Vertebral pneumaticity is correlated with serial variation in vertebral shape in storks.

Birds and their ornithodiran ancestors are unique among vertebrates in exhibiting air-filled sinuses in their postcranial bones, a phenomenon called postcranial skeletal pneumaticity. The factors that account for serial and interspecific variation in postcranial skeletal pneumaticity are poorly understood, although body size, ecology, and bone biomechanics have all been implicated as influencing the extent to which pneumatizing epithelia invade the skeleton and induce bone resorption. Here, I use high-resolution computed-tomography to holistically quantify vertebral pneumaticity in members of the neognath family Ciconiidae (storks), with pneumaticity measured as the relative volume of internal air space. These data are used to describe serial variation in extent of pneumaticity and to assess whether and how pneumaticity varies with the size and shape of a vertebra. Pneumaticity increases dramatically from the middle of the neck onwards, contrary to previous predictions that cervical pneumaticity should decrease toward the thorax to maintain structural integrity as the mass and bending moments of the neck increase. Although the largest vertebrae sampled are also the most pneumatic, vertebral size cannot on its own account for serial or interspecific variation in extent of pneumaticity. Vertebral shape, as quantified by three-dimensional geometric morphometrics, is found to be significantly correlated with extent of pneumaticity, with elongate vertebrae being less pneumatic than craniocaudally short and dorsoventrally tall vertebrae. Considered together, the results of this study are consistent with the hypothesis that shape- and position-specific biomechanics influence the amount of bone loss that can be safely tolerated. These results have potentially important implications for the evolution of vertebral morphology in birds and their extinct relatives.

Magnetic Resonance Imaging Investigation of Cervical-Spine Meniscoid Composition: A Validation Study.

OBJECTIVE: The composition of cervical-spine meniscoids may have clinical significance in neck-pain conditions, but the accuracy of assessment of meniscoid composition in vivo using magnetic resonance imaging has not been established. The aim of this study was to compare cervical-spine meniscoid composition by magnetic resonance imaging with histologic composition. METHODS: Four embalmed cadaveric cervical spines (mean [standard deviation] age, 79.5 [3.7] years; 1 female, 3 male) underwent magnetic resonance imaging, allowing radiologic classification of lateral atlantoaxial- and zygapophyseal-joint (C2-3 to C6-7) meniscoids as either mostly fatty, mixed tissue, or mostly connective tissue. Subsequently, each joint was dissected and disarticulated to allow excision of meniscoids for histologic processing. Each meniscoid was sectioned sagittally, stained with hematoxylin and eosin, examined using light microscopy, and classified as adipose, fibroadipose, or fibrous in composition. Data were analyzed using the kappa statistic with linear weighting. RESULTS: From dissection, 62 meniscoids were identified, excised, and processed; 46 of these 62 were visualized with magnetic resonance imaging. For single-rater identifying structures, agreement between assessment of meniscoid composition by magnetic resonance imaging and by microscopy was fair (κ = 0.24; 95% confidence interval, 0.02-0.46; P = .02). CONCLUSION: Findings suggest that the accuracy of this method of magnetic resonance imaging assessment of cervical-spine meniscoid composition may be limited. This should be considered when planning or interpreting research investigating meniscoid composition using magnetic resonance imaging.

Morphological Characteristics of the Spinous Process of Axis: Clinical Implications for Cervical Spine Manipulation.

OBJECTIVE: The purpose of this study was to evaluate the osseous variation of the axis spinous process as it may relate to palpation by clinicians. METHODS: Morphologies of the bifid spinous process in the intact dry axis of 121 Chinese adult were investigated and classified. The angular deflection of the spinous processes, the bifid spinous processes (the bifid portions of the spinous processes), and the length of the bifid spinous processes were observed and measured. RESULTS: The bifid spinous process morphologies were classified into 4 types: inverted-V shape (n = 49), inverted-U shape (n = 50), M shape (n = 18), and nonbifid spinous processes (n = 4). The direction of the spinous processes and bifid spinous processes were consistent because they depended on each other's direction of deviation. When the correlation between angular deflection of spinous processes and bifid spinous processes was analyzed, the right deviations of spinous process specimens (29 cases) showed that angular deflections of spinous processes were equal to bifid spinous processes and there was no statistically significant difference seen between them (t = 0.286, P > .05), whereas in the left deviations of spinous process specimens (49 cases), the angular deflection of spinous processes were not equal in length, but bigger than the bifid spinous processes, which was statistically significant (t = -3.079, P = .003 < .05). CONCLUSION: The anatomical structure of the spinous processes and the bifid spinous processes vary from one another, but they exhibit some regularity. In clinical spinal manipulation practice, the anatomical characteristic of the axis should be taken into account during cervical static palpation, diagnostic imaging, and treatment.

