Glossopharyngeal, Vagus and Accessory Nerves: Anatomy and Pathology.

The glossopharyngeal, vagus, and accessory nerves are discussed in this article, given their intimate anatomical and functional associations. Abnormalities of these lower cranial nerves may be intrinsic or extrinsic due to various disease processes. This article aims to review these nerves' anatomy and demonstrates the imaging aspect of the diseases which most commonly affect them.

Spinal Accessory and Suprascapular Nerve Injury After Human Bite.

ABSTRACT: This is a unique clinical case of spinal accessory and suprascapular nerve injury related to a human bite not yet described elsewhere. The case emphasizes the importance of considering local trauma of the posterior triangle of the neck in case of shoulder weakness with electrophysiologic evidence of combined spinal accessory and suprascapular nerve injury.

Accessory spinal nerve damage during a cervical lymph node biopsy: case report.

The lesion of the accessory spinal nerve is often of iatrogenic origin. We report the case of an injury after a right jugulocarotid lymph node biopsy. A 30-year-old patient was referred for the treatment of right cervical lymphadenopathy suspected of tuberculosis. After the intervention and confirmation of tuberculosis diagnosis, the patient presented a functional impotence of the right shoulder and swarming of the right hand. The clinical examination found an active limitation of the shoulder, and a wasting of the upper bundle of the right trapezius muscle and the sternocleidomastoid. The EMG showed axonotmesis of the accessory spinal nerve and the MRI an amyotrophy of the trapezius with denervation edema. A simple rehabilitation has been scheduled. Damage of the accessory spinal nerve most often occurs after local surgery. EMG is essential for diagnosis. Rehabilitation is the first therapeutic option. Surgery can be considered if it fails. The surgeons must consider the protection of the accessory spinal nerve in case of cervical lymph node surgery.

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.

MRI findings of spinal accessory neuropathy.

AIM: To characterise the magnetic resonance imaging (MRI) appearance of patients with spinal accessory nerve (SAN) denervation. MATERIAL AND METHODS: Twelve patients who had SAN denervation on electromyography (EMG) were included. The sternocleidomastoid and trapezius muscles and the SAN were assessed using MRI. RESULTS: Trapezius muscle atrophy was seen in 11 (92%), and of those patients, T2/short tau inversion recovery (STIR) signal hyperintensity was also demonstrated in seven (58%). All three patients with prior neck surgery had scarring around the SAN, and one of these patients demonstrated a neuroma, which was confirmed surgically. CONCLUSION: Features of SAN neuropathy on MRI include atrophy and T2/STIR signal hyperintensity of the trapezius, and in patients who have had posterior triangle neck surgery, scarring may be seen around the nerve.

Relevance of level IIb neck dissection in oral squamous cell carcinoma

BACKGROUND: The purpose of this study was to determine the prevalence of level IIb metastasis in patients with oral squamous cell carcinomas (OSCCs). MATERIAL AND METHODS: A prospective analysis of 56 patients with OSCC who underwent surgical treatment of the primary lesion with simultaneous neck dissection was performed. During neck dissection, level IIb lymph nodes were separately removed and processed. Neck dissection was bilateral in 26 patients (46%) and unilateral in 30 patients (54%). RESULTS: The mean number of nodes found in the level IIb specimens was 4.7 (range: 0-8 nodes). The prevalence of metastasis at level IIb was 0% in pN0 necks and 3.4% in pN+ necks, with an overall prevalence of 1.8%. A significant association between metastasis to level IIb and type of neck dissection was observed. There were no isolated metastases to level IIb without the involvement of other nodes in the remaining neck specimen. Four regional recurrences were observed during follow-up. CONCLUSIONS: Based on our findings, we suggest that dissection of the level IIb region in patients with OSCC may be required only in patients with multilevel neck metastasis or if level IIa metastasis is found intraoperatively

Quantification of Trapezius Muscle Innervation During Neck Dissections: Cervical Plexus Versus the Spinal Accessory Nerve.

OBJECTIVES: Despite increasing use of selective, nerve-sparing surgical techniques during neck dissections, the reported rate of postoperative paralysis of the trapezius muscle is still high. The aim of the study is to measure and compare motor inflow to the trapezius muscle, in order to better understand the peripheral neuroanatomy. METHODS: Intraoperative nerve monitoring (electroneurography) in patients undergoing routine neck dissection (n=18). The innervation of the 3 functional parts of the trapezius muscle was mapped and quantified through compound muscle action potentials. RESULTS: In 18/18 (100%) of the patients, the spinal accessory nerve (SAN) innervated all parts of the trapezius muscle. In 7/18 (39%) of the patients, an active motor branch from the cervical plexus was detected, equally distributed to all functional parts of the trapezius muscle, at levels comparable to the SAN. CONCLUSIONS: Compared to the SAN, branches from cervical plexus provide a significant amount of neural input to all parts of the trapezius muscle. Intraoperative nerve monitoring can be used in routine neck dissections to detect these branches, which may be important following surgical injury to the SAN.

