TITLE: Changes in proprioception and pain in patients with neck pain after upper
thoracic manipulation

  ABSTRACT:
[Purpose] The purpose of this study was to conduct cervical stability training and upper
thoracic manipulation for patients with chronic neck pain and then investigate the changes
of cervical proprioception and pain. [Subjects and Methods] Subjects were 30 workers with
mechanical neck pain, who were randomly divided into an upper thoracic manipulation group
and a cervical stability training group. Upper thoracic manipulation after cervical
stability training was conducted for the upper thoracic manipulation group, and only
stability training was conducted for the cervical stability training group. The
intervention period was six weeks, and consisted of three sessions a week, each of which
lasted for 30 minutes. For proprioception measurement, an electro-goniometer was used to
measure reposition sense before and after the intervention. The visual analogue scale was
used to assess pain. [Results] After the intervention, the error angle was significantly
smaller in flexion and right left side-bending, and pain was significantly reduced in the
upper thoracic manipulation group. According to the post intervention comparison of the
two groups, there were significant differences in the proprioception and pain values.
[Conclusion] Conducting both cervical stability training and upper thoracic manipulation
for patients with chronic neck pain was more helpful for the improvement of proprioception
and pain than cervical stability training alone.

BODY.INTRODUCTION:
Neck pain is a disease that most people experience at least once in their life time. Neck
pain is the main cause of an increase in economic and social health costs. To treat neck
pain, physical therapists often use therapeutic exercise, traction, joint mobilization, and
manipulation1, 2).  In the case of the patients with chronic neck pain, because of overuse, repetitive trauma,
serious trauma and muscle weakness, the range of elasticity of the non-contractile tissues
becomes enlarged, and stablize the neutral position, and contractile tissues become weak. As
a result, instability increases in the spinal segments, resulting in failure to maintain the
neutral position. Joint instability is accompanied by loss of somatosensory system function.
In addition, joint instability causes hyper-mobility of cervical segments, and restricts the
movement of the thoracic segments, which ultimately leads to functional restriction2).  Manipulation and mobilization are clinically employed often to improve cervical instability
and functional movement. Thoracic manipulation and joint mobilization help to increase the
restricted mobility of the spinal segments, to improve cervical mobility and stability, and
to recover functional movement and proprioception, and ultimately reducing pain and
functional disorder3, 4).  In order to recover cervical proprioception in patients with chronic neck pain, a
therapeutic approach is conducted to improve cervical instability, joint mobility, and
neuromuscular control. Cranio-cervical flexor (CCF) training aims at recovery of control of
the muscular system around the cervical spine and the recovery of cervical proprioception.
For improvement in cervical joint mobility, manipulation and mobilization are performed5).  Previous studies have reported that direct cervical manipulation is a dangerous cervical
treatment, because it can reduce the function of the spinal artery. For that reason, CCF
training is widely employed to improve proprioception, pain and range of motion (ROM), and
reduce the neck disability index (NDI) score of patients with neck pain4, 6).  Recently, indirect thoracic manipulation and mobilization have frequently been used to
treat patients with neck pain, because it is safer than direct manipulation. Spinal
manipulation elicits immediate effects on recovery of function, such as pain alleviation and
ROM improvement, than conservative physical therapy. In addition, according to previous
studies, manipulation is more effective at reducing pain than conservative muscle
training7).  Nevertheless, there is still a lack of research evidence supporting the efficacy of
manipulation. Therefore, the purpose of this study was to conduct cervical stability
training (CST) and upper thoracic manipulation (UTM) for patients with chronic neck pain and
investigate the changes in cervical proprioception and pain.

