Spine In Asymptomatic Subjects Research Articles

Head-Trunk Kinematics During High-Velocity–Low-Amplitude Manipulation of the Cervical Spine in Asymptomatic Subjects: Helical Axis Computation and Anatomic Motion Modeling

ObjectiveThis study aimed to analyze the in vivo 3-dimensional kinematics of the head during cervical manipulation including helical axis (HA) computation and anatomic motion representation. MethodsTwelve asymptomatic volunteers were included in this study. An osteopathic practitioner performed 1 to 3 manipulations (high-velocity and low-amplitude [HVLA] multiple component technique) of the cervical spine (between C2 and C5) with the patient in the sitting position. During manipulation, head motion was collected using an optoelectronic system and expressed relative to the thorax. Motion data were processed to analyze primary and coupled motions and HA parameters. Anatomic motion representation including HA was obtained. ResultsDuring manipulation, average maximal range of motion was 39° (SD, 6°), 21° (SD, 7°), and 8° (SD, 5°) for lateral bending (LB), axial rotation (AR), and flexion extension, respectively. For the impulse period, magnitude averaged of 8° (SD, 2°), 5° (SD, 2°), and 3° (SD, 2°), for LB, AR, and flexion extension, respectively. Mean impulse velocity was 139°/s (SD, 39°/s). Concerning AR/LB ratios, an average of 0.6 (SD, 0.3) was observed for global motion, premanipulation positioning, and impulse. Mean HA was mostly located ipsilateral to the impulse side and displayed an oblique orientation. ConclusionThis study demonstrated limited range of AR during cervical spine manipulation and provided new perspectives for the development of visualization tools, which might be helpful for practitioners and for the analysis of cervical manipulation using HA computation and anatomic representation of motion.

Is Disc Degeneration Painful?

Low back pain (LBP) is the world's most debilitating condition, affecting every population. Although LBP can be multifactorial, disc degeneration has been suggested to be a determinant. Disc degeneration is characterized by chemical and morphological changes to the disc, which may usher in changes to its biomechanics, interplay with the endplates and subchondral bone, and may lead to an inflammatory response that can irritate invading nerve fibers. Such changes to the disc and its surrounding area may contribute to pain generation, whose duration and intensity is uncertain. However, a divide is present in epidemiological studies regarding the association of disc degeneration and LBP, leading to the conclusion that disc degeneration is not always synonymous with LBP. This could be attributed to study design, inadequate statistical analyses, and phenotyping issues of degenerative spine changes as well as LBP. In addition, throughout the years, advances in medical imaging have helped broaden the understanding of disc degeneration and imaging pain generators as well the predictive utility of such imaging for future pain development/severity. The evolution of pain genetics research has provided further understanding why some individuals may be more likely to experience pain than others in the setting of degenerative spine changes. Further attention to the phenotyping of spine degeneration has noted that patterns of spine changes may play a role in LBP. The field of OMICS-epidemiology and the identification of additional biomarkers (e.g., metabolomics, adipokines, etc.) could further broaden the understanding between the association of disc degeneration and LBP. In addition, the phenotyping of disc degeneration requires further attention, demanding revisitation and reclassification of long-held classification schemes as well as being conscious of a direct link to their clinical relevance. A global standardization of disc degeneration and LBP is needed to help facilitate the collaboration of large-scale consortiums to address such salient spine-related concerns. Disclosure of Interest None declared References Battié MC, Videman T, Levalahti E, Gill K, Kaprio J. Heritability of low back pain and the role of disc degeneration. Pain 2007;131(3):272–280 Boden SD, Davis DO, Dina TS, Patronas NJ, Wiesel SW. Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation. J Bone Joint Surg Am 1990;72(3):403–408 Cheung KM, Samartzis D, Karppinen J, Luk KD. Are “patterns” of lumbar disc degeneration associated with low back pain?: new insights based on skipped level disc pathology. Spine 2012;37(7):E430-E438 Chou D, Samartzis D, Bellabarba C, et al. Degenerative magnetic resonance imaging changes in patients with chronic low back pain: a systematic review. Spine 2011;36(21, Suppl)S43-S53 Eskola PJ, Lemmelä S, Kjaer P, et al. Genetic association studies in lumbar disc degeneration: a systematic review. PLoS ONE 2012;7(11):e49995 Fourney DR, Andersson G, Arnold PM, et al. Chronic low back pain: a heterogeneous condition with challenges for an evidence-based approach. Spine 2011;36(21, Suppl)S1-S9 Karppinen J, Shen FH, Luk KD, Andersson GB, Cheung KM, Samartzis D. Management of degenerative disk disease and chronic low back pain. Orthop Clin North Am 2011;42(4):513-528, viii Livshits G, Popham M, Malkin I, et al. Lumbar disc degeneration and genetic factors are the main risk factors for low back pain in women: the UK Twin Spine Study. Ann Rheum Dis 2011;70(10):1740–1745 Luoma K, Riihimäki H, Luukkonen R, Raininko R, Viikari-Juntura E, Lamminen A. Low back pain in relation to lumbar disc degeneration. Spine 2000;25(4):487–492 Samartzis D, Karppinen J, Mok F, Fong DY, Luk KD, Cheung KM. A population-based study of juvenile disc degeneration and its association with overweight and obesity, low back pain, and diminished functional status. J Bone Joint Surg Am 2011;93(7):662–670 Takatalo J, Karppinen J, Niinimäki J, et al. Does lumbar disc degeneration on magnetic resonance imaging associate with low back symptom severity in young Finnish adults? Spine 2011;36(25):2180–2189 Waris E, Eskelin M, Hermunen H, Kiviluoto O, Paajanen H. Disc degeneration in low back pain: a 17-year follow-up study using magnetic resonance imaging. Spine 2007;32(6):681–684 Samartzis D, Ito K, Wang JC. Disk degeneration and pain. Global Spine J 2013;3(3):125–126

