Morphological study of the ansa cervicalis and the phrenic nerve

The course of the phrenic nerve in the neck region and its relationship with adjacent anatomical structures in the thoracic inlet

PUPOSE

This study aims to reveal the relationship of the phrenic nerve (PhN) with its neighboring structures in the lower neck region more comprehensively than previous studies and to minimize nerve damage by enabling invasive procedures in this region to be performed with high accuracy.

METHODS

Forty-one heminecks were evaluated. The relationship between the PhN and the anterior scalene muscle (ASM), internal thoracic artery (ITA), branches of subclavian artery (SA) and subclavian vein (SV) was examined.

RESULTS

It was observed that the PhN was located medial to the ASM in all cases. The distances were higher in male cadavers. The PhN was found to enter the thorax lateral to the ITA in 15/41 and medial to it in 25/41 sides. In 17/41 cases, the closest SA branch to the PhN was the thyrocervical trunk (TT) and in 24 cases the ITA. The PhN was located behind the SV in 38 cases and in front of it in 2 cases.The accessory PhN was found in 4/41 sides. There was no significant difference in morphometric findings between genders (p > 0.05). However, significant differences were observed between the parameters (p < 0.05).

CONCLUSION

The anatomy and variations of the PhN are of great importance in surgical interventions and invasive procedures in the neck region. The study provides important information to reduce the risk of damage to the PhN in surgical procedures. In addition, knowledge of the anatomical variations of the nerve may contribute to more successful results in nerve grafting and other surgical applications.

Functional Outcome following Phrenic Nerve Transfer in Brachial Plexus Injury

Background

Brachial plexus injuries are debilitating injuries resulting in paralyzed shoulder to global paralysis of the upper extremity. Treatment strategies have evolved over the years with nerve transfer forming the mainstay of surgical management. Phrenic nerve provides certain advantages as donor over other options but has been less preferred due to fear of pulmonary complications. In this study, we assess the functional outcomes of phrenic nerve transfer in brachial plexus injuries.

Materials and Methods

A retrospective study was performed on 18 patients operated between 2012 and 2017. The mean duration of injury to surgery was 4.56 months and mean follow-up was for 3.66 years. Phrenic nerve was used as donor to neurotize either biceps and brachialis branch of musculocutaneous nerve or suprascapular nerve. Assessment was done through Waikakul score for elbow flexion and Medical Research Council grading for shoulder abduction. Respiratory function assessment was done through questionnaire.

Results

Twelve (80%) patients recovered grade 3 and above elbow flexion with 6 patients having a positive endurance test according to Waikakul and a "very good" result. In phrenic to suprascapular transfer group (3 patients), all patients had more than grade 3 recovery of shoulder abduction. No patient complained of respiratory problems.

Conclusion

Phrenic nerve can be used as a reliable donor with suitable patient selection with good results in regaining muscle power without any anticipated effects on respiratory function.

Proposal for Manual Osteopathic Treatment of the Phrenic Nerve

The article reviews the anatomical path of the phrenic nerve and its anastomoses, with the most up-to-date knowledge reported in the literature. We have briefly reviewed the possible phrenic dysfunctions, with the final aim of presenting an osteopathic manual approach for the treatment of the most superficial portion of the nerve, using a gentle technique. The approach we propose is, therefore, a theory based on clinical experience and the rationale that we can extrapolate from the literature. We hope that the article will be a stimulus for further experimental investigations using the technique illustrated in the article. To the authors' knowledge, this is the first article that takes into consideration the hypothesis of an osteopathic treatment with gentle techniques for the phrenic nerve.

The Aberrant Origin of the Suprascapular Artery May Hide Neural Covariants: A Cadaveric Finding

The axillary artery is the continuation of the subclavian artery. Occasionally, some of the subclavian artery's distal branches may atypically originate from the axillary artery, such as the suprascapular artery. The suprascapular artery's distal (low) origin from the axillary artery, instead of the subclavian artery, may also be characterized as an aberrant suprascapular artery. The current cadaveric report describes the coexistence of an aberrant suprascapular artery (of axillary origin), variant course, and termination with atypically formatted nerves originating from the cervical (the phrenic nerve) and the brachial (the long thoracic and the median nerves) plexus. An unusual interconnection between the phrenic and the long thoracic nerves was also described. The aberrant suprascapular artery had an atypical termination below the superior transverse scapular ligament, along with the suprascapular vein and nerve. Except for the atypically formatted phrenic and long thoracic nerves, the aberrant suprascapular artery coexisted with an atypical passage of the anterior ramus of the C6 spinal nerve, through the middle scalene muscle, before the long thoracic nerve formation, and a variant formation of the median nerve. Understanding neurovascular variants is crucial for interventionists and surgeons who work in the supra- and infraclavicular areas. Being aware of the different origins of the brachial plexus branches, in the supraclavicular part, may help reduce the occurrence of iatrogenic axillary injury. Efforts should be made to expand the number of cadaveric studies that investigate the origin, course, interconnection, and branching patterns of these nerves and related covariants, in a systematic way, thus unifying their study and comprehension.

