Dynamic Bulging of Intervertebral Discs in the Degenerative Lumbar Spine
From: Spine (Phila Pa 1976). 2009 Oct 16
The effect of postural change on degenerative lumbar discs was quantified using novel kinematic magnetic resonance imaging. The purpose is to describe the bulging of degenerative intervertebral lumbar discs in vivo subjected to different postural loads using a novel kinematic magnetic resonance imaging.
Symptomatic lumbar disc degeneration is a leading cause of pain and disability throughout the world. Over 70% of US citizens will experience a debilitating episode of low back pain. Earlier reports of degenerative disc changes are cadaver studies or are performed with recumbent MRI that eliminates the functional effects of gravity and muscle power. Little data are available on the behavior of degenerative intervertebral discs in vivo under physiologic loads.
A total of 513 patients obtained kMRI. Disc bulging beyond the intervertebral space was quantified during upright neutral, flexion, and extension imaging. The degree of intervertebral disc degeneration was correlated using the Pfirrmann Classification. Moderately degenerated intervertebral discs (grade III and IV) demonstrated greater bulging than mildly degenerated discs (grade II). Severely degenerated discs (grade V) also showed a trend toward greater bulging, but this was not significant. Grade I discs at all levels moved posteriorly in flexion and anteriorly in extension when compared to neutral posture. However, mild to severe (grade II-V) degenerative discs behaved differently in response to postural loads. Extension resulted in significant posterior bulging, while flexion did not demonstrate obvious anterior derangement.
Disc bulging increases with the severity of disc degeneration. Grade I discs demonstrate the expected sagittal migration in response to postural load. However, more degenerative discs behave less predictably, and spine extension may result in significant posterior disc bulging. Degenerative changes in the intervertebral disc significantly affect the kinematic patterns under postural load in vivo. Kinematic magnetic resonance imaging is a useful tool to quantify the kinematic behavior of degenerative intervertertebral discs.
Cervical segmental motion at levels adjacent to disc herniation as determined with kinetic magnetic resonance imaging
From: Spine (Phila Pa 1976). 2009 Oct 15;34(22):2389-94
This article investigates the effects of cervical disc herniation on kinematics at adjacent vertebral motion segments. Kinetic magnetic resonance imaging is an alternative method to conventional MRI, which allows evaluation of the cervical spine in a more physiologic, weight-bearing position, and acquisition of images in flexion, extension, and neutral alignment. Kinetic magnetic resonance imaging has previously been used to evaluate the effects of disc degeneration on cervical kinematics. A total of 407 patients with neck pain without prior history of surgery were evaluated using kinetic magnetic resonance imaging. Translational motion, angular variation, and disc height were measured at each segment from C2-C3 through C7-T1. Other factors including the degree of disc degeneration, age, gender, and vertebral segment location were analyzed in order to determine any predisposing risk factors for segmental instability adjacent to disc herniations.
Spinal levels above the disc herniation exhibited, on average, a 7.2% decrease in translational motion per mm of disc herniation, without significant change in angular motion. Levels below the herniation demonstrated a 5.2% decrease in angular motion per mm of disc herniation without significant change in translational motion. The degree of disc degeneration had no significant effect on adjacent level motion. Disc herniation had no significant impact on disc height at adjacent levels, although disc degeneration correlated with decreased disc height above and increased disc height below.
Although disc height, translational motion, and angular variation are significantly affected at the level of a disc herniation, no significant changes are apparent in adjacent segments. This study indicates that herniated discs have no effect on ROM at adjacent levels regardless of the degree of disc degeneration or the size of disc herniation, suggesting that the natural progression of disc degeneration and adjacent segment disease may be separate, unrelated processes within the cervical spine.
Irregular head movement patterns in whiplash patients during a trajectory task
From: Exp Brain Res. 2009 Oct 10
Chronic neck pain has been associated with disturbances in the sensorimotor control system in both non traumatic and whiplash related neck pain, such as postural stability disturbances, head and eye movement disturbances, erratic and irregular cervical motion patterns and stiffer, less flexible movement patterns. This points to centrally mediated somatosensory alterations with neck pain that may contribute to ongoing symptoms. Some motor impairments seem to particularly associate with a traumatic origin of the pain. Greater deficits in tests of head and eye movement control and decreased postural stability seem to distinguish whiplash associated disorder patients. Some of these deficits appear in association with the complaint of dizziness and neck pain intensity.
Patients with whiplash associated disorders have shown less accuracy in trajectory head motion compared to asymptomatic controls, which comply with clinical observations. The aim of this study was to investigate whether a trajectory head movement task can differ between whiplash associated disorders patients, chronic non traumatic neck pain patients and asymptomatic controls. Study groups included subjects with whiplash associated disorders (n = 35) with persistent neck pain after a car accident, chronic non traumatic neck pain (n = 45), and asymptomatic controls (n = 48). Head motion was recorded from an unsupported standing position using a 3D Fastrak device. A laser pointer was attached to the head and by moving the head the subjects were asked to trace a figure of eight displayed on the wall at three different paces (slow, moderate and fast). The motion signal was decomposed into 1 Hz frequency bands and angular velocity (deg/s) within each frequency band was calculated. Significantly higher angular RMS velocity was found in the whiplash associated disorders group compared to the two other groups for the slow paced test (3-4 and 4-5 Hz frequency bands) and the moderate paced test (3-4 Hz frequency band) indicating irregular and uncoordinated movements. Angular RMS velocity was associated with pain and dizziness, but only with severe symptom levels. In conclusion, irregular head movements during a complex task were found in the whiplash associated disorders group, indicating altered central sensorimotor processing. The irregularities were found within frequency levels observable to clinicians.
