more marked in older subjects and possibly more frequent in singers than in non-singers. Laryngeal adduction asymmetries are probably of little importance for voice function.