Saturday, April 07, 2012

Pain and tissue damage are from different planets.

Kory Zimney at SomaSimple found and collected together a bunch of papers showing the complete lack of predictable correlation between "tissue damage" and pain, in the neck, shoulder and low back. Many of them are open access, so I thought I'd collect them here, too. 

1. Magnetic Resonance Imaging of the Lumbar Spine in People Without Back Pain

AbstractBACKGROUND:The relation between abnormalities in the lumbar spine and low back pain is controversial. We examined the prevalence of abnormal findings on magnetic resonance imaging (MRI) scans of the lumbar spine in people without back pain.METHODS:We performed MRI examinations on 98 asymptomatic people. The scans were read independently by two neuroradiologists who did not know the clinical status of the subjects. To reduce the possibility of bias in interpreting the studies, abnormal MRI scans from 27 people with back pain were mixed randomly with the scans from the asymptomatic people. We used the following standardized terms to classify the five intervertebral disks in the lumbosacral spine: normal, bulge (circumferential symmetric extension of the disk beyond the interspace), protrusion (focal or asymmetric extension of the disk beyond the interspace), and extrusion (more extreme extension of the disk beyond the interspace). Nonintervertebral disk abnormalities, such as facet arthropathy, were also documented.RESULTS:Thirty-six percent of the 98 asymptomatic subjects had normal disks at all levels. With the results of the two readings averaged, 52 percent of the subjects had a bulge at at least one level, 27 percent had a protrusion, and 1 percent had an extrusion. Thirty-eight percent had an abnormality of more than one intervertebral disk. The prevalence of bulges, but not of protrusions, increased with age. The most common nonintervertebral disk abnormalities were Schmorl's nodes (herniation of the disk into the vertebral-body end plate), found in 19 percent of the subjects; annular defects (disruption of the outer fibrous ring of the disk), in 14 percent; and facet arthropathy (degenerative disease of the posterior articular processes of the vertebrae), in 8 percent. The findings were similar in men and women.CONCLUSIONS:On MRI examination of the lumbar spine, many people without back pain have disk bulges or protrusions but not extrusions. Given the high prevalence of these findings and of back pain, the discovery by MRI of bulges or protrusions in people with low back pain may frequently be coincidental.
(What?? Over HALF of all these asymptomatic, no pain, no complaints, people, have a disc bulge??)

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

We performed magnetic resonance imaging on sixty-seven individuals who had never had low-back pain, sciatica, or neurogenic claudication. The scans were interpreted independently by three neuro-radiologists who had no knowledge about the presence or absence of clinical symptoms in the subjects. About one-third of the subjects were found to have a substantial abnormality. Of those who were less than sixty years old, 20 per cent had a herniated nucleus pulposus and one had spinal stenosis. In the group that was sixty years old or older, the findings were abnormal on about 57 per cent of the scans: 36 per cent of the subjects had a herniated nucleus pulposus and 21 per cent had spinal stenosis. There was degeneration or bulging of a disc at at least one lumbar level in 35 per cent of the subjects between twenty and thirty-nine years old and in all but one of the sixty to eighty-year-old subjects. In view of these findings in asymptomatic subjects, we concluded that abnormalities on magnetic resonance images must be strictly correlated with age and any clinical signs and symptoms before operative treatment is contemplated.

(You mean, like a third ... of ordinary people walking around without any pain, have a verifiably trashed back?)  

3. MRI Findings in Throwing Shoulders

Shoulders of throwing athletes are highly stressed joints and likely to have more structural abnormalities seen on magnetic resonance imaging scans. Prevalence and type of structural abnormalities, especially abnormalities of the rotator cuff tendons and the superolateral humeral head, and correlation of magnetic resonance imaging findings with symptoms and clinical tests, are not well known. Throwing and nonthrowing (symptomatic and asymptomatic) shoulders of 30 fully competitive professional handball players and 20 dominant shoulders of randomly selected volunteers were evaluated for comparison clinically and with magnetic resonance imaging. An average of seven abnormal magnetic resonance imaging findings was observed in the throwing shoulders; more than in the nonthrowing and the control shoulders. Although 93% of the throwing shoulders had abnormal magnetic resonance imaging findings, only 37% were symptomatic. Partial rotator cuff tears and mainly superolateral osteochondral defects of the humeral head were identified as typical throwing lesions. Symptoms correlated poorly with abnormalities seen on magnetic resonance imaging scans and findings from clinical tests. This suggests that the evaluation of an athlete’s throwing shoulder should be done very thoroughly and should not be based mainly on abnormalities seen on magnetic resonance imaging scans.