Empty fenestration of the internal jugular vein: a rare phenomenon.

Though there are common variations of the internal jugular vein (IJV), fenestrations are extremely rare. The lateral branch of the accessory nerve classically goes through the fenestration. We report a case of an empty fenestration of the IJV that was discovered during clearance of cervical lymph nodes. Original operative and radiographic images are shown.

High division of the spinal accessory nerve and communication with a C2 branch of the cervical plexus: a previously unreported anatomical variant.

Anatomical variations of the spinal accessory nerve are well known. We describe a previously unreported variant in which the nerve divided high in level II after crossing the internal jugular vein and before entering the sternomastoid muscle. Both branches were joined by a communication from the C2 cervical root. We discuss the clinical implications of this finding.

Efectos de la técnica de arcos botantes para la abertura de la sutura occipitomastoidea en la cervicalgia mecánica / Effects of flying buttresses for the opening of the occipitomastoid suture in mechanical neck pain

Introducción: La cervicalgia mecánica (CM) podría considerarse un problema de salud pública, ya que afecta a casi la mitad de la población en algún momento de su vida. En el 14% de la población, tiene una duración de 6 meses o más, provocando limitaciones laborales, en las actividades de la vida diaria así y de ocio. Objetivo: Analizar los efectos inmediatos de la técnica con arcos botantes (TAB) para la abertura de la sutura occipitomastoidea (OM), realizada bilateralmente, sobre la amplitud articular cervical, el umbral de dolor a la presión (UDP) y la intensidad del dolor. Material y Métodos: Estudio experimental, controlado, aleatorizado, doble ciego. Treinta (n=30) sujetos con CM, distribuidos aleatoriamente en dos grupos, Grupo Experimental (GE)(n=15) que recibió la TAB bilateralmente, y Grupo Control (GC) (n=15) que no recibió ninguna intervención. En ambos grupos se evaluaron (antes y después), la amplitud articular cervical, el UDP, los Puntos gatillo de Trapecios superiores y Escalenos anteriores (algómetría), y la intensidad del dolor en reposo y con cada movimiento cervical mediante una escala numérica del dolor (END). Resultados: El GE presenta mejoras estadísticamente significativas para las variables algométricas del trapecio superior derecho(p=0,033),trapecio superior izquierdo(p=0,03), la OM izquierda(p=0,003), el escaleno izquierdo(p=0,043), la amplitud de movimiento en rotación izquierda(p=0,04) y la intensidad del dolor a la rotación izquierda (p=0,013). Observamos tendencia a la significación estadística de la amplitud del movimiento de lateroflexión izquierda (p=0,056). Conclusiones: La técnica con arcos botantes para la abertura de la OM, aplicada en pacientes con CMC, aumenta el UDP en los músculol s trapecios, escaleno izquierdo y la sutura OM izquierda, la amplitud de movilidad y disminuye el dolor, durante la rotación cervical izquierda (AU)

Introduction: Mechanical neck pain (CM) could be considered a public health problem, affecting almost half of the population at some point in their lives. In 14% of the population, it has a duration of 6 months or more, causing labor limitations in activities of daily life and leisure. Objective: To analyze the immediate effects of the technique with flying buttresses (TFB) for the opening of the occipitomastoid (OM) suture, conducted bilaterally on the cervical joint extent, the pain pressure threshold (UDP) and the pain intensity. Material and methods: Experimental study, controlled, randomized, double-blind. Thirty (n = 30) subjects with CM, randomized into two groups: Experimental Group (GE) (n = 15) bilaterally received the TAB and Control Group (CG) (n = 15) that did not receive any intervention. In both groups, the cervical joint amplitude were evaluated (before and after), as well as the UDP, the trigger points of the higher trapezoids and anterior scalenes (algometry) and pain intensity at rest and with each cervical movement using a numerical pain scale (END). Results: The GE introduces significant improvements for algometrical variables of the right upper trapezius (p = 0.033), left upper trapezius (p = 0.03), the left OM (p = 0.003), the left scalene (p = 0.043), the range of motion in left rotation (p = 0.04) and pain intensity in left rotation (p = 0.013). We observed a trend towards statistical significance of the range of left sidebending (p = 0.056). Conclusions: The flying buttress technique for the opening of OM, applied in patients with CMC, increases the UDP in the trapezius muscles, left scalene and left OM suture, range of motion and decreases pain during left cervical rotation (AU)

The lower cranial nerves: IX, X, XI, XII.

