Accessory Phrenic Nerve Research Articles

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

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. 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. 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). 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.

Phrenic Nerve Transfer to Musculocutaneous Nerve: An Anatomical and Histological Study.

To restore elbow flexor muscle function in case of traumatic brachial plexus avulsion, the phrenic nerve transfer to the musculocutaneous nerve has become part of clinical practice. The nerve transfer can be done by means of video-assisted thoracic surgery without nerve graft or via supraclavicular approach in combination with an autograft. This study focuses on a detailed microscopic and macroscopic examination of the phrenic nerve. It will allow a better interpretation of existing clinical results and, thus, serve as a basis for future clinical studies. An anatomical study was conducted on 28 body donors of Caucasian origin (female n = 14, male n = 14). A sliding caliper and measuring tape were used to measure the diameter and length of the nerves. Sudan black staining was performed on 15 µm thick cryostat sections mounted on glass slides and the number of axons was determined by the ImageJ counting tool. In 23 individuals, the phrenic nerve could be examined on both sides. In 5 individuals, however, only one side was examined. Thus, a total of 51 nerves were examined. The mean length of the left phrenic nerves (33 cm (29-38 cm)) was significantly longer compared to the mean length of the right phrenic nerves (30 cm (24-33 cm)) (p < 0.001). Accessory phrenic nerves were present in 9 of 51 (18%) phrenic nerves. The mean number of phrenic nerves axons at the level of the first intercostal space in body donors with a right accessory phrenic nerve was significantly greater compared to the mean number of phrenic nerves axons at the same level in body donors without a right accessory phrenic nerve (3145 (range, 2688-3877) vs. 2278 (range, 1558-3276)), p = 0.034. A negative correlation was registered between age and the nerve number of axons in left (0.742, p < 0.001) and right (-0.273, p = 0.197) phrenic nerves. The mean distance from the upper edge of the ventral ramus of the fourth cervical spinal nerve to the point of entrance of the musculocutaneous nerve between the two parts of the coracobrachialis muscle was 19 cm (range, 15-24 cm) for the right and 20 cm (range, 15-25 cm) for the left arm. If an accessory phrenic nerve is available, it presumably should be spared. Thus, in that case, a supraclavicular approach in combination with a nerve graft would probably be of advantage.

Prevalence and anatomy of the anomalous subclavius posticus muscle and its clinical implications with emphasis in neurogenic thoracic outlet syndrome: Scoping review and meta-analysis

BackgroundThe subclavius muscle runs underneath the clavicle. However, there have been a few reports of a duplicated subclavius muscle which is commonly referred to as subclavius posticus muscle due to its orientation being posterior to the proper subclavius muscle. Its occurrence seems to potentially create a narrowing interval at the superior thoracic aperture as it crosses over the brachial plexus. It might also have functional influence on the shoulder girdle. PurposeTo provide comprehensive gross anatomy description of the variant “subclavius posticus muscle” and to investigate its reported clinical implications with emphasis on its involvement in causing brachial plexus compression. Basic proceduresA scoping review with meta-analysis of the gross anatomy of the subclavius posticus muscle was conducted along with investigating its correlation to the thoracic outlet syndrome. Forty-seven articles were pooled through two rounds of the selection process. The relevant information was extracted and meta-analyzed. Main findingsThe scoping review and meta-analysis of the 47 articles revealed a total prevalence of 11/2069 (4.9%); 10/1369 (5.1%) in cadaveric studies, and 1/700 (5.0%) in MRI studies. The subclavius posticus muscle is a short triangular muscle with an average length of 12 cm and an average width of 1 cm. It originates from the sternal end of the first rib in most cases with reported variants of one case originating from the costoclavicular ligament and one case where it was fused with the proper subclavius muscle. Its insertion is more variable: on the superior border of the scapula with variable length in 71.35%, on the coracoid process of the scapula in 25.42%, and on the clavicle in 0.90%. The subclavian nerve seems to be the dominant nerve supply with a 57.6% prevalence, while 25.8% are innervated by the suprascapular nerve. Other reported nerves were the nerve to the myolohyoid (4.5%), accessory phrenic nerve (4.5%), and a direct branch from the brachial plexus (2.0%). The blood supply was reported (only once) to be from the suprascapular artery. However, the venous drainage was not established at all. Principal conclusionsThe subclavius posticus muscle is a variant muscle occurring with a reported overall prevalence of 4.9%. It can compress the brachial plexus as it runs across at the space of the superior thoracic aperture with exquisite contact, and this can lead to a neurogenic thoracic outlet syndrome. It also can be involved in the vascular thoracic outlet syndrome. Lastly, it is important not to omit its potential influence in shoulder joint instability to some extent.