Effect of respiratory training on respiratory failure secondary to unilateral phrenic nerve injury: A case report

INTRODUCTION

Diaphragm is one of the most important respiratory muscles dominated by the phrenic nerve. Phrenic nerve injury would induce a series of clinical symptoms, including respiratory failure. Respiratory training could assist in regular treatment in improving the respiratory function and daily ability of respiratory failure patients.

CASE PRESENTATION

A 71-years-old female was enrolled for the disorders of consciousness of 4.5 hours observed by her family and was diagnosed with respiratory failure secondary to unilateral phrenic nerve injury. The patient received basic therapy combined with rehabilitation training, including the training of aspirate muscle, limb resistance, thoracic loosening, aerobic training, electrical stimulation on respiratory nerves, and airway clearance. The combining therapeutic strategy significantly improved the daily ability and respiratory of the patient. The ultrasound showed that after therapy, the diaphragmatic muscles were thickened and the range of diaphragmatic movement was also enhanced. The pulmonary function was also improved after therapy.

CONCLUSION

The combination of rehabilitation is suitable for the treatment of respiratory failure patients with clear causes of phrenic nerve injury. For patients with unexplained causes, rehabilitation could also be performed before the diagnosis. Patients with irreversible injury need long-term and family rehabilitation prescriptions.

The shoulder abductor strength is a novel predictor of tracheostomy in patients with traumatic cervical spinal cord injury

BACKGROUND

Early prediction of tracheostomy in traumatic cervical spinal cord injury (TCSCI) patients is often difficult. This study aims to clarify the association between shoulder abductor strength (SAS) and tracheostomy in patients with TCSCI.

METHODS

We retrospectively analyzed 513 TCSCI patients who were treated in our hospital. All patients were divided into a tracheostomy group and a non-tracheostomy group. The SAS was assessed using the Medical Research Council (MRC) Scale for Muscle Strength grading. Potential predictors were assessed for their association with tracheostomy in patients. A nomogram was developed based on multivariable logistic regression analysis (MLRA) to visualize the predictive ability of the SAS. Validation of the nomogram was performed to judge whether the nomogram was reliable for visual analysis of the SAS. Receiver operating characteristics curve, specificity, and sensitivity were also performed to assess the predictive ability of the SAS.

RESULTS

The proportion of patients with the SAS grade 0-2 was significantly higher in the tracheostomy group than in the non-tracheostomy group (88.1% vs. 54.8%, p = 0.001). The SAS grade 0-2 was identified as a significant predictor of the tracheostomy (OR: 4.505; 95% CI: 2.080-9.758; p = 0.001). Points corresponding to both the SAS grade 0-2 and the neurological level of injury at C2-C4 were between 60 and 70 in the nomogram. The area under the curve for the SAS grade 0-2 was 0.692. The sensitivity of SAS grade 0-2 was 0.239. The specificity of SAS grade 0-2 was 0.951.

CONCLUSIONS

SAS is a novel predictor of tracheostomy in patients after TCSCI. The SAS grade 0-2 had a good predictive ability of tracheostomy.

Endotracheal Tube Electrode Neuromonitoring for Placement of Vagal Nerve Stimulation for Epilepsy: Intraoperative Stimulation Thresholds

Vagal nerve stimulators (VNS) are indicated as a palliative treatment for medically refractory epilepsy. The vagus nerve may have a variable position within the carotid sheath and may be confused with a prominent ansa cervicalis. The objective of this study was to describe an intraoperative neuromonitoring technique for VNS placement and provide stimulation thresholds that may aid in the creation of stimulation protocols. A retrospective study was performed assessing 40 patients undergoing intraoperative vocal cord monitoring during vagal nerve stimulator placement surgery. Endotracheal electrodes were utilized to record vocal cord activity at various surgical time points. The stimulation thresholds were tested at the time of opening of the carotid sheath (mean 0.35 mA [range 0.08-1.00]), after full and circumferential dissection of the vagus nerve (0.34 mA [0.10-0.90]), after tenting of the vagus nerve in preparation for placement of the electrode (0.22 mA [0.06-1.20]), and after electrode placement (0.26 mA [0.05-1.20]). The vagus nerve was identified in all patients; it was located behind the common carotid artery (CCA) in two patients, on top of the internal jugular vein (IJV) in one patient, and in the typical location between the CCA and IJV in the remainder of patients. The average size of the vagus nerve was 2.9 mm [1.5-5.0]. Intraoperative vagus nerve stimulation represents a safe adjunctive tool that can help localize the nerve, particularly in the setting of varying anatomy or hazardous dissections. It may help reduce the potential for vagal trunk damage or electrode misplacement and potentially improve clinical outcomes.

