Original articleAn investigation into the effects of a unilaterally applied lumbar mobilisation technique on peripheral sympathetic nervous system activity in the lower limbs
Introduction
Lumbar spine disorders reportedly affect around 17.3 million people in the United Kingdom at an annual cost of £1bn to the NHS and £565m to private healthcare providers (Maniadakis and Gray, 2000).
Since the publication of the recommendations of the Clinical Standards Advisory Group (CSAG, 1994), the Royal College of General Practitioners (RCGP, 1998), the UKBEAM trial (UKBEAM Trial Team, 2004) and the Clinical Guidelines for the management of Persistent LBP (CSP, 2006), the use of spinal manipulative therapy (SMT) techniques for patients with lumbar symptoms has received support as a management strategy with 58.9% of UK therapists (Foster et al., 1999) and 83.7% of North American therapists (Li and Bombardier, 2001; Poitras et al., 2005) utilising SMT as a preferred treatment for patients with low back pain (LBP).
The available evidence regarding any neurophysiological or analgesic effects that occur as a result of treatment is not always clear (Assendelft et al., 1995). Although, the last two decades have seen the emergence of conceptual models supporting the use of SMT in the management of segmental pain and joint dysfunction (Zusman, 1986, Zusman, 2004; Wright, 1995). Hypothetical mechanisms of action of SMT include: direct physiological effects on articular and peri-articular structures (Wyke and Polacek, 1975), neurophysiological mechanisms at both spinal and supraspinal levels (Wright, 1995, Wright, 1999; Solly, 2004), endocrine/hormonal effects and a non-specific placebo effect (Zusman, 1986, Zusman, 2004; Katavich, 1998).
The dilemma facing the clinician, in determining the physiological and therapeutic effects of SMT interventions on patients, is the difficulty in accurately and quantitatively measuring the proposed effects on the key target tissue. Several researchers (Petersen et al., 1993; Vicenzino et al., 1994, Vicenzino et al., 1996; Wright and Vicenzino, 1995; Chiu and Wright, 1996; Sterling et al., 2001) have explored the neurophysiological basis of specific SMT techniques in the cervical spine and upper limbs, utilising the sympathetic nervous system (SNS) as a measure of neurophysiological response. Specific SNS changes have been reported following SMT, namely; sudomotor function (Petersen et al., 1993; Slater et al., 1994; Vicenzino et al., 1994; Wright and Vicenzino, 1995; Chiu and Wright, 1996; Sterling et al., 2001); cutaneous vasomotor changes (Petersen et al., 1993) and cardiac and respiratory functions (McGuiness et al., 1997; Vicenzino et al., 1998a). Chiu and Wright (1996) compared the effects of two different frequencies/speeds of oscillation (0.5 and 2 Hz) of a cervical spine joint mobilisation technique, and observed significant SNS responses with the 2 Hz technique. This work supported that of McGuiness et al. (1997) who investigated the effects of mobilisation techniques on the magnitude of the SNS response, revealing that an oscillatory technique produced the greatest effect. This is corroborated, in part, by the findings of Moulson and Watson (2006) who applied a non-oscillatory cervical sustained natural apophyseal glide (SNAG). Despite having a sympathoexcitatory response, the magnitude of this response was not significantly greater than the placebo condition within the treatment period suggesting that the oscillatory component of the technique is an important factor in changes to SNS activity (Kenney et al., 1991; Gebber et al., 1999).
Neurophysiological (SNS) effects following SMT have revealed that in humans SMT produces an immediate hypoalgesic and sympathoexcitatory effect on both asymptomatic and symptomatic subjects that are specific to mechanical nociception as opposed to thermal nociception and sympathoinhibition (Vicenzino et al., 1995, Vicenzino et al., 1996, Vicenzino et al., 1998b; Sterling et al., 2001). These findings have led to the concept that SMT may exert its initial effects by activating descending pain inhibitory systems (DPIS) from the peri-acqueductal gray (PAG) region of the brain and, depending on whether the response is excitatory or inhibitory could indicate whether or not it is a dorsal PAG or a ventral PAG response (Wright, 1995; Wright and Vicenzino, 1995). Kenney et al. (1991) have suggested the possibility of selective and functionally complementary coupling of different post-ganglionic sympathetic nerves and, specifically, the presence of an ipsilateral preference towards observed SNS discharge. So far, these findings have not yet been applied to physiotherapy research into SMT and the lumbar spine. Indeed, studies supporting this conceptual framework have been conducted on the cervical spine (Petersen et al., 1993; Slater et al., 1994; Vicenzino et al., 1995, Vicenzino et al., 1996, Vicenzino et al., 1998b; Wright and Vicenzino, 1995; Chiu and Wright, 1996; Sterling et al., 2001; Moulson and Watson, 2006) and upper limbs (Vicenzino et al., 1994; Simon et al., 1997).
This study aimed to explore the hypothesis that a specific mechanical mid-to-end range mobilisation technique, applied to the left Lumbar 4/5 ZP joint at a rate of 2 Hz, would result in a significant change from baseline in peripheral SNS activity (as measured by skin conductance—SC) that would be greatest in the ipsilateral leg during the intervention period compared to the contra-lateral limb, the placebo and the control conditions.