A CADAVERIC DISSECTION STUDY OF ACCESSORY PHRENIC NERVE

Accessory Phrenic Nerve (APN) provides additional nerve bres to the Phrenic nerve (PN) once the latter crosses the lateral border of Scalenus Anterior muscle. The literature on APN describes many variations in origin, course and termination of this rare nerve. An adequate knowledge of APN can signicantly reduce lesions to the nerve supply of diaphragm and prevent dysfunction that may follow. This study focuses on the frequency of Accessory phrenic nerve in 60 dissected heminecks of 30 adult cadavers at the Department of Anatomy, Government Medical College, Kozhikode. An incidence of 30% was recorded. The signicant contribution from APN to PN has been of major interest to surgeons and in developing various novel procedures on PN.

Erb’s Palsy in a Newborn Child and Clinicoanatomical Approach

Erb’s palsy is found in upper trunk of brachial plexus. C5, C6 roots join to from upper trunk. Each trunk again divides into anterior and posterior divisions. All trunks and divisions are found above the clavicle in the posterior triangle of neck. Branches from the upper trunk are suprascapular nerve and nerve to subclavius. Suprascapular nerve supplies supraspinatus and infraspinatus muscle along with it a articular trig to capsule of shoulder joint. Supraspinatus helps in initial 15 ºabduction at shoulder joint. Infraspinatus acts as lateral rotator of shoulder joint and assists subscapularis and teres minor muscles to abduct at this joint when there is contraction of middle fibers of deltoid and supraspinatus. Some fibers of C5 also give contribution to accessory phrenic nerve. Lateral cord of brachial plexus giving– musculocutaneous nerve, lateral pectoral nerve, lateral root of median nerve. Musculocutaneous nerve supplies all flexor muscles of arm like biceps brachii, brachialis, coracobrachialis. Brachialis muscle flexes the elbow joint, coracobrachialis is a weak flexor of shoulder joint and biceps brachii is a strong supinator of forearm, flexor of elbow joint only when forearm is supinated. Injury occurs in the Erb’s point found in the upper trunk of brachial plexus where there are emergence of six branches- C5 & C6 nerve roots, suprascapular nerve, nerve to subclavius, anterior and posterior division of upper trunk of the plexus. In this palsy, the arm remains medially rotated and adducted at the shoulder joint, the elbow is extended or semiflexed, forearm is pronated, and the wrist semiflexed. In this case a newborn child was found unable to flex his elbow, and abducted the arm on the right side. The limb is medially rotated, adducted in shoulder joint, semiflexion at the elbow joint and forearm pronated and wrist semiflexed. The child was kept on artificial respiratory ventilation. Plain Chest X-ray done to see if any musculoskeletal abnormality is there but no positive findings found so far. Both the clavicles and all ribs were found intact. Both domes of diaphragm were moving normally. On the other hand left sided upper limb found fully flexed at the elbow joint, supinated at forearm, abducted externally rotated at the shoulder joint and wrist extended. Moros reflex on the right side was absent but on left side it was clearly present. So, there is asymmetrical Moros reflex.