Cervical spondylosis as a possible hidden reason beyond delayed phrenic nerve distal motor latency

Background

Cervical spondylosis is a chronic degenerative condition of the cervical spine that can affect the cervical nerve roots. The origin of the phrenic nerve makes it vulnerable to injury. The purpose of this study is to investigate possible subtle phrenic nerve affection in patients with cervical spondylosis using nerve conduction studies (NCS). This study was conducted on 30 patients with cervical spondylosis above C5 and on 30 healthy volunteers. Nerve conduction studies of both phrenic nerves were performed in all cases.

Results

The patients with cervical spondylosis showed a statistically highly significant prolongation of phrenic nerve distal motor latency (DML) than the control group (P < 0.01). There was no significant difference regarding amplitude (P > 0.05). There was a significant correlation between DML and X-ray score (r < 0.05).

Conclusions

Cervical spondylosis is an underestimated cause of phrenic nerve delayed DML. There is a correlation between the delay of phrenic nerve DML and the severity of cervical spondylosis.

The terminal segment of the human phrenic nerve as a novel implantation site for diaphragm pacing electrodes: Anatomical and clinical description

BACKGROUND

Diaphragm pacing allows certain ventilator-dependent patients to achieve weaning from mechanical ventilation. The reference method consists in implanting intrathoracic contact electrodes around the phrenic nerve during video-assisted thoracic surgery, which involves time-consuming phrenic nerve dissection with a risk of nerve damage. Identifying a phrenic segment suitable for dissection-free implantation of electrodes would constitute progress.

STUDY DESIGN

This study characterizes a free terminal phrenic segment never fully described before. We conducted a cadaver study (n = 14) and a clinical observational study during thoracic procedures (n = 54).

RESULTS

A free terminal phrenic segment was observed on both sides in 100% of cases, "jumping" from the pericardium to the diaphragm and measuring 60 mm [95% confidence interval; 48-63] and 72.5 mm [65-82] (right left, respectively; p = 0.0038; cadaver study). This segment rolled up on itself at end-expiration and became unravelled and elongated with diaphragm descent (clinical study). Three categories of fat pads were defined (type 1: pericardiophrenic bundle free of surrounding fat; type 2: single fatty fringe leaving the phrenic nerve visible until diaphragmatic entry; type 3: multiple fatty fringes masking the site of penetration of the phrenic nerve) that depended on body mass index (p = 0.001, clinical study). Hematoxylin-eosin and toluidine blue staining (cadaver study) showed that all of the phrenic fibers in the distal, pre-branching part of the terminal segment were contained within a single epineurium containing a variable number of fascicles (right: 1 [95%CI 0.65-4.01]; left 5 [3.37-7.63]; p = 0.03).

CONCLUSION

Diaphragm pacing through periphrenic electrodes positioned on the terminal phrenic segment should be tested.

Phrenic Nerve Stimulator Placement via the Cervical Approach: Technique and Anatomic Considerations

BACKGROUND

Diaphragmatic pacing via phrenic nerve stimulation can help improve breathing and facilitate mechanical ventilation weaning in patients with respiratory failure secondary to brainstem injury, high cervical spinal cord injury, or congenital central hypoventilation. Devices can be placed utilizing several techniques; however, nuances regarding placement are not well published.

OBJECTIVE

To describe our experience with phrenic nerve stimulator placement via the cervical approach with a focus on surgical anatomy, variations, and technique.

METHODS

Placement of phrenic nerve stimulator via a cervical approach is described in detail.

RESULTS

Successful placement of phrenic nerve stimulator without complication.

CONCLUSION

The cervical approach for the placement of a phrenic nerve stimulator is a safe and effective option for patients. Detailed knowledge of anatomy and anatomic variations is required. Potential advantages and disadvantages are discussed.

Effectiveness of standard cervical physiotherapy plus diaphragm manual therapy on pain in patients with chronic neck pain: A randomized controlled trial

BACKGROUND

Literature concerning the effect of diaphragm treatment to reduce neck pain symptoms is scarce. Aim of this trial was to investigate the effects of diaphragm manual therapy associated with standard physiotherapy treatment on pain in patients with Chronic Neck Pain (CNP).

METHODS

In a private practice clinic, subjects with CNP were randomly assigned to receive three 30-min treatment sessions of standard cervical physiotherapy and Diaphragm Manual Therapy (DMT) or Sham Diaphragm Technique (SDT). Participants and assessors were blinded to the assignment. Primary outcome was pain, secondary outcomes were cervical active range of motion, pain pressure threshold, disability and quality of life measured at baseline, before and after each session, at 3 and 6-months. Adverse events were monitored. A non-parametric multivariate approach (combined permutation test) was applied to assess the effect of the treatment on all the outcomes. An intention to treat analysis was performed.

RESULTS

Forty patients were randomly allocated to DMT and SDT groups. Combined permutation test showed a significant higher improvement in DMT group compared to SDT group (p-value = 0.0002). The between-group comparisons on single outcomes showed a statistically significant improvement only for pain pressure threshold on upper trapezius (adjusted p-value = 0.029). No adverse events related to the intervention were registered.

