Richard A. Sherman

Electromyographic recordings of 5 types of low back pain subjects and non-pain controls in different positions.

&NA; Surface EMG recordings of bilateral paraspinal muscle tension were measured on 207 subjects (29 non‐back pain controls, 20 individuals with spondyloarthritis, 52 with intervertebral disk disorders, 66 with unspecified musculoskeletal backache, 17 with some combination of the above 3 groups and 23 subjects with other types of back pain, including unknown, scoliosis and psychogenic) in 6 positions: standing, bending from the waist, rising, sitting with back unsupported, sitting with back supported and prone. Results of both individual and group analyses revealed a significant main effect of diagnosis. Post hoc analyses (Duncans) revealed controls to have significantly lower overall EMG levels than the intervertebral disk disorders and unspecified musculoskeletal backache groups. A significant diagnosis by position interaction was observed. Analysis of simple main effects revealed this to be due primarily to control subjects during the standing position having lower EMG levels than all other groups, and intervertebral disk disorder subjects having higher EMG levels than all other groups during the supported sitting position. The importance of clearly defined diagnostic categories in low back pain research and the utility of measuring subjects in various positions are discussed.

Electromyographic recordings of low back pain subjects and non-pain controls in six different positions: effect of pain levels

&NA; Surface electromyographic (EMG) activity recordings of bilateral paraspinal muscle tension were measured twice on 20 non‐pain controls and on 46 low back pain subjects (21 individuals with intervertebral disk disorders and 25 subjects with unspecified musculoskeletal backache) during 6 positions: standing, bending from the waist, rising, sitting with back unsupported, sitting with back supported, and prone. Back pain subjects were measured during both low pain and high pain states. Results revealed a non‐significant trend for all subjects, regardless of diagnosis, to have higher paraspinal muscle tension levels on the second (or high pain) assessment. A significant diagnosis by position interaction was observed which was similar to the interaction in our previous study which employed only a single measurement session. Analysis of simple main effects revealed this to be due to control subjects during the standing position having lower EMG levels than the back pain groups, and intervertebral disk disorder subjects having higher EMG levels than the other groups during the supported sitting position. As in our previous study, diagnosis was found to be a clinically significant factor, in that controls had much fewer clinically abnormal readings than back pain patients. The lack of a significant effect for pain state is congruent with findings in the headache literature. The importance of clearly defined diagnostic categories in low back pain research and the utility of measuring subjects in various positions is discussed, as are possible explanations for lack of significant pain state findings.

Gait changes in adult onset hemiplegia.

Multiple parameters of gait were evaluated in 50 adult acquired hemiplegic patients and 30 control patients with no history of gait abnormality and no deviation from normal gait by observational analysis. Findings in the hemiplegic group include: 1) increase in the proportion of the gait cycle spent in stance and double-limb support phases in both the normal and affected limb; 2) consistent deviation from normal gait pattern by observation and objective pattern analysis; 3) abnormal phasic activity of specific muscles and muscle groups in the affected limb; and 4) a consistent electrogoniometric deviation from normal joint ankle progression in the affected hip, knee and ankle. These data lend credence to the hypothesis that gait deviation in adult acquired hemiplegia follows a consistent pattern varying with the severity of central nervous system involvement. These data also provide a baseline from which to measure therapeutic intervention in this complex patient population.

The mystery of phantom pain: growing evidence for psychophysiological mechanisms

The direct, and much of the indirect, evidence supporting the existence psychophysiological mechanisms for phantom limb pain is reviewed. Phantom pain is shown to be a symptom class composed of different, but similarly described problems, each having its own underlying mechanisms. At least some descriptive types of phantom pain probably have mainly peripheral, as opposed to only central, origins. Although much of the direct data are preliminary, burning phantom pain is probably related to decreased blood flow in the residual limb, while cramping phantom pain is mainly related to spikelike muscle spasms in the major muscles of the residual limb. Little support is provided for psychological causes for phantom pain, but the expression of phantom pain does appear to be influenced by psychological mechanisms similarly to the ways other chronic pain conditions are influenced. The importance of a careful psychophysiological assessment of patients to treatment success is discussed. Because several different mechanisms are involved, no one treatment is likely to be effective for all of the different types of phantom pain. Appropriate combinations of self-regulation strategies aimed at controlling the underlying physiological problems are likely to be effective in reducing the incidence and severity of burning and cramping types of phantom pain.

Concurrent variation of burning phantom limb and stump pain with near surface blood flow in the stump.

