From: J Electromyogr Kinesiol. 2012 Jan 28. [Epub ahead of print]

The objectives of this article are to (1) describe spinal manipulation use by time, place, and person, and (2) identify predictors of the use of spinal manipulation. We conducted a systematic review of the English-language literature published from January 1, 1980 through June 30, 2011. Of 822 citations identified, 213 were deemed potentially relevant; 75 were included after further consideration. Twenty-one additional articles were identified from reference lists. The literature is heavily weighted toward North America, Europe, and Australia and thus largely precludes inferences about spinal manipulation use in other parts of the world.

In the regions covered by the literature, chiropractors, osteopaths, and physical therapists are most likely to deliver spinal manipulation, often in conjunction with other conservative therapies. Back and neck pain are the most frequent indications for receiving spinal manipulation; non-musculoskeletal conditions comprise a very small percentage of indications. Although spinal manipulation is more commonly used in adults than children, evidence suggests that spinal manipulation may be more likely used for non-musculoskeletal ailments in children than in adults. Patient satisfaction with spinal manipulation is very high.

From: J Orthop Sports Phys Ther. 2012;42(1):21.

Neck pain is very common and fortunately resolves quickly in most individuals. However, in certain cases neck pain can last longer and result in chronic pain, limited neck motion, and disability. In fact, chronic neck pain is the second leading cause of workers’ compensation claims in the United States. Treatments that can quickly reduce pain, increase motion, and improve the ability of the muscles to protect the neck may help decrease long-term disability associated with neck pain. A variety of manual therapy treatments are currently used to manage neck pain. These treatments include mobilization, which slowly and repeatedly moves the neck joints and muscles, and manipulation, which delivers a single, small, quick movement to the joints and muscles.

Researchers treated 107 patients. About half of these patients received a manipulation of the neck, on the part closest to the head, and of the upper back. The other patients received manual therapy that mobilized the spine without using manipulation. After 48 hours, the patients who received the manipulation treatment experienced a 58% decrease in pain and a 50% decrease in disability. By contrast, patients who received the mobilization treatment only had a 13% decrease in pain and actually showed a 13% increase in disability. In addition, the patients who received the manipulation had increased motion and improved control of their neck muscles compared to the patients in the mobilization group. The researchers concluded that the combination of upper neck and back manipulation was more effective in the first 48 hours of treatment than the mobilization treatment. Potential benefits include less pain, better neck motion, and improved ability to perform daily activities.

Chiropractors have known this for decades! Unfortunately, assimilation by the medical profession is a priority and ultimately relates to greed through political means.

Source: Neck pain: manipulation of your neck and upper back leads to quicker recovery

From: Mil Med. 2011 Jan;176(1):106-9.

Military aircrew who fly modern, high performance combat aircraft, commonly called fast jet aircrew routinely operate in altered lateral and gravitational force environment. Both acute neck pain and chronic neck pain are common complaints of fast jet aircrew, often resulting in lost workdays and reduced functional performance. The cause of neck pain in most cases is musculoskeletal injury. Spinal pathology, such as fractures of the cervical vertebrae, stenosis of the spinal canal, disc herniation and premature spinal degeneration have been attributed to exposure to altered gravitational force.

The underlying mechanism of neck pain in fast jet aircrew has been attributed to a combination of altered gravitational force environment, inadequacies of the human neck to tolerate these high loads and adopting head postures that can injure the neck during aerial combat maneuvers. Strategies including prefight stretching, in flight bracing and neck strengthening exercises have been suggested to possibly prevent neck pain in fast jet aircrew, few studies have evaluated the effectiveness of these preventative strategies on reducing the incidence and severity of flight related neck pain.

Little is known about the effective management and rehabilitation of neck pain in fast jet aircrew. Injury management and rehabilitative strategies are, however, well researched in other forms of neck pain and injury including chronic neck pain and whiplash like disorders. This study documents the strategies used by fast jet aircrew to manage and rehabilitate flight related neck pain.