Section snippets
Subjects
The study recruited a convenience sample of 45 healthy, physiotherapeutically naïve, asymptomatic, non-smoking male volunteers (aged 18–25 years, mean 21.5 years, S.D.=1.85). All volunteers were further assessed for their suitability using inclusion and exclusion criteria as described in other studies (Vicenzino et al., 1994). Subjects were randomly assigned to one of the three subject groups using the third party, concealed randomisation method (Schulz et al., 1995). An all-male group was
Instrumentation and measurement
Physiological recording of SC was measured by a Biopac GSR100B Electro-dermal Activity Amplifier (MP30; Biopac Systems Inc., Santa Barbara, CA), employing a constant voltage technique and sampling the absolute, direct current SC at the rate of 20 samples per second.
Analysis of the SC data obtained involved calculation of the “Integral Measurement” for baseline, intervention and final rest periods. These were normalised to the time period of each experimental phase. Intervention period and final
Data analysis
With independent, matched-group designs, it is important to establish homogeneity of the subjects otherwise it is difficult to determine the influence that individuals may have on the final analysis (Sim and Wright, 2002).
Statistical analysis of the data was designed to test the three elements of the hypothesis: (1) that the SMT treatment would result in a PC in SC values from baseline that were greater than those of the placebo and control conditions; (2) that any PC observed would be greatest
Laboratory conditions
Room temperature was recorded at the beginning and end of each subject's experimental session as per published guidelines (Uematsu et al., 1988) with relative constancy within each session demonstrated (mean 24.9 °C, SD 0.275, range 24.4–25.5 °C) with a maximum within subject experimental room temperature variation being no more than 0.3 °C (mean 0.2 °C, SD 0.1 °C, range 0.0–0.3 °C).
Homogeneity of the matched groups
All 45 subjects completed the study (15 per group). Statistical analysis of subject variance (Levene's Test of
Discussion
The findings of this study demonstrated that a unilaterally applied antero-posterior accessory mobilisation technique administered at a rate of 2 Hz to the left side of the L4–5 segment resulted in statistically significant side-specific changes in peripheral SNS activity during the intervention period, and that this response was greater than those of the contra-lateral limb, and of both the placebo and control conditions.
To the authors’ knowledge, no previous studies have investigated whether
References (57)
- et al.
Credibility of analogue therapy rationales
Journal of Behavioural Therapy and Experimental Psychiatry
(1972) - et al.
A newly developed spinal simulator
Manual Therapy
(2000) - et al.
To compare the effects of different rates of application of a cervical mobilisation technique on sympathetic outflow to the upper limb in normal subjects
Manual Therapy
(1996) - et al.
Manipulative physiotherapists can reliably palpate nominated lumbar spinal levels
Manual Therapy
(1999) Differential effects of spinal manipulative therapy on acute and chronic muscle spasm: a proposal for mechanisms and efficacy
Manual Therapy
(1998)- et al.
The economic burden of back-pain in the UK
Pain
(2000) - et al.
Influence of a cervical mobilisation technique on respiratory and cardiovascular function
Manual Therapy
(1997) - et al.
Large segmental differences in spinal projections to the periaqueductal gray in the cat
Neuroscience
(1997) - et al.
The influence of an antero-posterior accessory glide of the glenohumeral joint on measures of peripheral sympathetic nervous system function in the upper limb
Manual Therapy
(1997) - et al.
Manual forces applied during posterior-to-anterior spinal mobilization: a review of the evidence
Journal of Manipulative and Physiological Therapeutics
(2006)
Cervical mobilisation: concurrent effects on pain, sympathetic nervous system activity and motor activity
Manual Therapy
The initial effects of a cervical spine manipulative physiotherapy treatment on the pain and dysfunction of lateral epicondylalgia
Pain
Cardiovascular and respiratory changes produced by the lateral glide mobilisation of the cervical spine
Manual Therapy
Hypoalgesia post-manipulation therapy: a review of a potential neurophysiological mechanism
Manual Therapy
Recent concepts in the neurophysiology of pain
Manual Therapy
Spinal manipulative therapy: review of some proposed mechanisms and a new hypothesis
Australian Journal of Physiotherapy
The relation between methodological quality and conclusions in reviews of spinal manipulation
Journal of the American Medical Association
The crossover study design and its clinical application
Nurse Researcher
Matching
British Medical Journal
Clinical guidelines for the physiotherapy management of persistent low back pain. Part 2. Manual therapy
Electromyographic and skin resistance responses to osteopathic manipulative treatment for low back pain
Journal of the American Osteopathic Association
Management of non-specific low back pain by physiotherapists in Britain and Ireland
Spine
Differential patterns of spinal sympathetic outflow involving a 10-Hz rhythm
Journal of Neurophysiology
Inter and intratherapist reliability of passive accessory movement technique
New Zealand Journal of Physiotherapy
Neurophysiological analysis of target-related sympathetic pathways—from animal to human: similarities and differences
Acta Physiologica Scandinavica
Differential relationships among discharges of postganglionic sympathetic nerves
American Journal of Physiology
Physical therapy management of low back pain: an exploratory survey of therapist approaches
Physical Therapy
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