Morphometric changes of the cervical intervertebral foramen: A comparative analysis of pre-manipulative positioning and physiological axial rotation.

BACKGROUND: Cervical foraminal impingement has been described as a source of radicular pain. Clinical tests and head motions have been reported for affecting the intervertebral foramen (IVF) dimensions. Although manual approaches are proposed in the management of cervical radiculopathy, their influence on the foraminal dimensions remains unclear. OBJECTIVES: To investigate the influence of pre-manipulative positioning versus cervical axial rotation on the foraminal dimensions of the lower cervical spine. METHODS: Thirty asymptomatic volunteers underwent CT scan imaging in neutral position and axial rotation or pre-manipulative positioning. The manipulation task was performed at C4-C5 following a multiple components procedure. 3D kinematics and IVF (height, width and area) were computed for each cervical segment. RESULTS: The results showed that foraminal changes are dependent on motion types and cervical levels. With reference to head rotation, IVF opening occurred on the ipsilateral side during pre-manipulative positioning while axial rotation involved the contralateral side. Regardless of the side considered, magnitudes of opening were similar between both attitudes while narrowing was lower at the target and adjacent levels during the pre-manipulative positioning. Some associations between segmental motion and IVF changes were observed for the target level and the overlying level. CONCLUSIONS: The present study demonstrated that pre-manipulative positioning targeting C4-C5 modified IVF dimensions differently than the passive axial rotation. The findings suggest that techniques which incorporate combined movement positioning influence segmental motion and IVF dimensions differently at the target segment, compared to unconstrained rotation. Further investigations are needed to determine the clinical outcomes of such an approach.

Validation of palpatory methods for evaluating anatomical bone landmarks of the cervical spine: a systematic review.

OBJECTIVE: The aim of this study was to systematically review the literature for validity of palpatory procedures for evaluating anatomical bone landmarks in the cervical spine. METHODS: A systematic search of electronic databases identified observational studies assessing validity and/or accuracy regarding evaluation of anatomical bone landmarks of cervical spine palpatory procedures. The databases used in the search included the US National Library of Medicine of the National Institutes of Health (MEDLINE/PubMed), the Regional Library of Medicine (Bireme), the Scientific Electronic Library Online (SciELO), the Physiotherapy Evidence Database (PEDro), the Latin American and Caribbean Health Sciences Literature database (LILACS), the Cochrane Library, and Coordination of Personnel Improvement of Higher Education (CAPES/Brazil). Data were extracted by a primary reviewer, and 2 independent reviewers used a critical appraisal tool to estimate the quality of the retrieved studies. The results were synthesized qualitatively within the Quality Assessment of Diagnostic Accuracy Studies criteria. After completing the synthesis and scoring, the reviewers applied classifications such as "low," "fair," and "good." RESULTS: The initial search yielded 69860 articles. After selection criteria were applied, 5 studies satisfied the eligibility criteria. Three studies verified the validity of the manual palpatory procedure, and 2 studies correlated the findings of the palpatory procedures with other measured results. According to Quality Assessment of Diagnostic Accuracy Studies criteria, 3 studies presented good methodological quality, and 2 presented fair methodological quality. Studies demonstrated an accuracy range from 51% to 87.8%. CONCLUSION: There are few studies that evaluate the validity of manual palpatory procedures for examining boney landmarks of the cervical spine. The 5 that were found showed fair to good methodological quality. However, we note that there may be poor external validity due to the sampling heterogeneity of these studies.

