Various energy devices had been used in thyroid surgery. Aim of study is to develop canine model for recurrent laryngeal nerve injury by harmonic scalpel and to evaluate feasibility of using this model for evaluating the safety use of harmonic scalpel during thyroid surgery. Nine dogs were divided into 3 groups according to distance between harmonic scalpel application and recurrent laryngeal nerve; group 1 (1 mm), 2 (2 mm), and 3 (3 mm). Vocal cord function was assessed pre- and postoperatively using video laryngoscopy. Harmonic scalpel was applied adjacent to left recurrent laryngeal nerve and, two weeks later, right recurrent laryngeal nerve at assigned distances. Recurrent laryngeal nerves were evaluated for subacute and acute morphologic changes. Laryngoscopy demonstrated 3 abnormal vocal cords in group 1, 1 in group 2, and no in group 3 (P=0.020). Subacute histologic changes were observed in nerves with abnormal function. Acute histologic changes were observed 5/8 (62.5%) in group 1, 1/7 (14.3%) in group 2, and not in group 3. We developed canine model for recurrent laryngeal injury. The functional outcomes matched with the histologic changes. These warrant further study to determine the safety margin for energy device in vicinity of recurrent laryngeal nerve.
Animals ; Dogs ; Laryngoscopy ; Recurrent Laryngeal Nerve ; Recurrent Laryngeal Nerve Injuries ; Thyroid Gland ; Vocal Cords

Humans ; Iatrogenic Disease ; prevention & control ; Monitoring, Intraoperative ; Recurrent Laryngeal Nerve ; physiology ; Recurrent Laryngeal Nerve Injuries

Objective: To determine the prevalence of vocal cord paralysis among post thyroidectomy patients based on severity and laterality, and explore possible associations with age, sex, diagnosis and type of thyroid lesion and surgical procedure. Methods: Design: Cross-sectional study. Setting: Tertiary Government Training Hospital. Participants: Records of patients who underwent thyroidectomy under the Department of Otorhinolaryngology – Head and Neck Surgery of the Ospital ng Maynila Medical Center from January 1, 2014 to June 30, 2021. Results: There were strong associations between the type of lesion and the presence of recurrent laryngeal nerve injury (V=.211, p=.001) and the diagnosis and the presence of RLNI (V=.245, p=.006). There were no significant associations between patient’s sex, age, diagnosis, type of thyroid lesion, surgical procedure with laterality and severity of RLNI. It was notable that all cases of bilateral recurrent laryngeal nerve injury were due to carcinoma only. Patients with malignant tumors were 2.8x (95% CI: 1.48-5.29) as likely to develop post surgical RLNI than those with benign tumors (p=.0015). Conclusion The factors that had a strong association with the presence of vocal cord paralysis among post-thyroidectomy patients were the diagnosis and type of thyroid lesion. Malignant thyroid lesions (specifically thyroid carcinoma) had a higher incidence of recurrent laryngeal nerve injury compared to benign thyroid lesions. More data from different institutions and including other predisposing factors may confirm our findings.
Paralysis ; Vocal Cords ; Thyroidectomy ; Recurrent Laryngeal Nerve ; Recurrent Laryngeal Nerve Injuries

Recovery from the laryngeal dysfunction caused by the recurrent laryngeal nerve (RLN) injury is not common. Recently, we have found that PEMS treatment improved the functional recovery rate and shortened the recovery time after RLN transection and reanastomosis in rat. In this study, we compared the morphology of RLN stumps according to their laryngeal functional status to investigate 1) the nerve morphology associated with functional recovery and 2) the possible underlying mechanism of persistent laryngeal dysfunction after RLN injury. We transected left RLN and then performed primary neurorrhaphy in Sprague-Dawley rats (n = 36). They were randomly divided into PEMS and control groups. 19 animals (10 PEMS group, 7 control group and 2 normal control animals) survived until the end of the experiment were included in the morphological analysis. Both the proximal and distal segments of reanastomosed RLN were obtained and the ultrastructural study was done using transmission electron microscope. There is no prominent morphological difference between the PEMS and control groups. In the functional recovery group, the findings suggestive of nerve regeneration were prominent both in the proximal and distal segments. Many regenerating axons were also observed in the proximal segments of RLNs in non-recovery group. But findings such as degenerating axons, infiltration of macrophage and inflammatory cells, increased collagen fibrils were frequently observed in this group. Even in the distal segments of functional non-recovery group, prominent regenerative findings were observed in 9 out of 10 (4 out of 5 PEMS and all control group animals) samples. We could not find any regenerating findings in one case of the PEMS group. Through the above results, failure of the nerve regeneration is unlikely the main cause of functional non-recovery after RLN injury in rat. Possible other causes such as synkinesis or definite but inadequate nerve regeneration should be considered and needs further investigation.
Animals ; Axons ; Collagen ; Macrophages ; Nerve Regeneration* ; Rats ; Rats, Sprague-Dawley ; Recurrent Laryngeal Nerve Injuries* ; Recurrent Laryngeal Nerve* ; Synkinesis

