Is Immobile vocal fold Related to the Spinal Accessory Nerve Agenesis?: A Case Report.

The spinal accessory nerve innervates the sternocleidomastoid and trapezius muscles, but the internal branch from the spinal accessory nerve is also contributing to the motor innervation of the larynx. For the first time, we report a case of an impairment of sternocleidomastoid, trapezius, and thyroarytenoid muscles from the same side. In our case, the anatomical variant that can explain this situation implies the cranial roots and some fibers from the spinal roots of the spinal accessory nerve to form the internal branch. In the case of agenesis of these spinal roots, the muscles reliant on it would be missing. For this reason, it is advisable to rule out laryngeal problems in patients with sternocleidomastoid and/or trapezius muscles impairment.

A contextual thematic analysis of the accessory nerve in Scottish historical medical collections of the Royal Colleges of Edinburgh and Glasgow.

INTRODUCTION: The classification of the accessory nerve (CN XI) remains a source of debate; its exact function has not been fully elucidated having also an atypical morphology for a cranial nerve. A better insight into its anatomical and physiological features is of clinical relevance. The aim was to conduct a review of 18th and 19th century books from the Royal Medical/Surgical Colleges in Scotland, United Kingdom. A contextual historical analysis of the depictions and descriptions of the accessory nerve could provide insight into the disparity in the current descriptions. MATERIALS AND METHODS: Online archive catalogues were systematically searched and, during site visits, resources were formally and contextually analyzed, with the information then thematically analyzed. The themes were discussed against a widely known reference textbook of the era. RESULTS: Based on the thematic analysis, the resources were categorized either as practical anatomy books or field-specific anatomy books including neuroanatomy atlases. This intended use, along with the target audience, influenced the scope and detail of information, typically with general anatomy for students in the practical resources, and specialist information in the field-specific resources. The authors' professional background also influenced the way the accessory nerve was described and/or depicted, with surgeons/physicians placing emphasis on the clinical aspects. Content variations could also be attributed to communication restrictions of the era, and associated purchasing costs. CONCLUSIONS: Although scientific advances are nowadays disseminated at a faster pace, actively bridging the gap between anatomical sciences and clinical research is still needed when considering the accessory nerve to further elucidate the mysteries of this structure.

Lower cranial nerve syndromes: a review.

The purpose of this paper is to provide a comprehensive review encompassing the syndromes associated with the lower cranial nerves (LCNs). We will discuss the anatomy of some of these syndromes and the historical contributors after whom they were named. The LCNs can be affected individually or in combination, since the cranial nerves at this level share their courses through the jugular foramen and hypoglossal canal and the extracranial spaces. Numerous alterations affecting them have been described in the literature, but much remains to be discovered on this topic. This paper will highlight some of the subtle differences among these syndromes. Symptoms and signs that have localization value for LCN lesions include impaired speech, deglutition, sensory functions, alterations in taste, autonomic dysfunction, neuralgic pain, dysphagia, head or neck pain, cardiac or gastrointestinal compromise, and weakness of the tongue, trapezius, or sternocleidomastoid muscles. To assess the manifestations of LCN lesions correctly, precise knowledge of the anatomy and physiology of the area is required. Treatments currently used for these conditions will also be addressed here. Effective treatments are available in several such cases, but a precondition for complete recovery is a correct and swift diagnosis.

Cell Types Promoting Goosebumps Form a Niche to Regulate Hair Follicle Stem Cells.

Piloerection (goosebumps) requires concerted actions of the hair follicle, the arrector pili muscle (APM), and the sympathetic nerve, providing a model to study interactions across epithelium, mesenchyme, and nerves. Here, we show that APMs and sympathetic nerves form a dual-component niche to modulate hair follicle stem cell (HFSC) activity. Sympathetic nerves form synapse-like structures with HFSCs and regulate HFSCs through norepinephrine, whereas APMs maintain sympathetic innervation to HFSCs. Without norepinephrine signaling, HFSCs enter deep quiescence by down-regulating the cell cycle and metabolism while up-regulating quiescence regulators Foxp1 and Fgf18. During development, HFSC progeny secretes Sonic Hedgehog (SHH) to direct the formation of this APM-sympathetic nerve niche, which in turn controls hair follicle regeneration in adults. Our results reveal a reciprocal interdependence between a regenerative tissue and its niche at different stages and demonstrate sympathetic nerves can modulate stem cells through synapse-like connections and neurotransmitters to couple tissue production with demands.