Function and structure of the deep cervical extensor muscles in patients with neck pain.

The deep cervical extensors are anatomically able to control segmental movements of the cervical spine in concert with the deep cervical flexors. Several investigations have confirmed changes in cervical flexor muscle control in patients with neck pain and as a result, effective evidence-based therapeutic exercises have been developed to address such dysfunctions. However, knowledge on how the deep extensor muscles behave in patients with neck pain disorders is scare. Structural changes such as higher concentration of fat within the muscle, variable cross-sectional area and higher proportions of type II fibres have been observed in the deep cervical extensors of patients with neck pain compared to healthy controls. These findings suggest that the behaviour of the deep extensors may be altered in patients with neck pain. Consistent with this hypothesis, a recent series of studies confirm that patients display reduced activation of the deep cervical extensors as well as less defined activation patterns. This article provides an overview of the various different structural and functional changes in the deep neck extensor muscles documented in patients with neck pain. Relevant recommendations for the management of muscle dysfunction in patients with neck pain are presented.

Transverse cervical nerve: implications for dental anesthesia.

The inferior alveolar nerve block (IANB) has the highest failure incidence of any dental anesthetic technique. Many authors have outlined potential reasons for these failures in permanent lower molars, including accessory innervations from the mylohyoid and mental foramen. However, the potential accessory innervation of posterior mandibular teeth from the transverse cervical nerve (TCN), a branch of ventral rami from the C2-C3 spinal nerves from the cervical plexus (CP), has been difficult to assess as a result of the small size and thickness of the mandibular accessory foramina and nerve branches, as well as due to the dissection technique performed. The goal of this study was to identify and trace the CP branches from fresh human cadaver tissue samples using the Sihler's technique. Two fresh human cadaver samples were used. Samples were fixed in neutralized formalin, macerated in potassium hydroxide, decalcified in acetic acid, stained in Ehrlich's hematoxylin, destained in acetic acid, and cleared in glycerin. Both specimens skin was dissected. The Sihler's technique delineated all nerves three dimensionally and helped to disclose structures of small size and thickness. The TCN from the CP, stained in blue, innervated the posterior mandible in one of the two samples. These results confirmed that the CP may supply accessory innervation to the inferior border of the posterior mandible through the TCN. These findings illustrate variations of anatomy that may account for IANB failures in posterior mandibular teeth and allows for clinical decisions for implementing supplemental anesthetic techniques.

Spinal cord injury induced by a cervical spinal cord stimulator.

OBJECTIVE: The use of cervical spinal cord stimulators for the treatment of refractory neck and upper extremity pain is widely accepted and growing in use as a treatment modality. This case highlights a previously unreported potential complication of spinal cord stimulators. METHODS: Analysis of a patient with a cervical spinal cord stimulator presenting with a spinal cord injury. Patient was followed from presentation in the emergency room until 1-year follow-up in the office. RESULTS: The patient in this case presented after a fall and sustained a cervical spinal cord injury induced by the electrodes of her spinal cord stimulator working as a space occupying mass. CONCLUSION: As more patients are undergoing implantation of spinal cord stimulators we must be aware of the long-term risks that can be encountered.

Morphological changes of the in vitro cervical vertebral canal and its cast form during flexion, extension, and lateral bending.

OBJECTIVE: The purpose of this study was to investigate and measure morphological changes in the vertebral canal and its cast form at the level of the cervical spine in vitro during flexion, extension, and lateral bending in cadaver specimens. METHODS: The morphological changes of vertebral canal and its contents were investigated and measured during experimental flexion, extension, and lateral bending of the cervical spine with 10 fresh specimens (Chinese); the cross-sections and sagittal diameters were also measured by pouring liquid wax into the intervertebral canal. RESULTS: During lateral bending, the nucleus pulposus was pushed to the opposite side and the inferior cervical nerve roots of the opposite side were stretched. Cross-sectional diameter at the level of C6-7 during flexion was larger than that in lateral bending (P < .05). Comparing extension with flexion, we found that changes in all segments' areas were significant (P < .05). There was no significant difference in the sagittal diameter at any segment during all postures (P > .05). CONCLUSIONS: During lateral bending, the nucleus pulposus of neck were pushed into the opposite side, and inferior cervical nerve roots of the opposite side were stretched. The C5, C6, and C7 nerve roots appeared to undergo excessive stretch when an excessive lateral bending beyond the physiologic range was undergone. This study provides some additional evidence about the mechanics of cervical spine motion.