To examine the type and effectiveness of various strategies used by Royal Australian Air Force fast jet aircrew in self-referral and management of flight-related neck pain, a 6-section, 18-question survey tool was distributed to 86 eligible Royal Australian Air Force aircrew. Selective results from the sections evaluating aircrew demographics, incidence of flight-related neck pain, and the self-referral strategies of aircrew to manage these injuries are presented here. Eighty-two Royal Australian Air Force fast jet aircrew responded to the survey. Ninety-five percent of the respondents experienced flight related neck pain.

The most commonly sought treatment modalities were on-base medical and physiotherapy services. Many respondents reported that currently provided on-base treatment and ancillary services such as chiropractic therapy are the most effective in alleviating symptoms. Further investigation into the effectiveness and safety of these ancillary therapies needs to be performed to allow appropriate consideration of their place in the management of neck pain in fast jet aircrew.

From: BMC Musculoskelet Disord. 2011 Feb 8;12(1):41. [Epub ahead of print]

Non-specific neck pain is frequent, with an annual prevalence estimated to be 30% to 50%. Often persistent or recurrent, neck pain is still being reported by 50% to 85% of patients 1 to 5 years after initial onset. Its course is usually episodic, and improvement is of variable degrees between episodes, but complete recovery is unusual for most patients. Manual therapy (mobilisation or manipulation), exercise intervention, low level laser therapy and, to a lesser extent, acupuncture, are more effective than no treatment, sham, or alternative interventions to stop episodes of neck pain. None of these strategies is, however, superior to any other. Evidence also indicates that supervised exercises with or without manual therapy are better than usual or no care and that a multimodal care approach combining exercise with manual therapy seems to be beneficial for non-specific chronic neck pain. Based on care episodes of 6 to 8 weeks with various blends of non-invasive interventions, no particular course of care improves the prognosis or appreciably affects the natural history of neck disorder or its recurrence. Evidence for the effectiveness of neck pain prevention strategies is therefore lacking.

Chiropractic intervention is usually directed toward neuromusculoskeletal problems, with around 25% of patients presenting to a chiropractor and complaining of neck pain. Spinal manipulative therapy is the chiropractor’s main therapeutic tool. A holistic paradigm is, however, at the foundation of this profession. A recent review of chiropractic preventive care indicates that more than 90% of surveyed chiropractors believe that it is helpful to patients. In the realm of public health, chiropractic preventive care is a strategy of tertiary prevention. In clinical practice, it is scheduled at regular intervals, is usually elective and is not based on the occurrence of symptoms. It is typically initiated after the resolution of a clinical problem, and is designed to preserve optimum health while minimizing recurrence. Only 1 randomised controlled trial investigating chiropractic preventive care efficacy in a non-specific low back pain population has been published. The results indicated that the group receiving preventive spinal manipulative therapy maintained improvement in disability level during the symptomatic period of care while the control group returned to its pre-trial disability level. However, no differences between the two groups were observed for pain. Other literature regarding chiropractic preventive care relates to surveys, focus groups, reviews or editorials, and many important characteristics of chiropractic preventive care have not been studied, such as its prevalence of use, its clinical indication, its effectiveness and its acceptance by patients.

Study participants were recruited if they had non-specific chronic neck pain, defined as pain of mechanical origin located in the anatomical region of the neck, with or without radiation to the head, trunk or limbs. The inclusion criteria were: aged between 18 and 60 years, neck pain lasting 12 weeks or more, no physical therapy, not currently under chiropractic care or rehabilitation for the neck area, willingness to adhere to the treatment protocol, and signed informed consent. Participants with concurrent headaches, non-radicular pain in the upper extremities and lower back pain were not excluded if neck pain was the main symptom. The exclusion criteria included neck pain due to a motor vehicle accident, neck surgery, severe osteoarthritis and inflammatory arthritis, neurological, cardiovascular, infectious metabolic and endocrine diseases, pregnancy and any cardinal signs of potential vertebral artery dissection.