Optimal reference electrode placement for accessory and axillary nerve conduction studies.

BACKGROUND: Various techniques are described for proximal motor nerve conduction studies (NCSs). We investigated alternative reference electrode (E2) locations for accessory and axillary NCSs. METHODS: Multi-channel recordings were made from trapezius or deltoid referred to different sites, and from those sites referred to a remote electrode. Responses were compared using grouped statistics, and correlation analysis. RESULTS: For accessory NCSs, all belly:E2 montages showed comparable responses but axillary NCSs were more variable. Low amplitude contamination was seen at the sternum and contralateral acromion but greater distortion using other potential E2 sites. In both accessory and axillary studies, the ipsilateral acromion showed moderate activity, which correlated with the belly:remote response. CONCLUSIONS: Variation in E2 electrode sites may significantly distort the measured compound muscle action potential (CMAP). For accessory and axillary NCS, a sternal reference has favorable characteristics. Other sites, such as ipsilateral acromion or deltoid insertion, may not yield a representative CMAP.

Gender, BMI and side-to-side differences in spinal accessory nerve conduction from the upper and middle components of the trapezius muscle.

INTRODUCTION: There is a variety of testing methods described in the literature for the spinal accessory nerve (SAN). This study aims to evaluate side-to-side, gender, and BMI differences with surface recording from the upper and middle trapezius using a standard distance to the upper trapezius. METHODS: Subjects underwent bilateral SAN conduction testing with the active recording electrodes over the superior border of the upper trapezius, midway between the acromion and the C7 spinous process, and over the middle trapezius 3 cm medial to the vertebral border of the scapula. RESULTS: Mean latency values were 2.17 ± 0.22 msec and 3.14 ± 0.40 msec for the upper and middle trapezius, respectively. Mean amplitude values were 8.02 ± 2.2 mV for the upper trapezius and 3.96 ± 1.77 mV for the middle trapezius. The mean side-to-side latency difference was 7.8% for the upper and 9.5% for the middle trapezius, while the mean side-to-side amplitude difference was 18.2% for the upper and 37.6% for the middle trapezius. BMI had a significant inverse effect on upper and middle trapezius amplitudes such that both males and females with lower BMI had larger amplitudes. There was a significant gender difference for upper and middle trapezius latency with faster latency values observed in females. CONCLUSIONS: SAN conduction with surface recording from the upper and middle trapezius is well tolerated. Side-to-side differences may be the best way to evaluate both amplitude and latency, so bilateral testing is essential in light of anatomical variation and BMI effects on amplitude.

Spinal Accessory Motor Neurons in the Mouse: A Special Type of Branchial Motor Neuron?

The spinal accessory nerve arises from motor neurons in the upper cervical spinal cord. The axons of these motor neurons exit dorsal to the ligamentum denticulatum and form the spinal accessory nerve. The nerve ascends in the spinal subarachnoid space to enter the posterior cranial fossa through the foramen magnum. The spinal accessory nerve then turns caudally to exit through the jugular foramen alongside the vagus and glossopharyngeal nerves, and then travels to supply the sternomastoid and trapezius muscles in the neck. The unusual course of the spinal accessory nerve has long prompted speculation that it is not a typical spinal motor nerve and that it might represent a caudal remnant of the branchial motor system. Our cell lineage tracing data, combined with images from public databases, show that the spinal accessory motor neurons in the mouse transiently express Phox2b, a transcription factor that is required for development of brain stem branchial motor nuclei. While this is strong prima facie evidence that the spinal accessory motor neurons should be classified as branchial motor, the evolutionary history of these motor neurons in anamniote vertebrates suggests that they may be considered to be an atypical branchial group that possesses both branchial and somatic characteristics. Anat Rec, 302:505-511, 2019. © 2018 Wiley Periodicals, Inc.

Electrophysiology of Cranial Nerve Testing: Spinal Accessory and Hypoglossal Nerves.

