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E Date

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The rates of false-positive lumbar discography in select patients without low back symptoms.

STUDY DESIGN: Experimental disc injections in subjects with no history of low back symptoms. OBJECTIVE: To determine in an experimental setting the relative pain response and pain-related behavior in selected subjects without a history of low back pain undergoing lumbar discography. This study aimed to select a study population that more closely represented patients undergoing discography in clinical practice. SUMMARY OF BACKGROUND DATA: Previous work has shown that in young, healthy men with little degenerative disc disease and no history of low back problems, discographic injections usually did not cause significant pain. This group differed from the patients who usually undergo discographic evaluation in clinical practice. Most clinical patients are older, have significant degenerative disc disease, have behavioral changes associated with chronic pain, and often have confounding psychosocial troubles. The authors undertook to study discography in subjects without low back pain but with clinical profiles similar to patients undergoing discography in clinical practice. METHODS: Twenty-six individuals, mean age 43 years, with no history of low back pain had lumber discography according to the strict protocol of Walsh et al. Of these, 10 were pain-free; 10 had chronic neck and arm pain, but no low back symptoms; and 6 had primary somatization disorders without low back symptoms.- RESULTS: Significant positive pain response and pain-related behavior with discography were found in 10% of the pain-free group, in 40% of the chronic cervical pain group, and in 83% of the somatization disorder group completing the injections. Twenty-four subjects had negative control discs. Discs with annular disruption were more likely to be painful on injection, particularly in those individuals with ongoing compensation issues, chronic pain, or abnormal psychological testing.- CONCLUSION: If strict criteria are applied, the rate of false-positive discography may be low in subjects with normal psychometric profiles and without chronic pain. Significantly painful injections were very common in subjects with annular disruption and chronic pain or abnormal psychometric testing.

Adult↗

Epidural recording of nerve conduction studies and surgical findings in radiculopathy.

We developed a method of studying nerve conduction along proximal nerves and nerve roots by delivering supramaximal stimuli to the tibial and peroneal nerves within the popliteal space and recording compound nerve action potentials from an epidural needle electrode at the L4-L5 interspace. For the purpose of investigating lumbar radiculopathies, a battery of averaged potentials was developed that could be read side-to-side for symmetry of amplitude and latency. Decreased amplitude and/or increased latency in peroneal or tibial conduction studies was attributed to L5 or S1 root pathology respectively. We report on 22 patients who were studied with this method and subsequently went to surgery. To evaluate the ability of the procedure to predict surgical findings, we reviewed the last 155 patients that we studied using epidural recording to find those who had subsequently gone to surgery and were sufficiently documented to allow analysis. The review yielded 22 cases and 69 root levels whose condition had been reported at surgery and studied by our method. Agreement was above what might be expected by chance p < .0001 (7.462; sign). The agreement on nerve root condition between nerve conduction studies and surgical findings suggests that the procedure's usefulness for confirming and localizing pathology in nerve root entrapments is similar to that offered by nerve conduction studies for entrapment neuropathies elsewhere.

Action Potentials↗

Temperature correction factors derived from normal subjects may be invalid in demyelinating neuropathies.

This study investigates the temperature effect on motor nerve conduction velocity (MNCV) in patients with neuropathic processes. Fourteen subjects, ages 18-77 yr old, with a diagnosis of uremic polyneuropathies (UPN, n = 5), diabetic polyneuropathies (DPN, n = 6) or carpal tunnel syndrome (CTS, n = 3) and ten normal controls were studied. After limb cooling in a cold water bath for 30 min, skin temperatures were sequentially obtained from the volar midwrist. Motor conduction velocities were obtained at 2-3 degrees increments between 22 and 33 degrees C. Results indicated a large individual variability; 0.1 to 1.8 in the median and 0.8 to 2.0 m/s/degrees C in the ulnar nerve when all three groups are considered together. There was a significant difference between the correction factors for control v DPN and control v CTS. A significant difference was also present for UPN v DPN and UPN v CTS (p < 0.05). There was a positive correlation (r = 0.746, p = 0.0001) between the baseline conduction velocities and the size of the correction factors in all the subjects. The effect of temperature on MNCV appears to be inversely correlated with the severity of conduction slowing or demyelination. These findings suggest that the use of a correction factor may be invalid when studying a demyelinated nerve, and that the extremity should be warmed to a specific temperature before an electrodiagnostic study.

Adolescent↗