The lower cranial nerves innervate the pharynx and larynx by the glossopharyngeal (CN IX) and vagus (CN X) (mixed) nerves, and provide motor innervation of the muscles of the neck by the accessory nerve (CN XI) and the tongue by the hypoglossal nerve (CN XII). The symptomatology provoked by an anomaly is often discrete and rarely in the forefront. As with all cranial nerves, the context and clinical examinations, in case of suspicion of impairment of the lower cranial nerves, are determinant in guiding the imaging. In fact, the impairment may be located in the brain stem, in the peribulbar cisterns, in the foramens or even in the deep spaces of the face. The clinical localization of the probable seat of the lesion helps in choosing the adapted protocol in MRI and eventually completes it with a CT-scan. In the bulb, the intra-axial pathology is dominated by brain ischemia (in particular, with Wallenberg syndrome) and multiple sclerosis. Cisternal pathology is tumoral with two tumors, schwannoma and meningioma. The occurrence is much lower than in the cochleovestibular nerves as well as the leptomeningeal nerves (infectious, inflammatory or tumoral). Finally, foramen pathology is tumoral with, outside of the usual schwannomas and meningiomas, paragangliomas. For radiologists, fairly hesitant to explore these lower cranial pairs, it is necessary to be familiar with (or relearn) the anatomy, master the exploratory technique and be aware of the diagnostic possibilities.

Do grossly identifiable ganglia lie along the spinal accessory nerve? A gross and histologic study with potential neurosurgical significance.

OBJECTIVE: To elucidate further the anatomy of focal enlargements that have been observed along the spinal accessory nerve (SAN) as it courses within the posterior cranial fossa. METHODS: Dissection of the posterior cranial fossa was performed on 27 adult cadavers with attention to the SAN and any focal enlargements associated with it. RESULTS: Grossly, four specimens (14.8%) were found to have focal enlargements associated with the SAN within the posterior cranial fossa. These structures were in intimate contact with the dorsal aspect of the spinal portion of the SAN in all specimens and measured a mean diameter of 1.9 mm. One right-sided male specimen had two focal enlargements. All focal enlargements were found within 1 cm of the foramen magnum. Histologically, no ganglion or neuronal cells were identified within these focal enlargements in any specimen. These focal enlargements are best described as ectopic glial nests or heterotopias within the leptomeninges around the SAN. CONCLUSIONS: The focal enlargements located along the SAN should not be termed ganglia. These structures do not contain neural structures and should not be mistaken for pathology of the posterior fossa.

Dorsal approach in transfer of the distal spinal accessory nerve into the suprascapular nerve: histomorphometric analysis and clinical results in 14 cases of upper brachial plexus injuries.

PURPOSE: The spinal accessory nerve (SAN) is conventionally transferred to the suprascapular nerve (SSN) through an incision in the supraclavicular region (the anterior approach) to improve shoulder function in brachial plexus injuries. This approach carries a risk of partial denervation of upper trapezius muscle. Here we describe how dorsal nerve transfer through an incision placed directly over the scapular spine preserves the proximal branches to the upper trapezius muscle and allows nerve transfer close to target muscles. METHODS: We report our experience with the dorsal approach in 14 cases managed between February 2007 and January 2008. Results were compared with 21 control cases treated by the anterior approach. In addition, we submitted proximal cut ends of the SAN in 10 cases from the experimental group for histomorphometry. RESULTS: A total of 11 patients had C5 and C6 injuries, whereas 3 had associated C7 injuries. The denervation period ranged between 3 and 10 months. In all cases, the distal SAN could be transferred to the SSN without a graft. Histomorphometry revealed an average of 1,671 myelinated axons. Shoulder abduction and external rotation were restored in 13 and 9 cases, respectively, compared with 16 and 12, respectively, in the control group. Electromyography revealed the first sign of reinnervation of infraspinatus muscle at 23 ± 4 weeks, compared with 30 ± 4 weeks in the control group. Initial evidence of shoulder abduction appeared earlier in the study population (28 ± 4 vs 34 ± 4 weeks). Shoulder abduction and external rotation in the study group ranged between 70° and 170° and 30° and 80°, compared with 65° and 160° and 22° and 55° in the control group. Using the Medical Research Council (MRC) grading system, at 6 months postreconstruction, 13 patients had M4 power in the trapezius muscle, whereas 1 had M3, compared with 5 in the control group who displayed grade 3 weakness. CONCLUSIONS: A dorsal approach for transfer of the distal SAN into the SSN is an alternative and effective technique in restoring shoulder function in upper brachial plexus injuries. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic III.