A STUDY OF THE MORPHOLOGICAL FEATURES OF THE HUMAN THORACO-ABDOMINAL DIAPHRAGM IN FOETUSES

Background: An incidence of 1 in 4000 of diaphragmatic hernias certainly warrants a thorough study especially in the light of possible noninvasive diagnostic techniques and treatment in utero. Aim: Study of the diaphragm in various gestational stages. Objectives: In-depth study of the thraco-abdominal diaphragm in fetuses was done as there is a paucity of literature. Morphometry of various aspects like attachments, foramina, blood supply and nerve supply. The major openings of the diaphragm were observed and as many structures as discernable were elucidated. The findings are compared with those of adult cadavers. Methods: 50 Fetuses of both sexes were procured from ANITS and KGH, Visakhapatnam and 10 adult cadavers were acquired from the Department of Anatomy from NRIIMS, Visakhapatnam for the study. Results: Variation of origin of inferior phrenic arteries were found. The accessory phrenic nerve was found arising from the nerve to subclavius. The eventration of the left dome of the diaphragm and oesophageal hiatus hernia with atretic lung were observed. Conclusion: Such a comprehensive study is of immense value for the detection of relevant hernias of the diaphragm in early intrauterine life by the clinicians and for alleviation of such disorders by surgical measures.

Origin and prevalence of the accessory phrenic nerve: A meta-analysis and clinical appraisal.

The accessory phrenic nerve (APN) is a common anatomical variant with differing reports of prevalence in the literature. It can be injured during operative procedures to the neck and thorax or by regional anesthetic techniques in its vicinity. Our aim was to provide a comprehensive evidence-based assessment of the prevalence and origins of the APN. The databases PubMed, China National Knowledge Infrastructure, ScienceDirect, EMBASE, BIOSIS, SciELO, and Web of Science were searched comprehensively, followed by assessment of eligibility and extraction of data concerning the APN. The data were pooled into a meta-analysis. A total of 17 studies were included in the meta-analysis. Fourteen studies (n = 1,941 hemi-necks) reported data on APN prevalence resulting in an overall pooled prevalence estimate of 36.5%. Nine studies (n = 941 APNs) reported data on the origin of the APN. Most commonly the APN originated from the ansa cervicalis (16.5%) followed by the nerve to the subclavius (15.8%). Subgroup analysis on the basis of laterality and geographic region revealed no statistically significant findings. The APN is a highly variable anatomical structure present in over one third of the population, most often originating from the ansa cervicalis or the nerve to the subclavius. Clinicians need to be aware of the varying constellation of symptoms that can arise from APN injury. Ultimately, knowledge of APN variation could provide for better outcomes and reduction of iatrogenic injuries, particularly in high-risk patients prone to long-term complications from diaphragmatic dysfunction. Clin. Anat. 30:1077-1082, 2017. © 2017 Wiley Periodicals, Inc.

Technique of supraclavicular decompression for neurogenic thoracic outlet syndrome

The supraclavicular approach to scalenectomy and first rib resection has been modified since the original description in 1985. The incision is 1 to 2 cm above the clavicle, 1 cm lateral to the midline, and 5 to 7 cm long. Subplatysmal skin flaps are created. The sternocleidomastoid muscle is mobilized on its lateral edge and retracted but not divided. The scalene fat pad is split vertically, the omohyoid muscle excised, and the C5 nerve root dissected free. The accessory phrenic nerve is identified, if present, arising medially from C5, and preserved. The rest of the plexus is dissected free, muscular and connective tissue removed from all nerve roots and trunks, and the subclavian artery identified. The phrenic nerve is identified on the medial edge of the anterior scalene muscle (ASM). The ASM is divided on the first rib. The ASM is elevated, freed, and divided as high as possible and free of C5. The middle scalene muscle is dissected. C5 and C6 branches of the long thoracic nerve are identified and protected as the portion of middle scalene muscle adjacent to the nerves of the plexus is excised. The decision on whether the first rib is to be removed is determined by whether the lower trunk of the plexus is touching the first rib. If the rib is removed, its posterior end is freed, divided, and 1 cm excised. The rest of the rib is freed from the intercostal muscles with a periosteal elevator or harmonic scalpel, the pleura is separated from the inner surface of the rib, and the anterior end divided with an infraclavicular rib cutter. The operation has been made safer by identifying and dissecting the C5 nerve root before looking for the phrenic nerve.

