Pros and Cons of C2 Nerve Sectioning/Preservation in Posterior Fusion for Congenital Atlantoaxial Dislocation.

OBJECTIVE: Deliberate C2 nerve root sectioning and its preservation have been described during posterior fusion for atlantoaxial dislocation (AAD). However, the associated outcomes have been less studied, especially in congenital AAD. Our objective was to study the clinical outcomes after C2 nerve root sectioning and the feasibility of C2 preservation in these patients. METHODS: The data from 190 patients were retrospectively studied. The decision to cut or preserve the C2 nerve root was determined by the preoperative radiologic findings and intraoperative suitability of its preservation. During follow-up, the patients were questioned about C2 nerve-related dysfunction. The pros and cons of sectioning or preservation of the C2 nerve root and the related feasibility factors are also described. RESULTS: Complex C1-C2 anatomy that required extensive dissection and drilling was seen in 139 patients. After C2 nerve root sectioning in 178 patients, none reported bothersome hypoesthesia, paresthesia, or dysesthesia that required medication. However, 9 patients (5.1%) developed nonhealing occipital ulcers and most required flap coverage or a skin graft. C2 nerve root preservation is feasible with an adequate inferior C1 lateral mass and normal-size ganglion. In patients with C1-occipital condyle hypoplasia, extremely oblique joints, spondyloptosis, incurved occiput, pseudofacets, and anomalous vertebral artery, preservation of the C2 nerve root is difficult. CONCLUSIONS: The advantages of sectioning the C2 nerve root are many. However, a subset of patients is prone to morbid occipital neuropathic ulcers. After C2 nerve sectioning, one should be cautious of such complications. C2 nerve root preservation should be strongly considered for patients with favorable anatomy.

Immunohistochemical investigation of nerve fiber presence and morphology in elderly cervical spine meniscoids.

BACKGROUND CONTEXT: Innervation of anatomical structures is fundamental to their capacity to generate nociceptive impulses. Cervical spine meniscoids are hypothesized to be contributors to neck pain; however, their innervation is not comprehensively understood. PURPOSE: This study aimed to examine the presence and morphology of nerve fibers within cervical spine meniscoids and adjacent joint capsules. STUDY DESIGN: This is a cross-sectional study. PATIENT SAMPLE: The sample consists of cervical hemispines of 12 embalmed cadavers (mean [standard deviation] age 82.9 [6.5] years, six female, six left). Either the right or the left half of the cervical spine (hemispine) of each cadaver was included in the sample. So six left sides and six right sides of the cadaver cervical spines made up the 12 hemispines that formed the sample. METHODS: Cervical spine meniscoids and adjacent joint capsules were excised from lateral atlantoaxial and cervical zygapophyseal (C2-C3 to C6-C7) joints (n=67), then paraffin embedded. Meniscoids were sectioned sagittally (5 µm), slide mounted, and immunohistochemistry was performed using primary antibodies to neurofilament heavy (NF-H) and pan-neurofilament (Pan-NF) to identify nerve tissue. The study was supported by institutional graduate student funding. The authors have no conflicts of interest to declare. RESULTS: Seventy-seven meniscoids (23 lateral atlantoaxial, 54 cervical zygapophyseal) were extracted and processed (154 sections in total). Sixty-four individual nerve fiber bundles were identified (26 NF-H positive, 38 Pan-NF positive) from 14 meniscoids. Nerves immunoreactive to both NF-H and Pan-NF were identified in 13 of 77 meniscoids (10 of 14 lateral atlantoaxial joint) from 11 joints (eight cadavers). Nerves were always located in joint capsules except three exclusively Pan-NF immunoreactive nerve fiber bundles from two adipose meniscoids. CONCLUSIONS: The low nerve prevalence in elderly cervical spine meniscoids, with nerves only found in two adipose type meniscoids, suggests these structures may play a minimal role in cervical nociception generation in this demographic. The joint capsules, which were more frequently innervated, appear to be more likely generators of nociception in the elderly. Joint capsule nerves were mostly NF-H positive, indicating potential Aδ-fiber presence.

Histological examination of the human obliquus capitis inferior myodural bridge.