PURPOSE: Vocal symptoms have been reported after thyroidectomy and even in the absence of injury to the recurrent laryngeal nerve or the external branch of the superior laryngeal nerve. The aim of this prospective study was to evaluate the subjective and objective voice changes in patients without laryngeal nerve injury after thyroidectomy. METHODS: The subjects had undergone total thyroidectomy for differentiated thyroid carcinoma from November 2007 to December 2008. Twenty-eight subjects (males: 8, females: 20) were selected for this study. Voice analysis was prospectively evaluated in the subjects at the time of preoperation and postoperation (10.8 months for the males and 11.7 months for the females). A subjective analysis was done using the visual analogue scale (VAS, 0: no symptom, 10: severe symptoms) and objective analyses were determined by several parameters such as the fundamental frequency (Fo), jitter, shimmer and the noise to harmonic ratio (NHR) using the multi-dimensional voice program. Maximum phonation time (MPT)was performed as an aerodynamic test. RESULTS: 3 patients (37.5%) among the males and 14 patients (70%) among the females had subjective postoperative voice change. The VAS showed a significant difference for the females (0 to 1.25±0.97, P<0.001), whereas no changes were shown for the males (0 to 0.88±1.25, P>0.05). The vocal parameters (Fo, jitter, shimmer, NHR) and MPT showed no significant changes for both the males and females (P>0.05). CONCLUSION: Subjective voice changes may occur after thyroidectomy without laryngeal nerve injury. Surgeons should take possible voice changes into consideration when informing patients before thyroidectomy.
Female ; Humans ; Laryngeal Nerve Injuries ; Laryngeal Nerves ; Male ; Noise ; Phonation ; Prospective Studies ; Recurrent Laryngeal Nerve ; Surgeons ; Thyroid Neoplasms ; Thyroidectomy* ; Voice

Recurrent laryngeal nerve injury can develop following cervical or thoracic surgery; however, few reports have described intraoperative recurrent laryngeal nerve monitoring. Consensus regarding the use of this technique during thoracic surgery is lacking. We used intraoperative recurrent laryngeal nerve monitoring in a patient with contralateral vocal cord paralysis who was scheduled for completion pneumonectomy. This case serves as an example of intraoperative recurrent laryngeal nerve monitoring during thoracic surgery and supports this indication for its use.
Consensus ; Humans ; Monitoring, Intraoperative ; Pneumonectomy ; Recurrent Laryngeal Nerve Injuries ; Recurrent Laryngeal Nerve* ; Thoracic Surgery ; Vocal Cord Paralysis* ; Vocal Cords*

Recurrent laryngeal nerve injury can develop following cervical or thoracic surgery; however, few reports have described intraoperative recurrent laryngeal nerve monitoring. Consensus regarding the use of this technique during thoracic surgery is lacking. We used intraoperative recurrent laryngeal nerve monitoring in a patient with contralateral vocal cord paralysis who was scheduled for completion pneumonectomy. This case serves as an example of intraoperative recurrent laryngeal nerve monitoring during thoracic surgery and supports this indication for its use.
Consensus ; Humans ; Monitoring, Intraoperative ; Pneumonectomy ; Recurrent Laryngeal Nerve Injuries ; Recurrent Laryngeal Nerve* ; Thoracic Surgery ; Vocal Cord Paralysis* ; Vocal Cords*