CONCLUSIONS

In patients with CNP, addition of diaphragm manual techniques to standard cervical treatment seems to give a better global outcome, but this improvement is of unclear clinical relevance; the primary outcome seems not to have a role. Further studies are needed to confirm and clarify these results.

TRIAL REGISTRATION

Release Date: July 18, 2017 Registered in ClinicalTrial.gov database ID: NCT03223285A.

Ultrasound Localization and Percutaneous Electrical Stimulation of the Hypoglossal Nerve and Ansa Cervicalis

OBJECTIVE

Hypoglossal nerve stimulation for obstructive sleep apnea (OSA) can be effective for appropriately selected patients, but current patient selection criteria are complex and still result in a proportion of nonresponders. Ansa cervicalis stimulation of the infrahyoid cervical strap muscles has recently been proposed as a new form of respiratory neurostimulation (RNS) therapy for OSA treatment. We hypothesized that percutaneous stimulation of both nerves in humans with temporary electrodes would make testing of the physiologic response to different RNS strategies possible.

STUDY DESIGN

Nonrandomized acute physiology study.

SETTING

Tertiary care hospital.

METHODS

Fifteen participants with OSA underwent ultrasonography and placement of percutaneous electrodes proximal to the medial division of the hypoglossal nerve and the branch of the ansa cervicalis innervating the sternothyroid muscle (ACST). Procedural success was documented in each participant, as were any failures or procedural complication.

RESULTS

The hypoglossal nerve was successfully localized in 15 of 15 (100%) participants and successfully stimulated in 13 of 15 (86.7%). The ACST was successfully localized in 15 of 15 (100%) participants and successfully stimulated in 14 of 15 (93.3%). Stimulation failure of the hypoglossal nerve was due to suboptimal electrode placement in 1 participant and electrode displacement in the other 2 cases. No complications occurred.

CONCLUSIONS

The hypoglossal nerve and ACST can be safely stimulated via percutaneous electrode placement. Larger trials of percutaneous stimulation may help to identify responders to different RNS therapies for OSA with temporary or permanent percutaneous electrodes. Techniques for electrode design, nerve localization, and electrode placement are described.

An unusual location of the ansa cervicalis

The ansa cervicalis (AC) is part of the cervical plexus and is formed by the ventral rami of spinal nerves C1-C3. It is usually formed by two roots that run parallel to each other and then form a loop anterior to the internal jugular vein. Herein, we report a rare case where the AC was found deep to the internal carotid artery and common carotid artery and had sympathetic contributions.

Ansa Cervicalis Stimulation: A New Direction in Neurostimulation for OSA

BACKGROUND

Hypoglossal nerve stimulation (HNS) is an alternative treatment option for patients with OSA unable to tolerate positive airway pressure but implant criteria limit treatment candidacy. Previous research indicates that caudal tracheal traction plays an important role in stabilizing upper airway patency.

RESEARCH QUESTION

Does contraction of the sternothyroid muscle with ansa cervicalis stimulation (ACS), which pulls the pharynx caudally via thyroid cartilage insertions, increase maximum inspiratory airflow (V_Imax)?

STUDY DESIGN AND METHODS

Hook-wire percutaneous electrodes were used to stimulate the medial branch of the right hypoglossal nerve and right branch of the ansa cervicalis innervating the sternothyroid muscle during propofol sedation. V_Imax was assessed during flow-limited inspiration with a pneumotachometer.

RESULTS

Eight participants with OSA were studied using ACS with and without HNS. Compared with baseline, the mean V_Imax increase with isolated ACS was 298%, or 473 mL/s (95% CI, 407-539). Isolated HNS increased mean V_Imax from baseline by 285%, or 260 mL/s (95% CI, 216-303). Adding ACS to HNS during flow-limited inspiration increased mean V_Imax by 151%, or 205 mL/s (95% CI, 174-236) over isolated HNS. Stimulation was significantly associated with increase in V_Imax in both experiments (P < .001).

INTERPRETATION

ACS independently increased V_Imax during propofol sedation and drove further increases in V_Imax when combined with HNS. The branch of the ansa cervicalis innervating the sternothyroid muscle is easily accessed. Confirmation of the ansa cervicalis as a viable neurostimulation target may enable caudal pharyngeal traction as a novel respiratory neurostimulation strategy for treating OSA.

Lessons learned to aid the successful outcome of pediatric recurrent laryngeal nerve reinnervation

While Ansa to recurrent laryngeal nerve reinnervation is gaining popularity in the treatment of unilateral vocal fold immobility, little has been reported on commonly encountered surgical challenges with this procedure. Here, we present a cohort of 21 pediatric patients who underwent this procedure with a full description of techniques used to overcome common challenges with this procedure. We report vocal and swallowing outcomes for these patients, with an overall success rate of 19/21 (90.5%) patients, with success defined as improvement of a half-consistency or resolution of vocal issues.

