Recurrent laryngeal nerve identification is the ‘gold standard’ in thyroidectomy, to determine nerve function security and prevent severe complications. This study assessed the topographical relationship between the recurrent laryngeal nerve and the inferior thyroid artery in patients undergoing total thyroidectomy, and determined its clinical impact.

A retrospective study was performed of patients undergoing total thyroidectomy in a single tertiary centre over a six-month period.

Sixty-four patients were included. Among the 128 recurrent laryngeal nerve dissections, the nerve was identified traversing the inferior thyroid artery anteriorly in 27.3 per cent, with equal distribution between the two sides. No significant sex association was reported. One patient had transient vocal fold palsy, and hypocalcaemia was observed in 21.9 per cent, yet there was no statistical association with the topographical variation of the recurrent laryngeal nerve.

Almost one-third of patients had an anatomical variation in which the recurrent laryngeal nerve ran superiorly to the inferior thyroid artery. Recurrent laryngeal nerve variation had no clinical impact on local complications or hypocalcaemia.

To evaluate the circumstances in which recurrent laryngeal nerve palsy occurs after thyroid surgery.

This study assessed 1026 patients who underwent surgery for benign thyroid disease over a seven-year period in a retrospective, single-centre study.

With a total of 1835 recurrent laryngeal nerves at risk, there were 38 cases (2.07 per cent) of transient recurrent laryngeal nerve palsy and 8 (0.44 per cent) of permanent recurrent laryngeal nerve palsy. No explanation was found for 10 of the 46 cases of recurrent laryngeal nerve palsy. Among the 38 other cases, the probable causes included poor identification of the recurrent laryngeal nerve during surgery, involuntary resection of the nerve and several other factors.

Apart from accidental resection of the recurrent laryngeal nerve during thyroid surgery, the causes of post-operative recurrent laryngeal nerve palsy are often unclear and likely multifactorial. Poor identification of the recurrent laryngeal nerve during surgery is still the main cause of post-operative recurrent laryngeal nerve palsy, even when intra-operative neuromonitoring is used.

Laryngeal re-innervation in paediatric unilateral vocal fold paralysis is a relatively new treatment option, of which there has been little reported experience in Europe.

In this European case report of a 13-year-old boy with dysphonia secondary to left-sided unilateral vocal fold paralysis after cardiac surgery, the patient underwent re-innervation using an ansa cervicalis to recurrent laryngeal nerve transfer, in combination with fat augmentation, after 12 years of nerve denervation. Perceptual analysis data, and acoustic and laryngoscopy recordings were acquired pre-operatively, and at one and two years post-operatively.

The patient's perceptual voice quality was improved. He experienced subjective improvement and is very satisfied with the result. As expected, laryngoscopy at one and two years after surgery showed no physiological mobility of the vocal fold concerned, but improved closure during phonation was achieved. Electromyography showed evidence of re-innervation.

Laryngeal re-innervation could be considered as a treatment option for unilateral vocal fold paralysis in children and adolescents, even after a long-term delay.

To evaluate the effect of body mass index and neck length on endotracheal tube movement during neck extension in thyroidectomy.

A prospective study was conducted of 30 patients undergoing thyroidectomy during an 8-month period. Patient characteristics were recorded and endotracheal tube displacement was determined.

Mean body mass index was 27.8 kg/m2 (range, 17.5–34.7 kg/m2) and mean neck circumference was 43.2 cm (range, 28–56 cm). The mean (± standard deviation) upward displacement of the endotracheal tube during neck extension was 7.17 ± 5.87 mm. Patients with a larger body mass index had a significantly greater amount of tube displacement (R2 = 0.67, p < 0.0001), as did patients with a smaller neck length (R2 = 0.48, p < 0.0001).

Neck extension results in upward displacement of the endotracheal tube. The amount of displacement is significantly higher in patients with a larger body mass index or shorter neck length. This has particular relevance for nerve monitoring in thyroidectomy.

The non-recurrent laryngeal nerve is subject to potential injury during thyroid surgery. Intra-operative identification and preservation of this nerve can be challenging. Its presence is associated with an aberrant subclavian artery and the developmental absence of the brachiocephalic trunk. This study aimed to evaluate the incidence of non-recurrent laryngeal nerves and present a new classification system for the course of these nerves.

Non-recurrent laryngeal nerves were identified on the right side in 15 patients who underwent thyroidectomy. The incidence of non-recurrent laryngeal nerves (during thyroidectomy) and aberrant subclavian arteries (using neck computed tomography) was evaluated, and the course of the nerves was classified according to their travelling patterns.