Anatomical variations of the phrenic nerve: an actualized review

Abstract Introduction: The phrenic nerve normally arises from ventral rami of C3, C4 and C5. It emerges laterally to the superior portion oflateral border of scalenus anterior muscle and presents a descendent course between subclavian artery and vein. It crosses anterior to internal thoracic artery and descends through the mediastinum, until the diaphragm muscle, to supply it with motor and sensitive fibers. Matherials and Methods: A bibliographic review was conducted, based on anatomy, neuroanatomy and surgical anatomy textbooks, published in Brazil and abroad, as well as a review of scientific articles, published over the last 20 years, available on research databases PubMed, Scielo, LILACS and MEDLINE, from keywords phrenic nerve, variation and anomaly. Results: Variations of the phrenic nerve are frequent, but they are not often discussed. Thus, we aimed to conduct an actualized review over the subject. Regarding the variations in the origin of the phrenic nerve, textbooks vaguely inform that it is mainly formed by C4, but the recent cadaveric studies pointed the segments C4 and C5 as the most common origin. About the variations in its course, the most described is its passage anterior to the subclavian vein, before reaching the thorax. However, the presence of accessory phrenic nerve represents the greatestvariation, mostly arising from nerve to subclavian. There are few reports in literature about the complications associated to these variations, but some are suggested, as the possibility of causing its damage during the puncture of the subclavian vein, when the nerve descends anterior to it, which may lead to a hemidiaphragmatic paresis. When variations are present, even simple procedures may cause injuries. Conclusion: Therefore it is fundamental to know the normal anatomy and the possible variations of the phrenic nerve, in order to perform safe procedures in its topography, as well as to enable a timely recognition of complications.

Electromyographic Permutation Entropy Quantifies Diaphragmatic Denervation and Reinnervation

Spontaneous reinnervation after diaphragmatic paralysis due to trauma, surgery, tumors and spinal cord injuries is frequently observed. A possible explanation could be collateral reinnervation, since the diaphragm is commonly double-innervated by the (accessory) phrenic nerve. Permutation entropy (PeEn), a complexity measure for time series, may reflect a functional state of neuromuscular transmission by quantifying the complexity of interactions across neural and muscular networks. In an established rat model, electromyographic signals of the diaphragm after phrenicotomy were analyzed using PeEn quantifying denervation and reinnervation. Thirty-three anesthetized rats were unilaterally phrenicotomized. After 1, 3, 9, 27 and 81 days, diaphragmatic electromyographic PeEn was analyzed in vivo from sternal, mid-costal and crural areas of both hemidiaphragms. After euthanasia of the animals, both hemidiaphragms were dissected for fiber type evaluation. The electromyographic incidence of an accessory phrenic nerve was 76%. At day 1 after phrenicotomy, PeEn (normalized values) was significantly diminished in the sternal (median: 0.69; interquartile range: 0.66–0.75) and mid-costal area (0.68; 0.66–0.72) compared to the non-denervated side (0.84; 0.78–0.90) at threshold p<0.05. In the crural area, innervated by the accessory phrenic nerve, PeEn remained unchanged (0.79; 0.72–0.86). During reinnervation over 81 days, PeEn normalized in the mid-costal area (0.84; 0.77–0.86), whereas it remained reduced in the sternal area (0.77; 0.70–0.81). Fiber type grouping, a histological sign for reinnervation, was found in the mid-costal area in 20% after 27 days and in 80% after 81 days. Collateral reinnervation can restore diaphragm activity after phrenicotomy. Electromyographic PeEn represents a new, distinctive assessment characterizing intramuscular function following denervation and reinnervation.

Neurotization of the phrenic nerve with accessory nerve for high cervical spinal cord injury with respiratory distress: an anatomic study.