Participants were advised to perform a home exercise program at least 3 times a week. The program was designed by an experienced kinesiologist and required low technology equipment (elastic tubing and foam physioballs). It included general range of motion (ROM) exercises that served for warm-up and cool down purposes, followed by 4 stretching/mobilization and 4 strengthening exercises (concentric and isometric contractions) of the cervical and upper thoracic spine, principally flexion/extension, lateral flexion and rotation of the cervical spine. Three series of each exercise were performed during a training session, with a 30- to 60-second rest period between each series. A complete training session lasted between 20 to 30 minutes.

This study hypothesised that participants in the combined intervention group would have less pain and disability and better function than participants from the 2 other groups during the preventive phase of the trial. In fact, all 3 groups showed primary and secondary outcomes scores similar to those obtained following the non-randomised, symptomatic phase. No significant change in HRQOL was associated with the preventive phase, but the 3 groups demonstrated statistically significant improvement in their fear avoidance behaviour scores over time. Overall spinal manipulation or spinal manipulation combined with exercises did not yield significant advantages when compared to the no treatment strategy.

The course of neck pain is usually described as episodes occurring over a lifetime with variable degrees of recovery between episodes. Furthermore, prior pain episodes are associated with poorer prognosis. In our study, more than 75% of experienced non-specific chronic neck pain, defined as recurring episodes or continuous pain, for more than 2 years at study onset. Given the course and natural history of neck pain, we expected that pain, function and disability of participants in the attention-control group would regress to pre-treatment levels during the 10 months of the preventive phase. Stabilisation of improvement in the attention-control group after the symptomatic phase raises questions regarding the causality of this change in the course of the disorder. The authors hypothesis relates to the attention-control group requiring more co-intervention of any type and choosing ice as a pain-relieving modality significantly more often than the 2 other groups. These additional strategies of self-management in terms of symptom attention-control and coping might explain, at least partially, the equivalence of the 3 groups in terms of pain, function and disability during the preventive phase of the trial.

Another plausible explanation for these results is the placebo effect, which refers to the outcome attributable to a procedure but not to its specific properties. Any perceived therapeutic action includes its specific and non-specific effects. The non-specific effects, also termed the “context of treatment”, represent the psychosocial aspect of every treatment. In this study, different clinicians were responsible for each of the 3 groups, and therefore the treating clinician (not only the treatment used) may have influenced the clinical outcomes. Many factors contribute to these outcomes, the 3 most often described being the patient, the provider and patient-provider interaction. From the patient’s perspective, the magnitude of the placebo response is highly variable between individuals, and patients’ expectations influence treatment outcomes, including the specific and non-specific effects. Chronic conditions with fluctuating courses, such as chronic neck pain, are usually more placebo-prone. Finally, many studies indicate that patient-provider interaction is a potent factor in health outcomes.

Many factors, such as a clear diagnosis, an opportunity for dialogue or the overall “context of treatment”, play a definite part in the placebo effect. It is therefore possible that being enrolled in a formal research project in a university setting heightens participants’ expectations of improvement, leading to an enhanced placebo effect and explaining, at least partially, the uniform response in the 3 groups. These non-specific effects would be principally attributable to the participants themselves and participant provider interaction. The statistically significant recovery in the 3 groups in fear avoidance behaviour scores over time might be an indication of such positive participant provider interaction.

Exercise adherence in the combined intervention group was 48.8%. This compares with previous estimates of adherence in home exercise programs for neck and low back pain, converging around 50%. This may in fact reflect the highest level of adherence for these clinical populations. Considering the overall benefits and relatively low risk associated with exercise, clinicians may consider this therapy has an adjunct to spinal manipulative therapy. However, several factors, such as frequent supervision and clarifications about exercises, are known to improve compliance and should consequently be considered in clinical trials involving exercise therapy.

The results of this study are important because there has been minimal previous research regarding the prevention of non-specific chronic neck pain. The results suggest that the mere fact of taking charge of and managing a patient for this condition might decrease the recurrence of pain episodes and, therefore, change the course of the disease. Considering the societal burden of non-specific chronic neck pain, the issue is worth investigating, both in terms of treatment efficacy and cost-effectiveness. Further research related to our hypothesis might be conducted in the form of a RCT.