The overall incidence of non-recurrent laryngeal nerves was 0.68 per cent. The travelling patterns of the nerves could be classified as: descending (33 per cent), vertical (27 per cent), ascending (20 per cent) or V-shaped (20 per cent).

Clinicians need to be aware of these variations to avoid non-recurrent laryngeal nerve damage. A retroesophageal subclavian artery (on neck computed tomography) virtually assures a non-recurrent laryngeal nerve. This information is important for preventing vocal fold paralysis. Following a review of non-recurrent laryngeal nerve travelling patterns, a new classification was devised.

The relationship of the recurrent laryngeal nerve to the superior parathyroid gland during consecutive thyroidectomies was prospectively evaluated. When one structure was noted, careful dissection was performed to locate the other structure, to preserve their natural anatomical relationship.

In total, 103 consecutive thyroid lobectomies were performed on 73 patients. The distance from the superior parathyroid gland to the recurrent laryngeal nerve was recorded.

In 88 cases (88.9 per cent), the superior parathyroid gland was identified within 5 mm of the recurrent laryngeal nerve. In 62 cases (62.6 per cent), the gland was within 1 mm of the recurrent laryngeal nerve. The height of the thyroid lobe was positively associated with the distance between the two structures (p = 0.001), as was the incidence of cancer (p = 0.033). The incidence of recurrent laryngeal nerve paresis was less than 4 per cent.

In most cases, the recurrent laryngeal nerve was found in close proximity to the superior parathyroid gland. In a thyroid gland with a large height, or in a cancerous lobe, this relationship is less reliable.

A non-recurrent inferior laryngeal nerve is a rare anomaly in which the nerve enters the larynx directly off the cervical vagus nerve, without descending to the thoracic level. It is very susceptible to damage during surgery. This report describes the important pre-operative radiological evaluations and surgical landmarks in a case of a non-recurrent inferior laryngeal nerve, identified during the recently developed technique of robotic thyroidectomy.

A 38-year-old woman presented with suspected papillary microcarcinoma, as indicated by aspiration cytology. Pre-operative computed tomography showed a right aberrant subclavian artery that indicated a possible right non-recurrent inferior laryngeal nerve. Using robotic thyroidectomy methods, it was possible to carefully dissect along the thyroid capsule. The laryngeal entrance point of the right non-recurrent inferior laryngeal nerve (a constant anatomical landmark) was successfully identified via the three-dimensional, high-magnification views provided by the robotic endoscope.

With proper knowledge of radiological and surgical anatomy, and the benefits of high-magnification endoscopic views, a non-recurrent inferior laryngeal nerve can be safely preserved during robotic surgery.

The false thyroid capsule is an important anatomical structure involved in thyroidectomy, yet it is rarely studied. This study aimed to define the anatomy of the false thyroid capsule, and its clinical significance.

A prospective study was performed involving 151 patients with goitre who underwent thyroid lobectomy. The anatomy of the false thyroid capsule was carefully documented intra-operatively.

The false thyroid capsule enclosed the inferior and middle thyroid veins and the superior thyroid vessels, forming a mesentery-like structure by attaching to the gland. Once the unilateral lobe had been removed, the thyroid mesentery could be seen to have a C-shaped edge. The recurrent laryngeal nerve, inferior thyroid artery and parathyroid glands were located beneath the C-shaped edge of the thyroid mesentery.

The thyroid mesentery is a distinctive structure that can be used as a guide for surgical dissection.

The presentation of vocal fold palsy with associated goitre has historically been considered to be due to malignancy with recurrent laryngeal nerve involvement.

In total, 830 consecutive patients who underwent thyroid surgery were reviewed. Patients with vocal fold paralysis and thyroid disease were examined to determine the aetiology of the paralysis.

Nine patients were identified with new onset vocal fold paralysis prior to thyroid surgery. Six of the patients with recurrent laryngeal nerve paralysis had benign thyroid disease, and for three of the patients the paralysis was secondary to malignancy.

Recurrent laryngeal nerve paralysis in the presence of thyroid disease is not pathognomonic for malignancy. The current literature may underestimate the association between vocal fold paralysis and benign thyroid disease. The paper also highlights the importance of recurrent laryngeal nerve preservation in patients who present with palsy and thyroid disease; the relief of benign compression often leads to complete recovery of recurrent laryngeal nerve paralysis.

The recurrent laryngeal nerve can be injured during surgery. This study investigated recurrent laryngeal nerve reinnervation.