Thermographic recordings of body temperature were performed on 30 consecutive amputees who reported stump and/or phantom limb pain. Each subject participated in between two and four recording sessions. Whenever possible, subjects came for recording sessions when their pain intensity was different from that of previous sessions. We found that a consistent inverse relationship occurred between intensity of pain and stump temperature relative to that of the intact limb for burning, throbbing, and tingling descriptions of both phantom and stump pain. Heat emanating from the limbs is an accurate reflection of near-surface blood flow. For subjects giving these descriptions of pain, tensing the limb was followed by a decrease in blood flow and an increase in pain. Neither of these relationships held for other descriptions of either phantom or stump pain.

Temporal relationships between changes in phantom limb pain intensity and changes in surface electromyogram of the residual limb

Previous studies of relationships between surface EMG of the residual limb and phantom pain have not shown which changed first. Thus, predictive relationships could not be demonstrated. 24 male (20) and female (4) amputees between the ages of 33 and 71 who reported either burning (3), cramping (8), shocking-shooting-stabbing (6), or a combination of these descriptions of phantom pain (7) participated in one or two recording sessions. Raw surface EMG from the major muscles of the residual limb was recorded while subjects activated an event marker to indicate changes in pain. All eight subjects with cramping phantom pain reported changes in pain after the recording showed sharply demarcated increases in EMG. Subjects reporting either shocking-shooting or burning pain did not show any consistent relationships between EMG and pain. Three of the four subjects reporting experiencing both shocking-shooting and cramping phantom pain simultaneously during recordings showed changes in EMG preceding changes in pain. Sensations of cramping phantom pain were preceded by increases in muscle tension in the residual limb in almost every instance for each of our subjects showing changes in cramping phantom pain. Thus, changes in muscle tension in the residual limb are likely to either be causes or close intermediaries for the cause of cramping phantom pain but not necessarily of other common descriptors.

Temporal stability of paraspinal electromyographic recordings in low back pain and non-pain subjects

This paper presents the results of two studies in which bilateral surface EMG recordings of paraspinal muscle tension were measured in 29 lower back pain and 20 normal subjects in 6 different positions (standing, bending from the waist, rising, sitting with back supported, sitting unsupported, prone) on two occasions, and a comparison of the data from both studies. Measures were highly reliable when examined using analysis of variance procedures. Statistically significant reliability coefficients were obtained when the absolute values of the measures were examined, although in some instances less than 20% of the variance was explained. When examined as relative [percent change from baseline (prone) condition] values, differences between the two groups were observed: the normals were statistically more reliable than lower back pain subjects during every condition. Implications for clinical work and both basic and applied research are discussed.

Relationships between near surface blood flow and altered sensations among spinal cord injured veterans.

Ten patients with clinical diagnoses of complete transverse spinal cord tissue destruction were interviewed about any sensations they felt below the level at which normal feelings were evident. All ten reported experiencing various feelings most of the time and nine reported that some of those feelings were usually quite painful. Videothermographs showing differences in skin temperature of 0.1 degrees celsius were taken to evaluate blood flow patterns to a depth of 1.5 cm. Changes in blood flow patterns were found to correlate highly with the level at which sensations changed from normal to abnormal and to correlate virtually exactly with the locations of pain reported from supposedly desenate areas.

Development of an ambulatory recorder for evaluation of muscle tension-related low back pain and fatigue in soldiers' normal environments.

We have developed an ambulatory recorder capable of monitoring low back muscle tension, trunk motion, and ratings of pain and fatigue. It weighs 22 ounces, fits into a canteen belt, and records every second for 18 hours. Eleven subjects wore the recorder during all walking hours for between 3 and 5 days. Six subjects had chronic low back pain due to muscle tension, three experienced low back pain after labor, and two had no pain. Movement and muscle tension correlated highly when subjects were pain free but not when they were in pain. Muscle tension increased before pain was experienced.

Reliability of an ambulatory electromyographic activity device for musculoskeletal pain disorders

A number of investigators in recent years have called for the development of devices that can monitor surface EMG levels in individuals normal environments for use with patients who suffer from disorders in which the etiology or maintenance of the pathology is presumed to be due at least in part to musculoskeletal dysfunction, such as low back pain, phantom limb pain and tension headache. This study examined the test-retest reliability of just such a device. Twenty-six healthy controls wore a lightweight (24 ounce) device which measured bilateral upper trapezius EMG, as well as peak and integral motion, for 5 consecutive days for up to 18 h each day. ANOVAs on the four measures revealed no difference between any of the four measures over the 5 days. Intra-class correlation coefficients for the two EMG variables across 5 days were both significant with alpha levels set at 0.01. The two EMG measures were highly correlated (r = 0.77); the two motion measures were also highly correlated (r = 0.60), but at a lower magnitude than EMG values; the relationship between EMG and motion was significant, but the magnitude of the between EMG motion correlations (0.26 and 0.35) were lower than the within EMG or motion ones. It was concluded that the test-retest reliability of the ambulatory monitoring device is within acceptable limits. Implications for the use of the device with musculoskeletal pain disorders--particularly headache--are discussed.