An investigation of stress and pain perception during manual therapy in asymptomatic subjects.

Stress perceived by the patient during the application of a manual therapy treatment technique may account for the reported findings of sympathoexcitation and hypoalgesia immediately after its application. This study investigated whether there was a difference in the level of perceived stress and pain before, during and after the application of a treatment condition (treatment, placebo or control technique), or whether the difference related to the time course of subject involvement in the study.Twenty-four asymptomatic subjects participated in a double-blind, placebo-controlled, within-subjects study in which stress was measured with a stress rating scale and a stress visual analogue scale. Pain experienced by the subject during the application of the treatment technique was measured with a visual analogue scale and modified McGill pain questionnaire. There was no effect of the treatment condition on perceived stress, but there was a reduction in stress levels over the time course of involvement in the experiment, as demonstrated by pre-application levels of stress. Pain was not produced by the treatment technique.This study demonstrated that stress and pain were not features of the lateral glide manipulation of the cervical spine in asymptomatic subjects. If the dorsal periaqueductal grey region is responsible for the initial effects of manual therapy, as has been previously suggested, then stress and pain do not appear to play a role in activating this system during the application of a manual therapy treatment technique in asymptomatic subjects. Copyright 1999 European Federation of Chapters of the International Association for the Study of Pain.

Cross-sectional area of posterior extensor muscles of the cervical spine in asymptomatic subjects: a 10-year longitudinal magnetic resonance imaging study

There has been no prospective study on age-related changes of the extensor muscles of the cervical spine in healthy subjects. This study was conducted to elucidate any association between the changes in cross-sectional area of the extensor muscles of the cervical spine on MRIs and cervical disc degeneration or the development of clinical symptoms. Sixty-two subjects who underwent MR imaging by a 1.5-Tesla machine between 1993 and 1996 as asymptomatic volunteers in a previous study were recruited again 10 years later for this follow-up study. The mean interval between the studies was 11.0 ± 0.7 years. The cross-sectional areas of the multifidus, semispinalis cervicis, semispinalis capitis, and splenius capitis at C3-C4, C4-C5, and C5-C6 intervertebral levels were measured on T2-weighted axial images using Image J 1.42. The mean cross-sectional areas of the deep extensor muscles were 1,396.8 ± 337.6 mm(2) at the C3-C4 level, 1,514.7 ± 381.0 mm(2) at the C4-C5 level, and 1,542.8 ± 373.5 mm(2) at the C5-C6 level in the previous investigation. The cross-sectional areas were 1,498.7 ± 374.4 mm(2) at the C3-C4 level, 1,569.9 ± 390.9 mm(2) at the C4-C5 level, and 1,599.6 ± 364.3 mm(2) at the 10-year follow-up. An increase in the cross-sectional area of the muscles was more frequently observed in subjects in their tens to thirties in the initial study, while a decrease was more frequently observed in those in their forties and older in the initial study. Disc degeneration was not correlated with a change in extensor muscle volume. Development of shoulder stiffness during follow-up was significantly negatively correlated with a change in the cross-sectional area of the deep extensor muscles.