Effects of Osteopathic Visceral Treatment in Patients with Gastroesophageal Reflux: A Randomized Controlled Trial

Osteopathic manual treatment has been recommended as a non-pharmacological therapy for Gastroesophageal Reflux Disease (GERD). However, to date, no study has supported the effectiveness of this intervention with respect to the symptoms of the disease. Our goal was to assess the effect of an osteopathic manual technique for the lower esophageal sphincter on GERD symptoms, cervical mobility and on the C4 spinous process pressure pain threshold (PPTs).

METHODS

A randomized, double-blind placebo-controlled trial was performed. Sixty subjects suffering from GERD participated in this study and were randomly assigned to either an experimental group (EG) (n = 29), who received the osteopathic technique for the lower esophageal sphincter, or to a control group (CG) (n = 31), who received a manual contact, which mimicked the osteopathic technique without exerting any therapeutic force. Randomization was computer-generated, with allocation concealed by sequentially numbered, opaque, sealed envelopes. The GerdQ questionnaire was used to assess symptom changes the week after intervention. Cervical Range of Motion (CROM) and algometer were used to evaluate cervical mobility and PPTs before and after both treatments. Before-after between groups comparison (t-test) was used for statistical analysis of the outcome, with two measurement points (GerdQ), while repeated-measures ANOVA was used for those outcomes with four measurement points (CROM and PPT).

RESULTS

The application of the osteopathic manual treatment in subjects with GERD produced a significant improvement in symptoms one week after the intervention (p = 0.005) with a between-groups difference of 1.49 points in GerdQ score (95% CI: 0.47-2.49). PPT C4 improved in the EG after the treatment (p = 0.034; η² = 0.048) (between-groups difference 8.78 Newton/cm²; 95% CI: 0.48-17.09). CROM also increased in the EG compared to the CG (p < 0.001; η² = 0.108) (between-groups difference 33.89 degrees; 95% CI: 15.17-52.61).

CONCLUSIONS

The manual osteopathic technique produces an improvement in GERD symptoms one week after treatment, cervical mobility, and PPTs. This may mean that osteopathic treatment is useful for improving symptoms of GERD.

Association Between Diaphragmatic Paralysis and Ipsilateral Cervical Spondylosis on MRI

PURPOSE

Diaphragmatic paralysis (DP) is an important cause of dyspnea with many underlying etiologies; however, frequently no cause is identified despite extensive investigation. We hypothesized that cervical spondylosis (CS), as manifest by cervical neuroforaminal stenosis on magnetic resonance imaging (MRI), is an underrecognized cause of unilateral DP.

METHODS

A retrospective study was performed assessing cervical spine imaging utilization in the investigation of unilateral DP, and the contribution of CS to its pathogenesis. To assess the relationship between CS and DP, comparison was made between severity of ipsilateral and contralateral foraminal stenosis on cervical spine MRI in individuals with idiopathic DP, and to controls with DP of known etiology.

RESULTS

Record searches identified 334 individuals with DP who were classified as idiopathic (n = 101) or DP of known etiology (n = 233). Of those with idiopathic DP, only 37% had undergone cervical spine imaging. Cervical spine MRIs, available for 32 individuals from the total cohort identified (n = 15 idiopathic DP, n = 17 DP of known etiology), were reviewed and severity of CS graded (0-2). In idiopathic DP, CS was significantly more severe (grade 2 stenosis) on the side of DP at C3-C4 (73% affected vs 13% unaffected side; p = 0.031) and C4-C5 (60% affected vs 20% unaffected side; p = 0.0039), while no difference was observed in DP of known etiology. Overall severity of CS across all cervical spine levels was significantly worse in idiopathic DP versus those with DP of known etiology.

CONCLUSIONS

In unilateral idiopathic DP, severity of CS is associated with DP laterality and is an underrecognized cause of diaphragmatic dysfunction. We propose that evaluation of 'idiopathic' DP should routinely include cervical spine imaging, preferably by MRI.

Congenital diaphragmatic eventration with absent left phrenic nerve in the fetal pig

We encountered a fetal pig with eventration of the diaphragm and pulmonary hypoplasia accompanied by phrenic nerve agenesis. The fetal pig was female measuring 34 cm in crown-rump length and about 1500 g in body weight. The diaphragm was a complete continuous sheet, but comprised a translucent membrane with residual muscular tissue only at the dorsolateral area of the right leaf of the diaphragm. The left leaf protruded extraordinarily toward the thoracic cavity. The left phrenic nerve was completely absent, while there was a slight remnant of the right phrenic nerve that supplied the dorsolateral muscular area of the right leaf. Both lungs were small, and the number of smaller bronchioles arising from the bronchioles was decreased to about half of that of the normal lung. Additionally, the right and left subclavius muscles and nerves could not be identified. These findings imply that the diaphragm, the subclavius muscle and nerves innervating them comprise a developmental module, which would secondarily affect lung development. It is considered that the present case is analogous to the animal model of congenital eventration of the diaphragm in humans.

