Hypoglossal Function Research Articles

Electromyography findings in radiation-induced unilateral tongue immobility.

We used electromyography to characterize hypoglossal nerve function among radiation-treated head and neck cancer survivors with later onset unilateral tongue immobility. Patients with unilateral tongue immobility without evidence of recurrent cancer were seen at a tertiary academic institution between February and September 2021. All patients were at least 2 years post-treatment with radiation therapy for head and neck squamous cell carcinoma. Participants were under annual surveillance and displayed no evidence of operative injury to the hypoglossal nerve. The median symptom-free interval for the 10 patients included in this study was 13.2 years (range 2-25 years). Myokymia alone was present in 3 of 10 patients, fibrillation potentials alone were present in 3 of 10 patients, and 1 subject displayed both fibrillation and myokymia. Three out of 10 patients had normal hypoglossal nerve function. These findings highlight how disparate mechanisms may underlie similar clinical presentations of radiation-induced neuromuscular dysfunction.

Intraoperative Neuromonitoring of Hypoglossal Nerves Using Transcranial and Direct Electrical Stimulation During Extracranial Internal Carotid Artery Surgery.

We explored whether the electromyogram (EMG) and the motor evoked potential (MEP) are useful for monitoring the function of the hypoglossal nerve during surgery targeting the cervical segment of the internal carotid artery. The present study included 6 patients with internal carotid arterial stenosis (1 patient underwent bilateral surgeries) and 1 patient with a cervical carotid artery aneurysm. In 5 of the 8 procedures, the EMGs were recorded. We examined whether changes in the MEP and/or EMG were capable of predicting postoperative hypoglossal nerve deficits. None of the 6 patients who underwent a total of 7 carotid endarterectomy (CEA) procedures experienced postoperative hypoglossal nerve morbidity. In 2 of the 7 procedures, the MEP disappeared or decreased significantly during CEA. In all 4 cases in which the hypoglossal nerve was directly stimulated during CEA, stable and reproducible EMGs were obtained throughout the manipulation of the internal carotid artery. Hypoglossal nerve morbidity was observed in the one case that underwent aneurysm removal and end-to-end anastomosis of the internal carotid artery. In this case, while the MEP decreased significantly during the operation, the EMG showed true-positive results and false-negative results, depending on the stimulation site. The monitoring of hypoglossal nerve function using EMG appears to be accurate if an appropriate stimulation site is selected. Hypoglossal nerve monitoring using MEP can produce false-positive results. Combined monitoring using both MEP and EMG is recommended in cases where exposure of the hypoglossal nerve is expected to be technically difficult.

Interposition Grafting of the Facial Nerve After Resection of a Large Facial Nerve Schwannoma: 2-Dimensional Operative Video

Abstract Facial nerve schwannomas can develop at any portion of the facial nerve. 1 When arising from the mastoid portion of the facial nerve, the tumor will progressively erode the mastoid, giving the schwannoma an aggressive radiological appearance. 1,2 The facial nerve is frequently already paralyzed, or no fascicles can be saved during resection. In these cases, end-to-end interposition grafting is the best option for facial reanimation. 1,3-5 The healthy proximal and distal facial nerves are prepared prior to grafting. The great auricular nerve is readily available near the surgical site and represents an excellent graft donor with minimal associated morbidity. 4,6 We demonstrate this technique through a case of a 48-yr-old male who presented with a complete right-sided facial nerve palsy due to a large facial schwannoma that invaded the mastoid and extended to the hypoglossal canal, causing hypoglossal nerve paralysis, and petrous carotid canal. His 4-yr follow-up showed no recurrent tumor with restored facial nerve function palsy to a House-Brackman grade III, and full recovery of his hypoglossal nerve function. The patient consented to the surgery and the publication of his image.