Cervical collar or physiotherapy versus wait and see policy for recent onset cervical radiculopathy: randomised trial.
From: BMJ. 2009 Oct 7;339:b3883
Cervical radiculopathy is a common disorder characterised by neck pain radiating to the arm and fingers corresponding to the dermatome involved. On examination, diminished muscle tendon reflexes, sensory disturbances, or motor weakness with dermatomal/ myotomal distribution can be found. The diagnosis is determined primarily on clinical grounds. Magnetic resonance imaging of the cervical spine usually shows the cause of the radiculopathy, which is usually spondylarthrosis or a herniated disc. This is often referred to as a pinched nerve.
Generally, degenerative cervical radiculopathy with subacute onset has a favourable prognosis, allowing a wait and see policy during the first six weeks. However, as pain is often excruciating during the first weeks to months, treatment to accelerate the improvement of pain and function would be highly valuable. Unfortunately, evidence is lacking for the effectiveness of any non-surgical treatment, including a wait and see policy, cervical collar, or physiotherapy. Two randomised trials comparing different non-invasive treatment methods in chronic cervical radiculopathy showed no benefit for physiotherapy or a cervical collar. Treatment in acute or subacute cervical radiculopathy has not yet been studied. Therefore,we evaluated the effectiveness of a semi-hard cervical collar in combination with taking as much rest as possible or physiotherapy and home exercises compared with a wait and see policy in recent onset cervical radiculopathy. We hypothesised that a treatment policy (collar or physiotherapy) would result in a faster decline in pain and improvement in function than would a wait and see policy.
To evaluate the effectiveness of treatment with collar or physiotherapy compared with a wait and see policy in recent onset cervical radiculopathy, neurology outpatient clinics in three Dutch hospitals included 205 patients with symptoms and signs of cervical radiculopathy of less than one month’s duration. Treatment with a semi-hard collar and taking rest for three to six weeks; 12 twice weekly sessions of physiotherapy and home exercises for six weeks; or continuation of daily activities as much as possible without specific treatment (control group).
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Cigarette smoking and chronic low back pain in the adult population
From: Clin Invest Med. 2009 Oct 1;32(5):E360-7
Chronic low back pain is one of the main causes of disability in the community. Although there have been studies suggesting an association between smoking and chronic low back pain, these studies were limited by the small numbers of patients, and they did not control for confounders. The objective of this study was to determine whether cigarette smoking is associated with an increased risk of chronic low back pain among adults.
Using Canadian Community Health Survey (cycle 3.1) data, 73,507 Canadians aged 20 to 59 yr were identified. Self-reported chronic low back pain status, smoking habits, sex, age, height, weight, level of activity and level of education were identified as well. Back pain secondary to fibromyalgia was excluded. Multivariate logistic regression analysis was used to detect effect modification and to adjust for covariates. Design effects associated with complex survey design were taken into consideration.
The prevalence of chronic low back pain was 23.3% in daily smokers and only 15.7% in non smokers. Age and sex were found to be effect modifiers, and the relationship between smoking and chronic low back pain risk was dependent on sex and age. The association between daily smoking and the risk of chronic low back pain was stronger among younger individuals. Occasional smoking slightly increased the odds of having chronic low back pain.
Daily smoking increases the risk of chronic low back pain among young adults, and this effect seems to be dose dependent. Back pain treatment programs may benefit from integrating smoking habit modification. Further research is required to develop effective prevention strategies.
Biomechanics of whiplash injury
From: Chin J Traumatol. 2009 Oct;12(5):305-14
Despite a large number of rear-end collisions on the road and a high frequency of whiplash injuries reported, the mechanism of whiplash injuries is not completely understood. One of the reasons is that the injury is not necessarily accompanied by obvious tissue damage detectable by X-ray or MRI. An extensive series of biomechanics studies, including injury epidemiology, neck kinematics, facet capsule ligament mechanics, injury mechanisms and injury criteria, were undertaken to help elucidate these whiplash injury mechanisms and gain a better understanding of cervical facet pain. These studies provide the following evidences to help explain the mechanisms of the whiplash injury: (1) Whiplash injuries are generally considered to be a soft tissue injury of the neck with symptoms such as neck pain and stiffness, shoulder weakness, dizziness, headache and memory loss, etc. (2) Based on kinematical studies on the cadaver and volunteers, there are three distinct periods that have the potential to cause injury to the neck. In the first stage, flexural deformation of the neck is observed along with a loss of cervical lordosis; in the second stage, the cervical spine assumes an S-shaped curve as the lower vertebrae begin to extend and gradually cause the upper vertebrae to extend; during the final stage, the entire neck is extended due to the extension moments at both ends. (3) The in vivo environment afforded by rodent models of injury offers particular utility for linking mechanics, nociception and behavioral outcomes. Experimental findings have examined strains across the facet joint as a mechanism of whiplash injury, and suggested a capsular strain threshold or a vertebral distraction threshold for whiplash-related injury, potentially producing neck pain. (4) Injuries to the facet capsule region of the neck are a major source of post-crash pain. There are several hypotheses on how whiplash-associated injury may occur and three of these injuries are related to strains within the facet capsule connected with events early in the impact. (5) There are several possible injury criteria to correlate with the duration of symptoms during reconstructions of actual crashes. These results form the biomechanical basis for a hypothesis that the facet joint capsule is a source of neck pain and that the pain may arise from large strains in the joint capsule that will cause pain receptors to fire.
