Osteopathic Regulation of Physiology
Douglas G. Richards, PhD, David L. McMillin,
MA, Eric A. Mein, MD, and Carl D. Nelson, DC
Meridian Institute, Virginia Beach, VA
Fall 2001 The AAO Journal
Volume 11, Number 3, pages 34-38
This study explored the effects on physiology of "holding the vasomotor
center," a historical technique of inhibitory pressure in the cervical
area, intended to affect sympathetic nervous system control of circulation.
Circulation, skin temperature, heart rate and breathing rate were measured
in 18 participants, during holding the vasomotor in comparison with a "sham"
manipulation - a gentle touching of the tops of the shoulders. There was
substantial individual variability, but averaging of the responses showed
increased circulation to the fingers, accompanied by increased finger temperature
and a briefly reduced heart rate followed by an increased heart rate, in
response to holding the vasomotor center. Touching the shoulders did not
result in any circulatory or temperature changes, but did cause a briefly
reduced heart rate identical to that from holding the vasomotor center.
Manual therapy encompasses both structural corrections and regulation
of physiology, but the regulatory aspects have received less attention
than the structural aspects. Nevertheless, regulation of physiology
played a significant role in historical osteopathy, and has received some
support from modern research. Our goal in this pilot study was to test
a claim from the early osteopathic literature, as a step toward discriminating
physiologically effective manipulations from those manipulations with the
potential to be "sham" controls in experiments.
Historical osteopathy often focused on regulation of physiology. For
example, Barber  states: "We all agree upon the one great point, that
man is a machine, and that nerve-centers have been discovered upon which
a pressure of the hand will cause the heart to slow or quicken its action,
from which we can regulate the action of the stomach, bowels, liver, pancreas,
kidneys, and the diaphragm" (p.28). He says, "With a thorough knowledge
of the various nerve-centers, and the innervation of the different tissues
and organs, the osteopath is able to coordinate the nerve-force of the
body. He can increase the nerve-current to almost any part of the being,
and can quiet an excessive one as well" (p.23).
Modern research offers some support for the effects of manipulation
on physiology, reviewed in Mein et.al. For example, animal work by Sato
and colleagues [3-5] supports the traditional concepts of stimulation and
inhibition. Working with anesthetized animals, they have traced reflexes
from various types of mechanical, thermal and chemical stimulation of the
skin to visceral effector organs including the heart, stomach, sweat glands,
bladder, and adrenal medulla.
Heart rate can be increased in anesthetized cats by stimulation of anyone
of a variety of skin areas. This reflex is produced mainly by an augmentation
of cardiac sympathetic efferent nerve activity. Similarly, in the anesthetized
rat, Sato demonstrated inhibition of gastric contractions by stimulating
the abdominal skin. Conversely, noxious stimulation of a hind paw sometimes
augments gastric motility, mediated by reflex facilitation of gastric vagal
efferent nerve activity.
In humans, there is also some evidence for the effects of manipulation
on physiology. For example, the thoracic lymphatic pump has been shown
to modify immune function [6,7] and manipulation has reduced hypertension.
[8,9] Purdy et al  demonstrated that gentle, soft tissue manipulation
in the suboccipital region can result in significant changes in blood flow
in the fingers, mediated by the sympathetic nervous system. In addition,
Purdy et al found that even a gentle touch in the same area, without manipulation,
had a measurable effect on finger blood flow. Their result is particularly
interesting because it demonstrates changes in the autonomic periphery
during manipulation of a dermatome unrelated to the area being measured.
One important issue that has arisen from studies on the efficacy of
manual therapy is that of the placebo effect and the nature of an appropriate
"sham" treatment. In a recent study of the effect of chiropractic on childhood
asthma, the sham treatment included soft tissue work similar to traditional
osteopathic manipulation.  The placebo condition included, among other
manipulations, "soft-tissue massage and gentle palpation" to the spine,
paraspinal muscles, and shoulders; "turning the subject's head from one
side to the other;" with the subject in a supine position "with the head
rotated slightly to each side, . . . an impulse applied to the external
occipital protuberance;" and with the subject in the prone position, "a
similar impulse was applied bilaterally to the scapulae."
The study yielded evidence for the efficacy of both treatments, but
the authors concluded that this result demonstrated the placebo effect.
