Recurrent laryngeal nerve paralysis: a complication of thyroidectomy

OBJECTIVE: To study factors related to recurrent laryngeal nerve (RLN) paralysis, a major complication of thyroidectomy. DESIGN: Retrospective study of outcome of patients' medical records. PATIENTS AND METHODS: Records of 361 patients who underwent thyroidectomy by otolaryngologists at Ramathibodi Hospital were reviewed for RLN paralysis. Main Outcome Measures: RLN injury was analyzed in relation to types of surgery, RLN identification, and histopathology. The analysis was based on the number of RLNs at risk. RESULTS: The incidence of permanent RLN paralysis was 2.38%. Both the permanent RLN paralysis and temporary RLN paralysis were significantly related to the histopathologic findings of malignancy (p < .005). The positive identification of RLN and the types of surgery were not found to be significant factors in either permanent RLN paralysis or temporary RLN paralysis. CONCLUSIONS: There was insufficient evidence to support that the identification of RLNs during surgery would be a significant factor in reducing the likelihood of RLN paralysis. However, RLNs should be identified to avoid iatrogenic injury and subsequent paralysis. Meticulous surgical technique should be applied in patients whose results of fine-needle aspiration biopsy suggested malignancy, as there is the possibility of difficult surgery and potential iatrogenic RLN paralysis in this group of thyroid patients.     

Thirty-eight-year evaluation of a surgical technique to protect the external branch of the superior laryngeal nerve during thyroidectomy

The purpose of this study is to evaluate a surgical technique for the preservation of the function of the external branch of the superior laryngeal nerve (EBSLN) during total thyroid lobectomy and total thyroidectomy. Permanent injury to this nerve can be a disaster, especially in singers and professional speakers who depend on control of pitch, and a clear and forceful voice. Voice changes may be either obvious or subtle. For better voice analysis, a detailed questionnaire is necessary. Thus, the evaluation in this study is based on laryngoscopy of 934 nerves in 675 patients and detailed subjective voice evaluation of 66 patients during the last 2 years of the study. There are 2 surgical principles. First, the EBSLN is not routinely exposed; the distal 1.5 to 2.0 cm (critical area) of the superior thyroid vessels are carefully dissected, exposed, and ligated, preferably independently. Careful observation ensures that the EBSLN is not included in the ligature. Second, the ultimate evaluation of the surgical technique is the effect of voice changes on the patient's lifestyle. Laryngoscopy of 934 nerves found bowing, temporary in 4 patients and permanent in 1 patient (limited follow-up). Of the 66 patients with voice evaluations, 14 had changes: 9 had temporary changes, while 5 had permanent changes. In these 14 patients, voice changes had no effect on lifestyle in 13, and the effects were indeterminate in 1 (unavailable for follow-up). The estimated deleterious effect of voice changes on lifestyle is no greater than 1.5% of the 66 patient responders.     

Recurrent laryngeal nerve paralysis after thyroid gland operations. Etiology and consequences]

In the period of 1 January 1990 to 31 December 1996 the thyroidectomy cases we performed were immediately followed by vocal cord evaluation using a flexible bronchoscope while the patient was still on the operating table. If an obvious cord paralysis was discovered, an exploration of the recurrent laryngeal nerve, to the level of the larynx, was performed. If the nerve was found to be intact, no further measures were taken. A severed nerve underwent suture repair. If an otolaryngologist diagnosed a vocal cord paralysis 1-5 days after surgery, a reoperation was recommended except in the cases where postoperative bronchoscopy had shown an easily mobile cord or the recurrent nerve was completely dissected during the operation. Within this 7-year period, we performed 3492 thyroidectomy operations. The diagnosis of subsequent unilateral postoperative vocal cord paralysis occurred in 48 cases. In 33 of these cases the status of the nerve in the surgical field was known: 4 patients had an intact nerve proved by complete dissection during thyroidectomy, in two patients the lesions of the nerve were detected intraoperatively (1 transsection, 1 partial resection), and 27 cases were followed by reoperation. Of the 33 patients mentioned above, in 19 instances the recurrent laryngeal nerve was found to be intact; 3 displayed signs of local trauma, and 11 were found to be severed with total discontinuity. Those patients with an intact nerve, or local nerve trauma only, went on to develop normal function within 6 months in 20 (91%) of 22 cases. Of the 11 with a severed nerve, 8 showed "autoparalysis" with good voice within 4-8 months, after suture repair in 10 cases. The patient with partial resection had no repair of the nerve. If immediate postoperative evaluation showed mobility of the vocal cords but a paralysis was detected later by an otolaryngologist and repeat intervention was not done, vocal cord function was spontaneously restored in 9 of 11 patients. Four patients refused reoperation. From 1990 to 1991, the recurrent laryngeal nerve was not always dissected during our thyroidectomy operations. However, this was done routinely from 1991 to 1996. Routine intraoperative dissection of the vocal cord nerve reduced the rate of postoperative cord paralysis from 2.0% to 1.2%. It also reduced the frequency of intraoperative nerve injury with total discontinuity from 0.58% to 0.23%.     