Releyendo a Sawamura Y, Abe H Hypoglossal–facial nerve side-to-end anastomosis for preservation of hypoglossal function: results of delayed treatment with a new technique J Neurosurg. 1997; 86:203–6

-

Hypoglossal Nerve Palsy due to Occipito-Cervical Kyphosis: A Case Report

Hypoglossal nerve palsy (HNP) is a potential cause of dysphagia. There have been few reports presenting with HNP associated with spinal diseases. Here, we report a case of HNP caused by postoperative upper cervical deformity. A 66-year-old man presented to our hospital with dysphasia and neck pain. One year prior to his first visit, he had been diagnosed with upper cervical tuberculosis and had undergone posterior C1-C2 fixation. These symptoms, however, further worsened nine months after the initial surgery. The physical examination led to the diagnosis of HNP. Radiographic examination revealed that the O-C kyphosis had been exacerbated and that this deformity was likely the primary cause of HNP. To restore the swallowing function, O-C fusion surgery was performed. Postoperatively, the patient showed immediate improvement of dysphasia with gradual recovery of hypoglossal nerve function. Our results indicate that the kyphosis in O-C junction would be a potential cause of HNP.

Descending hypoglossal branch-facial nerve anastomosis for severe facial paralysis after cerebellopontine angle tumor surgery

Objective To investigate the clinical effect of descending hypoglossal branch-facial nerve anastomosis for severe facial paralysis after cerebellopontine angle (CPA) tumor surgery. Methods From October 2010 to February 2014, 17 patients with severe facial paralysis whose House-Brackmann (H-B) grades were 5-6 or without clear facial nerve anatomical reservation after CPA tumor surgery were treated with the descending hypoglossal branch-facial nerve anastomosis at the Department of Neurosurgery, Beijing Xuanwu Hospital, Capital Medical University. Their clinical efficacy was observed retrospectively. Results After neuroanastomosis, no disability and death, no hoarseness, dysphagia and other neurological disorders were observed. In 17 patients, 15 (88.2%) were followed up for 6 to 53 months (mean 25). Facial nerve function H-B grade 2 was in 4 patients, grade 3 in 5 (33.3%), grade 4 in 5 (33.3%), and grade 5 in 1. One patient suffered ipsilateral tongue paralysis completely after procedure. The improvement of facial paralysis was most significant for orbicularis muscles, followed by the orbicularis oculi muscles, and the worst was the improvement of frontal muscles. All the patients benefited from the anastomosis. Although there was no significant improvement for patients with facial paralysis H-B grade 5, the patients felt that the dry eyes, the degree of redness and swelling reduced compare with before procedure. Conclusion Descending hypoglossal branch-facial nerve anastomosis can not only improve the facial nerve function in patients with severe facial paralysis in tumors of CPA regions, but also can avoid the influence on the hypoglossal nerve function. Key words: Cerebellopontine angle; Central nervous system neoplasms; Facial paralysis; Anastomosis, surgical; Facial nerve; Descending hypoglossal branch

Comparison of Direct Side-to-End and End-to-End Hypoglossal-Facial Anastomosis for Facial Nerve Repair