Age-Related Changes of Thoracic and Cervical Intervertebral Discs in Asymptomatic Subjects

Magnetic resonance imaging (MRI) study on degeneration of the thoracic spine in asymptomatic subjects. To investigate the incidence of degenerative MRI findings of the thoracic spine in asymptomatic subjects and to identify factors related to the degeneration of the thoracic discs. Studies on age-related degenerative changes of the thoracic spine are scarce. Ninety-four asymptomatic Japanese volunteers (48 men and 46 women, mean age of 48.0 +/- 13.4 years) underwent MRI of the thoracic and cervical spine and filled the questionnaire regarding life styles. The items evaluated on MRI using a numerical grading system were (1) decrease in the signal intensity of the intervertebral discs (DSI), (2) posterior disc protrusion (PDP), (3) anterior compression of the dural sac (ACD), and (4) disc space narrowing. Association between each degenerative MRI finding and several factors, including age, sex, smoking, sports, body mass index, and degeneration of cervical spine was investigated. Forty-four (46.8%) patients demonstrated positive degenerative MRI findings at 1 or more thoracic intervertebral levels. The percentage of the subjects with positive MRI findings was 37.2% in DSI, 30.9% in PDP, 29.8% in ACD, and 4.3% in disc space narrowing. The percentages of all MRI findings increased with aging. In 85 (90.4%) patients, degenerative MRI findings were positive in the cervical spine. DSI was significantly associated with age (odds ratio, 11.21, 95% confidence interval, 2.70-46.5), PDP with age (3.44, 1.02-16.61), smoking (4.94, 1.55-15.71) and presence of PDP in the cervical spine (4.25, 1.01-17.92), and ACD was associated with smoking (3.99, 1.28-12.44). Degenerative changes in the thoracic spine on MRI was observed in approximately half of the asymptomatic subjects, whereas their incidences were less frequent than those in the cervical spine. Factors significantly associated with degenerative changes in the thoracic spine included age, smoking, and degeneration in the cervical spine.

The effects of high-velocity low-amplitude thrust manipulation and mobilisation techniques on pressure pain threshold in the lumbar spine

Objective To compare changes in pressure pain threshold (PPT) following spinal high-velocity low-amplitude thrust manipulation (HVLAT) and spinal mobilisation. Design Fifty asymptomatic subjects (mean age 27 (6) years; 29 males and 21 females) volunteered to participate in a randomised controlled, singled blinded design study. Subjects were screened for suitability and were randomly allocated into one of three intervention groups where they received either a unilateral spinal HVLAT or a spinal mobilisation of the lumbar spine, or a sham ‘laser’ procedure (control). PPT measurements were made immediately pre- and post-intervention, using a hand-held algometer which was positioned directly over the lumbar spinous process. A two-way ANOVA with repeated measures was conducted to determine PPT changes between the groups. Statistical significance was set at the 0.05 level. Results There were no significant differences in PPT across time for each of the groups ( P = 0.584). The mobilisation group displayed a small increase, though not a significant change in the mean pressure pain threshold (0.434(0.55) kg/cm 2), although effect size was considered to be large (ES = 0.78). The HVLAT group demonstrated a decrease in the mean PPT (−0.173(0.48)) (ES = 0.36, small), and a smaller decrease was noted for the control group (0.105(0.425) kg/cm 2) (ES = 0.25, small). Conclusion Neither spinal HVLAT nor mobilisation had a significant effect on PPT of the lumbar spine in asymptomatic subjects. Only spinal mobilisation appeared to have a greater mean increase in PPT and effect size than the control group. Further investigation into the hypoalgesic effects of these techniques on symptomatic subjects is suggested.

