Anatomical basis of the anterior cervical spine approach: topographic study of the nerve structure

Selective ansa cervicalis nerve transfer to the marginal mandibular nerve for lower lip reanimation: An anatomical study in cadavers and a case report

BACKGROUND

Donor nerve options for lower lip reanimation are limited in patients undergoing oncological resection of the facial nerve. The ansa cervicalis nerve (ACN) is an advantageously situated donor with great potential but has not been examined in detail. In the current study, the anatomical technical feasibility of selective ACN to marginal mandibular nerve (MMN) transfer for restoration of lower lip tone and symmetry was explored. A clinical case is presented.

METHODS

Dissections were conducted in 21 hemifaces in non-embalmed human cadavers. The maximal harvestable length of ACN was measured and transfer to MMN was simulated. A 28-year-old male underwent ACN-MMN transfer after parotidectomy (carcinoma) and was evaluated 12 months post-operatively (modified Terzis' Lower Lip Grading Scale [25 observers] and photogrammetry).

RESULTS

The harvestable length of ACN was 100 ± 12 mm. A clinically significant anatomical variant ("short ansa") was present in 33% of cases (length: 37 ± 12 mm). Tensionless coaptation was possible in all cases only when using a modification of the surgical technique in "short ansa" cases (using an infrahyoid muscle nerve branch as an extension). The post-operative course of the clinical case was uneventful without complications, with improvement in tone, symmetry, and function at the lower lip at 12-month post-operative follow-up.

CONCLUSIONS

Selective ACN-MMN nerve transfer is anatomically feasible in facial paralysis following oncological ablative procedures. It allows direct nerve coaptation without significant donor site morbidity. The clinical case showed good outcomes 12 months post-operatively. A strategy when encountering the "short ansa" anatomical variant in clinical cases is proposed.

Platysma sparing approach to anterior cervical spine surgery: A less exposure surgery technique

Introduction

Authors aim to demonstrate the surgical technique and outcomes of using a platysma sparing approach to anterior cervical spine surgery.

Methods

Medical records of 496 prospective patients, group 1 (259 patients) with an outpatient platysma muscle-sparing approach. Group 2 (237 patients) with inpatient standard muscle-splitting approach.

Results

Intergroup comparison showed statistical significant improvement in VAS neck and NDI scores p = 0.009 and p = 0.012 and surgical operative time and estimated blood loss, p = 0.003 and p = 0.006 respectively.

Conclusion

This anatomy sparing technique demonstrates a safe, effective and reproducible approach to cervical spine surgery which is a goal of less exposure surgery philosophy.

Quantitative Risk Factor Analysis of Postoperative Dysphagia After Anterior Cervical Discectomy and Fusion (ACDF) Using the Eating Assessment Tool-10 (EAT-10)

STUDY DESIGN

A retrospective case series.

OBJECTIVE

The aim of this study was to utilize the Eating Assessment Tool-10 (EAT-10) to quantitatively analyze risk factors contributing to dysphagia after anterior cervical discectomy and fusion (ACDF).

SUMMARY OF BACKGROUND DATA

ACDF is one of the most common procedures performed in the United States, with postoperative dysphagia rates ranging from 2% to 60%. The EAT-10 is a self-administered, symptom-specific 10-item clinical instrument to document dysphagia symptom severity and has demonstrated excellent internal consistency, test-retest reliability, and criterion-based validity.

METHODS

This study utilized a retrospective chart review of 163 patients from July 2013 to October 2017 who underwent ACDF at a single institution and prospectively completed EAT-10 surveys pre- and postoperatively. EAT-10 scores were collected preoperatively and at postoperative day 1, day 14, 1 month, 3 months, 6 months, and 12 months. Preselected risk factors were abstracted from the patients' chart. Univariate analyses were performed to identify candidate variables that correlated with abnormal EAT-10 scores at each time point. Multivariate logistic regression was then utilized to identify risk factors that were independently correlated with abnormal EAT-10 scores at each time point.