To study the short-term effects of primary anastomosis of the recurrent laryngeal nerve, by laryngeal electromyography and histopathological analysis, in a rabbit model.

Twenty Zealand rabbits underwent either right recurrent laryngeal nerve (1) transection with excision of 1 cm or (2) transection and end-to-end primary anastomosis. Vocal fold movements, laryngeal electromyography results and histological changes were recorded.

Vocal fold analysis showed a paramedian vocal fold in both groups, with perceptible vibratory movements in group two. Electromyography revealed total denervation potentials in group one, but denervation and regeneration signs in group two. Histopathologically, hyperkeratosis and parakeratosis of the vocal fold mucosa were seen in group one, and signs of parakeratosis and hyperplasia in group two.

Even under ideal conditions for primary recurrent laryngeal nerve anastomosis, a return to normal muscle function is unlikely. However, such anastomosis prevents muscle atrophy, and should be performed as soon as possible. The degree of nerve recovery is associated with the number, amplitude and myelination level of fibrils returning to the original motor end-plaque.

The proper positioning of the Nerve Integrity Monitoring® endotracheal tube during recurrent laryngeal nerve monitoring is of paramount importance. This article describes our experience with the GlideScope® and explains how it can facilitate the accurate placement of the Nerve Integrity Monitoring endotracheal tube.

Endotracheal intubation with the Nerve Integrity Monitoring endotracheal tube was performed in 250 patients undergoing thyroidectomies using the GlideScope video laryngoscope. The correct positioning of the tube was determined according to impedance values of less than 5 kohm and an impedance imbalance of less than 1 kohm.

Successful intubation was achieved in all cases. The GlideScope aided the correct placement of the Nerve Integrity Monitoring endotracheal tube in the majority of the cases.

The GlideScope provides an excellent means to ensure the correct positioning of the Nerve Integrity Monitoring tube. It allows both the surgeon and the anaesthesiologist to participate in the intubation process and confirm correct placement of the tube, whilst also allowing gentle intubation with improved visibility.

To determine the differences in myelination between the human recurrent laryngeal nerve and superior laryngeal nerve.

Fifteen confirmed laryngeal nerve specimens were harvested from five cadavers. Cross-sections were examined under a photomicroscope and morphometric analysis performed.

There was a significantly greater number of myelinated fibres than unmyelinated fibres, in both the recurrent laryngeal nerve (p = 0.018) and the superior laryngeal nerve (p = 0.012). There was a significantly greater number of myelinated fibres in the superior laryngeal nerve, compared with the recurrent laryngeal nerve (p = 0.028). However, there was no significant difference in the number of unmyelinated fibres, comparing the two nerves (p = 0.116).

These findings support those of previous studies, and provide further evidence against the historical plexus theory of laryngeal nerve morphology. The differences in the degree of myelination, both within and between the human laryngeal nerves, may have clinical consequence regarding recovery of function following nerve injury.

We report an extremely rare case of coexisting, ipsilateral nonrecurrent inferior laryngeal nerve and recurrent inferior laryngeal nerve.

We present a case report and a review of the world literature concerning ipsilateral nonrecurrent inferior laryngeal nerve and recurrent inferior laryngeal nerve.

The presence of a coexisting, ipsilateral nonrecurrent inferior laryngeal nerve and recurrent inferior laryngeal nerve is a very rare embryological aberration which is associated with a right subclavian artery originating from the aortic arch. We report a case of coexisting, ipsilateral nonrecurrent and recurrent inferior laryngeal nerves associated with this vascular anomaly.

The surgeon must be aware of the possibility of coexisting, ipsilateral nonrecurrent inferior laryngeal nerve and recurrent inferior laryngeal nerve, and thus must trace the nerve in its entirety. Occasionally, what appears to be a nonrecurrent inferior laryngeal nerve will actually be a communicating branch between the recurrent inferior laryngeal nerve and the oesophageal or sympathetic ganglia. If such a neurological variant is present, the consequences of careless dissection could include not only vocal fold paralysis but also dysphagia (if the pharyngeal and oesophageal branches of nonrecurrent or recurrent inferior laryngeal nerve are injured).

To highlight a poorly known anatomical variation of the lateral lobe of the thyroid gland, which can be useful in identifying the recurrent laryngeal nerve during thyroid surgery.

We performed a three-year prospective study of 79 thyroid surgery patients. Great attention was paid to anatomical variations of the thyroid gland (i.e. the presence or absence of a distinct tubercle of Zuckerkandl), the recurrent laryngeal nerve and the location of the parathyroid glands.

