Kristi?n Briem, MHSc, PT
Peter Huijbregts, PT, DPT, OCS, FAAOMPT, FCAMT
Maria Thorsteinsdottir, MSC, PT
Abstract: The purpose of this pilot study was to examine the immediate effects of a manual therapy technique called Inhibitive Distraction (ID) on active range of motion (AROM) for cervical fl exion in patients with neck pain with or without concomitant headache. A secondary objective of this study was to see whether patient subgroups could be identifi ed who might benefi t more from ID by studying variables such as age, pain intensity, presence of headache, or pre-intervention AROM. We also looked at patients’ ability to identify pre- to post-intervention changes in their ability to actively move through a range of motion. Forty subjects (mean age 34.7 years; range 16–48 years) referred to a physical therapy clinic due to discomfort in the neck region were randomly assigned to an experimental and a control group. We used the CROM goniometer to measure pre- and post-intervention cervical fl exion AROM in the sagittal plane within a single treatment session. The between-group difference in AROM increase was not statistically signifi cant at P<0.05 with a mean post-intervention increase in ROM of 2.4° (SD 6.2°) for the experimental group and 1.2° (SD 5.8°) for the placebo group. We were also unable to identify potential subgroups more likely to respond to ID, although a trend emerged for greater improvement in chronic patients with headaches, lower pain levels, and less pre-intervention AROM. In the experimental group and in both groups combined, subjects noting increased AROM indeed had a significantly greater increase in AROM than those subjects not noting improvement. In conclusion, this study did not confi rm immediate effects of ID on cervical fl exion AROM but did provide indications for potential subgroups likely to benefit from this technique. Recommendations are provided with regard to future research and clinical use of the technique studied.
Key Words: Cervical, Active Range of Motion, Inhibitive Distraction, Neck Pain, Pilot Study
Neck pain as well as headache types with a proposed cervical etiology or contribution are highly prevalent disorders. Doug lass and Bope1 reported a point-prevalence for neck pain in the general population of 9%. They further noted a 1-month, 6-month, and lifetime prevalence of 10%, 54%, and 66%, respectively. In a cross-sectional population survey, Guez et al2 found an 18% prevalence for chronic neck pain (>6 months’ duration). Headache types associated with cervical spine dysfunction include tension-type and cervicogenic headache, occipital neuralgia, and—to a lesser extent—migraine headaches3. Tension-type head- ache affects two-thirds of men and over 80% of women in developed countries4. For the general population, the prevalence of cervicogenic headache varies between 0.4% and 2.5%; in those with chronic headaches, prevalence may be as high as 15% to 20%5.
Neck pain and headache are not only highly prevalent but also frequent reasons for patients to seek medical or physical therapy (PT) care. In the United States, neck pain accounts for almost 1% of all primary care physician visits1, and cervical spine diagnoses were the reason for referral in 16% of 1,258 outpatient PT patients, second only to lumbar spine-related diagnoses, which accounted for 19% of referrals6. No data are available on the prevalence of headache as a cause for PT management; however, Boissonnault6 reported headache as co-morbidity in 22% of 2,433 patients presenting for outpatient physical and occupational therapy, and headaches are reportedly the leading cause for visits to a neurologist4.
Physical therapists place a diagnostic emphasis on identifying impairments that may be amenable to management with interventions within their scope of practice. In this context, impairments are defi ned as any loss or abnormality of body structure or of a physiological or psychological function7. Studies have shown a strong correlation between neck pain and restricted cervical fl exion-extension mobility8,9, and limited motion may be the most relevant impairment associated with neck pain and headache of a proposed cervical etiology. Dvora?k et al10 attributed cervical hypomobility to either a voluntary or refl exogenic muscular restraint caused by pain or a purely mechanical restraint caused by degeneration of the joint surfaces and ligaments. Corresponding to said degenerative process, Cantu and Grodin11 described a fibrotic process in connective tissue, whereby it shrinks progressively, caused by arthrokinematic dysfunction, poor posture, overuse, habit patterns, or structural or movement imbalances. They further suggested that in many cases the surrounding musculature maintains a hypertonic recruitment pattern long after the inducing injury has healed, potentially immobilizing joints by the surrounding muscle hypertonicity.
Myofascial trigger points (MTrP) in the cervical muscles constitute another potentially relevant muscle dysfunction leading to limited cervical spine mobility. These are defined as hyperirritable spots in skeletal muscle with a potential to give rise to characteristic referred pain, motor dysfunction, and autonomic phenomena12. Motor aspects of MTrPs may include disturbed motor function, muscle weakness as a result of motor inhibition, and—most importantly in the context of this study—muscle stiffness and restricted range of motion13. Trigger points in the head and neck region have been implicated in the reported headache and central sensitization in patients with tension-type headache. Their referral patterns correspond to the pain characteristics and distribution reported by patients with cervicogenic headache, occipital neuralgia, and migraine headache3. Studies have reported signifi cantly greater numbers of active MTrPs in the suboccipital muscles of patients with tension-type headache and in patients with migraine headache when compared to asymptomatic controls14-16. Motor effects of these suboccipital MTrPs in the sense of muscle shortening may explain the increased forward head posture and decreased cervical AROM reported in patients with chronic tension-type headache or migraine headache as compared to asymptomatic controls14,16,17.
Relevant to the management of patients with neck pain and headache, Paris18 has described a technique called inhibitive distraction (ID) in which the therapist uses the fingertips of both hands to exert a sustained ventrocranial force on the occiput just caudal to the superior nuchal line (Figure 1). He proposed that this technique might inhibit the muscles inserting into the nuchal line and that it could be used to apply a distraction to the cervical spine structures. Paris18 did not claim this technique as his own, instead ascribing its origin to cranial osteopathy. Indeed, this technique has been described within various manual medicine disciplines under various names such as cranial base release, suboccipital release, and trigger point pressure release12,19-21. The proposed effects are mainly neurophysiological, perhaps circulatory, and mildly mechanical. McPartland20 described iatrogenesis with this technique, but Upledger19 rightly noted that his case descriptions indicated improper technique involving too much force. Over all, the technique seems safe if applied correctly.
Within the context of this study, the relevant suggested effects of ID on the cervical spine involve inhibition of local and general posterior muscle tone, inactivation of suboccipital muscle MTrPs, and gentle joint mobilization. These effects are all hypothesized to result in an increase in cervical flexion AROM. Therefore, the purpose of this pilot study was to examine the immediate effects of ID on AROM into cervical flexion in patients with neck pain with or without concomitant headache. The main objective was to show whether, when used alone in a single treatment session, this intervention would significantly increase cervical flexion AROM. A secondary objective of this study was to see whether patient subgroups could be identifi ed that might benefit more from ID by studying variables such as age, pain intensity, presence of headache, or pre-intervention AROM and by looking at patients’ ability to identify pre- to post-intervention changes in their ability to actively move through a range of motion.