This study was designed to examine the anatomical relationship between the obliquus capitis inferior (OCI) muscle and the cervical dura mater at the histological level. Eight human cadavers, with an average age of 65 ± 7.9 years were selected from a convenience sample for suboccipital dissection. Twelve OCI muscle specimens were excised, 100% of which emitted grossly visible soft tissue tracts that inserted into the posterolateral aspect of the cervical dura. These 12 myodural specimens were excised as single, continuous structures and sent for H&E staining. One sample also underwent immuno-peroxidase staining. Microscopic evaluation confirmed a connective tissue bridge emanating from the OCI muscular body and attaching to the posterolateral aspect of the cervical dura mater in 75% of the specimens. Microtome slices of the remaining 25% were not able to capture muscle, connective tissue and dura within the same plane and were therefore unable to be properly analyzed. The sample sent for neuro-analysis stained positively for several neuronal fascicles traveling within, and passing through the OCI myodural bridge. This study histologically confirms the presence of a connective tissue bridge that links the OCI muscle to the dura mater and the presence of neuronal tissue within this connection warrants further examination. This structure may represent a component of normal human anatomy. In addition to its hypothetical role in human homeostasis, it may contribute to certain neuropathological conditions, as well.

Ventral innervation of the lateral C1-C2 joint: an anatomical study.

OBJECTIVE: Clinical observation has suggested the presence of ventral cervical extra-articular pain pathways in patients with C1-C2 joint pain. However, the existence of ventral innervation to the C1-C2 joint has not been documented. The objective of this study was to determine whether ventral innervation to the lateral C1-C2 joint exists, and to describe its relational anatomy. DESIGN: Gross and microscopic dissection was performed on 11 embalmed human cadavers. Wire segments were placed on identified ventral plexus nerves and radiographic imaging obtained in multiple planes. Histologic staining of prevertebral plexus nerves was performed with Osmium and compared with tissue controls. RESULTS: A superficial and deep cervical prevertebral plexus was identified terminating in the ventral joint capsule of the C1-C2 joint in all cadavers examined (21 sides). The location of the deep cervical prevertebral plexus was consistent within the C2 ventral gutter. Osmium staining confirmed the presence of myelin in plexus specimens. CONCLUSION: In this study, two cervical prevertebral plexuses (superficial and deep) were identified that have not previously been described. Terminal branches of the plexuses entered the ventral joint capsule of the lateral C1-C2 joint and were seen approaching the dens. Findings provide and explanation for the clinical observation that electrical stimulation in the C2 ventral gutter can reproduce headache in patients with C1-C2 joint pain.

Role of the C2 articular branches in occipital headache: an anatomical study.

One of the most important structures involved in the pathogenesis of occipital headache is the lateral atlanto-axial joint. Previous studies demonstrated that injection of this joint with local anesthetic can alleviate occipital headache, while injection of contrast medium exacerbates it. The aim of our study is to improve the understanding of the nerve supply to the lateral atlanto-axial joint by the C2 nerve elements, in order to determine the optimal target for an anesthetic block of this area. Ten C2 spinal nerves and roots were dissected in five embalmed cadavers with the aid of a 40X microscope and the lateral atlanto-axial joint was shown to be extensively supplied by articular branches of C2 nerve elements (dorsal ganglion, spinal nerve, and ventral ramus). Following our observations on their distribution, we propose a target for local anesthetic injection of the C2 articular branches that is based on reliable landmarks and is easily identifiable at fluoroscopy. We suggest that local anesthetic injection at this target point could be of benefit in the relief of occipital pain due to cervical trauma or degenerative disease involving the lateral atlanto-axial joint.

Occipital headaches stemming from the lateral atlanto-axial (C1-2) joint.

Studies in normal volunteers have demonstrated that the lateral atlanto-axial joints (C1-2) are capable of causing pain in the occiput, but few clinical studies have validated this source of occipital headache. The present study tested the null hypothesis that the lateral atlanto-axial joints are not a common source of occipital headache. Patients presenting with occipital pain underwent diagnostic blocks of their lateral atlanto-axial joints if they demonstrated clinical features presumptively suggestive of a C1-2 origin for their pain. Of 34 patients investigated, 21 obtained complete relief of their headache following diagnostic blocks, indicating that a C1-2 source of occipital pain is not rare. The clinical features used to select patients for blocks, however, had a positive predictive value of only 60%. Further study of headaches from C1-2 seems justified in order to establish more definitively the prevalence of this condition and how it might become better recognized in practice.

The optimal transarticular c1-2 screw length and the location of the hypoglossal nerve.