The hypoglossal facial anastomosis (HFA) is the gold standard for facial reanimation in patients with severe facial nerve palsy. The major drawbacks of the classic HFA technique are lingual morbidities due to hypoglossal nerve transection. The side-to-end HFA is a modification of the classic technique with fewer tongue-related morbidities. In this study we compared the outcome of the classic end-to-end and the direct side-to-end HFA surgeries performed at our center in regards to the facial reanimation success rate and tongue-related morbidities. Twenty-six successive cases of HFA were enrolled. In 9 of them end-to-end anastomoses were performed, and 17 had direct side-to-end anastomoses. The House-Brackmann (HB) and Pitty and Tator (PT) scales were used to document surgical outcome. The hemiglossal atrophy, swallowing, and hypoglossal nerve function were assessed at follow-up. The original pathology was vestibular schwannoma in 15, meningioma in 4, brain stem glioma in 4, and other pathologies in 3. The mean interval between facial palsy and HFA was 18 months (range: 0-60). The median follow-up period was 20 months. The PT grade at follow-up was worse in patients with a longer interval from facial palsy and HFA (P value: 0.041). The lesion type was the only other factor that affected PT grade (the best results in vestibular schwannoma and the worst in the other pathologies group, P value: 0.038). The recovery period for facial tonicity was longer in patients with radiation therapy before HFA (13.5 vs. 8.5 months) and those with a longer than 2-year interval from facial palsy to HFA (13.5 vs. 8.5 months). Although no significant difference between the side-to-end and the end-to-end groups was seen in terms of facial nerve functional recovery, patients from the side-to-end group had a significantly lower rate of lingual morbidities (tongue hemiatrophy: 100% vs. 5.8%, swallowing difficulty: 55% vs. 11.7%, speech disorder 33% vs. 0%). With the side-to-end HFA technique the functional restoration outcome is at least as good as that following the classic end-to-end HFA, but the complications related to the complete hypoglossal nerve transection can be avoided. Best results are achieved if this procedure is performed within the first 2 years after facial nerve injury. Patients with facial palsy of longer duration also have the chance for good functional restoration after HFA.

Comparison of hemihypoglossal- and accessory-facial neurorrhaphy for treating facial paralysis in rats

The aim of this study was to determine the effectiveness of hypoglossal-facial nerve “side”-to-end (HemiHN–FN) and accessory-facial nerve end-to-end (AN–FN) neurorrhaphy using a predegenerated nerve graft (PNG) for reanimating facial paralysis in a rat FN injury model. A total of 25 rats with complete unilateral facial paralysis resulting from section of the right FN were divided into 5 groups (n=5 each) that were submitted to immediate, delayed (3months after FN injury) or no (control) FN reconstruction procedures involving HemiHN–FN or AN–FN neurorrhaphy. Approximately 3months after FN reconstruction, cholera toxin subunit B conjugate Alexa 555 (CTB-Alexa 555) was injected into the ipsilateral whisker pad muscle and CTB-Alexa 555-labeled neurons were observed in the hypoglossal or accessory nuclei of all the FN reconstruction rats, but none of these neurons were found in the controls. There were numerous myelinated and nonmyelinated axons in both PNG and repaired FN of the FN reconstruction rats. No differences were found for these numbers between the two neurorrhaphy methods for each of the treatment time points, indicating the equal effectiveness of axon regeneration. However, a significantly higher number of CTB-Alexa 555-labeled neurons was observed in the hypoglossal nucleus of the immediate HemiHN–FN neurorrhaphy-treated rats when compared to that in the accessory nucleus of the immediate AN–FN neurorrhaphy-treated rats, consistent with the surface values of the recorded MAPs at the whisker pad muscle while electro-stimulating the FN. These results suggest that HemiHN–FN neurorrhaphy produces more efficient innervation of the paralyzed facial muscles than AN–FN neurorrhaphy without sacrificing ipsilateral hypoglossal function. Taking into consideration the clinical relevance of these findings for postoperative complications and functional reanimation in relation to the central plasticity, we suggest that HemiHN–FN neurorrhaphy may be the preferable facial reanimation procedure after an FN injury.

Unilateral Recurrent Laryngeal and Hypoglossal Nerve Paralysis Following Rhinoplasty: A Case Report and review of Articles

Introduction: Injury to cranial nerves IX, X, and XII is a known complication of laryngoscopy and intubation. Here we present a patient with concurrent hypoglossal and recurrent laryngeal nerve paralysis after rhinoplasty. Case Report: The patient was a 27-year-old woman who was candidate for rhinoplastic surgery. The next morning after the operation, the patient complained of dysphonia and a sore throat .7 days after the operation she was still complaining of dysphonia. She underwent a direct laryngoscopy, and right TVC paralysis was observed. Right hypoglossal nerve paralysis was also detected during physical cranial nerve function tests. Hypoglossal and recurrent laryngeal nerve function was completely recovered after 5 and 7 months, respectively, and no complication was remained. Conclusion: Accurate and atraumatic intubation and extubation, true positioning of the head and neck, delicate and gentle packing of the oropharynx, and maintenance of mean blood pressure at a safe level are appropriate methods to prevent this complication during anesthesia and surgical procedures.

