Motor Neuron Excitability Attenuation as a Sequel to Lumbosacral Manipulation in Subacute Low Back Pain Patients and Asymptomatic Adults: A Cross-Sectional H-Reflex Study.

OBJECTIVE: The purpose of the study was to compare a time series of tibial nerve H-reflex trials between patients with subacute low back pain (LBP) and asymptomatic adults using pre and post high-velocity, low-amplitude (HVLA) spinal manipulation (SM) and control procedures. METHODS: Asymptomatic adults (n = 66) and patients with subacute LBP (n = 45) were randomized into 3 lumbosacral procedures: side-posture positioning, joint preloading with no thrust, and HVLA SM. A time series of 40 Hmax/Mmax ratios at a rate of 0.1 Hz were recorded in blocks of 10 trials at baseline and after the lumbosacral procedures at time points corresponding to immediately after, 5 minutes after, and 10 minutes after the procedure. Descriptive time series analysis techniques included time plots, outlier detection, and autocorrelation functions. A mixed analysis of variance model (group × procedure × time) was used to compare the effects of lumbosacral procedures on Hmax/Mmax ratios between the patients with subacute LBP and asymptomatic participants. RESULTS: The time series analysis and the significant lumbosacral × time interaction term (P < .05) indicated that inhibition of the Hmax/Mmax ratios at the 10-second postlumbosacral procedure time point was greatest after the HVLA SM procedure. The effects of lumbosacral procedures on Hmax/Mmax ratios were similar between patients with subacute LBP and asymptomatic participants. CONCLUSIONS: Although nonspecific effects of movement or position artifacts on the Hmax/Mmax ratio were present, a reliable and valid attenuation of the Hmax/Mmax ratio occurred as a specific aspect of HVLA SM in both asymptomatic adults and patients with subacute LBP.

Motor-evoked potentials recorded from lumbar erector spinae muscles: a study of corticospinal excitability changes associated with spinal manipulation.

OBJECTIVE: The purpose of this study was to determine if high-velocity, low-amplitude spinal manipulation (SM) altered the effects of corticospinal excitability on motoneuron activity innervating the paraspinal muscles. In a previous study using transcranial magnetic stimulation (TMS), augmentation of motor-evoked potentials (MEPs) from the gastrocnemius muscle after lumbar SM was reported. To date, there is no known report of the effect of SM on paraspinal muscle excitability. METHODS: The experimental design was a prospective physiologic evaluation of the effects of SM on corticospinal excitability in asymptomatic subjects. The TMS-induced MEPs were recorded from relaxed lumbar erector spinae muscles of 72 asymptomatic subjects. The MEP amplitudes were evaluated pre-SM and post-SM or conditions involving prethrust positioning and joint loading or control. RESULTS: There was a transient increase in MEP amplitudes from the paraspinal muscles as a consequence of lumbar SM (F([6,414]) = 8.49; P < .05) without concomitant changes after prethrust positioning and joint loading or in control subjects (P > .05). These data findings were substantiated by a significant condition x time interaction term (F([12,414]) = 2.28; P < .05). CONCLUSIONS: These data suggest that there is a postsynaptic facilitation of alpha motoneurons and/or corticomotoneurons innervating paraspinal muscles as a consequence of SM. It appears that SM may offer unique sensory input to the excitability of the motor system as compared to prethrust positioning and joint loading and control conditions.

A pilot study comparing two manual therapy interventions for carpal tunnel syndrome.

OBJECTIVE: The purpose of this study was to determine the clinical efficacy of manual therapy interventions for relieving the signs and symptoms of carpal tunnel syndrome (CTS) by comparing 2 forms of manual therapy techniques: Graston Instrument-assisted soft tissue mobilization (GISTM) and STM administered with the clinician hands. METHODS: The study was a prospective comparative research design in the setting of a research laboratory. Volunteers were recruited with symptoms suggestive of CTS based upon a phone interview and confirmed by electrodiagnostic study findings, symptom characteristics, and physical examination findings during an initial screening visit. Eligible patients with CTS were randomly allocated to receive either GISTM or STM. Interventions were, on average, twice a week for 4 weeks and once a week for 2 additional weeks. Outcome measures included (1) sensory and motor nerve conduction evaluations of the median nerve; (2) subjective pain evaluations of the hand using visual analog scales and Katz hand diagrams; (3) self-reported ratings of symptom severity and functional status; and (4) clinical assessments of sensory and motor functions of the hand via physical examination procedures. Parametric and nonparametric statistics compared treated CTS hand and control hand and between the treatment interventions, across time (baseline, immediate post, and at 3 months' follow-up). RESULTS: After both manual therapy interventions, there were improvements to nerve conduction latencies, wrist strength, and wrist motion. The improvements detected by our subjective evaluations of the signs and symptoms of CTS and patient satisfaction with the treatment outcomes provided additional evidence for the clinical efficacy of these 2 manual therapies for CTS. The improvements were maintained at 3 months for both treatment interventions. Data from the control hand did not change across measurement time points. CONCLUSIONS: Although the clinical improvements were not different between the 2 manual therapy techniques, which were compared prospectively, the data substantiated the clinical efficacy of conservative treatment options for mild to moderate CTS.

