Manipulation, spinal

Related Terms

Chiropractic adjustment, chiropractic manipulation, chiropractic manipulative therapy, chiropractic spinal manipulation, manual physiotherapy, manual therapy, spinal adjustive manipulation, spinal manipulation, spinal manipulative therapy, SMT.
Not included in this review: Osteopathic manipulative therapy, mobilization, mobilization therapy, physical therapy. Traction is a physical modality used primarily in physical therapy, and is inconsistently utilized in chiropractic offices.

Background

Overview: Chiropractic is a health care discipline that focuses on the relationship between musculoskeletal structure (primarily the spine) and body function (as coordinated by the nervous system), and how this relationship affects the preservation and restoration of health. The broad term "spinal manipulative therapy" incorporates all types of manual techniques, including chiropractic.
History: Spinal manipulation was used medicinally as early as 2700 B.C. in ancient Chinese medicine. Hippocrates and Galen used manipulative techniques, and the word "chiropractic" is derived from Greek chiropraktikos, meaning "effective treatment by hand."
In the late 1800s, David Daniel Palmer systematized the principles upon which modern chiropractic is based, suggesting that abnormal nerve function is the primary cause of disorders, and recommending adjustment of the spine as an effective therapy. The Palmer School of Chiropractic opened in 1895, and one-third of students were physicians. Acceptance of Palmer's principles in the medical community varied, and some early chiropractors were imprisoned (including Palmer himself). A schism between chiropractors and medical doctors persisted, and between 1977-1987, an antitrust lawsuit was brought against the American Medical Association for systematic bias against the chiropractic profession (which was ultimately successful).
Divisions existed within the chiropractic community as well, and during the early 20th century, two schools of thought emerged: One group ("straights") asserted that subluxation is the underlying cause of disease. A second group ("mixers") worked in a multidisciplinary setting with physicians, and accepted other pathophysiologic theories of disease. Two different chiropractic associations were founded between 1920-1926 reflecting this division: the International Chiropractic Association (ICA) and the American Chiropractic Association (ACA), respectively.
In 1972, chiropractic treatment became reimbursable by Medicare. In 1974, nationally recognized standards were adopted by the Council on Chiropractic Education (CCE), and were recognized by the U.S. Department of Education. All U.S. chiropractic colleges achieved accreditation by the CCE by 1975. Currently, all 50 U.S. states have statutes recognizing and regulating the practice of chiropractic.
Currently: In the United States, chiropractors are the most frequently used non-physician primary health providers, after dentists (1;2). There are more than 60,000 licensed American chiropractors (3), a number expected to reach 100,000 by 2010 (4). Almost 80% of all visits to chiropractors are for musculoskeletal complaints (5), and more than 40% are for back pain (6). In 1999, 11% of adults and more than 30% of patients with low back pain visited a chiropractor (7). For two-thirds of patients, a chiropractor was the only provider seen for these complaints (8).
The cost effectiveness of chiropractic care remains controversial and is not clearly established (9-12).
Techniques: There are more than 100 distinct chiropractic and spinal manipulative adjusting techniques, and there is variability between practitioners. Some approaches use highly specialized tables or hand-held equipment. Techniques that are widely taught in chiropractic schools include: Diversified, Extremity Adjusting, Activator, Gonstead, Cox Flexion-Distraction, and Thompson. Other techniques are taught on chiropractic campuses outside of the established curriculum, and many are taught in seminars that are not sanctioned as a part of the established chiropractic curriculum. Categories of therapeutic approaches include the following:
Manipulation: A primary chiropractic therapeutic application that involves applying a specific amount of force vectored through a specific plane of motion of a spinal or peripheral joint, in order to reduce joint restriction and facilitate normal range of motion. Long-lever manipulation uses the femur, shoulder, head, or pelvis to affect larger sections of the spine in a non-specific manner. Specific short lever, dynamic thrusts utilize a specific contact on a transverse spinous process of vertebra, muscle, or ligament. Point pressure manipulation includes the gouging or manual stimulation of specific points without attempting to actually massage a muscle or move a joint.
Mechanical traction: A technique that incorporates the use of an external system of applied resistance to facilitate joint decompression of the spine or extremity. Manual traction is often performed on a segment of the spine without attempting to mobilize the joint through a specific passive movement.
Massage/soft tissue mobilization: A category of soft tissue therapeutic techniques used to reduce muscle spasm, soreness, or tightness. These procedures are directed at the subcutaneous, muscular, or tendinous tissues and do not result in significant joint movement. Example techniques include myofascial trigger point therapy, cross friction massage, active release therapy, muscle stripping, and rolfing. Mobilization or articulation technique uses slow rhythmic movements rather than quick sharp thrusts, and may be performed within the passive range of motion of the spine.
Electrical muscle stimulation (EMS)/interferential therapy: A therapeutic modality using two medium-frequency currents that intersect. The intersecting current is believed by some practitioners to reduce muscle spasm and pain.
Diathermy: A technique that uses high-frequency electrical currents to produce specific "thermal" effects.
Ultrasound: A technique that uses high-frequency sound waves with the goal of producing "micromassage" and "deep tissue heat."
Cryotherapy: A technique that uses ice therapy or icepacks for control of joint pain and inflammation.
Hydroculator packs: A technique that uses therapeutic heat application.
Rehabilitation/exercise prescription: Exercise-based programs designed to improve function (rehabilitation programs) are sometimes used as part of an overall management strategy.
Dietary counseling/nutritional support: Weight modulation and dietary change may be recommended as part of an overall management strategy.
Health promotion/preventative services: Chiropractors often provide health promotion and prevention services, including an emphasis on exercise, adjustment/manipulation, dietary advice, vitamins, and relaxation.
Diagnostic procedures: Chiropractors use a number of diagnostic imaging tests, including x-ray, computerized tomography (CT) scans, magnetic resonance imaging (MRI), and thermography.