The relationship between lingual and hypoglossal nerve function and quality of life in head and neck cancer

Sensorimotor impairment of the tongue has the potential to affect speech and swallowing. The purpose of this study was to critically examine the effects of nerve preservation and reinnervation after reconstruction of the base of tongue on patient-perceived outcomes of quality of life (QoL) related to speech and swallowing through completion of the EORTC QLQ-H&N35 standardised questionnaire. Thirty participants with a diagnosis of base of tongue cancer underwent primary resection and reconstruction with a radial forearm free flap, which may or may not have included nerve repair to the lingual nerve, hypoglossal nerve or both. Eight QoL domains sensitive to changes in motor and sensory nerve function were included in the analysis. Transected lingual and hypoglossal nerves were associated with difficulty in swallowing, social eating, dry mouth and social contact. There were fewer problems reported when these nerves were either repaired or left intact. There were no significant differences between patient nerve status and QoL outcomes for speech, sticky saliva and use of feeding tubes. This study was the first to examine the impact of sensory or motor nerve transection and reconstruction on health-related QoL outcomes.

Combination of hypoglossal-facial nerve surgical reconstruction and neurotrophin-3 gene therapy for facial palsy

Facial nerve injury results in facial palsy that has great impact on the psychosocial conditions of affected patients. Reconstruction of the facial nerve to restore facial symmetry and expression is still a significant surgical challenge. In this study, the authors assessed a hypoglossal-facial nerve anastomosis method combined with neurotrophic factor gene therapy to treat facial palsy in adult rats after facial nerve injury. Surgery consisted of the interposition of a predegenerated nerve graft (PNG) that was anastomosed with the hypoglossal and facial nerves at each of its extremities. The hypoglossal nerve was cut approximately 50% for this anastomosis to conserve partial hypoglossal function. Before their transplantation, the PNGs were genetically engineered using lentiviral vectors to induce overexpression of the neurotrophic factor neurotrophin-3 (NT-3) to improve axonal regrowth in the reconstructed nerve pathway. Reconstruction was performed after facial nerve injury, either immediately or after a delay of 9 weeks. The rats were followed up for 4 months postoperatively, and treatment outcomes were then assessed. Compared with the functional innervation in control rats that underwent facial nerve injury without subsequent treatment, functional innervation of the paralyzed whisker pad by hypoglossal motoneurons in rats treated 4 months after nerve reconstruction was evidenced by the retrograde transport of neuronal tracers, the recording of muscle action potentials conducted by the PNG, and the recovery of facial symmetry. Although a better outcome was observed when reconstruction was performed immediately after facial nerve injury, reconstruction with NT3-treated PNGs significantly improved functional reinnervation of the paralyzed whisker pad even when implantation occurred 9 weeks posttrauma. Results demonstrated that hypoglossal-facial nerve anastomosis facilitates innervation of paralyzed facial muscle via hypoglossal motoneurons without sacrificing ipsilateral hemitongue function. Neurotrophin-3 treatment through gene therapy could effectively improve such innervation, even after delayed reconstruction. These findings suggest that the combination of surgical reconstruction and NT-3 gene therapy is promising for its potential application in treating facial palsy in humans.