We have disagreed, pointing out the importance of considering the diversity
of manual techniques when studying manual therapy. [12-15] In particular,
soft tissue techniques that do not involve high velocity, low amplitude
(HVLA) thrusts on the spine may have significant physiological effects,
as shown in the Purdy et al  study.
We had a particular interest in techniques affecting the sympathetic/parasympathetic
balance and influencing circulation, since this is an important consideration
in therapy for asthma. Rather than looking at a complex, full treatment,
we chose to study a simple maneuver from traditional osteopathy, in comparison
with another simple maneuver not expected to have a direct effect on the
sympathetic nervous system.
We chose a manipulation intended to inhibit the superior cervical ganglion;
a primary vasomotor center discussed in various early osteopathic manuals.
[2,16-18] The vasomotor system controls the circulation of the body. Inhibition,
defined as holding a steady pressure on the cervical vasomotor center,
was said to dilate the blood vessels by reducing sympathetic nervous system
activity, increasing circulation to such areas as the hands and feet. Barber
 used the expression "holding the vasomotor" when referring to this
technique. His description of the move was as follows: "Place the hands
upon the sides of the neck, the fingers almost meeting over the spine of
the upper cervicals; tip the head backward, pressing hard upon the vasomotor
center four or five minutes . . ." (p.260). Figure
1, from the 1910 Text-Book of Osteopathy 19 illustrates the
maneuver as we used it in the current study. The move was said to be particularly
useful in treating headache and reducing fevers associated with infectious
A. T. Still realized the therapeutic potential of steady pressure on
the cervical ganglion when he used an inhibitive technique (lying with
his neck in a sling) to relieve his own headaches.  Later, when writing
Philosophy of Osteopathy in 1899,  he included an entire chapter
by William Smith on "The Superior Cervical Ganglion." Smith discussed the
effects of inhibitory pressure upon the upper four cervical nerves: "the
capillaries over the entire surface of the body flushed, this being accompanied
by a fall in pulse rate and a marked diminution of the temperature [note
that he does not specify which temperature - he probably means the internal
body temperature]" (p.267). In another passage Smith discussed inhibition
of the superior cervical ganglion, and noted that it should produce "relaxation
of the vascular walls . . . the skin will become flushed and moist . .
. the vagus is now allowed full sway, and we must find slowing of the heartbeat"
We had two questions. The first was whether the effects of such a maneuver
on physiology could be measured. The second was whether the maneuver of
holding the vasomotor had specific effects that were different from those
of a "sham" treatment - simply lightly touching the tops of both shoulders
simultaneously, for the same duration as the vasomotor inhibition. Note
that, like the sham treatment in the Balon et al  study on asthma,
these manipulations involved the soft tissue of the neck and shoulders.
Eighteen volunteers (6 male, 12 female, mean age 51, SD 11.1, range
28-74) participated in the project. There were no specific selection criteria;
all participants were questioned concerning any conditions that might affect
circulation. Although several reported poor circulation to the extremities,
these participants were included since a possible change in circulation
was relevant to the hypothesis. All participants provided informed consent
prior to their participation; the consent form included a statement that
the experiment had no therapeutic purpose, but was solely to collect physiological
data. Each person took part in one or two sessions, as described below.
Physiological measurement was performed using a Biopak Systems MP100WSW
data acquisition system. Measures included heart rate (calculated from
electrocardiograph beat-to-beat interval), depth of breathing (from temperature
measurement of inhalation and exhalation through the nose), circulation
to the finger (right thumb) and toe (right big toe) from a photoplethysmograph,
and temperature of left thumb. Room temperature was maintained at between
68 and 73 degrees F (20.0 and 22.8 degrees C). This was intended to provide
a slight thermal stress, cooling the extremities.
The subjects were instructed to lie on a table for 40 minutes, while
we measured the physiological variables. They were told to simply relax.
After a 10-minute baseline, a therapist would either hold the vasomotor
center, or lightly touch the tops of the shoulders, for 5 minutes. The
order was randomly chosen to avoid effects simply due to how long the person
had been lying on the table. Then, after another 10-minute period of relaxation,
the other manipulation would be given for 5 minutes, and the session would
end with a final 10-minute period of relaxation.