RESULTS

Female gender, younger patients, and increased operating room (OR) time was associated with increased rates of dysphagia in the early postoperative period. History of obstructive sleep apnea, history of asthma, increased American Society of Anesthesiologists (ASA) score, and a larger number of spinal levels included in the surgery were correlated with increased dysphagia in the later postoperative periods.

CONCLUSION

Dysphagia is common following ACDF. Factors associated with longer-term dysphagia seem to be more associated with pre-existing medical comorbidities. Understanding risk factors that correlate with increased rates of dysphagia has the potential to improve preoperative patient counseling and changes in operative management.

LEVEL OF EVIDENCE

4.

Option for transverse midline incision and other factors that determine patient's decision to have cervical spine surgery

BACKGROUND

Authors aim to determine patients' preference for surgical incision and factors affecting the decision for surgery to the anterior neck.

METHODS

A questionnaire was presented prior to evaluation and if preceded to surgery followup given.

RESULTS

243 patients completed questionnaire, with 60% female population and younger than 50 years. 151 patients preferred a transverse midline incision with a statistically significant increase in outcomes and cosmesis importance and a decrease in the importance of board certification.

CONCLUSION

Findings of questionnaire demonstrate that patients' prefer a transverse midline anterior neck incision, with surgical outcomes being the overall factor affecting decision making.

Anatomic Relationship Between Right Recurrent Laryngeal Nerve and Cervical Fascia and Its Application Significance in Anterior Cervical Spine Surgical Approach

STUDY DESIGN

An anatomic study of anterior cervical dissection of 42 embalmed cadavers.

OBJECTIVE

The aim was to study the anatomic relationship between recurrent laryngeal nerve (RLN) and cervical fascia combined with the requirements in anterior cervical spine surgery (ACSS).

SUMMARY OF BACKGROUND DATA

There has been no systematic research about how to avoid RLN injury in anterior cervical spine surgical approach from the aspect of the anatomic relationship between RLN and cervical fascia.

METHODS

Forty-two adult cadavers were dissected to observe the relationships between RLN and different cervical fascia layers.

RESULTS

RLN pierced out the alar fascia from the inner edge of the carotid sheath in all cases, and the piercing position in 22 cases (52.4%) was located at the lower segment of T1. The enter point into visceral fascia of RLN was located at C7-T1 in 25 cases (59.5%). The middle layer of deep cervical fascia exhibited the most stable anatomic relationship with RLN at the carotid sheath confluence site. Pulling visceral sheath leftwards would significantly increase the RLN tension.

CONCLUSION

Using the close and stable relationship between RLN and cervical fascia could help to avoid RLN injury in anterior cervical spine surgical approach.

LEVEL OF EVIDENCE

4.

Relationship between the ansa cervicalis and the omohyoid muscle: clinical consequences in parathyroid surgery

PURPOSE

To determine the position of the lower loop of the ansa cervicalis (AC) compared to the inferior edge of the omohyoid muscle to guide minimally invasive surgery for the lateral oblique approach of parathyroid glands.

METHODS

Authors performed 36 anatomical dissections in the laboratory of anatomy (Laboratoire d'Anatomie Des Alpes Françaises) of the Grenoble medical school in 2012 on human cadavers. They independently measured the distance between the caudal extremity of the AC and the lower edge of the superior belly of the omohyoid muscle. Then, they controlled this measure on pictures.

RESULTS

The study shows a majority of long AC (under the omohyoid muscle) in 66.7 % of cases. In addition, the AC was located on an average value of 0.1 cm below the lower edge of the omohyoid muscle (median -0.5 cm). Thus, two-thirds of AC are between 0 and -2 cm under the omohyoid muscle. Furthermore, the AC is generally non-symmetrical: there is a mean difference of 1.3 cm between the left and right AC. In this series, there are as many long AC on the right side as on the left side.

CONCLUSIONS

These results are in contradiction with literature data. To preserve the ansa cervicalis and its phonatory functions, it is necessary for the surgeon to perform a systematic per operative identification of the AC because the position of the AC is mainly under the omohyoid muscle and because of an asymmetry. Per operative neurostimulation and/or magnified lenses might be helpful during the surgical approach.