A total of 71 right lobectomies and 74 left lobectomies were performed. Five tubercles of Zuckerkandl were identified (7.04 per cent of cases) and were useful in detecting the recurrent laryngeal nerve (but only on the right side).

The tubercle of Zuckerkandl is a poorly known and variable anatomical feature of the thyroid gland which may not, in fact, be so rare. It arises for embryological reasons, and it can be a reliable anatomical landmark for identifying the recurrent laryngeal nerve during thyroid surgery. It should be included in the Nomina Anatomica as the ‘processus posterior glandulae thyroideae’ described by Zuckerkandl.

To evaluate the functional results obtained after voice therapy in patients with unilateral vocal fold paralysis caused by different aetiologies.

Prospective analysis of the outcome of unilateral vocal fold paralysis cases treated at our speech and language rehabilitation service from November 2003 to January 2006. Thirty cases underwent behavioural treatment, between two and six weeks after unilateral vocal fold paralysis onset. A multi-dimensional assessment was carried out before, immediately after and six months after treatment.

After behavioural therapy, the prevalence of complete glottal closure increased significantly (p < 0.05). Subjects' pre-therapy mean values for jitter, shimmer and noise-to-harmonic ratio were statistically significantly different from those taken both immediately and six months after treatment (p < 0.05). The mean values for voice turbulence index significantly improved only six months after therapy (0.08 vs 0.04). At both post-treatment assessments, voice range profile analysis showed a significant decrease of lowest voice frequency and a significant increase of the number of semitones (p < 0.05). Mean values for grade, instability, breathiness, asthenia and voice handicap index scores were significantly decreased both immediately and six months after treatment, compared with pre-treatment values (p < 0.05).

Early voice therapy may enable significant improvement in vocal function, allowing the patient to avoid surgery.

To develop and characterise an experimental model of recurrent laryngeal nerve injury for the study of viral gene therapy.

Twenty rats underwent unilateral recurrent laryngeal nerve injury. After vocal fold mobility was observed, larynges were serially sectioned, and immunohistochemical techniques were employed to stain for neurofilament and motor endplates in order for a blinded investigator to determine the percentage of nerve–endplate contact, as a histological indicator of an intact neuromuscular connection.

All animal procedures resulted in complete, ipsilateral vocal fold paralysis that recovered by three weeks. The mean nerve–endplate contact percentage was 11.6 per cent at one week, 53.9 per cent at two weeks, 88.6 per cent at three weeks, 81.7 per cent at four weeks and 86.6 per cent at five weeks. The differences between results at week one and week three were statistically significant (p < 0.01). The mean nerve–endplate contact percentage on the control side was 86.8 per cent.

There was a dramatic, measurable decrease in nerve–endplate contact percentage following crush injury to the recurrent laryngeal nerve. Spontaneous recovery was observed by three weeks post-injury. This model will be used to investigate the potential therapeutic role of viral gene therapy for the treatment of recurrent laryngeal nerve injury.

We aimed to highlight a rare anatomical variation involving the recurrent laryngeal nerve, and to emphasise its implications for thyroid surgery.

Over a period of 13 years, 993 patients underwent thyroid surgery; 1557 recurrent laryngeal nerves (887 on the right side) were exposed.

Three non-recurrent laryngeal nerves were found on the right side, associated with a retro-oesophageal subclavian artery. One case was suspected before surgery.

Several variations in the path and branches of the recurrent laryngeal nerve have been reported in the literature. The frequency of occurrence of a non-recurrent laryngeal nerve is about 1 per cent, for patients undergoing thyroid surgery. Other surgically relevant anatomical variations of the recurrent laryngeal nerve include associations with the inferior thyroid artery and the presence of nerve branches.

The recurrent laryngeal nerve must be carefully dissected and totally exposed during thyroid surgery in order to best preserve its function. Moreover, the thyroid surgeon must be aware of the existence of anatomical variations, which are not as rare as one may think.

We discuss the case of a 73-year-old woman with a six-month history of hoarseness secondary to an aortic arch pseudoaneurysm.

We present the findings of an extensive review of the literature relating to cardiovascular disorders involving the recurrent laryngeal nerve (i.e. Ortner's syndrome).

Ortner's syndrome, also known as cardiovocal syndrome, is a rare condition, with few reports in the literature.

This is only the second documented case of Ortner's syndrome in Great Britain and Ireland, and the first demonstrating an aortic pseudoaneurysm.