BACKGROUND: Injury to the hypoglossal nerve is a complication associated with transarticular C1-2 screw placement. This complication can be caused by a misdirected or too long screw. Little is known about the optimal screw length and its relationship to the hypoglossal nerve. METHODS: Twenty cervical spine specimens were used to study the optimal length of the transarticular C1-2 screw. Using the Magerl technique, a 3.0 mm drill bit was inserted into the C2 lateral mass, passing through the C1-2 facet joint and penetrating the upper portion of the ventral cortex of the lateral mass of the atlas. After drilling, the hole length was measured between the dorsal cortex of the C2 inferior articular process and the ventral cortex of the C1 lateral mass. In addition, six sagittal-sectioned cadavers were carefully dissected to observe the location of the hypoglossal nerve in the anterior aspect of the atlantoaxial region. RESULTS: The results of the measurements showed that the mean optimal screw path length for all specimens was 38.1 +/- 2.2 mm with a range of 34-43 mm. There was no significant difference between sexes in the screw path length (p 0.05). The hypoglossal nerve lies vertically in front of the lateral portion of the C1 lateral mass and the C1-2 facet joint. The area where the hypoglossal nerve lies is approximately 2-3 mm lateral to the middle of the anterior aspect of the C1 lateral mass. CONCLUSIONS: This study suggests that the mean optimal transarticular C1-2 screw length may be 38 mm; however, the determination of the accurate optimal C1-2 screw length should be made on an individual basis. Risk to the hypoglossal nerve can be eliminated if Magerl's technique is performed exactly.

Atlanto-occipital and lateral atlanto-axial joint pain patterns.

STUDY DESIGN: Five asymptomatic subjects underwent provocative injections of the lateral atlanto-axial and atlanto-occipital joints. OBJECTIVES: This study isolated and stimulated the lateral atlanto-axial and atlanto-occipital joints via fluoroscopically guided intra-articular injections to determine if they are potential pain generators. If they are pain generators, preliminary pain pattern maps will be constructed. SUMMARY OF BACKGROUND DATA: The cervical zygapophyseal joints (C2-3 to C6-7) are potential pain generators as demonstrated by referred pain induced via isolated intra-articular joint injections in normal subjects. Tentative referral patterns based on direct mechanical stimulation of the lateral atlanto-axial and atlanto-occipital joints have not been reported. METHODS: Five volunteers without histories of upper cervical pain underwent two joint injections each. In all five subjects, the left atlanto-occipital and right lateral atlanto-axial joints were stimulated via injection of contrast medium causing distension of the joint capsule. RESULTS: Referred pain was produced with all ten injections. The lateral atlanto-axial injections resulted in consistent referral patterns, whereas the atlanto-occipital referral patterns varied significantly. A tentative composite diagram of the experimentally induced pain was created for each joint. CONCLUSION: This study confirms the nociceptive ability of these cervical synovial joints. This study may assist the clinician in the differential diagnosis of head and neck pain.

[Earache and functional disorders of the cervical spine]. / Ohrschmerz und Funktionsstörungen der Halswirbelsäule.

The importance of the cervical spine in routine ENT practice is discussed, using the example of otalgia due to disorders of the cervical vertebra: Evaluation and follow-ups of 13,000 patients showed that 6% had diseases caused by the cervical spine. Frequency, pathophysiology and treatment results of cervicogenic otalgia are presented. The principles of adequate functional diagnostics and therapy of cervical spine disorders are explained.

The cervical zygapophysial joints as a source of neck pain.

Diagnostic cervical medial branch blocks and zygapophysial joint blocks were used to test the hypothesis that the cervical zygapophyseal joints can be the source of pain in patients with idiopathic neck pain. Complete temporary relief of all symptoms was obtained in 17 out of 24 consecutive patients. Two major groups of patients were those with neck pain and headache stemming from the C2-3 joints, and those with neck pain and shoulder pain stemming from the C5-6 joints. Internal-control observations in nine of the 17 patients established the diagnostic validity of the blocks used. The high yield of positive responders in this study probably reflects the propensity of patients with zygapophysial joint syndromes to gravitate to a pain clinic when this condition is not recognised in conventional clinical practice.

Neck tongue syndrome: operative management.

A 53-year-old woman with assimilation of the atlas to the occiput presented with paraesthesiae in the right half of her tongue and ipsilateral neck pain aggravated by head turning. After being intermittent for several years, the symptoms eventually became persistent and increasingly incapacitating. At operation, the C2 spinal nerves were found to be compressed by protuberant atlanto-axial joints, particularly on the right side. The superficial parts of the resected C2 spinal nerves showed a loss of both myelinated and unmyelinated nerve fibres. After operation, the patient experienced partial relief of her symptoms.