Lack of efficacy of manual therapy in children and adolescents with suspected cervicogenic headache: results of a prospective, randomized, placebo-controlled, and blinded trial.

OBJECTIVE: Clinical trials concerning cervical spine manipulation and mobilization in children and adolescents with cervicogenic headache are lacking. METHODS: We performed a multicenter, prospective, randomized, placebo-controlled, and blinded trial in 52 children and adolescents (21 boys, 31 girls) aged 7-15. After prospective baseline documentation for 2 months patients were either assigned to placebo or true manipulation with another 2-month follow-up. Main outcome measures were defined as: percentage of days with headache, total duration of headache, days with school absence due to headache, consume of analgesics, intensity of headache. RESULTS: We did not find a significant difference comparing the groups with placebo and true manipulation with respect to the defined main outcome measures. CONCLUSIONS: We were not able to show an efficacy of cervical spine manipulation in 52 children and adolescents.

Neck pain.

Neck pain is less common than low back pain but still a relatively common reason for seeing a primary care physician. Therefore, it is necessary for the primary care physician to be comfortable with salient points in the history and to be able to perform a basic neurologic examination. Important aspects of the history and physical examination are reviewed. Important clinical syndromes and treatment options are also reviewed.

Measurement of cervical posture in the sagittal plane.

BACKGROUND: This article provides a historical perspective and an overview of different ways of measuring sagittal plane cervical posture in clinical and research settings. SPECIAL FEATURES: Measures of cervical posture are considered, in terms of their purpose, their reliability and validity, and their capacity to provide knowledge about cervical posture. SUMMARY: Despite technological advances in measurement techniques, there is still much to learn about cervical posture in terms of understanding how the neck balances the head against the force of gravity. The individual spinal segments of the neck assume different relative positions, depending on the individual's genetics; anatomical construction; occupational demands; muscle strength and endurance; as well as mental state, personality, and culture. Valid measures which can capture this objectively and reliably continue to challenge clinicians and researchers.

Cercopithecoid cervical vertebral morphology and implications for the presence of Theropithecus in early Pleistocene Europe.

While it is recognized that the overall configuration of the vertebral column, as well as the size and shape of individual vertebrae, differ within and between primate taxa, relatively little is known about the degree to which vertebral morphology reflects a phylogenetic signal or the degree to which vertebral elements can be used in accurate taxonomic classification. Isolated vertebrae are occasionally found in fossil assemblages, and proper taxonomic identification is necessary to make inferences about the animal's biology and place it in a broader phylogenetic and evolutionary context. Recently, three large primate cervical vertebrae (C3, C5, and C6) from Pirro Nord, Italy (early Pleistocene, late Villafranchian) were attributed to the genus Theropithecus based on size comparisons with extant cercopithecoid primates (Rook et al., 2004, J. Hum. Evol. 47, 267-277). These fossils were suggested to indicate an early dispersal of this genus out of Africa around 1.6-1.3 Ma possibly co-incident with early Pleistocene dispersals of Homo. Because of the potential importance of these fossils for interpreting Theropithecus evolution and the relatively few morphological data on primate cervical vertebral morphology, we examined the size and shape of cervical vertebrae in a large sample of extant cercopithecoid taxa (n=106). Specifically, we evaluated whether subfamily and genus level assignments can be made on the basis of isolated cervical elements. Discriminant analyses reveal that scaled shape variables are good discriminators of taxonomic affinity at the subfamily level but are poor discriminators at the genus level. Least-squares regressions show that raw linear dimensions of cervical vertebral morphology are good predictors of body mass in the extant sample. Our regression results produce a likely body mass estimate of 22-38 kg for the Pirro Nord cervical vertebrae. Based on these regression estimates, the poor ability to discriminate cervical vertebrae at the genus level, and paleoenvironmental reconstructions of Pirro Nord, it is unlikely that the Pirro Nord fossils can be confidently attributed to the genus Theropithecus. These findings have important implications for recent interpretations of the nature of Theropithecus dispersal out of Africa.