High cervical spinal cord injury is associated with high morbidity and mortality. Traditional treatments carry various complications such as infection, pacemaker failure and undesirable movement. Thus, a secure surgical strategy with fewer complications analogous to physiological ventilation is still required. We hope to offer one potential method to decrease the complications and improve survival qualities of patients from the aspect of anatomy. The purpose of the study is to provide anatomic details on the accessory nerve and phrenic nerve for neurotization in patients with high spinal cord injuries. 38 cadavers (76 accessory and 76 phrenic nerves) were dissected in the study. The width, length and thickness of each accessory nerve and phrenic nerve above clavicle were measured. The distances from several landmarks on accessory nerve to the origin and the end of the phrenic nerve above clavicle were measured too. Then, the number of motor nerve fibers on different sections of the nerves was calculated using the technique of immunohistochemistry. The accessory nerves distal to its sternocleidomastoid muscular branches were 1.52 ± 0.32 mm ~1.54 ± 0.29 mm in width, 0.52 ± 0.18 mm ~ 0.56 ± 0.20mm in thickness and 9.52 ± 0.98 cm in length. And the phrenic nerves above clavicle were 1.44 ± 0.23 mm ~ 1.45 ± 0.24 mm in width, 0.47 ± 0.15 mm ~ 0.56 ± 0.25 mm in thickness and 6.48 ± 0.78 cm in length. The distance between the starting point of accessory nerve and phrenic nerve were 3.24 ± 1.17 cm, and the distance between the starting point of accessory nerve and the end of the phrenic nerve above clavicle were 8.72 ± 0.84 cm. The numbers of motor nerve fibers in accessory nerve were 1,038 ± 320~1,102 ± 216, before giving out the sternocleidomastoid muscular branches. The number of motor nerve fibers in the phrenic nerve was 911 ± 321~1,338 ± 467. The accessory nerve and the phrenic were similar in width, thickness and the number of motor nerve fibers. And the lengths of accessory nerve were long enough for neuritisation with phrenic nerve.

COMPLICATIONS DURING A SUPRACLAVICULAR ANESTHESIA OF THE BRACHIAL PLEXUS WITH INTERSCALENE APPROACH

SUMMARY A hemidiaphragmatic paresis is one of the most frequently observed complications following the supraclavicular anesthesia of the brachial plexus with interscalene approach. In patients, crucially dependant on adequate diaphragmatic function, hemidiaphragmatic paresis may provoke acute respiratory disturbances. The aim of this study was to analyze the anatomical features the brachial plexus with regard of the anesthesia of specific areas of the shoulder and the upper limb. A dissection of the cervical and the brachial plexuses was done in human cadavers. We established that in some cases the phrenic nerve and the accessory phrenic nerve arise from the superior trunk of the brachial plexus. This type of anatomical arrangement significantly increases the risk of hemidiaphragmatic paresis during supraclavicular anesthesia with interscalene approach because the anesthetic tends to invade the supraclavicular space.

Accessory phrenic nerve: A rarely discussed common variation with clinical implications

Accessory phrenic nerve: A rarely discussed common variation with clinical implications

Anatomic research on the transposition of accessory nerve to phrenic nerve

To comprehend the anatomic characteristics and correlations between the accessory nerve and the phrenic nerve in the adult corpses. The bilateral accessory nerves, phrenic nerves, and their branches of 20 adult corpses (38 sides) were underwent exposure. The morphologic data of the accessory nerves and the phrenic nerves above clavicle were measured. In addition, the minimal and maximal distances from several points on the accessory nerve to the full length of the phrenic nerve above clavicle were measured. Then, the number of motor nerve fibers on different locations of the nerves utilizing the method of immunohistochemistry were counted and compared. The accessory nerves after sending out the sternocleido-mastoid muscular branches were similar in the morphologic data with the phrenic nerves. Meanwhile, the accessory nerve had a coiled appearance within this geometrical area. The possibly minimal distance between the accessory nerve and phrenic nerve was (3.19 ± 1.23) cm, and the possibly maximal distance between the starting point of accessory nerve and the end of the phrenic nerve above clavicle was (8.71 ± 0.75) cm. The accessory nerve and the phrenic nerve are similar in the anatomic evidences and the number of motor nerve fibers. And the length of accessory nerve is sufficiently long to connect with phrenic nerve as needed. It is possible to suture them without strain directly.

Variations in the formation of supraclavicular brachial plexus among Kenyans

Objective: To describe the pattern and prevalence of variations that occur in the supraclavicular part of the brachial plexus in a Kenyan population. Study design: Descriptive cross-sectional study. Materials and methods: Ninety-four brachial plexuses from forty-seven formalin fixed cadavers were displayed by gross dissection. Results: The presence of at least one variation from the classical anatomy was observed in 73 (77.7%) of the 94 plexuses. The roots and trunks were involved in 32 (34%) of the plexuses . Preand postfixed roots were present in 23 (24.7%) and 3 (3.2%), respectively. The presence of four trunks, and trunks passing between the scalene medius and posterior were also noted. The long thoracic nerve was variant in 51 (54.3%) of the plexuses. Unusual relations of the phrenic nerve to scalene muscles and the subclavian vein were encountered. Conclusion: The presence of four trunks and an accessory phrenic nerve passing through the subclavian vein are probably described and reported for the first time. However, most of the variations of the BP among Kenyans are similar to those reported in the other populations.