Multiple techniques have been developed for the electrodiagnostic evaluation of cranial nerves XI and XII. Each of these carries both benefits and limitations, with more techniques and data being available in the literature for spinal accessory than hypoglossal nerve evaluation. Spinal accessory and hypoglossal neuropathy are relatively uncommon cranial mononeuropathies that may be evaluated in the outpatient electrodiagnostic laboratory setting. A review of available literature using PubMed was conducted regarding electrodiagnostic technique in the evaluation of spinal accessory and hypoglossal nerves searching for both routine nerve conduction studies and repetitive nerve conduction studies. The review provided herein provides a resource by which clinical neurophysiologists may develop and implement clinical and research protocols for the evaluation of both of these lower cranial nerves in the outpatient setting.

Nerve and vein preserving neck dissections for oral cancers: a prospective evaluation of spinal accessory nerve function and internal jugular vein patency following treatment.

Nerve and vein preserving modification of the radical neck dissection is commonly used in the management of oral squamous cell cancers. There is limited literature addressing nerve function and vein patency following treatment. We prospectively analysed 65 patients with nerve conduction study using surface electromyography at baseline, 1 month and 6 months post-surgery and colour Doppler of the internal jugular vein at baseline and 1 month post-surgery. We also studied functional outcomes of nerve sparing with arm abduction test and Neck Dissection Quality of Life questionnaire. There was a statistically significant increase in mean latency of motor action potential and decrease in the mean amplitude of the motor action potential following surgery, suggesting nerve dysfunction. Following surgery, there was a significant decrease in the diameter of the vein as well as an increase in the velocity of blood flow; there was partial thrombus in 5% of individuals. In conclusion, even though nerve dysfunction compromised shoulder abduction, vein dysfunction rarely resulted in any significant clinical impact.

Functional anatomy of the accessory nerve studied through intraoperative electrophysiological mapping.

OBJECTIVE Classically the 11th cranial nerve (CN XI, or accessory nerve) is described as having a cranial and a spinal root, the latter arising from the upper segments of the spinal cord through a number of very fine rootlets. According to classical knowledge, the cranial root gives motor innervation to the vocal cords, whereas the spinal root provides the motor innervation of the sternocleidomastoid muscle (SCM) and of the upper portions of the trapezius muscle (TZ). The specific function of each of the rootlets of the spinal component is not well known. Therefore the authors aimed to map, using intraoperative direct electrical stimulation and electromyographic (EMG) recordings, the innervation territory of these rootlets in relation to their exit level from the CNS. METHODS Forty-nine patients undergoing surgery with intradural exposure at the craniocervical junction were enrolled in the study. The EMG recordings included the sternal and clavicular parts of the SCM (SCM-S and SCM-C), the superior and middle parts of the TZ (TZ-S and TZ-M), and whenever possible the vocal cords. The main trunk of CN XI, its roots (both cranial and spinal), and when possible the fine cervical rootlets, were stimulated at predetermined locations, from the jugular foramen down to the lowest cervical level exposed. The EMG responses were collected, and a map of the responses was drawn up. RESULTS Monitoring and stimulation of the spinal root were performed in all cases, whereas for the cranial root this was possible in only 19 cases. A total of 262 stimulation sites were explored: 70 at the common trunk of the nerve, 19 at the cranial root, 136 at various levels on the spinal root, and 37 at the cervical rootlets. A vocal cord response was obtained by stimulation of the cranial root in 84.2% (16/19); absence of response was considered to have a technical origin. In no case did the vocal cords respond to the stimulation of the spinal root or rootlets. Stimulation of the cervical rootlets yielded responses that differed according to the level of stimulation: at C-1 the SCM-S responded 95.8% of the time (23/24); at C-2 the SCM-C responded 90.0% of the time (9/10); at C-3 the TZ-S responded 66.6% of the time (2/3); and below that level only the TZ-M responded. The spinal root stimulated at its various levels responded accordingly. CONCLUSIONS The function of each of the rootlets of CN XI appears to be specific. The cranial root contributes, independently of the spinal root, to the innervation of the vocal cords, which makes it a specific entity. The spinal root innervates the SCM and TZ with a cranio-caudal motor organization of its cervical rootlets.

The unique axon trajectory of the accessory nerve is determined by intrinsic properties of the neural tube in the avian embryo.

