Surgical landmarks for identification and preservation of the internal branch of the superior laryngeal nerve.

OBJECTIVE: To determine the topographical anatomic features of the internal branch of the superior laryngeal nerve (ibSLN) at the thyrohyoid membrane entrance area in relation to certain consistent anatomical structures. MATERIALS: METHODS: Twenty-two fresh adult head cadavers (9 male, 13 female; age range 52-95 years) with no signs of abnormality in the neck were dissected to determine the anatomic relationship of ibSLN and superior border of thyroid cartilage, thyroid notch, carotid bifurcation, hyoid corpus, and hyoid greater cornu. RESULTS: The topographical relationship between ibSLN and superior border of thyroid cartilage, thyroid notch, carotid bifurcation, hyoid corpus, and hyoid greater cornu was identified bilaterally in all cadavers. According to the measures, danger zone and safe zone areas for surgical could be predicted and for surgical manipulations as well. CONCLUSION: We provided the surgical anatomy and important landmarks for determining the internal branch of superior laryngeal nerve in the thyrohyoid membrane entrance region to avoid surgical damage during surgeries of this region.

Internal branch of superior laryngeal nerve block by dexamethasone alleviates sore throat after thyroidectomy: a randomized controlled trial.

PURPOSE: Postoperative sore throat (POST) is a common complaint following thyroidectomy. Dexamethasone was reported to alleviate POST when administered via different routes. This study aimed to compare the effects of local spray and perineural injection surrounding the internal branch of superior laryngeal nerve (iSLN) in preventing POST and alleviating postoperative impaired voice function. METHODS: A randomized, double-blinded, controlled trial was performed to test the efficacy of the iSLN block in inhibiting of POST. A total of 161 patients who underwent elective thyroidectomy were randomly allocated to two groups. Group Spray: 4 mg dexamethasone was sprayed on to the vocal cord; Group iSLN: bilateral perineural injection with 4 mg dexamethasone around the iSLN. The incidence and severity of POST, swallowing pain, and its side effects were evaluated. Postoperative acoustic analysis, including jitter and shimmer, was also performed. RESULTS: Group iSLN exhibited a significantly less incidence and intensity of POST at 6 h and 24 h (P < 0.001). The patients experienced less swallowing pain at 6 h (P < 0.001) after the surgery, compared with Group Spray. When compared with Group Spray, Group iSLN improved postoperative voice function, which was characterized by lower jitter and lower shimmer value at 6 h and 24 h (P < 0.001) after the surgery. The severity of postoperative cough is higher in Group Spray (P < 0.001). CONCLUSIONS: Among patients undergoing elective thyroidectomy, those who received perineural injection surrounding iSLN with dexamethasone had improved voice function and presented with more excellence in the inhibition of POST and cough, in comparison with the local spray. REGISTER INFORMATION: This trial was registered in the Chinese Clinical Trial Registry on 4th Jan, 2021 (ChiCTR2100042145). The trial is registered at http://www.chictr.org.cn/showproj.aspx?proj=120142 .

Ultrasound-Guided Superior Laryngeal Nerve Block Facilitates Anesthesia Management in Bariatric Surgery.

BACKGROUND: Patients with obesity usually have a narrow pharyngeal cavity. They are prone to exposure difficulties and intubation failure during endotracheal intubation, and even face mask oxygen supply difficulties and hypoxemia in severe cases. We described the successful completion of conscious endotracheal intubation with superior laryngeal nerve internal branch block (SLNi) in a patient with pathologic obesity. CASE REPORT: A 29-year-old, nondiabetic man with severe obesity (weight 211 kg, height 186 cm, and body mass index [BMI] 60.99 kg/m2) was scheduled for a laparoscopic sleeve gastrectomy. The superior laryngeal nerve internal branch was blocked under ultrasound guidance to eliminate the cough induced by fiberscope during awake endotracheal intubation. Why Should an Emergency Physician Be Aware of This? The cough caused by fiberscope was completely suppressed and the awake endotracheal intubation was completed successfully.

Topographic anatomy of the internal branch of the superior laryngeal nerve.

PURPOSE: The aim of this study was to investigate the surgical and topographical anatomy of the internal branch of the superior laryngeal nerve (ibSLN) in laryngectomy patients. METHODS: Patients aged 36-90 years old who underwent a total laryngectomy operation with a diagnosis of laryngeal carcinoma participated in the study. Fifteen patients who underwent a total laryngectomy operation between June 2015 and November 2016 were included in the study. A total of 29 superior laryngeal nerves (SLN) of 15 patients were studied. The position of the nerve was photographed before the thyrohyoid membrane (THM) was passed during dissection. The relationship and course of the ibSLN with respect to the superior laryngeal artery (SLA) were observed. The distance to adjacent formations and branching variants were examined along the course of the nerve. RESULTS: Of the total 29 ibSLN, 17 were divided into three branches and 12 into two branches. In all cases except for one, the ibSLN course after piercing the THM was determined. The ibSLN penetrated the THM at a mean of 12.0 ± 2.61 mm (6-16 mm) from the superior border of the thyroid cartilage. The ibSLN penetrated the THM with a mean distance of 9.34 ± 1.65 (6-12) mm from the inferior border of the hyoid bone. CONCLUSION: Our study demonstrated the surgical and topographical features of the ibSLN with respect to the THM, and provided a more precise knowledge of its anatomy in laryngectomy patients. It thus may help head and neck surgeons identify this nerve.