Ortner's syndrome: a centenary review of unilateral recurrent laryngeal nerve palsy secondary to cardiothoracic disease

Ortner's Syndrome (described 100 years ago in 1897) is a clinical entity with hoarseness due to a left recurrent laryngeal nerve (LRLN) palsy caused by cardiac disease. A 35-year-old woman presented with a LRLN palsy due to a huge thoracic aneurysm. The anatomy of the LRLN and the cardiothoracic complaints which may cause the palsy are discussed.     

Nonrecurrent recurrent nerve. Danger in thyroid and parathyroid surgery. Apropos of 9 cases

Main difficulties in thyroid surgery are represented by recurrent nerve anatomy and parathyroid glands. Nerve injury or accidental truncation cause definitive impairment. Risk of recurrent paralysis is 0.5 to 3% for advanced teams. Early investigation and dissection of this nerve are considered mandatory for preservation. This practice is also highly indicated due to anatomical variations, cause for accidental truncation. The most difficult case is encountered when there is nerve non recurrence, due to variations in origin and path of the nerve. Inferior laryngeal nerve non recurrence can be present on the right side, it is uncommon but possible on the left side. We have evaluated a series of 1165 cervicotomies undertaken for thyroidectomy or parathyroid gland approach. There were 9 cases of non recurrence. Literature review allowed us to study anatomical variations and nerve relationships.     

Loss of large myelinated nerve fibres of the recurrent laryngeal nerve in patients with multiple system atrophy and vocal cord palsy

Prevalence rate and etiology were studied in severely handicapped children of school age in Nagano prefecture as of July, 1994. Severely retarded children were defined as those whose IQ's were lower than 35 and who were unable to walk. The total number of severely retarded children was 165. The prevalence rate was 0.71/1000, 90% of them being in class 1 or 2 of Oshima's classification (bedridden or unable to sit alone and with IQ less than 20), and 26% being cared for at home. Their average gestational age was 38.5 weeks, and the average birthweight 2,772 g. At birth none of them had extremely low birth weight. Etiology of the handicaps was classified as follows; congenital 26.1%; maternal infection 3.0%; prenatal 3.6%; perinatal 27.3%; postnatal 13.9% and unknown 26.1%. Asphyxia decreased gradually but the number of low birth weight premature infants increased. When postnatal etiologies were excluded, the patients with unknown etiology occupied 30.3%, 23.3% of them being light-for-dates baby. The examination of the case histories revealed that causes of unknown etiology are prenatal. If we add unknown etiology to congenital, maternal infection, and prenatal etiology, the prenatal origin is 68%.     

Embryological considerations of thyroid surgery: developmental anatomy of the thyroid, parathyroids and the recurrent laryngeal nerve

The surgeon planning a thyroidectomy must be prepared to find variations in three important structures in the neck. He must be prepared to find ectopic thyroid nodules above, below or lateral to the normally located thyroid gland. Any unattached nodule should be considered malignant until proved otherwise. He must identify and preserve parathyroid glands that may not lie in the typical location. He must be prepared to encounter recurrent laryngeal nerves that do not recur. The surgeon who remembers the embryology of the structures in the neck may occasionally be astonished, but never surprised.     