The most striking result initially was the presence of a great deal
of individual variability. For example, the baseline finger temperature
ranged from 74 degrees F to 96.5 degrees F. But by averaging over many
sessions (23 total sessions in this report), we were able to clearly see
the typical effects of these maneuvers on physiology. Over time, with no
treatment at all, circulation and skin temperature tend to drop in a cool
room, and heart rate decreases as the body relaxes. We were looking for
departures from this general trend.
Figure 2 shows the average effect on finger
circulation. The standard deviation of the blood volume pulse from the
photoplethysmograph was used as a measure of circulation. The graph shows
5 minutes before the treatment, the 5-minute treatment, and 5 minutes after
the treatment. Holding the vasomotor is the solid line; the shoulder
touch is the dotted line. The graph shows that, on the average, about a
minute into the treatment, circulation goes up with the active treatment,
while it stays the same with the sham treatment.
Figure 3 shows the average effect on finger
temperature. The means have been adjusted to show identical temperature
at the beginning of the measurement period. Note that the effect on temperature
is smoother and longer lasting than the one on circulation. It takes a
while for the flow of blood to the surface to actually warm the skin, and
then the skin holds heat longer after the blood flow has decreased.
Figure 4 shows the effect on heart rate. This
was especially interesting to us, since in the first minute of both maneuvers,
heart rate decreases. A decrease of heart rate is consistent with the historical
osteopathic literature.  However, here it seems to be a general response
to being touched. Then heart rate increases for the "holding the vasomotor"
maneuver, while for the shoulder touch there is no change.
The early osteopaths made strong claims about the effects of manipulation
on physiology. This pilot study provides evidence that, with an average
of many subjects, the circulatory effects of holding the vasomotor center
can be demonstrated. However, the variability both within and between subjects
was so great that caution must be exercised in accepting any generalization
about effects. It is also clear that treatments involving the neck and
shoulder, including ones intended as sham treatments, have the potential
for physiological effects and should not be thought of as placebo controls.
Variability - both baseline variability unrelated to the manipulation,
and variability in response to the manipulation - is the greatest challenge
in this research, making statistical analysis difficult. Driscoll and DiCicco,
 who are also exploring the effects of manipulation on physiology (heart
rate variability), faced a similar problem of variability that swamped
the desired effect. They were able to reduce the variability by driving
heart rate with timed breathing, but noted that this may override any effects
from manipulation. We are exploring ways to reduce variability by selecting
subjects based on preliminary measurements of physiology.
Another significant issue raised by the results concerns the time frame
of the measurements. The baseline must be sufficiently long to establish
a trend or to allow the variability to stabilize. The treatment period
must be sufficiently long for an effect to occur, but not so long that
the response habituates or reverses. For example, in a preliminary experiment
we found a reversal effect, where inhibition would appear about halfway
into a 10-minute period of stimulation.
The measurement period must be sufficient to allow for any lag between
the treatment and the response, and for any persistence of the effect after
the end of the treatment. For example, a study by Harris and Wagnon 
looked at finger temperature 10 seconds after an HVLA chiropractic adjustment,
finding evidence of physiological effects. Our data suggest that even with
a rapid increase in peripheral circulation, there is a lag of 30 seconds
or more for temperature to rise, making their results difficult to interpret.
Finally, persistence of effects can complicate studies in which a series
of manipulations are given.
The heart rate result shows how hard it may be to define a "sham" treatment
for scientific study. Our sham maneuver was a light touch of the tops of
both shoulders, which is not a location of significance in the osteopathic
literature. The shoulder touch response is likely to be a nonspecific reaction
to being touched, but there remains the possibility of specific effects
on the autonomic nervous system from points distant from the spine. As
noted previously, Purdy et al  found that a light touch on the occipital
area had an effect on digital blood flow. Several participants in the current
project pointed out that the points of shoulder contact might be relevant
in acupressure. Alternatively, some of the Chapman's points used in osteopathic
manipulative therapy bear little obvious relation to the target organ.
For example, the anterior points for the eye problems of retinitis and
conjunctivitis are located on the front of the humerus,24 (p.18). Even
light stroking of the skin has claims of major effects on lymphatic physiology.
 We concur with Purdy et al  that manipulation of the cervical
area can have useful physiological effects, and could be applicable to
the treatment of entities such as migraine or other hyperautonomic states.
In addition, it is clear that even simple touching is not an inert placebo,
and that the effects of touching itself bear further investigation.