Infraclavicular brachial plexus block in adults: a comprehensive review based on a unified nomenclature system

Over the last decade, considerable progress has been made regarding infraclavicular brachial plexus block (ICB) in adults, especially since the introduction of ultrasound guidance. The advancements in ICB have been attributed to the development of various approaches to improve the success rate and reduce complications. This has also necessitated a unified nomenclature system to facilitate comparison among different approaches. This review aimed to propose an anatomical nomenclature system by classifying ICB approaches into proximal and distal ones to aid future research and provide practice advisories according to recent updates. We also comprehensively discuss various aspects of this nomenclature system. Our review suggests that ultrasound-guided ICB should be categorized as an advanced technique that should be performed under supervision and dual guidance. For one-shot block, the conventional distal approach is still preferred but should be modified to follow ergonomic practice, with the arm in the proper position. For continuous ICB, the proximal approach is promising for reducing local anesthetic volume and increasing efficacy. Nevertheless, further studies are warranted in this direction. We provide practice advisories to maximize safety and minimize adverse events, and recommend designing future studies on ICB according to these findings based on the unified nomenclature system.

Report of a non-looped variant of ansa cervicalis with omohyoid innervation from accessory nerve branch and omohyoid attachment to mastoid process

INTRODUCTION

A variant of the innervation of the infrahyoid neck musculature is reported in which the typical looped ansa cervicalis structure is absent. In this variant, the infrahyoid muscles (sternohyoid, sternothyroid omohyoid and thyrohyoid) were innervated by a presumptive superior root of "ansa cervicalis" traveling with vagus nerve (CN X) and not branching from hypoglossal nerve (CN XII). The omohyoid muscle, typically innervated by the inferior root of ansa cervicalis, is instead innervated by nerve fibers branching from the accessory nerve (CN XI). This formation created a non-looping variant of ansa cervicalis. Furthermore, the omohyoid muscle did not attach to the hyoid bone but instead attached to the mastoid process of the temporal bone by merging its fibers superiorly and posteriorly with the clavicular portion of the sternocleidomastoid muscle, creating a "sternocleidoomomastoid" muscle innervated by a branch of accessory nerve.

MATERIALS AND METHODS

This variation was found in one black male cadaver from a cohort of 25 male and female cadavers.

RESULTS

Only one variation of ansa cervicalis was observed.

CONCLUSIONS

As neck dissections and surgical procedures of this region are performed for a variety of conditions-including coronary artery bypass grafting and metastatic neck disease-variations of this type are of broad clinical surgical importance.

Dual innervation may occur in a partially denervated muscle

INTRODUCTION

With a view to simplifying surgical techniques for selective laryngeal reinnervation, we addressed the question of whether it is feasible to receive additional innervation by a partially denervated muscle using an infrahyoid muscle model.

METHODS

In 90 rats (6 groups of 15), phrenic nerve transfer was used to reinnervate the sternothyroid muscle. In some cases, residual innervation by the original nerve was present. Three months later we performed electromyographic studies, contraction strength measurements, histologic assessment, and retrograde labeling.

RESULTS

Muscles reinnervated by the phrenic nerve had a greater "dual-response" rate (in terms of nerve latency, contraction strength, and retrograde labeling) than muscles in the control groups.

DISCUSSION

The phrenic nerve can impart its inspiratory properties to an initially denervated strap muscle-even when residual innervation is present. The preservation of contractile potential confirmed the feasibility of dual innervation in a previously injured muscle. Muscle Nerve 59:108-115, 2019.

Incidence of Accessory Phrenic Nerve and its Clinical Significance: A Cadaveric Study

The description of accessory phrenic nerve (APN) in the standard textbooks and available literature is vague and sometimes limited to few lines. The incidence of APN varies a great deal from 17.6 % to 80.9 % in the available literature. The aim of the present study was to calculate the incidence and variation of APN in Indian population. Material and methods: Forty five adult formalin-fixed cadavers (35 male, 10 female; 90 sides) used for gross anatomy dissection for undergraduates; during the 2 year period 2006–2007 were considered. Findings were recorded at different stages of the dissection. Results: Out of 90 body sides studied, the APN was present in 48 sides (53.3 %). In 17 of the above sides the APN was confined to the cervical region (Cervical type) and in 31 sides the APN entered the thorax (Thoracic type), all anterior to the subclavian vein (SV). In eleven specimens the APN was found bilaterally. Conclusion: The incidence of APN, with its course and relation to the various structures in cervical and thoracic region will help the surgeons while performing internal thoracic artery (ITA) grafting and other radical neck surgery.

Abnormal Origin and Course of the Accessory Phrenic Nerve: Case Report

In the current cadaveric study an unusual sizeable accessory phrenic nerve (APN) was encountered emerging from the trunk of the supraclavicular nerves and forming a triangular loop that was anastomosing with the phrenic nerve. That neural loop surrounded the superficial cervical artery which displayed a spiral course. The form of a triangular loop of APN involving the aforementioned artery and originating from the supraclavicular nerve to the best of our knowledge has not been documented previously in the literature. The variable morphological features of the APN along with its clinical applications are briefly discussed.