The results also indicate that there is no additional benefit for patients with non-specific chronic neck pain to receive monthly preventive spinal manipulative therapy or monthly preventive spinal manipulative therapy with a home exercise program compared to meeting a chiropractor once every 2 months to discuss neck problems. In view of the rare but possible adverse reactions to cervical spinal manipulative therapy, this tends to reject chiropractic preventive care when spinal manipulative therapy is the main intervention. However, the premise of chiropractic preventive care stating that regular treatments, designed to preserve optimum health, will also minimize the recurrence of clinical problems, might hold true when intervention is geared towards reassurance, patient education, help with self-management and active care strategies.

A final implication of these results is the equivalence between the spinal manipulative therapy and combined intervention groups. The actual, best evidence regarding treatment for non-specific chronic neck pain is a combined approach involving manual therapy and exercise. It is possible that the best strategy for prevention of non-specific chronic neck pain might not be similar to the best strategy for treatment of this condition. Further research is warranted in this regard.

From: Man Ther. 2010 Aug 31. [Epub ahead of print]

Neck pain is a common musculoskeletal disorder in the general population. In Saskatchewan, Canada, Cote et al. reported that the age-standardized lifetime prevalence of neck pain was 66.7%. In a telephone survey performed in Hong Kong, Chiu and Leung reported that the lifetime prevalence of neck pain was 65.4% and the 12-month prevalence was 53.6% (41.0% in male, 59.0% in female). Neck pain is costly in terms of treatment, individual suffering, and time lost to work absentee.

Growing evidence has confirmed that the use of manipulation with exercise or the use of mobilization with exercise in treating neck pain has better clinical outcomes than other major and common modalities.

Owing to the intrinsic biomechanical linkage with the cervical spine, disturbances in the biomechanics of the thoracic spine could be a primary contributor to neck pain. Flynn et al. reported that with the use of thoracic manipulation, there was immediate improvement in neck pain. However the lack of comparative group in this trial renders the cause-and-effect relationship inconclusive. Many clinicians have intuitively adopted the use of thoracic manipulation to treat neck pain patients, although there is a lack of scientific evidence. Cleland et al. reported that thoracic spine is the area that is most often manipulated.

There are studies investigating the effect of thoracic manipulation in treating acute and subacute mechanical neck pain, but to date, no studies have investigated the effect in patients with chronic neck pain. In a randomized controlled trial, Cleland et al. demonstrated an immediate analgesic effect in patients with mechanical neck pain. However the study was limited to a short-term follow-up and the effects on disability and physical impairments e.g. cervical range of motion was not evaluated.

In contrast, Parkin-Smith and Penter demonstrated that the combination of cervical and thoracic manipulation did not result in any significant benefit than cervical manipulation alone. Another trial comparing the effect of thoracic manipulation and instructed exercise in the management of neck-shoulder pain revealed that there was a statistically significant reduction in the level of perceived worst pain after 12-months follow-up.

As there is a lack of general consensus on the efficacy of thoracic manipulation for patients with neck pain, a well designed trial studying the clinical effects of thoracic manipulation in treating mechanical neck pain with substantial period of follow-up is necessary.

The aim of this study was to assess the effectiveness of thoracic manipulation on patients with chronic neck pain. 120 patients aged between 18 and 55 were randomly allocated into two groups: an experimental group which received thoracic manipulation and a control group without the manipulative procedure. Both groups received infrared radiation therapy and a standard set of educational material. Thoracic manipulation and infrared radiation therapy were given twice weekly for 8 sessions. Outcome measures included craniovertebral angle, neck pain, neck disability, health-related quality of life status and neck mobility. These outcome measures were assessed immediately after 8 sessions of treatment, 3-months and at a 6-month follow-up.

Patients that received thoracic manipulation showed significantly greater improvement in pain intensity, craniovertebral angle, NPQ, neck flexion, and the Physical Component Score of the SF36 Questionnaire than the control group immediately post-intervention. All these improvements were maintained at the 6-month follow-ups. This study shows that thoracic manipulation was effective in reducing neck pain, improving dysfunction and neck posture and neck range of motion for patients with chronic mechanical neck pain up to a half-year post-treatment.