Theory

There are traditional and scientifically-based hypotheses regarding the mechanism of action of chiropractic and spinal manipulation. There is overlap between some of these theories, with research in several areas. However, the physiologic mechanism of spinal manipulation remains largely unknown.
Traditional theories: The vertebral subluxation hypothesis proposes that alterations in normal anatomical/physiologic relationships between contiguous articular structures result in disease, and that chiropractic/manipulative methods can reduce these positional abnormalities (13-18). "Vitalism" is the concept that the body has the innate ability to heal itself if relieved of spinal irritations or subluxations (19). Correction of subluxations has been suggested to restore the flow of life force throughout the body, resulting in a brief convalescence and a return to optimum health (20;21). There is limited scientific evidence in these areas (22;23).
The nerve compression hypothesis suggests that intervertebral subluxations can cause irritation or compression of spinal nerve roots and interfere with nerve transmission (14). The fixation hypothesis proposes that vertebral muscles become locked and lose range of motion, leading to the release of neurotoxic mediators and abnormal nerve conduction (24;25). The axoplasmic aberration hypothesis asserts that compression of spinal nerves or nerve roots may hinder axoplasmic transport and damage nerves.
It has been proposed that chiropractic may reduce nerve impingement at intervertebral foramina (26), alter the distribution of loads between joints (27-30), create gaps between joints and break up fibrous adhesions that interfere with normal function (31), improve range of motion (32-35), improve immune function (36;37); and foster healing through the clinician-patient relationship (20;38-43).
Scientific research: Animal experiments report that vertebral displacement may alter the function of nerves arising from intervertebral muscles and influence heart rate and blood pressure (44-46). Human studies report possible changes in patterns of nerve conduction and reflexes during spinal manipulation, although the evidence is not definitive (47-62). Reduced sensitivity to painful stimuli has been reported in some studies of spinal manipulation (63-68), but not in others (69). Some studies report elevated plasma levels of substance P (70;71) and endorphins (72-77) following spinal manipulation, although other research reports no effects (78-80).
Problems in chiropractic research: Because spinal manipulation involves the hands-on application of a physical therapy, blinding in studies presents a challenge. Often, the effects of treatment are evaluated by those administering therapy. These individuals are not blinded to the type of treatment being administered (unlike assessors in pharmacologic studies in which active and placebo drugs are similar in appearance). This is a potential source of bias. Similarly, placebo control is difficult, and necessitates the use of "sham manipulation" (81). Existing studies are difficult to compare with each other, because methods of manipulation vary between trials, and definitions of medical conditions/diagnoses are inconsistent. Most research has used non-standardized, subjective outcome measures that cannot be pooled.