Usefulness and limitations of 99mTc-MIBI scintigraphy for detection of parathyroid lesions

To evaluate the usefulness of MIBI scintigraphy (MIBI) for parathyroid lesions, the detectability of lesions by MIBI was compared with that by Tl-Tc subtraction imaging, ultrasonography, CT and MRI in 56 histologically proved lesions. In neck lesions, ultrasonography (92%) and MIBI (85%) showed better detectability than those by the other three modalities. With MIBI, detectability was decreased for smaller parathyroid lesions that coexisted with thyroid disease. Among the five modalities, MIBI showed the highest detectability (88%) for ectopic or metastatic lesions. The smallest parathyroid lesions detected by MIBI were a parathyroid adenoma weighing 220mg and a parathyroid hyperplasia weighing 200mg. MIBI was thought to be more valuable for ectopic or metastatic parathyroid lesions.     

Postoperative hypocalcemia in patients who did or did not undergo parathyroid autotransplantation during thyroidectomy: a comparative study

BACKGROUND: Permanent hypoparathyroidism is a recognized complication of thyroidectomy. Apart from preservation of parathyroid glands in situ by meticulous dissection, parathyroid autotransplantation (PTHAT) has been performed increasingly to avoid permanent hypoparathyroidism. METHODS: From January 1995 to October 1997, PTHAT was performed routinely for devascularized or inadvertently removed glands in 98 (36%) of 271 patients undergoing thyroidectomy. Potential risk factors and the impact of PTHAT on postoperative hypocalcemia were studied. RESULTS: Postoperative hypocalcemia occurred in 40 patients (14.8%), whereas 5 patients (1.8%) had permanent hypocalcemia during a median follow-up of 9 months. The incidence of transient hypocalcemia (n = 35) was higher in patients who underwent PTHAT (21.4%) than in patients who did not undergo PTHAT (8.1%) (P < .01). Permanent hypocalcemia occurred only in patients who did not undergo PTHAT. None of the 21 patients who had postoperative hypocalemia after PTHAT had permanent hypoparathyroidism compared with 26% (5/19) of patients who did not undergo PTHAT (P = .018). When the resected thyroid gland was examined for parathyroid tissue, the incidence of positive identification was higher in patients who did not undergo PTHAT (13%) than in patients who did undergo PTHAT (4%) (P = .015). CONCLUSIONS: Patients with postoperative hypocalcemia after PTHAT have virtually no risk of having permanent hypoparathyroidism. A more careful examination of the resected thyroid tissue can help to identify inadvertently removed parathyroid glands for autotransplantation.     

The utility of isolating the recurrent nerve and parathyroids in the prevention of complications in thyroid surgery. The role of the superior laryngeal nerve and C cells

The authors emphasize systematic isolation of the recurrent nerve and of the parathyroids, to prevent complications in surgery of the thyroid. Moreover they try to underline the significance of the superior laryngeal nerve and the role of parafollicular cells (today unknown) for a rational and modern therapy of the non-neoplastic diseases of the thyroid.     

Anatomy of the human internal superior laryngeal nerve

The mucosa of the larynx contains one of the most dense concentrations of sensory receptors in the human body. This sensitivity is used for reflexes that protect the lungs, and even momentary loss of this function is followed rapidly by life-threatening pneumonia. The internal superior laryngeal nerve (ISLN) supplies the innervation to this area, and, to date, the distribution and branching pattern of this nerve is unknown. Five adult human larynges were processed by using Sihler's stain, a technique that clears soft tissue while counterstaining nerves. The whole-mount specimens were then dissected to demonstrate the branching of the ISLN from its main trunk down to the level of terminal axons. The human ISLN is divided into three divisions: The superior division supplies mainly the mucosa of the laryngeal surface of the epiglottis; the middle division supplies the mucosa of the true and false vocal folds and the aryepiglottic fold; and the inferior division supplies the mucosa of the arytenoid region, subglottis, anterior wall of the hypopharynx, and upper esophageal sphincter. Several dense sensory plexi that cross the midline were seen on the laryngeal surface of the epiglottis and arytenoid region. The human ISLN also appears to supply motor innervation to the interarytenoid (IA) muscle. A detailed map is presented of the distribution of the ISLN within the human larynx. The areas seen to receive the greatest innervation are the same areas that have been shown by physiological experiments to be the most sensate: the laryngeal surface of the epiglottis, the false and true vocal folds, and the arytenoid region. The observation that the human ISLN appears to supply motor innervation to the IA muscle is contrary to current concepts of the ISLN as a purely sensory nerve. These findings are relevant to understanding how the laryngeal protective reflexes work during activities like swallowing. The nerve maps can be used to guide surgical attempts to reinnervate the laryngeal mucosa when sensation is lost due to neurological disease.     