Spinal manipulation postepidural injection for lumbar and cervical radiculopathy: a retrospective case series.

OBJECTIVE: To describe the safety and potential therapeutic benefit of spinal manipulation postepidural injection in the nonsurgical treatment of patients with cervical and lumbar radiculopathy. METHODS: The study design was a retrospective review of outcomes of 20 cervical and 60 lumbar radiculopathy patients who underwent spinal manipulation postepidural injection in a hospital setting. Patients received either fluoroscopically guided or computed tomography (CT)-guided epidural injection of a combination of lidocaine and Depo-Medrol. The manual therapy consisted of an immediate postepidural application of flexion distraction mobilization and then high-velocity, low-amplitude spinal manipulation to the affected spinal regions. Outcome criteria were empirically defined as significant improvement, temporary improvement, or no change. The minimum follow-up time for all patients was 1 year. RESULTS: There were no complications associated with spinal manipulation, whereas 3 complications associated with the epidural injection procedure were noted. Of lumbar spine patients, 36.67% (n = 22) noted significant improvement, 41.67% (n = 25) experienced temporary improvement, and 21.67% (n = 13) reported no change. Of the patients undergoing spinal manipulation after cervical epidural injection, 50% (n = 10) noted significant improvement, 30% (n = 6) experienced temporary improvement, whereas 20% (n = 4) exhibited no change. CONCLUSIONS: These data suggest that spinal manipulation postepidural injection is a safe nonsurgical procedure to use in the treatment of the patient with radiculopathy of spinal origin. This is also the first report of the use of spinal manipulation postepidural injection in the cervical spine.

Spinal reflex excitability changes after lumbar spine passive flexion mobilization.

BACKGROUND: Flexion distraction has gained increased credibility as a therapeutic modality for treatment of low back pain. Although important work in the area has elucidated the intradiskal pressure profiles during flexion distraction, the accompanying neural responses have yet to be described. OBJECTIVE: The purpose of this pilot study was to assess neural reflex responses to motion with 3 degrees of freedom applied to the lumbar spine and to evaluate H-reflex responses of the soleus. METHODS: Subjects (n = 12) were measured for H-maximum reflexes determined from stimulus response recruitment curves measured in neutral prone position. The mean of 10 evoked H-waves (at H-maximum stimulus intensity) were measured in neutral position, flexion, left and right lateral flexion, and axial rotation of the trunk on an adjusting table. H-reflexes were expressed as a percentage of maximal M-wave for the criterion measure. Spinal range of motion was quantified by digitization. RESULTS: The data showed variation in some movement ranges, notwithstanding identical table positioning for all subjects. Mean H-reflex amplitude was decreased (15.2 +/- 5.8 mV to 13.8 +/- 5.8 mV), and the H/M ratio was also decreased in flexion compared with neutral (55.0% +/- 19.1% to 50.3% +/- 19.4%; P <.05). CONCLUSIONS: Trunk flexion is accompanied by inhibition of the motor neuron pool. Slight perturbations in numerous afferent receptors are known to significantly alter the H-reflex. The absence of measurable changes in lateral flexion and trunk rotation may indicate that both slow- and fast-adapting receptors could be involved in lumbar motion. These preliminary findings suggest the need for further dynamic motion studies of the flexion distraction neurophysiologic condition.

Comparison of tibial nerve H-reflex excitability after cervical and lumbar spine manipulation.