Sternocleidomastoid innervation from an aberrant nerve arising from the hypoglossal nerve: a prospective study of 160 neck dissections

BACKGROUND

Anatomical variants of the spinal root of the accessory nerve and cervical plexus are well known but other variants are exceptionally rare.

METHODS

A prospective study of 160 selective neck dissections was undertaken following an index case, where a presumed C1 nerve (travelling with the hypoglossal nerve) was found to innervate sternocleidomastoid (SCM). A search was subsequently made for this variant while not compromising the neck dissection surgery itself. Eight cases could not be included due to metastatic disease precluding safe dissection in this area. A nerve stimulator was used to confirm the motor supply to SCM.

RESULTS

This nerve variant was found in 4/160 necks (2.5 %). In all cases, it originated directly from the hypoglossal nerve and stimulation resulted in isolated SCM contraction. No accessory nerve anomalies were found.

CONCLUSION

This finding adds to the knowledge of variants in this area. Meticulous dissection and preservation of all nerves, where possible, is important for optimising functional outcomes following surgery.

Phrenic Nerve Injury After Radiofrequency Denervation of the Cervical Medial Branches

Radiofrequency denervation of the cervical medial branches is a possible treatment for chronic cervical facet pain syndrome when conservative management has failed. According to the literature, complications after radiofrequency denervation of the cervical medial branches are rare. We report a case of possible phrenic nerve injury after ipsilateral radiofrequency denervation of the cervical medial branches following a posterolateral approach.

Phrenic nerve transfer to the musculocutaneous nerve for the repair of brachial plexus injury: electrophysiological characteristics

Phrenic nerve transfer is a major dynamic treatment used to repair brachial plexus root avulsion. We analyzed 72 relevant articles on phrenic nerve transfer to repair injured brachial plexus that were indexed by Science Citation Index. The keywords searched were brachial plexus injury, phrenic nerve, repair, surgery, protection, nerve transfer, and nerve graft. In addition, we performed neurophysiological analysis of the preoperative condition and prognosis of 10 patients undergoing ipsilateral phrenic nerve transfer to the musculocutaneous nerve in our hospital from 2008 to 201 3 and observed the electromyograms of the biceps brachii and motor conduction function of the musculocutaneous nerve. Clinically, approximately 28% of patients had brachial plexus injury combined with phrenic nerve injury, and injured phrenic nerve cannot be used as a nerve graft. After phrenic nerve transfer to the musculocutaneous nerve, the regenerated potentials first appeared at 3 months. Recovery of motor unit action potential occurred 6 months later and became more apparent at 12 months. The percent of patients recovering 'excellent' and 'good' muscle strength in the biceps brachii was 80% after 18 months. At 12 months after surgery, motor nerve conduction potential appeared in the musculocutaneous nerve in seven cases. These data suggest that preoperative evaluation of phrenic nerve function may help identify the most appropriate nerve graft in patients with an injured brachial plexus. The functional recovery of a transplanted nerve can be dynamically observed after the surgery.

Perineural spread of malignant melanoma from the mandible to the brachial plexus: case report

Perineural spread is a well-known mechanism of dissemination of head and neck malignancies. There are few reports of melanoma involving the brachial plexus in the literature. To their knowledge, the authors report the first known case of perineural spread of malignant melanoma to the brachial plexus. Clinicoradiological and anatomopathological correlation is presented, highlighting the importance of peripheral nerve communications in perineural spread.

The continuity of the body: hypothesis of treatment of the five diaphragms

The diaphragm muscle should not be seen as a segment but as part of a body system. This muscle is an important crossroads of information for the entire body, from the trigeminal system to the pelvic floor, passing from thoracic diaphragm to the floor of the mouth: the network of breath. Viola Frymann first spoke of the treatment of three diaphragms, and more recently four diaphragms have been discussed. Current scientific knowledge has led to discussion of the manual treatment of five diaphragms. This article highlights the anatomic connections and fascial and neurologic aspects of the diaphragm muscle, with four other structures considered as diaphragms: that is, the five diaphragms. The logic of the manual treatment proposed here is based on a concept and diagnostic work that should be the basis for any area of the body: The patient never just has a localized symptom but rather a system that adapts to a question.

Innervation of the lower third of the sternocleidomastoid muscle by the ansa cervicalis through the C1 descendens hypoglossal branch: a previously unreported anatomical variant

We describe a previously unreported anatomical variant (found during a routine neck dissection) in which the lower third of the sternocleidomastoid was innervated by the C1 branch of the ansa cervicalis (descendens hypoglossi).

Comparison of 3 procedures for hypoglossal-facial anastomosis

OBJECTIVE

We aimed to evaluate rehabilitation of complete facial palsy with 3 procedures for hypoglossal-facial anastomosis: end-to-end ("original"), partial end-to-end with interpositional jump grafting ("jump") and the new partial end to end without grafting ("modified").