Evidence Table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *


The use of spinal manipulative therapy for the relief of tension or migraine headache has been reported in several controlled human trials (82-92), systematic reviews (93-96), and case reports (97-105). Overall, the quality of studies is not high, with incomplete reporting of design, inconsistent use of techniques between studies, and variable results. Despite these methodologic problems, overall the evidence suggests some benefits in the prevention of episodic tension headache. Effects on migraine headache have not been demonstrated. Better quality research is necessary in this area before a firm conclusion can be drawn.

Patients should be aware of the safety concerns surrounding cervical/neck manipulation before starting this type of therapy.

 B


The use of spinal manipulative therapy for the relief of tension or migraine headache has been reported in several controlled human trials (82-92), systematic reviews (93-96), and case reports (97-105). Overall, the quality of studies is not high, with incomplete reporting of design, inconsistent use of techniques between studies, and variable results. Despite these methodologic problems, overall the evidence suggests some benefits in the prevention of episodic tension headache. Effects on migraine headache have not been demonstrated. Better quality research is necessary in this area before a firm conclusion can be drawn.

Patients should be aware of the safety concerns surrounding cervical/neck manipulation before starting this type of therapy.

 B

There are more than 150 published human trials and case reports that detail the use of chiropractic manipulation in patients with low back pain. Results are variable, with some studies reporting benefits, and others suggesting no significant effects. Most trials are not well designed or reported, with inconsistent use of definitions of disease, techniques, and measured outcomes. Several analyses (meta-analyses) have attempted to pool the results of the better-quality trials (106-120). However, combining or comparing results of different trials is difficult due to inconsistencies between studies, and these meta-analyses have also reported variable effects. Despite these problems with existing research, the available scientific evidence overall suggests some improvement in pain symptoms. Better research is necessary before a definitive conclusion can be reached.

 B

There are more than 150 published human trials and case reports that detail the use of chiropractic manipulation in patients with low back pain. Results are variable, with some studies reporting benefits, and others suggesting no significant effects. Most trials are not well designed or reported, with inconsistent use of definitions of disease, techniques, and measured outcomes. Several analyses (meta-analyses) have attempted to pool the results of the better-quality trials (106-120). However, combining or comparing results of different trials is difficult due to inconsistencies between studies, and these meta-analyses have also reported variable effects. Despite these problems with existing research, the available scientific evidence overall suggests some improvement in pain symptoms. Better research is necessary before a definitive conclusion can be reached.

 B

There is not enough reliable scientific evidence to conclude whether chiropractic techniques are beneficial in the management of acute back pain when compared to other approaches, including conservative management (121-129).

C

There is not enough reliable scientific evidence to conclude whether chiropractic techniques are beneficial in the management of acute back pain when compared to other approaches, including conservative management (121-129).

C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of migraine headache. There is limited human evidence in this area (97;100;103;130-135).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of migraine headache. There is limited human evidence in this area (97;100;103;130-135).

 C


Multiple studies have examined the effects of spinal manipulation in patients with herniated lumbar discs (136-147). Results are variable, with some studies reporting benefits, and others finding no effects. Various techniques, measurement systems, and study designs have been used, and overall the quality of studies has been poor. Better quality research is necessary before a firm conclusion can be drawn.

 C


Multiple studies have examined the effects of spinal manipulation in patients with herniated lumbar discs (136-147). Results are variable, with some studies reporting benefits, and others finding no effects. Various techniques, measurement systems, and study designs have been used, and overall the quality of studies has been poor. Better quality research is necessary before a firm conclusion can be drawn.

 C


Multiple studies have examined the effects of spinal manipulation in patients with acute or chronic neck pain (148-162). Overall, the quality of studies has been poor, and reviews of this topic have been unable to form clear or convincing conclusions due to variability between studies and methodologic weaknesses (163-170). Cervical spine manipulation and mobilization appear to have equal effects (171;172). Better quality research is necessary before a firm conclusion can be drawn.