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Hudson-Kimberly Publishing Co. 1898.
3. Sato A. Somatovisceral reflexes. J Manipulative Physiol Ther 1995:18:597-602.
4. Sato A. Reflex modulation of visceral functions by somatic afferent
activity. In: Patterson, MM, Howell, JN, editors. The Central Connection:
Somatovisceral/Viscerosomatic Interaction. 1989 International Symposium.
Athens, Ohio: American Academy of Osteopathy. 1992:53-76.
5. Sato A, Sato Y, Suzuki A, Uchida S. Neural mechanisms of the reflex
inhibition and excitation of gastric motility elicited by acupuncture-like
stimulation in anesthetized rats. Neurosci Res. 1993:18:53-62.
6. Measel JW, Jr. The effect of the lymphatic pump on the immune response.
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assayed by bacterial agglutination and passive hemagglutination. JAOA.
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of lymphatic and splenic pump techniques on the antibody response to hepatitis
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8. Mannino JR. The application of neurologic reflexes to the treatment
of hypertension. JAOA. 1979:79:225-231.
9. Morgan JP, Dickey JL, Hunt HH, Hudgins PM. A controlled trial of
spinal manipulation in the management of hypertension. JAOA. 1985:85:308-312.
10.Purdy WR, Frank JJ, Oliver B. Suboccipital dermatomyotomic stimulation
and digital blood flow. JAOA. 1996:96:5:285-9.
11.Halon J, Aker PD, Crowther ER, Danielson C, Cox PG, O'Shaughnessy
D, Walker C, Goldsmith CH, Duku E, Sears MR. A comparison of active and
simulated chiropractic manipulation as adjunctive treatment for childhood
asthma. N Engl J Med. 1998:339:1013-1020.
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asthma [Letter]. N Engl J Med. 1999: 340:391-392.
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diversity and other challenges to chiropractic integration. J Manipulative
Physiol Ther. 2000:23:3:202-07.
14.Mein EA, Greenman PE, McMillin, DL, Richards DG, Nelson, CD. Manual
medicine diversity: research pitfalls and the emerging medical paradigm.
JAOA, in press, 2001.
15.McMillin DL, Richards DG, Mein EA, Nelson CD. [Letter]. The AAO
16.Hazzard C. Principles of Osteopathy (Third Edition). Kirksville,
MO, Charles Hazzard, 1899.
17. Feidler FJ. The Household Osteopath. New York. Broadway Publishing
18. Davis AP. Neuropathy. The New Science of Drugless Healing
Amply Illustrated and Explained. Cincinnati, OH. F. L. Rowe. 1909.
19. Text-Book of Osteopathy. Chicago, IL, American College of
20. Still AT: Autobiography of Andrew Taylor Still. Kirksville,
MO. A. T. Still. 1897.
21.Smith W. Chapter 20 - The Superior Cervical Ganglion. In Still AT,
ed. Philosophy of Osteopathy. Kirksville, MO, A. T. Still, 1899.
22. Driscoll D, DiCicco G. The effects of metronome breathing on the
variability of autonomic activity measurements. J Manipulative Physiol
23.Harris W, Wagnon RJ. The effects of chiropractic adjustments on distal
skin temperature. J Manipulative Physiol Ther. 1987:10:57-60.
24.Kuchera ML, Kuchera W A. Osteopathic Considerations in Systemic
Dysfunction. Kirksville, MO. KCOM Press. 1991.
25.Kurz I: Textbook of Dr. Vodder's Manual Lymph Drainage. Volume 2:
Therapy. Brussels. Hang International. 1986.
Note: The complete texts of the historical sources on osteopathy are
all available on the Meridian Institute web site, www.meridianinstitute.com,
in the Early American Manual Therapy section.
|Figure 1. Illustration of historical osteopathic method of "holding
the vasomotor " used in this study,from 1910 Text-Book of Osteopathy.
|Figure 2. Effect of "holding the vasomotor " on finger circulation
((solid line), compared with light shoulder touch (dotted line).
|Figure 3. Effect of "holding the vasomotor " on finger temperature
((solid line), compared with light shoulder touch (dotted line).
|Figure 4. Effect of "holding the vasomotor " on heart rate ((solid
line),compared with light shoulder touch (dotted line).