The effect of thoracic manipulation was shown to be positive in reducing neck pain, improving dysfunction and neck posture, and neck range of motion up to half a year post-treatment. In treating patients with chronic mechanical neck pain, thoracic manipulation could be a choice for effective management.

Type of thoracic manipulation:

1. The subject lay supine with the arms crossed over the chest and hands passed around the shoulder with the thoracic spine was in neutral position.

2. The hand of the therapist contacted with a neutral hand position over the spinous process of the selected thoracic level (inferior vertebra of the motion segment).

3. The other hand stabilized the head, neck, and upper thoracic spine of the subject.

4. Gently, flexion of the thoracic spine was introduced until slight tension was palpated in the tissues at the therapist’s contact point.

5. Then, a high velocity, low-amplitude technique downward toward the couch and in a cephalad direction was applied.

6. A cracking or popping sound accompanied all manipulations.

7. If no popping sound was heard on the first attempt, the therapist repositioned the subject, and the therapist performed a second manipulation over the same selected thoracic level(s).

8. A maximum of 2 attempts was performed on each subject at each session.

From: Arch Phys Med Rehabil. 2010 Sep;91(9):1313-1318

To determine whether neck manipulation is more effective for neck pain than mobilization, a randomized controlled trial with blind assessment of outcome was undertaken by the authors. The setting was Primary care physiotherapy, chiropractic, and osteopathy clinics in Sydney, Australia.

Patients (N=182) with nonspecific neck pain less than 3 months in duration and deemed suitable for treatment with manipulation by the treating practitioner were randomly assigned to receive treatment with neck manipulation (n=91) or mobilization (n=91). Patients in both groups received 4 treatments over 2 weeks, from which the number of days taken to recover from the episode of neck pain.

The median number of days to recovery of pain was 47 in the manipulation group and 43 in the mobilization group. Participants treated with neck manipulation did not experience more rapid recovery than those treated with neck mobilization. The authors concluded that neck manipulation is not appreciably more effective than mobilization. The authors further noted that the use of neck manipulation therefore cannot be justified on the basis of superior effectiveness.

It would be interesting to note a similar number of patients without any neck manipulation or mobilization and the number of median days to recover from nonspecific neck pain of less than 3 months duration. Additionally, the conclusion that “the use of neck manipulation therefore cannot be justified on the basis of superior effectiveness” should include – for nonspecific neck pain less than 3 months in duration with 4 treatments over a 2 week period. Without the entire article, one can only speculate why 4 treatments over 2 weeks would be deemed reasonable treatment for a nonspecific entity with either modality.

I presume the full article would delineate the criteria for being deemed suitable for treatment with manipulation or mobilization by the treating practitioner and if the evaluation methods were uniform between practitioners. Furthermore, the article should indicate specific analysis to reach a broad conclusion that manipulation cannot be justified on the basis of superior effectiveness – in fact, the abstract should have indicated that mobilization was more effective than manipulation for nonspecific neck pain of less than 3 months duration in a heterogeneous group of treating practitioners performing 4 treatments over a 2 week period.

From: Work. 2010;35(3):369-94

The literature relevant to the treatment of Whiplash Associated Disorders is extensive and heterogeneous. A Participatory Action Research approach was used to engage a chiropractic community of practice and stakeholders in a systematic review to address a general question: ‘Does chiropractic management of whiplash associated disorders clients have an effect on improving health status?’ A systematic review of the empirical studies relevant to whiplash associated disorders interventions was conducted followed by a review of the evidence.

The initial search identified 1,155 articles. Ninety-two of the articles were retrieved, and 27 articles consistent with specific criteria of whiplash associated disorders intervention were analyzed in-depth. The best evidence supporting the chiropractic management of clients with whiplash associated disorders is reported. Further review identified ways to overcome gaps needed to inform clinical practice and culminated in the development of a proposed care model: the whiplash associated disorders-plus model.