 C


Multiple studies have examined the effects of spinal manipulation in patients with acute or chronic neck pain (148-162). Overall, the quality of studies has been poor, and reviews of this topic have been unable to form clear or convincing conclusions due to variability between studies and methodologic weaknesses (163-170). Cervical spine manipulation and mobilization appear to have equal effects (171;172). Better quality research is necessary before a firm conclusion can be drawn.

 C


Several studies report the effects of chiropractic spinal manipulative therapy on breathing indices and quality of life in children and adults with asthma (173-180). Results are variable, and in the studies with positive results, mostly subjective but not objective (lung function test) changes are reported. Due to methodologic problems and variable results, no clear conclusions can be drawn in this area.

C


Several studies report the effects of chiropractic spinal manipulative therapy on breathing indices and quality of life in children and adults with asthma (173-180). Results are variable, and in the studies with positive results, mostly subjective but not objective (lung function test) changes are reported. Due to methodologic problems and variable results, no clear conclusions can be drawn in this area.

C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of carpal tunnel syndrome (181-184). Early evidence and some experts suggest that chiropractic manipulation may be as effective as conservative treatments such as anti-inflammatory drugs or splinting.

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of carpal tunnel syndrome (181-184). Early evidence and some experts suggest that chiropractic manipulation may be as effective as conservative treatments such as anti-inflammatory drugs or splinting.

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of cervical disc herniation (185;186).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of cervical disc herniation (185;186).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of COPD (187-189).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of COPD (187-189).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of chronic pelvic pain (CPP) (190-194).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of chronic pelvic pain (CPP) (190-194).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of duodenal ulcer (195).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of duodenal ulcer (195).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of dysmenorrhea (196-201).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of dysmenorrhea (196-201).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of fibromyalgia (202-205).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of fibromyalgia (202-205).

 C


The effects of spinal manipulative techniques on blood pressure remain controversial. It has been hypothesized that nervous system effects of spinal manipulation can lower both systolic and diastolic pressure. Numerous trials, reviews, and commentaries have been published in this area (206-220). Although some studies are suggestive, overall the existing evidence remains indeterminate due to methodologic weaknesses and variability between studies. Better research is necessary before a firm conclusion can be drawn.

Nevertheless, caution should be used in patients with low blood pressure or taking medications that may lower blood pressure further.

 C


The effects of spinal manipulative techniques on blood pressure remain controversial. It has been hypothesized that nervous system effects of spinal manipulation can lower both systolic and diastolic pressure. Numerous trials, reviews, and commentaries have been published in this area (206-220). Although some studies are suggestive, overall the existing evidence remains indeterminate due to methodologic weaknesses and variability between studies. Better research is necessary before a firm conclusion can be drawn.

Nevertheless, caution should be used in patients with low blood pressure or taking medications that may lower blood pressure further.

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques on CD4 count or quality of life in patients with HIV/AIDS (221).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques on CD4 count or quality of life in patients with HIV/AIDS (221).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of infantile colic (222-228).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of infantile colic (222-228).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of jet lag, and preliminary evidence suggests a lack of benefit (229).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of jet lag, and preliminary evidence suggests a lack of benefit (229).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of nocturnal enuresis (230-233).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of nocturnal enuresis (230-233).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of otitis media in children (234-236).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of otitis media in children (234-236).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of Parkinson's disease (237;238).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of Parkinson's disease (237;238).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of phobias (239-241).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of phobias (239-241).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of pneumonia in the elderly (242).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of pneumonia in the elderly (242).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of premenstrual syndrome (243;244).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of premenstrual syndrome (243;244).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques for respiratory tract infections (245-248).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques for respiratory tract infections (245-248).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of seizure disorder (249).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of seizure disorder (249).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques for shoulder pain, frozen shoulder, or rotator cuff injuries (250-255).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques for shoulder pain, frozen shoulder, or rotator cuff injuries (250-255).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of ankle inversion sprains (256).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of ankle inversion sprains (256).

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of TMJ (257-261)

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques in the management of TMJ (257-261)

 C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques for the recovery or prevention of visual field narrowing (262-267).