Superior laryngeal nerve anatomy in corpses not preserved in formaldehyde: contribution to the operative technique

PURPOSE: To carry out an anatomic study of superior laryngeal nerve in not preserved in formaldehyde and not frozen corpses. METHODS: Thirty-eight male corpses from the Minas Gerais Medico-legal Institute (IML) were studied. In 18 corpses dissection was performed bilaterally and in 20 only on the left side, total number 56 nerves dissected. Their descriptive segments measurements and the anatomic relations with the cervical structures of the region were described. This nerve was statistically analyzed; the variables were corpse side (Friedman´s test (p<0.05), height (Pearson), racial group (Kruskal-Wallis). RESULTS: The superior laryngeal nerve presented a definite anatomical disposition in all the 56 nerves studied, emerging from the nervus vagus inferior ganglion. The superior laryngeal nerve trunk was in average longer in corpses over 25 years old (p<0.05). Significant differences (p<0.05) between the internal and external branches were observed in all racial groups, and the internal branch average was inferior to the external branch average. There were not significant differences between the 18 studied corpses' left and right sides paired measurements. CONCLUSIONS: Concerning emergence, trunk, bifurcation and major branches, the 56 studied nerves disposition had a definite anatomic pattern. The superior laryngeal nerve trunk was in average longer in corpses over 25 years old. In this study, the external branch of the laryngeal nerve was in average longer than the internal branch.

Ansa cervicalis as a variant of spinal accessory nerve plexus: a case report

The ansa cervicalis is a neural loop in the neck formed by the union of two main nerve roots, namely superior and inferior roots, derived from ventral rami of the cervical nerves. With the expanding use of the ansa cervicalis for reinnervation procedures and the fact that it is located in the vicinity of major nerves and vessels of the neck, knowledge of the topography and morphology of this loop is quite necessary in the modern era. Any variation in the course, contributing roots or branching pattern of the ansa cervicalis, potentially alters and perhaps complicates the course of the procedures involving this nerve such as neurorrhaphy, skull base surgery, neck dissection, and anterior cervical spinal approach. Here, we present an unusual case of an ansa cervicalis encountered upon routine dissection of an adult male cadaver. In this case, the inferior root of the ansa cervicalis was formed by the joining of two rootlets, one originating from spinal accessory nerve and the other from a branch of the cervical plexus to the sternocleidomastoid muscle. The fibers traversing the branch of spinal accessory nerve were derived from the first segments of the cervical spinal cord. This case demonstrates a variant of the spinal accessory nerve plexus that contributed to the formation of the ansa cervicalis. Review of the literature was performed to reveal the possible clinical aspects of this anatomical variation.

Effect of approach side during anterior cervical discectomy and fusion on the incidence of recurrent laryngeal nerve injury

OBJECT

This retrospective study was designed to determine whether side of approach during instrumented, one- or two-level primary anterior cervical discectomy and fusion (ACDF) affects the incidence of recurrent laryngeal nerve (RLN) injury diagnosed by observation of the vocal cords (OVC).

METHODS

Records of all patients who underwent one- or two-level instrumented primary ACDF (418 patients) between January 1995 and February 2004 were reviewed. Data collected from these charts included surgeon, patient demographics, preoperative diagnosis, side of exposure, number of vertebral levels fused, and presence of RLN injury diagnosed by OVC after referral for persistent dysphonia. Time from surgery to OVC for patients with right-sided exposures was not statistically different from that for patients with left-sided exposures. Of 418 patients, 278 (66.5%) had right-sided exposures and 140 (33.5%) had left-sided exposures. Eight RLN injuries (1.9%) were noted-five in patients with right-sided exposures (1.8%) and three in patients with left-sided exposures (2.1%). The difference between right- and left-sided injury rates was shown to be nonsignificant using Fisher exact tests.

CONCLUSIONS

Results indicate that, given the study's sample size, side of approach during instrumented, one- or two-level primary ACDF has no significant effect on RLN injury incidence in patients with persistent dysphonia referred for OVC. The definitive answer regarding the true incidence of RLN injury relative to approach side awaits a prospective study with preoperative, immediate postoperative, and periodic OVC in a large, homogeneous population with sufficient numbers of patients with right- and left-sided approaches.