Parathyroid autotransplantation in patients with parathyroid disease and total thyroidectomy. Indications in 117 cases

Parathyroid autotransplantation is a known and increasingly utilized procedure. It is indicated in patients with primary parathyroid hyperplasia, in patients with primary hypercalcemia who have normal parathyroid tissue devascularized during surgery, in patients with secondary and tertiary parathyroid hyperplasia, and in patients with total thyroidectomy when normal parathyroid tissue is accidentally or unavoidably removed or completely devascularized. No normal viable parathyroid tissue should be autotransplanted. This procedure was performed in 13 dialysis patients, 27 primary hypercalcemic patients and 77 patients with thyroidectomy. The hypercalcemic patients had autotransplantations into muscle pockets in the volar surface of the forearm, while the thyroidectomy patients had autotransplantation into the sternocleidomastoid muscles. The application of parathyroid autotransplantation is a major technical and physiologic breakthrough in the field of thyroid and parathyroid surgery. It should greatly reduce the morbidity associated with permanent hypocalcemia in this type of extensive surgery.     

Usefulness of the intubating laryngeal mask airway for cases with predicted difficult intubation

We evaluated the usefulness of the intubating laryngeal mask airway (ILMA) in patients who were predicted to have possible difficult airway. Patients with possible difficult airway were defined as those with limited head extension, Mallampati's classification of grade IV, thyro-mental distance < 4 cm, or Cormack grade III-IV on the laryngoscopy. The control group was consisted of the patients without these conditions or impaired mouth opening. Insertion of the ILMA was successfully performed in all patients of both groups. In the group of possible difficult airway, 83% of patients were intubated through the ILMA successfully, and in the control group, 86%. We conclude that the ILMA may become an additional tool in patients with difficult intubation.     

Risk factors and follow-up of recurrent laryngeal nerve paralysis after first surgeries of benign thyroid diseases. Results of a retrospective analysis of 1,556 patients

PATIENTS AND METHODS: risk factors of recurrent laryngeal nerve (RLN) palsy after thyroid gland surgery were evaluated retrospectively in 1556 patients who were submitted to an operation because of a benign thyroid disease. Recurrences were also excluded. RESULTS: RLN palsy occurred in 6.6%. In relation to the nerves at risk the incidence of primary postoperative nerve damages was 4.3%. After a long-term follow-up of in total 18 months the incidence of permanent nerve palsy was 1.6% (related to the nerves at risk: 1.1%) as 75.5% of the paralyses were transient in an average of 6.2 months. Substernal goitres especially when sternotomy became necessary, the ligature of the inferior laryngeal artery, serious perioperative complications and total lobectomy in comparison to subtotal resection were important risk factors for primary postoperative RLN palsy (p < 0.05 resp. p < 0.01). The ligature of the inferior laryngeal artery and the extension of resection were indeed significant risk factors also for permanent nerve damages, but the other factors had no influence on the risk of permanent RLN palsy. However, the non-exposure of RLN in subtotal lobectomy was significantly associated (p < 0.01) with permanent, but not with transient nerve palsy. CONCLUSION: The exposure of the RLN is one of the most important procedures during thyroid surgery and particular also during subtotal lobectomy to reduce the rate of permanent RLN damages.     

Prospective biochemical and scintigraphic evaluation of autografted normal parathyroid glands in patients undergoing thyroid operations

Recent reports suggest that oral choline supplement may alter the cerebral choline/creatine (Cho/Cr) ratio and might be used to treat neurodegenerative disorders of cholinergic transmission. Using both 1H and 31P MRS, we reexamined the Cho/Cr ratio and quantified cerebral choline and its major constituents: phosphoethanolamine (PE), phosphorylcholine (PC), glycerophosphorylethanolamine (GPE), and glycerophosphorylcholine (GPC). In the four brain locations examined, no significant increases in Cho/Cr, [Cho], or in its major constituents were found in response to an oral challenge of 50 mg/kg of choline bitartrate. Oral choline did not significantly affect human cerebral metabolism in the short term.