The accessory nerve is a cranial nerve, composed of only motor axons, which control neck muscles. Its axons ascend many segments along the lateral surface of the cervical spinal cord and hindbrain. At the level of the first somite, they pass ventrally through the somitic mesoderm into the periphery. The factors governing the unique root trajectory are unknown. Ablation experiments at the accessory nerve outlet points have shown that somites do not regulate the trajectory of the accessory nerve fibres. Factors from the neural tube that may control the longitudinal pathfinding of the accessory nerve fibres were tested by heterotopic transplantations of an occipital neural tube to the cervical and thoracic level. These transplantations resulted in a typical accessory nerve trajectory in the cervical and thoracic spinal cord. In contrast, cervical neural tube grafts were unable to give rise to the typical accessory nerve root pattern when transplanted to occipital level. Our results show that the formation of the unique axon root pattern of the accessory nerve is an intrinsic property of the neural tube.

Intra-operative monitoring of the spinal accessory nerve: a systematic review.

OBJECTIVE: To investigate evidence that intra-operative nerve monitoring of the spinal accessory nerve affects the prevalence of post-operative shoulder morbidity and predicts functional outcome. METHODS: A search of the Medline, Scopus and Cochrane databases from 1995 to October 2012 was undertaken, using the search terms 'monitoring, intra-operative' and 'accessory nerve'. Articles were included if they pertained to intra-operative accessory nerve monitoring undertaken during neck dissection surgery and included a functional shoulder outcome measure. Further relevant articles were obtained by screening the reference lists of retrieved articles. RESULTS: Only three articles met the inclusion criteria of the review. Two of these included studies suggesting that intra-operative nerve monitoring shows greater specificity than sensitivity in predicting post-operative shoulder dysfunction. Only one study, with a small sample size, assessed intra-operative nerve monitoring in neck dissection patients. CONCLUSION: It is unclear whether intra-operative nerve monitoring is a useful tool for reducing the prevalence of accessory nerve injury and predicting post-operative functional shoulder outcome in patients undergoing neck dissection. Larger, randomised studies are required to determine whether such monitoring is a valuable surgical adjunct.

Quality of life, shoulder range of motion, and spinal accessory nerve status in 5-year survivors of head and neck cancer.

OBJECTIVE: To determine the association of neck dissection and radiation treatment for head and neck cancer (HNC) with subsequent shoulder range of motion (ROM) and quality of life (QOL) in 5-year survivors. DESIGN: A cross-sectional convenience sample. SETTING: Otolaryngology clinics at tertiary care hospital and Veterans Affairs medical center. PATIENTS: Five-year, disease-free survivors of HNC. METHODS: Demographic and cancer treatment information was collected, including type of neck dissection (none, spinal accessory "nerve sparing," and "nerve sacrificing") and radiation. QOL questionnaires were administered, and shoulder ROM was measured. MAIN OUTCOME MEASUREMENTS: University of Washington Quality of Life (UWQOL), Functional Assessment of Cancer Therapy (FACT) Head and Neck, and Performance Status Scale for Head and Neck. Shoulder ROM measurements included abduction, adduction, flexion, extension, internal and external rotation. RESULTS: One hundred and five survivors completed QOL surveys; 85 survivors underwent additional shoulder ROM evaluations. The nerve sacrifice group exhibited significantly poorer scores for UWQOL measures of disfigurement, level of activity, recreation and/or entertainment, speech and shoulder disability, and willingness to eat in public, FACT functional well-being, and FACT Head and Neck (P < .05). Shoulder ROM for flexion and abduction was poorest in the nerve sacrifice group (P < .05). Radiation was associated with significantly worse UWQOL swallowing (P < .05), but no other differences were found for QOL or ROM measurements. Decreased QOL scores were associated with decreased shoulder flexion and abduction (P < .05). Survivors with decreased shoulder abduction had significantly (P < .05) worse scores in disfigurement, recreation and/or entertainment, employment, shoulder disability, and FACT emotional well-being. CONCLUSIONS: Sparing the spinal accessory nerve during neck dissection is associated with significantly less long-term shoulder disability in 5-year survivors of HNC. QOL measures demonstrated the highest level of function in the no dissection group, an intermediate level of functioning with nerve sparing, and poorest function when the nerve is sacrificed. Decreased shoulder flexion and abduction is associated with reduced QOL in long-term survivors of HNC.

[Post-operative functional evaluation of accessory nerve reconstruction].