There is a baseline of evidence that suggests chiropractic care improves cervical range of motion and pain in the management of whiplash associated disorders. However, the level of this evidence relevant to clinical practice remains low or draws on clinical consensus at this time. The whiplash associated disorders-plus model has implications for use by chiropractors and interdisciplinary professionals in the assessment and management of acute, subacute and chronic pain due to whiplash associated disorders. Furthermore, the whiplash associated disorders-plus model can be used in the future study of interventions and outcomes to advance evidence-based care in the management of whiplash associated disorders.

From: N Z Med J. 2010 Apr 9;123(1312):36-44

Some chiropractors and their associations claim that chiropractic is effective for conditions that lack sound supporting evidence or scientific rationale. This study therefore sought to determine the frequency of World Wide Web claims of chiropractors and their associations to treat, asthma, headache, migraine, infant colic, colic, ear infection, earache, otitis media, neck pain, whiplash (not supported by sound evidence), and lower back pain (supported by some evidence).

A review of 200 chiropractor websites and 9 chiropractic associations’ World Wide Web claims in Australia, Canada, New Zealand, the United Kingdom, and the United States was conducted between 1 October 2008 and 26 November 2008. The outcome measure was claims (either direct or indirect) regarding the eight reviewed conditions, made in the context of chiropractic treatment.

The authors found evidence that 190 (95%) chiropractor websites made unsubstantiated claims regarding at least one of the conditions. When colic and infant colic data were collapsed into one heading, there was evidence that 76 (38%) chiropractor websites made unsubstantiated claims about all the conditions not supported by sound evidence. Fifty-six (28%) websites and 4 of the 9 (44%) associations made claims about lower back pain, whereas 179 (90%) websites and all 9 associations made unsubstantiated claims about headache, migraine. Unsubstantiated claims were made about asthma, ear infection, earache, otitis media, neck pain.

The majority of chiropractors and their associations in the English-speaking world seem to make therapeutic claims that are not supported by sound evidence, whilst only 28% of chiropractor websites promote lower back pain, which is supported by some evidence. The authors suggest the ubiquity of the unsubstantiated claims constitutes an ethical and public health issue.

It is unclear from the abstract of this article what “sound evidence” and “some evidence” is considered or based on. To make a statement that website claims by some chiropractors constitute an ethical and public health issue is a bold and biased opinion. The fact that medical professionals and their associates are absorbing chiropractic methods would indicate these claims are not an ethical and public health issue. Additionally, chiropractors have been practicing for more than 100 years without using medications or surgery. To state that there is no evidence to support the use of chiropractic methods for neck pain or whiplash is an ethical and public health issue. Current evidence supports the use of chiropractic methods for cervicogenic headache. Perhaps the entire article would prove more efficacious in defining “sound evidence” and “some evidence”, along with relating these claims as an ethical and public health issue, however, the conclusions reached by the authors based on 209 website claims (ubiquitous?) in 5 countries are certainly biased and their motivations should be questioned.

Based on the authors conclusions, I recommend that all chiropractic and association websites state, “We might help some lower back pain, but that’s it!” or “If your looking for sound evidence, try drugs and surgery”.

From: Work. 2010;35(3):369-94

The literature relevant to the treatment of Whiplash Associated Disorders is extensive and heterogeneous. A Participatory Action Research (PAR) approach was used to engage a chiropractic community of practice and stakeholders in a systematic review to address a general question: ‘Does chiropractic management of Whiplash Associated Disorder clients have an effect on improving health status?’ A systematic review of the empirical studies relevant to Whiplash Associated Disorders interventions was conducted followed by a review of the evidence.

The initial search identified 1,155 articles. Ninety-two of the articles were retrieved, and 27 articles consistent with specific criteria of Whiplash Associated Disorder intervention were analyzed in-depth. The best evidence supporting the chiropractic management of clients with Whiplash Associated Disorders is reported. Further review identified ways to overcome gaps needed to inform clinical practice and culminated in the development of a proposed care model: the Whiplash Associated Disorders-Plus Model.

There is a baseline of evidence that suggests chiropractic care improves cervical range of motion (cROM) and pain in the management of Whiplash Associated Disorders. However, the level of this evidence relevant to clinical practice remains low or draws on clinical consensus at this time. The Whiplash Associated Disorders-Plus Model has implications for use by chiropractors and interdisciplinary professionals in the assessment and management of acute, subacute and chronic pain due to Whiplash Associated Disorders. Furthermore, the Whiplash Associated Disorders-Plus Model can be used in the future study of interventions and outcomes to advance evidence-based care in the management of Whiplash Associated Disorders.