Manual fixation versus locking during upper cervical segmental mobilization. Part 2: an in vitro three-dimensional arthrokinematic analysis of manual axial rotation and lateral bending mobilization of the atlanto-axial joint.

BACKGROUND: Three-dimensional kinematic aspects of coupled motion during manual cervical mobilization have not previously been studied. Using an in vitro 3D-motion analysis method, the kinematic effects of two different segmental techniques for axial rotation and lateral bending mobilization of the upper cervical spine were investigated as a second part of the study (in part one, kinematic effects of flexion-extension mobilization have been investigated). METHODS: Axial rotation and lateral bending mobilization of the atlanto-occipital and atlanto-axial segments were analysed in vitro using an electromagnetic tracking device. Local reference frames were defined based on bony reference points that were registered using a 3D-digitizing stylus. Five embalmed and one fresh specimen were analysed. Segmental motion was registered simultaneously in the atlanto-occipital and the atlanto-axial joints during manual mobilization through the full range of axial rotation and lateral bending mobility. The 3D-kinematic aspects during regional mobilization were compared with those during segmental mobilization with manual fixation and during segmental mobilization using a locking technique. RESULTS: During both segmental axial rotation techniques of the atlanto-axial joint, a significant reduction of the coupled lateral bending and flexion-extension motion was observed. The locking technique also induced an increase in the main axial rotation component. During lateral bending mobilization of the atlanto-axial joint, the manual fixation technique reduced the effect on the coupled flexion-extension component significantly. INTERPRETATIONS: These results suggest that for manual segmental axial rotation and lateral bending mobilization of the upper cervical spine segmental manual fixation or locking may be preferred in different situations depending on the desired effects. This study brings additional information to the data provided by part 1 of this study on the 3D-arthrokinematic effects of flexion-extension mobilization.

Identification of greater occipital nerve landmarks for the treatment of occipital neuralgia.

Important structures involved in the pathogenesis of occipital headache include the aponeurotic attachments of the trapezius and semispinalis capitis muscles to the occipital bone. The greater occipital nerve (GON) can become entrapped as it passes through these aponeuroses, causing symptoms of occipital neuralgia. The aim of this study was to identify topographic landmarks for accurate identification of GON, which might facilitate its anaesthetic blockade. The course and distribution of GON and its relation to the aponeuroses of the trapezius and semispinalis capitis were examined in 100 formalin-fixed adult cadavers. In addition, the relative position of the nerve on a horizontal line between the external occipital protuberance and the mastoid process, as well as between the mastoid processes was measured. The greater occipital nerve was found bilaterally in all specimens. It was located at a mean distance of 3.8 cm (range 1.5-7.5 cm) lateral to a vertical line through the external occipital protuberance and the spinous processes of the cervical vertebrae 2-7. It was also located approximately 41% of the distance along the intermastoid line (medial to a mastoid process) and 22% of the distance between the external occipital protuberance and the mastoid process. The location of GON for anaesthesia or any other neurosurgical procedure has been established as one thumb's breadth lateral to the external occipital protuberance (2 cm laterally) and approximately at the base of the thumb nail (2 cm inferior). This is the first study proposing the use of landmarks in relation to anthropometric measurements. On the basis of these observations we propose a target zone for local anaesthetic injection that is based on easily identifiable landmarks and suggest that injection at this target point could be of benefit in the relief of occipital neuralgia.

Sagittal skin contour of the cervical spine: interexaminer and intraexaminer reliability of the flexicurve instrument.