Right accessory phrenic nerve passing through an annulus of the subclavian vein

Clinical AnatomyVolume 21, Issue 8 p. 779-780 Compendium of Anatomical Variants Right accessory phrenic nerve passing through an annulus of the subclavian vein M. Codesido, M. Codesido Anatomy Department, Universidad Austral, Buenos Aires, ArgentinaSearch for more papers by this authorR.A. Guerri-Guttenberg, Corresponding Author R.A. Guerri-Guttenberg [email protected] Anatomy Department, Universidad Austral, Buenos Aires, ArgentinaAnatomy Department, Austral University, Juan Domingo Perón 1500, B1664INZ, Pilar, Buenos Aires, ArgentinaSearch for more papers by this author M. Codesido, M. Codesido Anatomy Department, Universidad Austral, Buenos Aires, ArgentinaSearch for more papers by this authorR.A. Guerri-Guttenberg, Corresponding Author R.A. Guerri-Guttenberg [email protected] Anatomy Department, Universidad Austral, Buenos Aires, ArgentinaAnatomy Department, Austral University, Juan Domingo Perón 1500, B1664INZ, Pilar, Buenos Aires, ArgentinaSearch for more papers by this author First published: 14 July 2008 https://doi.org/10.1002/ca.20657Citations: 9AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume21, Issue8November 2008Pages 779-780 RelatedInformation

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. 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. 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. 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.

Schwannoma of the accessory phrenic nerve

Otolaryngologists are frequently confronted with the management of cervical tumors. Neurogenic tumors concern, especially, the cranial, sympathetic, or peripheral nerve sheathes. These tumors are benign and grow slowly. The involvement of the cervical part of the phrenic nerve is exceptional, and only 2 cases are reported in the literature. We describe the first case of a cervical schwannoma involving the accessory phrenic nerve. The anatomy and function of the accessory phrenic nerve are reviewed.

Surgical Anatomy of the Accessory Phrenic Nerve

Reports place the frequency of phrenic nerve injury after cardiac operations between 10% and 85%, emphasizing the importance of an accurate anatomic description of the diaphragm's innervating nerves to reduce iatrogenic injury, length of hospitalization, and associated costs. The aim of our study was to explore the anatomic variations of the accessory phrenic nerve and relate these findings to phrenic nerve injury. Eighty adult formalin-fixed cadavers were dissected, resulting in 160 nerve specimens. Fifty nerve specimens were also examined laparoscopically with findings later confirmed through gross dissection. All nerves contributing to the phrenic nerve after crossing the anterior scalene were considered to be accessory phrenic nerves. The phrenic nerve was present in all specimens, and 99 (61.8%) also had an accessory phrenic nerve. The accessory phrenic nerve arose from the nerve to subclavius in 60 specimens (60.6%), ansa cervicalis in 12 (12.1%), and nerve to sternohyoid in 7 (7%). The accessory phrenic nerve joined with the phrenic nerve in the thorax anterior to the subclavian vein in 45 (45.5%) specimens and posterior in 17 (22.2%). A phrenic-accessory phrenic nerve loop was found around the subclavian vein in 45 (35 on the right, 10 on the left) specimens and around the internal thoracic artery in 38 (31 on the right, 7 on the left). To reduce injuries to the diaphragm, the presence of an accessory phrenic nerve should be considered before mobilization and skeletonization of the internal thoracic artery above the second rib.

Options and Results in Nerve Reconstruction of Elbow Flexion in Patients with Post-Traumatic Brachial Plexus Injury

If active elbow flexion must be reconstructed in brachial plexus lesions, the option of nerve reconstruction should always be considered first. Depending on the etiology, there are several possibilities for re-neurotization of the musculocutaneous nerve, such as intraplexual reconstruction from the C6 root, or extraplexual reconstruction from the accessory nerve, phrenic nerve, intercostal nerves, ulnar nerve, pectoral nerve, and contralateral C7 root.