From: J Manipulative Physiol Ther. 2010 March – April;33(3):168-177.

Chronic neck pain is a common problem in modern, industrialized countries. It has been estimated that 67% of people will experience neck pain at some point in their lives. A proportion of these individuals with neck pain do not experience complete resolution of their pain and disability, which can turn into a more complex chronic pain syndrome. What is not well understood is what causes neck pain to become chronic. An emerging school of thought in the mechanism of chronicity in nonspecific neck pain is that it is related to abnormal muscle recruitment patterns, which may put the spine at greater risk of further injury. Impaired neuromuscular function in patients with chronic neck pain is becoming increasingly recognized, most notably, an impaired ability to activate the neck flexor muscles during rapid limb movements and an impaired ability to relax the neck extensor muscles.

The solution proposed in previous research has been based on the idea of using specific exercise strategies to improve these impaired neuromuscular patterns. Recent research indicates that both exercise and chiropractic care involving spinal manipulation may also be able to improve these impaired neuromuscular patterns. Chiropractic techniques appear to be able to help normalize altered patterns of muscle recruitment and sequencing observed in the presence of musculoskeletal impairments and pain.

Contemporary research into the pathogenesis of nonspecific neck pain relates to the manifestation of abnormal muscle recruitment patterns. Impaired neuromuscular function in patients with chronic neck pain is becoming increasingly recognized, most notably the impaired activation of the neck flexor muscles during rapid upper limb movement. An additional measure that may be used for impaired neuromuscular function is the cervical flexion-relaxation response, a measure of the ability to relax the cervical extensors at full forward flexion. There is a lack of evidence for how commonly used interventions for chronic neck pain, such as spinal manipulation or exercise, may change these measures of impaired neuromuscular function in the neck.

The flexion-relaxation response, commonly measured in the posterior kinetic chain muscles (such as the erector spinae, hamstrings), is the electrical silence that is observed during full forward flexion of the trunk or neck as the passive structures of the spine maintain stability. Individuals with either chronic neck or back pain have been shown to exhibit heightened muscle activity at full flexion of the neck and trunk, respectively. Recent results suggest that for the lumbar spine, the flexion-relaxation response may be an important marker of neuromuscular impairment, which can show improvement with an appropriate intervention. After an exercise intervention for individuals with chronic low back pain, it was shown that changes in the flexion-relaxation response explained 38% of the improvement in self-reported disability. This change seems to be predominantly manifested as improved relaxation at full trunk flexion. Although the cervical flexion-relaxation response is a reliable measure able to discriminate between patients with and without chronic neck pain, it is not known if this response will change after treatment interventions.

Similar to the deep abdominal muscles, the cervical flexor muscles have a pattern of activating within 50 milliseconds before the onset of activity in the deltoid muscles during rapid upper limb movements in healthy subjects. Falla et al (2004) showed impaired feed-forward activation in people with chronic neck pain. When subjects with a history of neck pain performed arm flexion, the activation onsets of deep cervical flexors ipsilateral to the sight of arm movement as well as the contralateral (right) sternocleidomastoid and anterior scalene muscles were significantly delayed compared with the relative latencies for the control group.

A recent review by Vernon et al found moderate to high quality evidence that manipulation at 6, 12, and up to 104 weeks was an effective treatment for neck pain not due to whiplash with effect sizes from 0.56 to 3.2, most of which would be considered large. These effect sizes were maintained up to 12 weeks posttreatment. Only 2 studies had long-term data but still showed large effect sizes for up to 104 weeks. A Cochrane review found a strong benefit of manipulation and/or mobilization combined with exercise vs waiting list controls for pain reduction, improvement in function and global perceived effort. What has not been assessed in most neck pain intervention studies is whether the treatment is able to affect neuromuscular function. It may be that manipulation is able to affect one type of neuromuscular impairment and another specific exercise, and that the combined treatment effect may be synergistic. It may also be that improved neuromuscular function may be a marker of an effective treatment.