A nerve reconstruction was performed in 20 patients whose spinal accessory nerve was resected during total neck dissection. Re-anastomosis or a cable graft was performed between both cut ends of the accessory nerve in 14 patients (accessory nerve reconstruction group), and between the peripheral cut end of the accessory nerve and the central cut end of the cervical nerve (C2 or C3) in 6 patients (cervical/accessory nerve reconstruction group). There was no difference in the postoperative shoulder functions between the reconstruction groups, and both groups were significantly better than the group without reconstruction (n = 13), although they tended to be poorer than the nerve preservation group (n = 41).

Motor innervation of the trapezius muscle: Intraoperative motor conduction study during neck dissection.

OBJECTIVES: To evaluate the motor input from the spinal accessory nerve (SAN) and the branches of the cervical plexus in an intraoperative motor nerve conduction study measuring motor action potentials by direct stimulation of the exposed nerve during neck dissection. METHODS: The entire length of the SAN and the contributions from the upper cervical plexus were preserved. Compound muscle action potentials were measured for each part of the trapezius muscle on stimulation of the SAN, C2, C3, and C4 nerves. RESULTS: With stimulation of the spinal nerve, evoked responses were obtained from all 24 patients in the descending, transverse, and ascending trapezius muscle. C2 contributions were noted in 2 out of 24 patients; however, no patient revealed responses in all three parts of the muscle. C3 contributions were seen in 11 out of 24 patients, supplying all three parts of the muscle in 8 patients, and C4 contributions were noted in 20 out of 24 patients, supplying all three parts of the muscle in 16 of them. CONCLUSIONS: The SAN provided the most consistent motor input to the trapezius muscle. The C2, C3, and C4 nerves also provided motor input to the trapezius muscle; however, they were either inconsistently present or, when present, irregularly innervated the three parts of the trapezius muscle.

Crossed responses found in human trapezius muscles are not H-reflexes.

INTRODUCTION: We sought to confirm the presence of crossed short-latency reflexes in trapezius. METHODS: Mmax and Hmax were measured in the ipsilateral trapezius in 10 subjects by percutaneous electrical stimulation of the accessory nerve and the cervical nerves of C3/4 respectively. Repeated stimulation of the C3/4 cervical nerves was performed during 3 different tasks (relaxation, contraction of ipsilateral side, contraction of contralateral side). RESULTS: Ipsilaterally, responses increased significantly with an increase in the prestimulus electromyogram (EMG) and decreased significantly with a decrease in prestimulus EMG. Contralateral potentials increased significantly with contraction of the trapezius ipsilateral to the stimulus compared with contraction of the muscle in which they were recorded and decreased significantly with increasing distance from the ipsilateral side. CONCLUSIONS: We found ipsilateral and contralateral responses consistent with previous findings. However, we conclude that the contralateral response in trapezius is not a crossed reflex.

Minimizing shoulder syndrome with intra-operative spinal accessory nerve monitoring for neck dissection.

The objective of this study was to analyze the safety and results of intra-operative SAN (spinal accessary nerve) monitoring during selective neck dissection, with emphasis on shoulder syndrome. Twenty-five consecutive patients with head and neck cancer were studied. Selective neck dissection was performed by a single clinical fellow under the supervision of the department chief using an intra-operative SAN monitor. Electrophysiological data were recorded after initial identification of the SAN and continued until just before closure. Electromyographic evaluation was carried out to assess SAN function one month postoperatively. Shoulder disability was also evaluated at this time using a questionnaire for shoulder syndrome (shrug, flexion, abduction, winging, and pain). No patients had postoperative shoulder syndrome involving shrug, flexion, abduction, or winging. Twenty-two of the 25 (88%) patients had shoulder pain, but the average pain score was low (2.3 ± 1.3). No patients had neck recurrence during at least 1 year of follow up. By using nerve monitoring during selective neck dissection, no patient developed significant "shoulder syndrome", with the exception of slight pain.

Occipital somites guide motor axons of the accessory nerve in the avian embryo.