METHODS

A medical jury reviewed videos of 36 patients with complete facial palsy who underwent surgery from 1998 to 2008 by original (n = 13), jump (n = 13), and modified (n = 10) procedures. The jury of 5 ear, nose, and throat surgeons who were blinded to the procedure evaluated rehabilitation by 3 facial nerve grading systems-House and Brackman (HB), Sunnybrook, and Freyss scales-and 3 subjective scores for the face at rest and during voluntary and emotional motions.

RESULTS

Recovery time was shorter with the modified and original procedures than jump procedure (5, 6, and 8 mo, respectively). All patients achieved at least good results. Scores on the HB scale (I-VI) were mainly III. HB and Sunnybrook scores did not differ by procedure. Freyss score was better for the modified procedure than original and jump procedures. Scores for the face at rest did not differ by procedure, but those during voluntary and emotional movements were worse for the jump procedure than for other procedures. Synkinesis was more severe with the original procedure than other procedures.

CONCLUSION

The 3 procedures give satisfactory results for rehabilitation after surgery for facial palsy. The original procedure should be performed in patients with strong mimic or long-standing facial palsy. The jump procedure is delicate and entails risk of weak reinnervation. The modified procedure is a good compromise in terms of muscle tone and side effects.

An anatomical variation in the formation of the inferior root of ansa cervicalis

During regular dissections, we observed an unusual organization of the inferior root of Ansa Cervicalis (AC). The superior root of ansa arose normally from the hypoglossal nerve. The ventral ramus of the C2 spinal nerve divided into two branches. One of its branches joined the superior root independently to form a loop at a higher level. Another branch ran along the vagus nerve, joined with the ventral ramus of C3 spinal nerve, finally connected with the superior root and formed the second loop at a lower level. No variation was found in formation of superior root. Knowledge on the possible deviations in the formation of these roots is clinically important, to prevent iatrogenic injuries in surgical procedures such as thyroplasties, arytenoids adductions, and Teflon injections.

Anatomic connections of the diaphragm: influence of respiration on the body system

The article explains the scientific reasons for the diaphragm muscle being an important crossroads for information involving the entire body. The diaphragm muscle extends from the trigeminal system to the pelvic floor, passing from the thoracic diaphragm to the floor of the mouth. Like many structures in the human body, the diaphragm muscle has more than one function, and has links throughout the body, and provides the network necessary for breathing. To assess and treat this muscle effectively, it is necessary to be aware of its anatomic, fascial, and neurologic complexity in the control of breathing. The patient is never a symptom localized, but a system that adapts to a corporeal dysfunction.

Some unusual types of formation of the ansa cervicalis in humans and proposal of a new morphological classification

Ansa cervicalis (ansa hypoglossi) is a peripheral nerve structure-the primary choice for laryngeal reinnervation. Because the ansa formation is quite variable in humans, it is an object of a number of proposed classifications. Two interesting cases of formation of the ansa cervicalis were found during routine anatomical dissections. In the first case the unusual ansa had three basic roots-a superior one from the hypoglossal nerve, an aberrant middle root from the vagus nerve and an inferior root, coming from the cervical ventral branches. In the second case an ansa was described having roots from the vagus nerve and cervical ventral branches. Based on the reported variations and extensive review of the pertinent literature, a new morphological classification of the ansa cervicalis formation in human is proposed here.

A new scenario of the evolutionary derivation of the mammalian diaphragm from shoulder muscles

The evolutionary origin of the diaphragm remains unclear, due to the lack of a comparable structure in other extant taxa. However, recent researches into the developmental mechanism of this structure have yielded new insights into its origin. Here we summarize current understanding regarding the development of the diaphragm, and present a possible scenario for the evolutionary acquisition of this uniquely mammalian structure. Recent developmental analyses indicate that the diaphragm and forelimb muscles are derived from a shared cell population during embryonic development. Therefore, the embryonic positions of forelimb muscle progenitors, which correspond to the position of the brachial plexus, likely played an important role in the evolution of the diaphragm. We surveyed the literature to reexamine the position of the brachial plexus among living amniotes and confirmed that the cervico-thoracic transition in ribs reflects the brachial plexus position. Using this osteological correlate, we concluded that the anterior borders of the brachial plexuses in the stem synapsids were positioned at the level of the fourth spinal nerve, suggesting that the forelimb buds were laid in close proximity of the infrahyoid muscles. The topology of the phrenic and suprascapular nerves of mammals is similar to that of subscapular and supracoracoid nerves, respectively, of the other amniotes, suggesting that the diaphragm evolved from a muscle positioned medial to the pectoral girdle (cf. subscapular muscle). We hypothesize that the diaphragm was acquired in two steps: first, forelimb muscle cells were incorporated into tissues to form a primitive diaphragm in the stem synapsid grade, and second, the diaphragm in cynodonts became entrapped in the region controlled by pulmonary development.