Unexpected Airway Obstruction Caused by Bilateral Hypoglossal Nerve Palsy Following Second Radical Neck Dissection

A 67-year-old woman underwent right radical neck dissection for cervical lymph node metastasis from maxillary gingival carcinoma. Two months later, metastasis in the left superior internal jugular lymph nodes were discovered, and left radical neck dissection was performed. Postoperatively, airway obstruction occurred despite performing extubation after confirming that the patient had fully recovered from anesthesia. Bilateral hypoglossal nerve palsy was diagnosed and the patient was reintubated. After extubation on the following day, airway obstruction was relieved, but slurred speech and impaired swallowing were persistent. In view of this, hypoglossal nerve function should be examined before the second radical neck dissection on the contralateral side.

Intraparotid Facial Nerve Schwannoma with Temporal Bone Extension

Objective: To present a rare case of facial schwannoma manifesting as a parotid mass and discuss its diagnosis and treatment.Methods: Design: Case Report Setting: Tertiary Government Hospital Patient: OneResults: A 48-year-old female was seen for a 2-year progressive left hemifacial paralysis and a 5-month gradually enlarging left infraauricular mass with episodes of tinnitus but intact hearing and balance. Physical examination showed a left-sided House Brackmann grade VI facial paralysis and a 5 x 4 x 3 cm soft, ill-defined, slightly movable, nontender, left infraauricular mass. Gadolinium-enhanced magnetic resonance imaging revealed a 5 cm heterogeneouslyenhancing lobulated mass centered within the deep lobe of the left parotid gland extending to the left mastoid, with facial nerve involvement. A diagnosis of a facial nerve tumor, probably a schwannoma, was entertained. Pure tone audiometry revealed normal hearing thresholds for both ears with dips at 6-8 KHz on the left. The patient underwent total parotidectomy withfacial nerve tumor resection via transmastoid approach, with simultaneous facial – hypoglossal nerve anastomosis reconstruction. Histopathologic findings confirmed the diagnosis of a schwannoma. Postoperative facial function was Grade VI. Hearing and hypoglossal nerve function were preserved.Conclusion: A progressive hemifacial paralysis of chronic duration with or without the presence of an infra-auricular mass should raise the suspicion of a facial nerve tumor. Gadolinium-enhanced magnetic resonance imaging is valuable since intraparotid facial nerve schwannomas are mostly diagnosed intraoperatively when the neoplasm and the nerve are exposed and determined to be contiguous. The clinician should be aware that not all parotid masses are salivary gland in origin.Keywords: intraparotid facial nerve schwannoma, facial nerve paralysis, parotid mass

Implant‐Related Outcomes following Hypoglossal Nerve Implant for OSA

Objective: Obstructive sleep apnea (OSA) is a common disorder associated with multiple abnormal health outcomes. Failure of surgical treatment may be secondary to obstruction at the level of the tongue. To assess the non-disease related outcomes of an implantable hypoglossal nerve (CN XII) stimulating system (Inspire, Inspire Medical, Minneapolis, Minnesota). Method: Multicenter academic prospective trial of a unilateral hypoglossal nerve implant system (stimulation lead, sense lead and pulse generator). Implant procedure, technical details of stimulation titration, directed functional examinations, tongue EMG studies, and complications were reviewed from 31 implanted subjects. Results: Follow up averaged 424 days. Serious adverse events included delayed infection with explantation (n = 1), insufficient stimulation with explantation (n = 1), explantation per patient request (n = 1), and acute infection/inflammation (n = 1). Minor local pain/stiffness (n = 7), transient odynophagia (n = 4), stitch abscess (n = 1), local swelling (n = 1), fever (n = 1) were observed. Stimulation thresholds for sensation, morphologic change, and sub-discomfort (1.6 ± 0.6, 2.1 ± 0.7, 2.6 ± 0.8 respectively) did not change at 2, 4 and 6 months post-implant). At over 1 year follow-up, no abnormal findings in speech, swallowing, tongue morphology, or hypoglossal nerve function were observed. Conclusion: Placement of a CN XII implant system is technically feasible. Serious adverse outcomes occurred in 6% (delayed infection, inadequate stimulation requiring explantation). At over one year, placement of a CN XII implant for treatment of OSA demonstrates stable stimulation thresholds and is functionally well tolerated.