Variable composition of the internal and external branches of the accessory nerve.

The purpose of this study was to clarify the composition of the internal and external branches (IB and EB) of the accessory nerve. Fifty-seven half heads of 34 adult cadavers were used. The IB and EB of the accessory nerve were mixed with the cranial root (CR), vagus nerve, and spinal root (SR). The IB was classified into five types and the EB into four types according to their composition. The IB consisted of only CR in 7.0% of the 57 cases, and of the CR and the vagus nerve in 52.6%; the IB did not exist in 12.3%. The EB was only composed of the SR in 19.3% of cases, the SR and CR in 52.6%, and the SR, CR, and the vagus nerve in 21.1%. There were 14 combinations of IB and EB types. The most common combination was the IB with the CR and the vagus nerve, and the EB with the SR and CR (31.6%). The combination of IB and EB comprising CR and SR, respectively, was not observed. The IB and EB are known to consist of the CR and SR of the accessory nerve, respectively. However, this study shows that there are no IB and EB comprising only the CR and SR, respectively, and the branches have various combinations of the CR, SR, and vagus nerve.

Preservation of superior laryngeal nerve in transoral surgery: A technology to enhance the recovery of swallowing function after surgery of hypopharyngeal carcinoma.

OBJECTIVES: We intended to preserve the internal branch of superior laryngeal nerve in transoral surgery of hypopharyngeal squamous cell carcinoma and observe swallowing function recovery. METHODS: 26 patients with hypopharyngeal squamous cell carcinoma underwent transoral surgery with the preservation of internal branch of superior laryngeal nerve. Sensation in the pharyngolaryngeal mucosa was tested by flexible laryngoscope and swallow function was evaluated by water swallow test and MD Anderson Dysphagia Inventory questionnaire after surgery. RESULTS: Surgeries were successfully performed in all patients. The internal branch of superior laryngeal nerve were preserved in all patients. Testing of mucosa sensation revealed the presence of the cough reflex in most patients. The water swallow test showed that 12 cases (46.15%) on the 1st day, 23 cases (88.46%) on the 7th day and 25 cases (96.15%) on the 14th day after operation had normal swallowing function. The mean score of MD Anderson Dysphagia Inventory was 98 on the 14th day after operation. All patients achieved an oral soft diet at a median of 3 days (range, 2-6 days), full normal oral diet at a median of 5.5 days (range, 4-10 days) and removal of the nasogastric tube at a median of 6 days (range, 5-11 days). During the two-year follow-up, 3 patients recured, 1 patient died of lung metastasis. CONCLUSIONS: Preserving of the internal branch of superior laryngeal nerve in transoral surgery is feasible, and it can help to achieve a satisfactory recovery of the swallowing function after surgery of hypopharyngeal squamous cell carcinoma.

Clinical Application of Ultrasound-Guided Internal Branch of Superior Laryngeal Nerve Block in Patients with Severe COPD Undergoing Awake Fibreoptic Nasotracheal Intubation: A Randomized Controlled Clinical Trial.

Purpose: The aim was to investigate the time for intubation, adverse events and the comfort score of ultrasound-guided internal branch of superior laryngeal nerve block in patients with severe chronic obstructive pulmonary disorder (COPD) undergoing awake fibreoptic nasotracheal intubation. Methods: Sixty patients with COPD who needed awake fibreoptic nasotracheal intubation were randomly and evenly divided into the ultrasound-guided internal branch of the superior laryngeal nerve block group (group S) and the control group (group C). All patients received procedural sedation with dexmedetomidine and adequate topical anaesthesia of the upper respiratory tract. Then, bilateral block was performed (with 2 mL of 2% lidocaine or the same volume of saline) followed by fibreoptic nasotracheal intubation. The primary outcomes were time for intubation, adverse reactions and comfort score. The secondary outcomes were haemodynamic changes and serum norepinephrine (NE) and adrenaline (AD) concentrations immediately before intubation (T0); immediately after intubation to the laryngopharynx (T1); and immediately (T2), 5 min (T3) and 10 min (T4) after intubation between the groups. Results: Compared with group C, the time for intubation, the incidence of adverse reactions and the comfort score in group S were significantly lower (P<0.01). Compared with T0, the mean arterial pressure (MAP), heart rate (HR), NE and AD were significantly higher at T1 - T4 in group C (P<0.05), but were not obviously higher at T1 - T4 in group S (P>0.05). MAP, HR, NE and AD at T1-T4 were significantly lower in group S than in group C (P<0.05). Conclusion: Ultrasound-guided internal branch of the superior laryngeal nerve block can effectively shorten the time for intubation, reduce the incidence of adverse reactions, improve comfort score, maintain considerable haemodynamic stability and inhibit stress response in patients with severe COPD undergoing awake fibreoptic nasotracheal intubation.