Evaluation of jugular foramen nerves by using b-FFE, T2-weighted DRIVE, T2-weighted FSE and post-contrast T1-weighted MRI sequences.

PURPOSE: To assess the most effective magnetic resonance imaging (MRI) sequence for the visualization of the 9th, 10th, and 11th cranial nerves (glossopharyngeal, vagus, and accessory nerves, respectively) in their intraforaminal/canalicular courses. MATERIALS AND METHODS: Balanced fast-field echo (b-FFE), 3D-T2W DRIVE, T2W 2D TSE and post-contrast T1W MRI sequences were all applied and we tried to get the best sequence for the exact assessment of the 9th, 10th, and 11th cranial nerves. Six hundred nerves of 100 patients without symptoms of neurovascular compression were examined using the above sequences. Imaging analysis was graded as: a) nerves analyzed by certainty (score of 2), b) nerves analyzed partially (score of 1), and c) nerves not identified (score of 0). RESULTS: In all three nerves, the best sequence for the visualization of the cisternal and intraforaminal course was b-FFE, with 58%, 73%, 62%, and all together 64.3% success in showing the fascicles of the 9th-11th nerves. This sequence with a very short time of repetition, symmetrical and balanced gradient around the echo time allowed very fast imaging and a high signal to noise ratio. T2W TSE sequence was superior to the DRIVE T2W sequence in assessing the cisternal and intraforaminal part of all three nerves. Post-contrast T1W sequence was probably the worst sequence in showing all three nerves. CONCLUSION: b-FFE gradient echo MRI sequence with high spatial resolution is the optimal sequence for determining the courses of 9th-11th cranial nerves.

Neuritis ossificans of a cranial nerve.

The authors report the case of intracranial neuritis ossificans presenting as chronic accessory neuropathy. Neuritis ossificans is a rare reactive nerve disease that has been reported to affect systemic peripheral nerves. To the best of the authors' knowledge, this is the first documented case of neuritis ossificans observed in a cranial nerve. The lesion was revealed on imaging studies and appeared, intraoperatively, as a nonsessile intradural lesion with significant calcification of rootlets of the lower cranial nerves. Microscopically, the lesion featured zonal heterotopic calcification typical of neuritis ossificans. Although it is a rare entity, neuritis ossificans can be considered in the differential diagnosis of lower cranial nerve neuropathy.

The glossopharyngeal, vagus and spinal accessory nerves.

The glossopharyngeal, vagus and spinal accessory nerves are closely related anatomically, and to a certain extent, functionally. We present an overview of their anatomy, highlighting the important clinical and imaging implications. The main pathologic lesions arising from these nerves are also discussed and the imaging features reviewed.

Surgical challenges associated with the morphology of the spinal accessory nerve in the posterior cervical triangle: functional or structural?

OBJECT: The spinal accessory nerve (SAN) has been reported to have a distinctly coiled appearance in its course through the posterior cervical triangle of the neck. As this is unusual compared with other peripheral nerves including the cranial nerves, the present histological analysis was performed to further elucidate the reason for this anatomy with potential application in nerve injury and repair. METHODS: Ten adult cadavers underwent dissection of the neck. The SAN was harvested proximally and within the posterior cervical triangle. For comparison with other cranial nerves within the neck, the cervical vagus and hypoglossal nerves were also harvested. All nerves underwent histological analysis. Additionally, 2 human fetuses (11 and 20 weeks' gestation) underwent examination of the SAN in the posterior cervical triangle, and 3 randomly selected specimens were submitted for electromicroscopy. RESULTS: All SANs were found to have a straight gross configuration proximal to the posterior triangle and a coiled appearance within this geometrical area. Histologically, no differences were identified for the SAN in these 2 locations (that is, proximal to and within the posterior cervical triangle). The histology of the SAN both with routine analysis and electron microscopy was similar in both regions and to nerves used as controls (for example, vagus and hypoglossal nerves). Interestingly, both fetal specimens were found to have coiled SANs in the posterior cervical triangle. CONCLUSIONS: Based on this study, it appears that the tortuous course of the SAN in the posterior triangle arises from functional as opposed to structural forces. It is hoped that this analysis will provide some insight into the nature behind the morphology observed in the SAN within the posterior cervical triangle and aid in future investigations regarding its injury. Moreover, such a coiled nature of this nerve may assist the neurosurgeon in identifying it during, for example, neurotization procedures.