Solitary Paraganglioma of the Hypoglossal Nerve.

We report the case history of solitary hypoglossal paraganglioma in a 64-year-old woman. The surgical difficulties encountered in the removal of this challenging tumor are discussed and as a literature review provided. A 64-year-old woman presented with a short history of dysphonia, occasional dysphagia, tinnitus, altered taste, and unilateral left-sided tongue wasting. On examination, there was left lower motor hypoglossal paralysis. Imaging showed a discrete enhancing lobulated mass, measuring 2 × 2 cm, in the region of the hypoglossal nerve extending into the hypoglossal canal suggestive of hypoglossal paraganglioma. A left dorsolateral suboccipital craniotomy was performed with the patient in the sitting position. The hypoglossal nerve appeared to be enlarged, and the jugular foramen was normal. Complete surgical debulking of the tumor was not attempted because of its vascular nature. The nerve was decompressed, and neuropathology confirmed a low-grade paraganglioma arising from the hypoglossal nerve. The patient was scheduled to receive stereotactic radiation for further management. When a case of solitary hypoglossal paraganglioma is encountered in clinical practice, the aim of management should be mainly focused on achieving a diagnosis and preserving the hypoglossal nerve function. If there is evidence of vascularity in the lesion noted on magnetic resonance imaging, a preoperative angiogram should be obtained with a view for embolization. We decompressed the hypoglossal canal and achieved good improvement in the patient's symptoms. We recommend stereotactic radiosurgery for remnant and small hypoglossal tumors and regular follow-up with magnetic resonance imaging scans.

Primary Alimentary Lymphoma with Metastasis to the Liver Causing Encephalopathy in a Horse

A 23-year-old, 467-kg Palomino mare was examined for evaluation of sudden onset severe ataxia and depression. The mare had been found down in a pasture and was unable to rise. She was observed, by her owner, to be normal 24 hours earlier. This mare had resided with this owner for approximately 1.5 years, had always lived out on pasture, and had experienced numerous episodes of colic since the time she was purchased. Recent reported feed changes included introduction of new hay. Upon arrival at the hospital, the mare was severely ataxic in all 4 limbs and extremely disoriented. She head-pressed several times during the course of the evaluation and yawned repeatedly. The mare was tachycardic, with a heart rate of 98 beats per minute, and tachypneic, with a respiratory rate of 60 breaths per minute, and the mucous membranes were hyperemic and purple, with a capillary refill time of greater than 3 seconds. The mare was blind bilaterally, as indicated by absence of both menace and pupillary light responses. She had bilateral facial nerve paralysis and decreased hypoglossal nerve function. She was able to prehend, but was dysphagic with decreased tongue tone and movement. Analysis of the venous blood revealed metabolic acidosis and respiratory alkalosis with a normal pH of 7.38 (reference range 7.32–7.44), HCO3 of 13 mEq/L (reference range 25–30 mEq/L), PCO2 of 21.2 mmHg (reference range 36–46 mmHg), and BE of -12 mEq/L (reference range -1-1 mEq/L).a It also revealed a low blood urea nitrogen concentration of 8 mg/dL (reference range 11–27 mg/dL) and a high blood glucose concentration of 263 mg/dL (reference range 63–134 mg/dL).a Both packed cell volume and total solids were high at 52% (reference range 32–53%), and 8 g/dL (reference range 5.8–7.7 g/dL), respectively. The blood ammonia concentration was 120 μmol/L (reference range 18–78 μmol/L)b.