Preservation of Internal Branch of Superior Laryngeal Nerve during Surgery for Hypopharyngeal Cancer.

OBJECTIVES: This study was performed to evaluate the significance of intraoperative preservation of the internal branch of the superior laryngeal nerve (ibSLN) during surgery for hypopharyngeal squamous cell carcinoma (HSCC). METHODS: Twelve patients with HSCC underwent surgery between January 2017 and December 2018. Sensation in the hypopharyngeal mucosa was tested using a flexible laryngeal endoscope on postoperative day 5. RESULTS: Surgeries were successfully performed in 10 patients with HSCC arising from the internal wall of the pyriform fossa and in 2 patients with HSCC arising from the posterior wall of the hypopharynx. The main trunk of the ibSLN was preserved in all patients. Testing of sensation in the hypopharyngeal mucosa revealed the presence of the cough reflex in all patients. All patients achieved a full normal oral diet at a median of 8.5 days (range, 6-11 days) and removal of the tracheal tube at a median of 10 days (range, 7-12 days). CONCLUSIONS: Our results showed that preservation of the ibSLN during surgery for HSCC is feasible and important in the recovery of sensation in the hypopharyngeal mucosa.

The Internal Superior Laryngeal Nerve in Humans: Evidence for Pure Sensory Function.

OBJECTIVES: To determine if the internal branch of the superior laryngeal nerve (iSLN) provides direct motor innervation to the interarytenoid muscle, a laryngeal adductor critical for airway protection. We studied the iSLN-evoked motor response in the interarytenoid and other laryngeal muscles. If the iSLN is purely sensory, there will be no detectable short latency motor response upon supramaximal stimulation, indicating the absence of a direct efferent conduction path. STUDY DESIGN: Intraoperative case series. METHODS: In seven anesthetized patients undergoing laryngectomy for unilateral laryngeal carcinoma, the iSLN of the unaffected side was electrically stimulated intraoperatively with 0.1-ms pulses of progressive intensities until supramaximal stimulation was reached. Electromyographic responses were measured in the ipsilateral interarytenoid, thyroarytenoid, and cricothyroid muscles. RESULTS: None of the subjects exhibited short-latency interarytenoid motor responses to iSLN stimulation. Supramaximal electrical stimulation of the intact iSLN evoked ipsilateral motor responses with long latencies: 18.7-38.5 ms in the interarytenoid (n = 6) and 17.8-24.9 ms in the thyroarytenoid (n = 5). Supramaximal stimulation of the recurrent laryngeal nerve evoked ipsilateral motor responses with short latencies: 1.6-3.9 ms in the interarytenoid (n = 6) and 1.6-2.7 ms in the thyroarytenoid (n = 6). CONCLUSION: The iSLN provides no functional efferent motor innervation to the interarytenoid muscles. The iSLN exclusively evokes an interarytenoid motor response via afferent activation of central neural circuits that mediate the laryngeal reflex arc. These findings suggest that the role of the iSLN in vital laryngopharyngeal functions, such as normal swallowing and protection of the airway from aspiration, is purely sensory. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E207-E211, 2021.

Endovascular Treatment of Type Ib Endoleak after Evar Using the IBD Device: A Case Report.

In the modern endovascular era, abdominal aortic aneurysm repair is still not free of complications with re-interventions following endovascular aneurysm repair (EVAR) being more common than with open surgical repair. A variety of endovascular, open surgical and combined techniques were described according to the anatomical considerations and general health of the patient to achieve the best possible result after these complications. In cases of type Ib endoleak following aorto-uni-lateral EVAR for an abdominal aortic aneurysm, the use of the internal branched device (IBD) constitutes a safe and effective technique.

Are the interarytenoid muscles supplied by branches of both the recurrent and superior laryngeal nerves?

OBJECTIVES/HYPOTHESIS: It has been generally accepted that the branches of the internal branch of the superior laryngeal nerve to the interarytenoid muscle are exclusively sensory. However, some experimental studies have suggested that these branches may contain motor axons, and therefore that the interarytenoid muscle is supplied by both the superior and recurrent laryngeal nerves. The aim of this work was to determine whether motor axons to the interarytenoid muscles are present in both laryngeal nerves. STUDY DESIGN: Basic research. METHODS: Twelve human internal branches of the superior laryngeal nerve were dissected, and its branches to the interarytenoid muscle were removed and processed for choline-acetyltransferase immunohistochemistry, a method not used previously in studying the nerve fiber composition of the laryngeal nerves. RESULTS: The internal branch of the superior laryngeal nerve divided into two to five branches to the interarytenoid muscle. All branches contained motor axons, with the proportion of motor axons varying from 6% to 31%. CONCLUSION: The present study confirms that the internal branch of the superior laryngeal nerve provides a motor innervation to the interarytenoid muscles. LEVEL OF EVIDENCE: N/A. Laryngoscope, 126:1117-1122, 2016.