OBJECTIVE: To explore the extralaryngeal furcation variation of the recurrent laryngeal nerve (RLN) in total thyroidectomy. METHOD: The clinical data of 216 RLNs from 108 patients undergone total thyroidectomy were retrospectively analyzed. RESULT: RLN was found during every operation and exposed in whole course until access into larynx. Twenty (9.26%) pieces of RLNs showed bifurcated or trifurcated RLNs before access into larynx. Ratio of furcation is lower than that reported before internationally. Bifurcations of RLNs on the left were more than that on the right. CONCLUSION The protection of RLN is important for thyroid operation, especially in total thyroidetomy. Variation of extralaryngeal furcation of RLN usually leads to injury of RLN. Understanding of variation of RLN could decrease nerve function related complication.
Humans ; Larynx ; Recurrent Laryngeal Nerve ; pathology ; Recurrent Laryngeal Nerve Injuries ; diagnosis ; Retrospective Studies ; Thyroid Gland ; surgery ; Thyroidectomy

OBJECTIVE: To investigate the electrophysiological characteristics and pathological changes in different recurrent laryngeal nerve injury models. METHOD: Twenty dogs were divided into different models of recurrent laryngeal nerve injury. Electrophysiological changes of animal models and histopathological changes in laryngeal muscles were investigated at different time. RESULT: Amplitude of MUP in TA decreased at first and then increased a little, while duration of MUP keeps decreased. The latent periods of the evoked potential in the incomplete injury group increased at first and then went down. In animal histopathological investigation, the lighter of the muscle injuries and the bigger of the diameter of muscle fibers and fascicles, and the smaller of the number of cellular nucleolus per square inch. In the early periods after injury, the correlation among the standard amplitude, threshold amplitude, maximum amplitude of EP and the diameter of fascicles were positive; while in the late period, the correlation among the amplitude, duration, area of MUP and nucleolus number was positive. CONCLUSION The physiological characteristics of laryngeal nerves and muscles could be known. LEMG was an important method in diagnosis of laryngeal nerve and muscle diseases.
Animals ; Disease Models, Animal ; Dogs ; Electromyography ; Evoked Potentials ; Laryngeal Muscles ; innervation ; physiopathology ; Recurrent Laryngeal Nerve Injuries

OBJECTIVETo study the display of different types injuries of recurrent laryngeal nerve (RLN) in laryngeal electromyography (LEMG).

METHODSLEMGs of one hundred and forty-seven patients (147 sides) with traumatic unilateral vocal cord paralysis (UVCP) were studied. After LEMGs, the RLNs exploration operations were performed. The condition of RLNs injury and laryngeal muscles was observed and recorded during the operation.

RESULTSThe severe injuries of RLNs were found during operation. The types of injuries were listed as ligation (58 cases), adhesion (28 cases) and cut (61 cases). The waveform morphology of LEMG was recorded less in the patients with the RLNs cut than that in the patients with the RLN ligation or adhesion, respectively. 75.4% RLNs cut showed spontaneous waveform while 96.4% RLNs adhesion and 94.8% RLNs ligation. When the RLN was cut off, single pattern was showed oftener. When the RLN was adhered or ligated, mixed pattern was showed oftener. 92.9% RLN adhesion showed misdirect-regeneration-potentials while 70.7% RLN ligation and 24.6% RLN cut. There were significant difference between two types, but the compound muscular active potential (CMAP) amplitude wasn't significantly different. Evoked amplitude could be recorded in 91.4% patients with ligation and its amplitude was (23.6 +/- 8.1)%, in 85.7% patients with adhesion and its amplitude (16.3 +/- 5.2)%, in 29.5% patients with cut and its amplitude (2.6 +/- 4.2)%.

CONCLUSIONSThe display of different injuries of RLN in LEMG presents significant difference. If RLN was cut off, the CMAP might be recorded in most cases. The clinical injury of RLN often is followed by sub-clinic reinnervation.

Adult ; Aged ; Electromyography ; Female ; Humans ; Laryngeal Muscles ; injuries ; Male ; Middle Aged ; Recurrent Laryngeal Nerve ; physiopathology ; Recurrent Laryngeal Nerve Injuries ; Vocal Cord Paralysis ; pathology ; physiopathology ; Young Adult