Primary Alimentary Lymphoma with Metastasis to the Liver Causing Encephalopathy in a Horse

A 23‐year‐old, 467‐kg Palomino mare was examined for evaluation of sudden onset severe ataxia and depression. The mare had been found down in a pasture and was unable to rise. She was observed, by her owner, to be normal 24 hours earlier. This mare had resided with this owner for approximately 1.5 years, had always lived out on pasture, and had experienced numerous episodes of colic since the time she was purchased. Recent reported feed changes included introduction of new hay. Upon arrival at the hospital, the mare was severely ataxic in all 4 limbs and extremely disoriented. She head‐pressed several times during the course of the evaluation and yawned repeatedly. The mare was tachycardic, with a heart rate of 98 beats per minute, and tachypneic, with a respiratory rate of 60 breaths per minute, and the mucous membranes were hyperemic and purple, with a capillary refill time of greater than 3 seconds. The mare was blind bilaterally, as indicated by absence of both menace and pupillary light responses. She had bilateral facial nerve paralysis and decreased hypoglossal nerve function. She was able to prehend, but was dysphagic with decreased tongue tone and movement. Analysis of the venous blood revealed metabolic acidosis and respiratory alkalosis with a normal pH of 7.38 (reference range 7.32–7.44), HCO3 of 13 mEq/L (reference range 25–30 mEq/L), PCO2 of 21.2 mmHg (reference range 36–46 mmHg), and BE of ‐12 mEq/L (reference range ‐1‐1 mEq/L).a It also revealed a low blood urea nitrogen concentration of 8 mg/dL (reference range 11–27 mg/dL) and a high blood glucose concentration of 263 mg/dL (reference range 63–134 mg/dL).a Both packed cell volume and total solids were high at 52% (reference range 32–53%), and 8 g/dL (reference range 5.8–7.7 g/dL), respectively. The blood ammonia concentration was 120 μmol/L (reference range 18–78 μmol/L)b.

Unilateral hypoglossal nerve injury following the use of a ProSeal™ laryngeal mask

We would like to report a complication following the use of a ProSeal™ laryngeal mask airway (PLMA) (Intavent Orthofix Ltd, Maidenhead, UK). A 28-year-old male required open reduction and internal fixation of a comminuted tibial plateau fracture. General anaesthesia was induced with infusions of propofol and remifentanil and his airway secured with a size 5 PLMA. The laryngeal mask was inflated with 40 ml of air. Anaesthesia was maintained with propofol, remifentanil, and nitrous oxide 70% in oxygen. Anaesthesia and surgery (which lasted 3.5 h) were uneventful. The PLMA was removed as the patient woke and was noted to be apparently overinflated. There were no immediate postoperative complications. The following day the patient complained of difficulty in swallowing and numbness on the left side of his tongue, present since shortly after waking up. Examination confirmed unilateral hypoglossal nerve injury. Throughout the rest of his time in hospital eating remained difficult. Full recovery of his hypoglossal nerve function was slow but complete at 4 months. Hypoglossal nerve, lingual nerve and recurrent laryngeal nerve injury have previously been reported during use of the classic laryngeal mask [1–4]. In most cases a full recovery was made. In one case hypoglossal nerve injury was accompanied by severe weight loss [1] and in another unilateral recurrent laryngeal nerve injury lead to permanent vocal cord paralysis [4]. The mechanism of injury is neuropraxia, due to pressure on the pharynx from the airway. In the case of the hypoglossal nerve this occurs at the medial side of the hyoid bone as the nerve crosses the greater cornu [5]. This is the first report of nerve injury associated with the PLMA. The PLMA has a larger cuff than the classic laryngeal mask airway and has a posterior extension. As a result the mask makes a larger area of contact with the pharynx and exerts lower pharyngeal pressures for the same intracuff volume [6]. The PLMA allows a better airway seal than the classic laryngeal mask airway for any given intracuff volume [6]. The rise in PLMA-airway seal is greatest for the first 10 ml of inflation, across the size range [6]. This, and other data suggest, that the PLMA is the least likely of the laryngeal masks to cause complications associated with increased pressure on pharyngeal mucosa, with the classic also better than the intubating laryngeal mask [7]. The 40 ml of air inserted into this PLMA represents the maximum volume that should be inserted into a size 5 PLMA. It is likely that the use of nitrous oxide and the long duration of surgery [8] both contributed to increased intracuff pressure, increased pharyngeal mucosal pressure and therefore neuropraxia. Audit elsewhere has shown that use of the maximum recommended volumes of air in all laryngeal masks routinely leads to intracuff pressures in excess of 120 cmH2O [9] and our own local audit has confirmed this. The practice of reducing the volume of air in the cuffs of laryngeal mask airways to half the recommended maximum has been shown not to interfere with mask function [10]. Brain has recommended both for the classic laryngeal mask airway and the PLMA that the maximum intracuff pressure should not exceed 60 cmH2O [11,12] and this information is contained in the instruction manuals of both devices [13,14]. At an intracuff pressure of 60 cmH2O, the pressure exerted on all areas of the mucosa by the PLMA is below that considered critical for mucosal perfusion [6]. Following this case, we have altered the practice in our hospital in order to try to prevent recurrence of this and similar complications. We have introduced cuff inflator/pressure gauges (VBM Mediztechnic, Sulz, Germany) to all areas where laryngeal mask airways are used allowing inflation to pressure of 60 cmH2O, and to enable monitoring of that pressure throughout anaesthesia. It appears that without use of such monitoring it is not possible to use the devices as recommended by the manufacturers. Dr Cook has received an honorarium from Intavent Orthofix Ltd, manufacturers of the laryngeal masks and has advised a number of airway companies.