OBJECTIVES: To evaluate reliability of a simple instrument, the flexicurve, in determining cervical sagittal skin contour. METHODS: This study obtained repeated random measurements involving 3 investigators and 30 subjects once per day over a 2-day trial period. Thirty normal subjects were examined for cervical spine skin contour twice by 3 separate investigators with a 1-day delay. With subjects in a neutral standing position, investigators placed the flexicurve on the posterior portion of the subject's neck from the external occipital protuberance to the vertebral prominens and traced the flexicurve shape onto paper. The tracings were divided into 6 equal arcs and digitized. Statistical computation was performed on the depth at 5 points, arc angle, and arc radius of curvature. Interexaminer and intraexaminer correlation coefficients (ICCs) were calculated to determine reliability. RESULTS: All interexaminer correlation coefficients were in the poor range (<0.40). For the arc radius, arc angle, depth at top one third, and depth at bottom two thirds, the intraexaminer correlation coefficients were in the poor range. For the 3 deepest depths, the intraexaminer correlation coefficients were in the fair range (0.4-0.50). CONCLUSION: The flexicurve showed marginal reliability with most (12/16) ICCs in the poor range (ICC <0.40) and 4 values in the fair range (0.4 < ICC < 0.5).

Environmental factors and cervical artery dissection.

A history of a minor precipitating event is frequently elicited in patients with a spontaneous dissection of the carotid or vertebral artery. Other precipitating events associated with hyperextension or rotation of the neck include practicing yoga, painting a ceiling, coughing, vomiting, sneezing, the receipt of anesthesia, and the act of resuscitation. Chiropractic manipulation of the neck has been associated with carotid artery dissection and, particularly, vertebral artery dissection. Another risk factor for spontaneous dissections seems to be a recent history of a respiratory tract infection. The possibility of an infectious trigger is supported by the finding of a seasonal variation in the incidence of spontaneous dissections, with a peak incidence in fall. A potential link with common risk factors for vascular disease, such as tobacco use, hypertension, and the use of oral contraceptives, has not been systematically evaluated, but atherosclerosis appears to be distinctly uncommon in patients with a dissection of the carotid or vertebral arteries. In conclusion, although any hypotheses on the pathogenic mechanisms linking environmental factors and dissection remain speculative at present, we believe that these hypotheses may contribute to better define the spectrum of pathogenic conditions predisposing a cervical artery to dissection and provide arguments to better investigate the single or combined effect of such susceptibility factors in future studies.

Conformal rotation therapy with central axis beam block is a feasible alternative to intensity-modulated radiotherapy for chordomas of the cervical spine.

AIMS: Paraspinal tumours, such as chordoma, represent a treatment challenge for oncologists, requiring high dose to the target volume without exceeding the tolerance dose of the spinal cord. Intensity-modulated radiotherapy (IMRT) is helpful in achieving sharp dose gradients and conformation of dose to the target volume. We present a simpler technique--conformal rotation therapy with a central axis beam block (CRT + BB), which can provide similar dose distributions. MATERIALS AND METHODS: A patient with a cervical chordoma developed postoperative recurrence and was treated with high-dose palliative radiotherapy. Treatment was delivered using CRT + BB, with three fixed beams and three coplanar arcs. A dose of 62 Gy in 31 fractions was delivered to the 100% isodose, giving a maximum spinal cord dose of 49.6 Gy. The patient relapsed 2 years later, and was re-treated using the same technique to a dose of 57 Gy in 30 fractions. Estimates of spinal cord repair rates in primates were used to determine the tolerance dose of the spinal cord for re-treatment. The patient remained well for a further 25 months before developing local recurrence, which was treated with palliative chemotherapy. RESULTS: Re-treatment plans using CRT + BB and IMRT were compared. Dose-volume histograms show equivalence of dose to the spinal cord, although the IMRT plan delivered a slightly higher dose to tumour and lower dose to surrounding soft tissues. CONCLUSION: Treatment using CRT + BB requires careful planning and discussion with neurosurgeons before surgery. The normal curvature of the cervical spine must be eliminated if possible, and the patient must be immobilised with the neck horizontal. If these geometric constraints can be satisfied, then CRT + BB can be used as a safe and effective alternative treatment to IMRT for tumours at this site.