Tip of the greater horn of the hyoid bone: a landmark for cervical surgery

The purpose of this study was to assess the relevance of the tip of the greater horn of the hyoid bone (THB) in the localization of the carotid bifurcation, the superior thyroid and lingual arteries, and the hypoglossal and superior laryngeal nerves. Measurements of these structures with respect to the THB were also made. Thirty perfusion-fixed human cadavers (60 specimens) were studied. Sharp measurements were made along two orthogonal axes crossing exactly on the THB. The vertical axis was parallel to the craniocaudal axis of the body. Taking the THB as a landmark, the five structures were identified in all the specimens. The mean value, standard deviation, and range of measurements for each structure studied are given in the text. This study shows the THB to be a useful landmark which is an aid to locating the aforementioned structures with confidence, and concludes that knowledge of this landmark would be beneficial for the surgeon dealing with the mid neck area.

Dysphagia, hoarseness, and unilateral true vocal fold motion impairment following anterior cervical diskectomy and fusion

The charts of 100 patients who underwent anterior cervical diskectomy with fusion performed at our institution between January 1996 and February 1999 were reviewed. The incidences of hoarseness, dysphagia, and unilateral true vocal fold motion impairment were calculated. Univariate logistic regression was used to estimate the relationship of several patient and technical factors to the rates of occurrence of hoarseness and dysphagia. Patient age was found to be a significant predictor of postoperative dysphagia (p < .006), with an odds ratio of 1.113 (95% confidence limits, 1.04, 1.21) per year of age. Other factors studied were not found to be significant predictors. The overall incidence of these complications from the world literature was also calculated. The overall incidences of dysphagia, hoarseness, and unilateral true vocal fold motion impairment in the literature were calculated as 12.3%, 4.9%, and 1.4%, respectively. We conclude that dysphagia, hoarseness, and unilateral vocal fold motion impairment continue to remain significant complications of anterior cervical diskectomy with fusion. Older patients may be at higher risk for dysphagia.

Bilateral oblique approach to parathyroid glands

OBJECTIVE

To propose a simple and minimally invasive approach for parathyroid surgery.

SUMMARY BACKGROUND DATA

Minimally invasive approaches to the parathyroid glands may involve preoperative morphologic explorations, perioperative biologic controls, or videocervicoscopy, a new method.

METHODS

The authors describe 597 patients who underwent parathyroidectomy through an original bilateral oblique approach between 1976 and 1997. None underwent morphologic exploration or biologic perioperative monitoring. In primary hyperparathyroidism, the four glands are controlled and it is possible to check their abnormalities of location or number. In secondary hyperparathyroidism and multiple endocrine neoplasia (MEN), a total or subtotal parathyroidectomy is performed.

RESULTS

The results and vocal morbidity are the same as that from authors using transverse cervicotomy, but this approach is more comfortable for the patient and allows total exploration of the location through short incisions without bleeding, visceral contusions, or muscle lesion.

CONCLUSIONS

This cervicotomy is easy and secure even if the surgeon is not trained in this approach because it uses and respects the anatomy of the cervical fasciae. It can be used without preoperative localization, intraoperative monitoring, or specialized material. But this approach could be also proposed for unilateral exploration guided by these methods and for surgical treatment of recurrent hyperparathyroidism after a transverse cervicotomy.

Ansa cervicalis nerve: review of the topographic anatomy and morphology

In recent years, there has been a proliferation of techniques utilizing the ansa cervicalis nerve to reinnervate the paralyzed larynx. The anatomic course and morphology of the ansa cervicalis are complicated by the variable course and location along the great vessels of the neck, as well as the significant differences observed in the arrangement of its contributing roots and regional branching patterns. Herein, we review the surgical anatomic course of ansa cervicalis and its innervation of the muscles of the neck, and develop specific recommendations with respect to the use of this nerve in laryngeal reinnervation.