Determination of the changes in the hypoglossal nerve function after suspension laryngoscopy with needle electromyography of the tongue.

The purpose of this study was to determine changes in the hypoglossal nerve function after suspension laryngoscopy with needle electromyography of the tongue. This study also attempted to determine the possible relationship between the predictive factors of intubation difficulty by using the intubation difficulty scale, which was introduced by Adnet et al., duration of suspension laryngoscopy and changes in hypoglossal nerve function after suspension laryngoscopy. The study was performed on 39 patients who underwent suspension laryngoscopy for benign glottic pathology. Pre-operative airway assessment was evaluated by the intubation difficulty scale and the duration of suspension laryngoscopy was recorded. Needle electromyography of the tongue was performed three or four weeks after the suspension laryngoscopy. After needle electromyography of the tongue, increased polyphasia was found in 13 patients (33 per cent), bilaterally in three of them. The interference pattern was reduced in two of these 13 patients. There was no statistically significant difference in predictive factors of intubation difficulty and the duration of the operation between these 13 patients with increased polyphasia and the remaining 26 patients with completely normal electromyography findings. These findings show that, in spite of normal clinical tongue function, subclinical changes can be detected by needle electromyography of the tongue after suspension laryngoscopy.

顔面神経舌下神経端側吻合術の経験

Hypoglossal-facial nerve anastomosis is a procedure for restoring facial nerve function after facial palsy caused by surgery for removal of cerebellopontine angle tumors. Classical hypoglossal-facial nerve anastomosis, however, sacrifices the hypoglossal nerve, inevitably causing hemitongue atrophy. To preserve hypoglossal nerve function, we tried hypoglossal-facial nerve side-to-end anastomosis for a 67-year-old woman who suffered from complete facial nerve palsy due to the removal of an acoustic neuroma. In this technique, the facial nerve in the mastoid cavity is exposed to the level of the external genu and then transected. The hypoglossal nerve is also exposed at the level of the axis and dissected as proximally as possible. One-third of the hypoglossal nerve is transected and the distal stump of the facial nerve is anastomosed without tension. In the postoperative stage, this technique provided facial reanimation without hypoglossal nerve dysfunction within one year. In conclusion, hypoglossal-facial nerve side-to-end anastomosis is a useful treatment for patients with long-standing facial palsy who do not want to have tongue dysfunction.