BACKGROUND: Previous investigations indicate that spinal manipulation leads to short-term attenuation of alpha-motoneuron excitability, when assessed by means of the Hoffmann reflex. Past studies, however, are limited to regional effects, such as lumbar manipulation effects on lumbar alpha-motoneuron activity. OBJECTIVE: This study compared and contrasted the effects of cervical and lumbar spine manipulation on the excitability of the lumbar alpha-motoneuronal pool in human subjects without low back pain, and compared the effects of cervical (nonregional) and lumbar (regional) spinal manipulation on lumbar alpha-motoneuron pool excitability in healthy subjects. The specific aim of this study was to determine if the inhibitory effects on the lumbar alpha-motoneuron pool associated with spinal manipulation are limited to the specific region in which the manipulative procedure is applied, or if rostral (cervical) manipulation can also influence caudal (lumbar) motoneuron excitability. METHOD: Thirty-six nonpatient human subjects were used to study the effect of cervical and lumbar spinal manipulation on the amplitude of the tibial nerve Hoffmann reflex, recorded from the gastrocnemius muscle. The Hoffmann reflex (H-reflex) technique allows for an indirect index of motoneuron pool excitability by means of peripheral nerve Ia-afferent fiber stimulation. Reflexes were recorded before and after spinal manipulative procedures. RESULTS: Lumbar spinal manipulation, as measured by amplitude changes of the tibial nerve H-reflex, attenuated lumbar alpha-motoneuronal activity. Suppression of motoneuronal excitability was significant (P <.05) but transient, with a return to baseline within 60 seconds after manipulation. Cervical spinal manipulation had no significant effect on lumbar motoneuron activity. CONCLUSION: These data indicate that the inhibitory effects of spinal manipulation on motoneuronal excitability are regional, rather than global.

The effect of chiropractic manipulation on salivary cortisol levels.

BACKGROUND: The stress response in humans is a healthy response and is necessary for life. The effects of chiropractic manipulation (CM), if any, on stress are ill-defined. Cortisol has been used as an accurate measure of the stress response system in humans. Salivary cortisol is a noninvasive technique to accurately quantify biologically active cortisol. OBJECTIVE: To determine whether basal salivary cortisol levels can be properly detected and whether CM has any direct effect on basal salivary cortisol levels in humans. METHODS: Subjects were adult male students attending a chiropractic college. Salivary samples were collected for 5 weeks. During Week 1, samples were collected by the students at home upon waking. During Weeks 2 through 5, home samples were collected upon waking and were followed by an additional time course of samples collected in a laboratory setting before and after CM. Salivary cortisol was measured by enzyme-linked immunoassay. RESULTS: Chiropractic manipulative therapy did not significantly change basal salivary cortisol levels. The time course of acute changes to cortisol levels was independent of testing week and group. A decrease in salivary cortisol was detected over time on each trial testing day. Overall, cortisol levels significantly decreased from the time of the home samples until the pretreatment laboratory measurement (P <.05). Cortisol levels subsequently decreased from pretreatment to 15 minutes after treatment (P <.05). After treatment, there were progressive decreases in cortisol levels from the 15- and 30-minute time points to the 60-minute time point (P <.05). CONCLUSION: The results of this pilot study suggest that there is no effect of CM on salivary cortisol levels in asymptomatic subjects. As such, we conclude that neither the anticipation of CM nor the spinal manipulative procedure itself induces a state of stress or anxiety.

First Prize: Central motor excitability changes after spinal manipulation: a transcranial magnetic stimulation study.

BACKGROUND: The physiologic mechanism by which spinal manipulation may reduce pain and muscular spasm is not fully understood. One such mechanistic theory proposed is that spinal manipulation may intervene in the cycle of pain and spasm by affecting the resting excitability of the motoneuron pool in the spinal cord. Previous data from our laboratory indicate that spinal manipulation leads to attenuation of the excitability of the motor neuron pool when assessed by means of peripheral nerve Ia-afferent stimulation (Hoffmann reflex). OBJECTIVE: The purpose of this study was to determine the effects of lumbar spinal manipulation on the excitability of the motor neuron pool as assessed by means of transcranial magnetic stimulation. METHODS: Motor-evoked potentials were recorded subsequent to transcranial magnetic stimulation. The motor-evoked potential peak-to-peak amplitudes in the right gastrocnemius muscle of healthy volunteers (n = 24) were measured before and after homolateral L5-S1 spinal manipulation (experimental group) or side-posture positioning with no manipulative thrust applied (control group). Immediately after the group-specific procedure, and again at 5 and 10 minutes after the procedure, 10 motor-evoked potential responses were measured at a rate of 0.05 Hz. An optical tracking system (OptoTRAK, Northern Digital Inc, Waterloo, Canada [<0.10 mm root-mean-square]) was used to monitor the 3-dimensional (3-D) position and orientation of the transcranial magnetic stimulation coil, in real time, for each trial. RESULTS: The amplitudes of the motor-evoked potentials were significantly facilitated from 20 to 60 seconds relative to the prebaseline value after L5-S1 spinal manipulation, without a concomitant change after the positioning (control) procedure. CONCLUSIONS: When motor neuron pool excitability is measured directly by central corticospinal activation with transcranial magnetic stimulation techniques, a transient but significant facilitation occurs as a consequence of spinal manipulation. Thus, a basic neurophysiologic response to spinal manipulation is central motor facilitation.