Prevalence of Herniated Intervertebral Discs of the Cervical Spine in Asymptomatic Subjects Using MRI Scans

Prevalence of Herniated Intervertebral Discs of the Cervical Spine in Asymptomatic Subjects Using MRI Scans

Prevalence of Herniated Intervertebral Discs of the Cervical Spine in Asymptomatic Subjects Using MRI Scans

AbstractIntroduction. Our objective was to review articles that report the prevalence of cervical disc herniations in asymptomatic subjects using MRIs and conduct a qualitative systematic review.Methods. A MEDLINE search for articles published between 1974 and 2004 was performed, and five articles were retained in this review.Results. Teresi et al. (1987) studied 35 asymptomatic subjects retrospectively and 65 asymptomatic subjects prospectively, and found 20% of subjects aged 45–54 years, 35% of subjects aged 55–64 years, and 57% of subjects older than 64 years had cervical disc herniations/bulges. Boden et al. (1990) studied 63 asymptomatic subjects and found 10% of subjects of less than 40 years and 5% of subjects older than 40 years had disc herniations. Lehto et al. (1994) studied 89 asymptomatic subjects and found that each of 2 subjects (one 29 and the other 56 years) had a disc prolapse; the prevalence was 2.2%. Matsumoto et al. (1998) studied 497 asymptomatic subjects. They found that 70 of 2480 ...

Radiographic Analysis of the Sagittal Alignment and Balance of the Spine in Asymptomatic Subjects

There is an increasing recognition of the clinical importance of the sagittal plane alignment of the spine. A prospective study of several radiographic parameters of the sagittal profile of the spine was conducted to determine the physiological values of these parameters, to calculate the variations of these parameters according to epidemiological and morphological data, and to study the relationships among all of these parameters. Sagittal radiographs of the head, spine, and pelvis of 300 asymptomatic volunteers, made with the subject standing, were evaluated. The following parameters were measured: lumbar lordosis, thoracic kyphosis, T9 sagittal offset, sacral slope, pelvic incidence, pelvic tilt, intervertebral angulation, and vertebral wedging angle from T9 to S1. The radiographs were digitized, and all measurements were performed with use of a software program. Two different analyses, a descriptive analysis characterizing these parameters and a multivariate analysis, were performed in order to study the relationships among all of them. The mean values (and standard deviations) were 60 degrees 10 degrees for maximum lumbar lordosis, 41 degrees +/- 8.4 degrees for sacral slope, 13 degrees +/- 6 degrees for pelvic tilt, 55 degrees +/-10.6 degrees for pelvic incidence, and 10.3 degrees +/- 3.1 degrees for T9 sagittal offset. A strong correlation was found between the sacral slope and the pelvic incidence (r = 0.8); between maximum lumbar lordosis and sacral slope (r = 0.86); between pelvic incidence and pelvic tilt (r = 0.66); between maximum lumbar lordosis and pelvic incidence, pelvic tilt, and maximum thoracic kyphosis (r = 0.9); and, finally, between pelvic incidence and T9 sagittal offset, sacral slope, pelvic tilt, maximum lumbar lordosis, and thoracic kyphosis (r = 0.98). The T9 sagittal offset, reflecting the sagittal balance of the spine, was dependent on three separate factors: a linear combination of the pelvic incidence, maximum lumbar lordosis, and sacral slope; the pelvic tilt; and the thoracic kyphosis. This description of the physiological spinal sagittal balance should serve as a baseline in the evaluation of pathological conditions associated with abnormal angular parameter values. Before a patient with spinal sagittal imbalance is treated, the reciprocal balance between various spinal angular parameters needs to be taken into account. The correlations between angular parameters may also be useful in calculating the corrections to be obtained during treatment.

The effect of manipulation and mobilisation on pressure pain thresholds in the thoracic spine

High velocity low amplitude (HVLA) thrust manipulation and mobilisation are commonly used by manual therapists to relieve spinal pain and improve mobility. The aim of this controlled, single blinded study was to investigate the effect of manipulation and mobilisation on pressure-pain thresholds (PPT) in the thoracic spine in an asymptomatic population. Subjects (N=96) were screened for tender thoracic segments, and PPT measurements were made using an electronic pressure algometer immediately before and after treatment intervention. Subjects were randomly allocated into three intervention groups, and received either a single high velocity extension thrust, thirty seconds of extension mobilisation, or thirty seconds of sham treatment (control) consisting of ‘laser acupuncture’. Within-group pre and post-intervention PPT values were analysed using dependent t-tests, revealing significant changes in the mobilisation (p<0.01) and manipulation (p=0.04) groups, but not the sham treatment group (p=0.88). Analysis of mean group changes with a one-way ANOVA and post-hoc analysis revealed a significant difference between the mobilisation and control group (p=0.01), but no significant difference between the manipulation and control group (p=0.67). Pre-post effect sizes in the mobilisation group were medium to large (d=0.72), small to medium for manipulation (d=0.32), and small in the control group (d=0.02). Both manipulation and mobilisation produced significantly increased PPTs (decreased sensitivity to pressure) in the thoracic spine, whereas the sham treatment did not. Mobilisation appeared to be more effective than manipulation for increasing PPTs when applied to the thoracic spine in asymptomatic subjects.