The accessory nerve (nervus accessorius) displays a unique organization in that its axons ascend along the rostrocaudal axis after exiting the cervical spinal cord and medulla oblongata and thereafter project ventrally into the periphery at the first somite level. Little is known about how this organization is achieved. We have investigated the role of somites in the guidance of motor axons of the accessory nerve using heterotopic transplantations of somites in avian embryos. The formation of not only accessory nerve but also the vagal nerve was affected, when a more caudal occipital somite (somites 2-4) was grafted to the position of the first occipital somite. Our study reveals that only the first occipital somite permits the development of ventral projection of accessory axons, a process that is inhibited by more caudal occipital somites.

[The relationship between operation type, adjuvant radiation therapy, spinal accessory nerve and quality of life in patients with laryngeal cancer]. / Larenks kanserli hastalarda ameliyat tipi, adjuvan radyoterapi ve spinal aksesuvar sinir ile yasam kalitesi arasindaki iliski.

OBJECTIVES: In this study, we aimed to investigate the effect of operation type, adjuvant radiation therapy (RT), and preserved spinal accessory nerve on the quality of life in patients with laryngeal cancer. PATIENTS AND METHODS: A total of 191 consecutive patients (185 males, 6 females; mean age 59±10 years; range 42 to 79 years) who were operated due to laryngeal cancer were included. The quality of life scores were estimated using the Washington University Quality of Life Questionnaire, version IV. The patients were divided into six groups according to the operation type, the need for postoperative RT and preserved or operated spinal accessory nerve during the neck dissection. Group 1 consisted of patients with total or near total laryngectomy; group 2 consisted of those with partial laryngeal surgery; group 3 consisted of those with postoperative RT; group 4 consisted of those without postoperative RT; group 5 consisted of those with preserved 11th cranial nerve during the neck dissection, and group 6 consisted of those with non-preserved 11th cranial nerve during the neck dissection. The questionnaire scores were compared among the groups. RESULTS: The compact quality of life scores were 77.4±11.3 in group 1, 86.2±7.2 in group 2, 79.1±9.5 in group 3, 83.4±10.6 in group 4, 87.3±9.4 in group 5, and 79.4±10.8 in group 6. There was a statistically significant difference in the compact quality of life scores among the surgery groups, neck dissection groups and RT groups (p=0.018, p<0.001, p<0.001, respectively). There was no effect of preserved 11th cranial nerve on daily activity, swallowing, chewing, appearance, recreation, salivation, taste, speech, mood, and anxiety parameters. This nerve was not preserved in 71.9% of the patients who were urged to change their job due to shoulder problems. The difference was statistically significant (p<0.001). CONCLUSION: According to our study results, we concluded that partial laryngectomy improved the quality of life, rather than total or near-total laryngectomy, while postoperative RT had an adverse effect on the quality of life and preserved spinal accessory nerve during the neck dissection had a positive impact on the quality of life in patients with laryngeal cancer.

Elucidation of target muscle and detailed development of dorsal motor neurons in chick embryo spinal cord.

The avian cervical spinal cord includes motoneurons (MNs) that send their axons through the dorsal roots. They have been called dorsal motoneurons (dMNs) and assumed to correspond to MNs of the accessory nerve that innervate the cucullaris muscle (SAN-MNs). However, their target muscles have not been elucidated to date. The present study sought to determine the targets and the specific combination of transcription factors expressed by dMNs and SAN-MNs and to describe the detailed development of dMNs. Experiments with tracing techniques confirmed that axons of dMNs innervated the cucullaris muscle. Retrogradely labeled dMNs were distributed in the ventral horn of C3 and more caudal segments. In most cases, some dMNs were also observed in the C2 segment. It was also demonstrated that SAN-MNs existed in the ventral horn of the C1-2 segments and the adjacent caudal hindbrain. Both SAN-MNs and dMNs expressed Isl1 but did not express Isl2, MNR2, or Lhx3. Rather, these MNs expressed Phox2b, a marker for branchial motoneurons (brMNs), although the intensity of expression was weaker. Dorsal MNs and SAN-MNs were derived from the Nkx2.2-positive precursor domain and migrated dorsally. Dorsal MNs remain in the ventral domain of the neural tube, unlike brMNs in the brainstem. These results indicate that dMNs and SAN-MNs belong to a common MN population innervating the cucullaris muscle and also suggest that they are similar to brMNs of the brainstem, although there are differences in Phox2b expression and in the final location of each population. J. Comp. Neurol. 521: 2987-3002, 2013. © 2013 Wiley Periodicals, Inc.