C


There is not enough reliable scientific evidence to conclude the effects of chiropractic techniques for the recovery or prevention of visual field narrowing (262-267).

C


Despite promising preliminary results, there is not enough reliable scientific evidence to conclude the effects of chiropractic techniques for the improvement of symptoms related to whiplash injuries (268-272).

 C


Despite promising preliminary results, there is not enough reliable scientific evidence to conclude the effects of chiropractic techniques for the improvement of symptoms related to whiplash injuries (268-272).

 C
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)

Tradition / Theory

The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

Safety

Many complementary techniques are practiced by healthcare professionals with formal training, in accordance with the standards of national organizations. However, this is not universally the case, and adverse effects are possible. Due to limited research, in some cases only limited safety information is available.

Attribution

This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

Aker, P. D., Gross, A. R., Goldsmith, C. H., and Peloso, P. Conservative management of mechanical neck pain: systematic overview and meta-analysis. BMJ 11-23-1996;313(7068):1291-1296.
Beneliyahu, D. J. Magnetic resonance imaging and clinical follow-up: study of 27 patients receiving chiropractic care for cervical and lumbar disc herniations. J Manipulative Physiol Ther 1996;19(9):597-606.
Bronfort, G., Evans, R. L., Kubic, P., and Filkin, P. Chronic pediatric asthma and chiropractic spinal manipulation: A prospective clinical series and randomized clinical pilot study. J Manipulative Physiol Ther 2001;24(6):369-377.
Deyle, G. D., Henderson, N. E., Matekel, R. L., Ryder, M. G., Garber, M. B., and Allison, S. C. Effectiveness of manual physical therapy and exercise in osteoarthritis of the knee. A randomized, controlled trial. Ann.Intern.Med 2-1-2000;132(3):173-181.
Froehle, R. M. Ear infection: a retrospective study examining improvement from chiropractic care and analyzing for influencing factors. J Manipulative Physiol Ther 1996;19(3):169-177.
Hawk, C., Long, C., and Azad, A. Chiropractic care for women with chronic pelvic pain: a prospective single-group intervention study. J Manipulative Physiol Ther 1997;20(2):73-79.
Hondras, M. A., Linde, K., and Jones, A. P. Manual therapy for asthma. Cochrane.Database.Syst.Rev 2005;(2):CD001002.
Natural Standard: The Authority on Integrative Medicine.
Pistolese, R. A. Epilepsy and seizure disorders: a review of literature relative to chiropractic care of children. J Manipulative Physiol Ther 2001;24(3):199-205.
Plaugher, G., Long, C. R., Alcantara, J., Silveus, A. D., Wood, H., Lotun, K., Menke, J. M., Meeker, W. C., and Rowe, S. H. Practice-based randomized controlled-comparison clinical trial of chiropractic adjustments and brief massage treatment at sites of subluxation in subjects with essential hypertension: pilot study. J Manipulative Physiol Ther 2002;25(4):221-239.
Schiller, L. Effectiveness of spinal manipulative therapy in the treatment of mechanical thoracic spine pain: a pilot randomized clinical trial. J Manipulative Physiol Ther 2001;24(6):394-401.
Winters, J. C., Jorritsma, W., Groenier, K. H., Sobel, J. S., Meyboom-de Jong, B., and Arendzen, H. J. Treatment of shoulder complaints in general practice: long term results of a randomised, single blind study comparing physiotherapy, manipulation, and corticosteroid injection. BMJ 5-22-1999;318(7195):1395-1396.
Winters, J. C., Sobel, J. S., Groenier, K. H., Arendzen, H. J., and Meyboom-de Jong, B. Comparison of physiotherapy, manipulation, and corticosteroid injection for treating shoulder complaints in general practice: randomised, single blind study. BMJ 5-3-1997;314(7090):1320-1325.
Wreje, U., Nordgren, B., and Aberg, H. Treatment of pelvic joint dysfunction in primary care--a controlled study. Scand J Prim Health Care 1992;10(4):310-315.
Yates, R. G., Lamping, D. L., Abram, N. L., and Wright, C. Effects of chiropractic treatment on blood pressure and anxiety: a randomized, controlled trial. J Manipulative Physiol Ther 1988;11(6):484-488.