An investigation into the production of intra-articular gas bubbles and increase in joint space in the zygapophyseal joints of the cervical spine in asymptomatic subjects after spinal manipulation

Objectives To analyze the size and density of cervical zygapophyseal joint spaces in asymptomatic subjects using computed tomography (CT) and plain film radiography. The joint spaces were analyzed before manipulation without traction, before manipulation with manual traction, after manipulation without traction, and after manipulation with manual traction. The data obtained before the manipulation were compared with data obtained after the manipulation to determine if significant alterations occurred. Design Twenty-two asymptomatic subjects were placed into 1 or more of 6 possible experimental groups. In all experimental groups, except for experiment 1, the subjects underwent: (step 1) a premanipulation radiograph and/or CT scan, (step 2) a premanipulation plus traction radiograph and/or CT scan, (step 3) a postmanipulation radiograph and/or CT scan, and (step 4) a postmanipulation plus traction radiograph and/or CT scan. Results Except for experiment 2, there was no significant change in the width, area, and density values of the zygapophyseal joint spaces immediately after the manipulation in either the traction or traction-free positions of the neck, and no visible radiolucent cavities were demonstrated in any view. Conclusion No evidence of gas in the joint space or obvious increase in zygapophyseal joint space width immediately after the manipulation was found. This was evident in both the traction and traction-free postmanipulation scans and plain film images. This is not consistent with the current understanding of cavitation in joints, in particular, the refractory period.

Spinal reflex excitability changes after cervical and lumbar spinal manipulation: a comparative study

Background context: Spinal manipulation (SM) is a commonly employed nonoperative treatment modality in the management of patients with neck, low back or pelvic pain. One basic physiologic response to SM is a transient decrease in motoneuron activity as assessed using the Hoffmann reflex (H-reflex) technique. Previous research from our laboratory indicates that both SM with a high-velocity, low-amplitude thrust and mobilization without thrust produced a profound but transient attenuation of motoneuronal activity of the lumbosacral spine in asymptomatic subjects. To date, effects of cervical SM procedures on the excitability cervical motoneuron pools are unknown. Purpose: The objective of this research was to a gain a more complete understanding of the physiologic effects of SM procedures on motoneuron activity, by comparing the effects of regional SM on cervical and lumbar motoneuron pool excitability. Study design/setting: Maximal H-reflex amplitudes were recorded before and after SM in both the cervical and lumbar regions of asymptomatic subjects in two successive experimental sessions. Patient sample: Asymptomatic, young healthy volunteers were used in this study. Outcome measures: Changes in flexor carpi radialis and gastrocnemius H-reflex amplitudes before and after SM procedures. Methods: H-reflexes recorded form the tibial and median nerves were evaluated before and after lumbar and cervical SM, respectively. Results: Both Lumbar and cervical SM produced a transient but significant attenuation of motoneuron excitability. The attenuation of the tibial nerve H-reflex amplitude was proportionately greater than that of the median nerve, which occurred after cervical SM. Conclusions: SM procedures lead to transient suppression of motoneuron excitability, as assessed by the H-reflex technique. Lumbar spine SM appears to lead to greater attenuation of motoneuron activity compared with that of the cervical region. Thus, these two distinct regions of the spine may possess different responsiveness levels to spinal manipulative therapy.

Influence of standardized mobilization on the posteroanterior stiffness of the lumbar spine in asymptomatic subjects.