The purpose of this study was to evaluate manipulation-based chiropractic care combined with strengthening exercises as compared with strengthening exercises only for the treatment of chronic neck pain, with the inclusion of the cervical flexion-relaxation response and cervical feed-forward activation latencies as measures of neuromuscular activation.

The main hypotheses of this study were (1) that improvements in functional capacity would be greatest for patients who received the combination of chiropractic care and exercise compared with exercise only and (2) that these improvements would be reflected by changes in neuromuscular deficits.

The major finding in this study was that chiropractic care combined with 8 weeks of exercise and exercise alone are both effective at reducing perceived levels of functional neck disability and pain. The null hypothesis was proven in this study because there were no significant differences between the 2 groups. The effective size calculations for the differences between the 2 groups was .293, which is a small effect,28 and the sample size calculations indicated that 145 subjects per group would be needed to show a difference between the 2 groups based on the NDI. Population scores suggest that both groups had mild disability at baseline, and although a decrease in score was observed in both groups, the classification did not change after the intervention. It may be because both groups were in the “mild category,” and it was a pilot study that the study lacked sufficient power to show a difference between treatments. There was also a lot of variability in the degree of change between individual subjects as shown by the large SDs, which had the effect of decreasing the effective size and increasing the estimated sample size required to show a difference between the 2 groups. Another important consideration is whether the small difference between the 2 groups has enough clinical relevance to justify the costs of an RCT involving 290 participants.

There was a decrease for both groups in current pain scores and “worst pain,” which was significant overall, but again, because of the large degree of variability between the groups, the effect sizes were small for both, and sample size estimates indicated that 88 subjects per group would be needed to show a difference between treatments for “pain now” and 82 per group for “worst pain.”

Improvements in the flexion-relaxation results would be indicated by an increased flexion-relaxation response, indicating improved relaxation (decreased myoelectric activity at full flexion). Both groups would be considered initially impaired based on previous work in the lumbar spine. The flexion-relaxation response actually worsened slightly for the exercise group and improved minimally for the manipulation group. This result contrasts with previous work, which showed that an 8-week exercise intervention was able to improve the flexion-relaxation response in the lumbar spine. The fact that the manipulation group group that had manipulation before exercise improved slightly is in keeping with previous work in the lumbar spine. This trend toward improvement in the manipulation group group as compared with the exercise group group is in keeping with the authors initial hypothesis and suggests spinal manipulation before exercise may help to normalize neuromuscular function and enable people to better cope with the demands of exercise. Given the reasonably low number of participants required to determine whether the 2 forms of treatment have differential effects on this outcome measure, the authors could recommend a future RCT with 40 participants per group to allow for dropouts.

Improvements in feed-forward responses would be indicated by faster onset times in the cervical flexor muscles in relation to deltoid onset times (within 50 milliseconds). Previous work by Falla et al indicated that chronic neck pain patients exhibit delayed activation of the cervical flexor muscles. The baseline results for feed-forward activation were not impaired in the chronic neck pain patients who participated in this trial when compared with Falla’s results. This could explain the lack of finding for the anterior scalene muscles in the manipulation group group compared with Marshall and Murphy’s study where only subjects who showed evidence of delayed feed-forward activation received spinal manipulation therapy. The authors do not think the feed-forward changes reported in this study should be used for sample size calculations, because the participants did not actually show delayed activation before the treatments.

An important consideration in interpreting our results is that 8 weeks may not be enough time to show the full range of improvement in neuromuscular measures. A more recent article by Marshall and Murphy for the low back has indicated that at a 9-month follow-up feed-forward activation had improved in a group of chronic low back pain patients even though these changes were not present after 12 weeks of exercise.

This pilot study showed that both exercise and exercise combined with manipulation can improve pain and disability in people with long-term neck pain. The study indicates that the flexion-relaxation response changes had an effective size of .636, and 32 subjects per group would be needed to show a difference between the 2 treatments with an a of .05 and a power of 0.8.