(Structural abnormalities don't go together with shoulder pain in pitchers? What? No correlation between tissue "damage" and pain?)

4. MRI of cervical intervertebral discs in asymptomatic subjects

We studied degenerative changes in the cervical intervertebral discs of 497 asymptomatic subjects by MRI and evaluated disc degeneration by loss of signal intensity, posterior and anterior disc protrusion, narrowing of the disc space and foraminal stenosis. In each subject, five disc levels from C2-C3 to C6-C7 were evaluated.
The frequency of all degenerative findings increased linearly with age. Disc degeneration was the most common observation, being present in 17% of discs of men and 12% of those of women in their twenties, and 86% and 89%  of discs of both men and women over 60 years of age. We found significant differences in frequency between genders for posterior disc protrusion and foraminal stenosis. The former, with demonstrable compression of the spinal cord, was observed in 7.6% of subjects, mostly over 50 years of age.
Our results should be taken into account when interpreting the MRI findings in patients with symptomatic disorders of the cervical spine.

(Even spinal cord compression? No symptoms? Wow. See? Asymptomatic people, bad images, pain and tissue damage have nothing to DO with each other!)

5. Natural history of lumbar disc hernia with radicular leg pain: Spontaneous MRI changes of the herniated mass and correlation with clinical outcome

A prospective sequential MRI study was done to investigate the morphologic changes of the lumbar disc hernia(LDH). We also studied the relationship between the MRI changes and the type of LDH and the clinical outcome. MRI was performed every 3 months from the onset for a maximum of 24 months in 42 patients with radicular leg pain and symptoms definitely diagnosed as caused by LDH. The size of the herniated mass was determined by the ratio of the anteroposterior diameter of the spinal canal to the maximum diameter of the LDH mass on T2-weighted axial images.
The clinical outcome was evaluated as excellent, good, or poor depending on leg pain and physical findings. The JOA (Japanese Orthopaedic Association) score for LDH was also used to assess the outcome.
Thirty-seven (88%) of the 42 patients showed >50% reduction of the hernia on MRI 3–12 months after onset, and the morphologic changes of the herniated mass were well correlated with the clinical outcome.

(Seriously? These things go away all by themselves? What?? Get out of town!)


Adam said...

These are good but the I think this article does it better:

They found that nearly 40% of patients who presented to the er with "life-threatening injuries" stated that they did not feel pain at the time of injury.

Diane Jacobs said...

Thanks Adam: Here is what I hope is a better link to that..

Acute pain in an emergency clinic: latency of onset and descriptor patterns related to different injuries.

"Features of acute pain were examined in patients at an emergency clinic. Patients who had severe, life-threatening injuries or who were agitated, drunk, or 'in shock' were excluded from the study. Of 138 patients who were alert, rational and coherent, 51 (37%) stated that they did not feel pain at the time of injury. The majority of these patients reported onset of pain within an hour of injury, although the delays were as long as 9 h or more in some patients. The predominant emotions of the patients were embarrassment at appearing careless or worry about loss of wages. None expressed any pleasure or indicated any prospect of gain as a result of the injury. The occurrence of delays in pain onset was related to the nature of the injury. Of 46 patients whose injuries were limited to skin (lacerations, cuts, abrasions, burns), 53% had a pain-free period. Of 86 patients with deep-tissue injuries (fractures, sprains, bruises, amputation of a finger, stabs and crushes), only 28% had a pain-free period. The McGill Pain Questionnaire was administered to patients who felt pain immediately after injury or after a delay, and revealed a normal distribution of sensory scores but very low affective scores compared to patients with chronic pain. The results indicate that the relationship between injury and pain is highly variable and complex."