Spinal mobilization is commonly used to relieve pain and assist recovery of mobility in individuals with low back pain. Fundamental to this concept is the belief that spinal mobilization will influence the mechanical properties of the symptomatic motion segment. The objective of the present study was to examine the segmental effects of a standardized mobilization procedure on the posteroanterior (PA) stiffness of the lumbar spine. Audio and visual feedback was used to train a physiotherapist to perform PA mobilization at a consistent load and frequency. After training, twenty-four subjects without low back pain were recruited for the intervention phase of the study. The spinal posteroanterior mobilization (SPAM) apparatus was used to measure the PA stiffness of the lumbar spine at three measurement sites (L1, L3 and L5). The trained physiotherapist then applied the standardized PA mobilization technique via the L3 spinous process for two minutes. Following mobilization, PA stiffness was measured three times at the three locations. The physiotherapist was able to apply a standardized mobilization with a mean force of 146 N (standard deviation (SD) 8 N) at a frequency of 1.5 Hz. The first trial on each assessment demonstrated a pre-condition effect. Two minutes' PA mobilization resulted in no significant change in the PA stiffness of the lumbar spine at the level to which the mobilization was applied, or at the L1 and L5 segments. The 95% confidence intervals (CI) of the difference in PA stiffness before and after testing included zero at each measurement site. Clinicians should pre-condition the spine when assessing PA stiffness both before and after interventions. A standardized mobilization of 150 N at 1.5 Hz for two minutes had no segmental effect on spinal PA stiffness. Subsequent studies need to consider other mechanisms that may contribute to the changes that occur after PA spinal mobilization.

An investigation of stress and pain perception during manual therapy in asymptomatic subjects

Stress perceived by the patient during the application of a manual therapy treatment technique may account for the reported findings of sympathoexcitation and hypoalgesia immediately after its application. This study investigated whether there was a difference in the level of perceived stress and pain before, during and after the application of a treatment condition (treatment, placebo or control technique), or whether the difference related to the time course of subject involvement in the study. Twenty-four asymptomatic subjects participated in a double-blind, placebo-controlled, within-subjects study in which stress was measured with a stress rating scale and a stress visual analogue scale. Pain experienced by the subject during the application of the treatment technique was measured with a visual analogue scale and modified McGill pain questionnaire. There was no effect of the treatment condition on perceived stress, but there was a reduction in stress levels over the time course of involvement in the experiment, as demonstrated by pre-application levels of stress. Pain was not produced by the treatment technique. This study demonstrated that stress and pain were not features of the lateral glide manipulation of the cervical spine in asymptomatic subjects. If the dorsal periaqueductal grey region is responsible for the initial effects of manual therapy, as has been previously suggested, then stress and pain do not appear to play a role in activating this system during the application of a manual therapy treatment technique in asymptomatic subjects.

Abnormal magnetic-resonance scans of the cervical spine in asymptomatic subjects.

Abnormal magnetic-resonance scans of the cervical spine in asymptomatic subjects.

Abnormal magnetic-resonance scans of the cervical spine in asymptomatic subjects. A prospective investigation.

Abnormal magnetic-resonance scans of the cervical spine in asymptomatic subjects. A prospective investigation.

Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation.

Previous investigations with plain radiography, myelography, and computed tomography have shown that degenerative disease of the cervical spine frequently occurs in the absence of clinical symptoms. We studied the magnetic resonance-imaging scans of sixty-three volunteers who had no history of symptoms indicative of cervical disease. The scans were mixed randomly with thirty-seven scans of patients who had a symptomatic lesion of the cervical spine, and all of the scans were interpreted independently by three neuroradiologists. The scans were interpreted as demonstrating an abnormality in 19 per cent of the asymptomatic subjects: 14 per cent of those who were less than forty years old and 28 per cent of those who were older than forty. Of the subjects who were less than forty, 10 per cent had a herniated nucleus pulposus and 4 per cent had foraminal stenosis. Of the subjects who were older than forty, 5 per cent had a herniated nucleus pulposus; 3 per cent, bulging of the disc; and 20 per cent, foraminal stenosis. Narrowing of a disc space, degeneration of a disc, spurs, or compression of the cord were also recorded. The disc was degenerated or narrowed at one level or more in 25 per cent of the subjects who were less than forty years old and in almost 60 per cent of those who were older than forty. The prevalence of abnormal magnetic-resonance images of the cervical spine as related to age in asymptomatic individuals emphasizes the dangers of predicating operative decisions on diagnostic tests without precisely matching those findings with clinical signs and symptoms.