BODY.SUBJECTS AND METHODS:
The subjects were 30 subjects with chronic mechanical neck pain who agreed to participate
in this study. The inclusion criteria were: unilateral or bilateral pain in the posterior
neck or shoulder region, and pain in the cervical region when moving or palpating the
cervical region, which had lasted for more than 12 weeks, and was rated higher than four on
a visual analogue scale (VAS). The exclusion criteria were: a diagnosis of cervical
radiculopathy, previous experience of spinal manipulation, a history of fracture or
dislocation of the cervical or thoracic spine, a history of surgical operation on the
cervical or thoracic spine, hypertension, heart disease, or pregnancy.  The research protocol was approved by the Research Ethics Committee for Human Research of
Konyang University, Korea.  UTM comprised 2 methods. Method 1: Upper thoracic lift manipulation. The subjects were
asked to lock their fingers together, put their hands on the back of the neck, and sit in a
chair without a back support. Then, a rolled towel was placed over the target spinal
segment. A therapist stood behind the subject, and leant forward toward the rolled towel, or
the target spinal segment. The therapist held the forearm of the subject, and flexed the
subject's neck and upper thoracic completely up to the spinal segment, creating a force
against the rolled towel using the subject's forearm, and held the subject's elbow in a
horizontal adduction motion while lifting the subject toward the therapist in the
posterior-anterior direction; and then applied thrust manipulation to the subject along with
horizontal adduction and expiration4).  Method 2: Thoracic manipulation in the supine position. The therapist stood next to the
subject. And placed a hand on the subject's transverse process on the inferior segment of
the target spinal segment. The subject puts his/her arms on the chest or locked their
fingers at the back of the head and neck. The therapist held the subject's arms to keep the
subject close, then put the manipulation hand on the target spinal segment and used the
supporting hand to fix the subject's elbows with the therapist's forearm. After performing
flexion up to the subject's target segment, the therapist applied thrust manipulation in the
anterior-to-posterior direction while the subject inhaled and exhaled. The target segments
were T1 to T44).  CTS consisted of static stability training for re-education and dynamic stability training
for muscle endurance and power8). The
static stability training used a pressure biofeedback unit (PBU), and it was based on CCF
training for activating the deep muscles such as the longus colli and longus capitis. In
dynamic stability training, the subjects maintained cervical flexion, and active assistive
and active methods were conducted. After they had maintained cervical stability, the
subjects performed dynamic training through extremity movement. The subjects were asked to
pay attention to the cervical stability during training9).  To measure the cervical proprioception of the patients with chronic neck pain, the cervical
reposition test was conducted using an electro-goniometer (Mobee, Bitburg, 2013, Germany).
The study subjects were asked to sit in an upright position comfortably in a chair. The
target position was randomly chosen from among 30%, 60%, and 90% of the maximal ROM. The
subjects kept the target position for 3 seconds, repeated it 5 times10). For measurement, the reposition test was conducted at the
set angle 3 times. The rest time between measurements was 15 seconds. Measurement directions
were set to flexion, extension, right and left side-bending. The subjects were asked to sit
upright and wear black sunglasses to inhibit their vision, and to move actively toward the
target position in a random order. The difference between the target angle and the actual
angle was used in the analysis11). All
subjects were asked to mark on a VAS scale ranging from 0 to 10 for the subjective
assessment of pain. VAS is a simple way for the subjects to express their level of pain and
has high reproducibility. It is also an evaluation method with high validity (r=0.77) and
reliability (r=0.99)12) (Table 1Table 1.Comparison of proprioception and pain within groups and between groups
(N=30)Manipulation group (n=15)Control group (n=15)Flexion (angle)Pre6.07 (2.02)5.67 (2.06)Post2.47 (1.55)†**4.27 (1.44)†,‡**ExtensionPre4.87 (1.81)4.87 (2.48)Post3.27 (0.96)†**3.53 (1.81)†**Rt sidebendPre6.20 (1.79)6.73 (2.55)Post1.87 (1.30)†**5.00 (2.14)†,‡**Lt sidebendPre6.60 (1.55)6.53 (1.89)Post1.00 (1.20)†**4.67 (1.88)†,‡**VASPre7.13 (0.83)6.93 (1.44)Post1.93 (0.70)†**3.40 (0.74)†,‡**Values are expressed as mean (SD). *p<0.05, **p<0.01, †Within group
comparison, ‡Between group comparison).  For data analysis, SPSS version 18.0 (SPSS, Inc., Chicago, USA) was used. Frequency
analysis and descriptive statistics were employed to compare the general characteristics of
the subjects. The independent t-test was conducted to compare the thoracic manipulation
group and the CST group. The paired t-test was performed to compare the pre- and post
intervention results of the UTM and the CST. The level of statistical significance was
chosen as 0.05.

BODY.RESULTS:
There were 8 male and 7 female in the manipulation group, and 7 male and 8 female in the
control group. The mean age of the subjects was 30.80 years in the manipulation group and
28.07 years in the control group. The average weight, height and BMI were 63.23 kg,
164.87 cm and 23.20 kg/m2, respectively in the manipulation group, and 62.89 kg,
168.13 cm and 21.93 kg/m2, respectively in the control group. The UTM showed
significantly smaller repositioning error in flexion and right and left side-bending and
greater reduction in pain than the CST group (p<0.01). Both the UTM and CST groups showed
significant differences in proprioception and pain after the intervention (p<0.01).

BODY.DISCUSSION:
In this study, CST was conducted for the patients with chronic neck pain, followed by UTM
for six weeks. After that, the changes in proprioception and pain were analyzed. After the
interventions, the UTM group showed significant reductions in error angles which were less
than those in the CST group, and the pain level of the UTM group was also significantly
reduced.  Proprioception receptors, such as mechanoreceptors and free nerve endings, are found in the
skin, facial, muscles, tendons, joint capsules, and ligaments. When active or passive
movement occurs, receptors transmit the movement information to the central nervous system
(CNS)13). High velocity low amplitude
manipulation stimulates mechanoreceptors located in the muscles, ligaments, and joint
capsules improving their responses in transmitting to the CNS; thus, helping the recovery of
proprioception. It is known that manipulation mechanically stimulates joint capsules and
thus leading to increased mobility of the spinal segments and increases ROM, which lessens
the fear of movement by smoothly transmitting movement information to the CNS, thereby
reducing pain1, 14).  According to many previous studies, the combined approach of a therapeutic exercise program
and manipulation is more effective at recovering the proprioception of patients with neck
pain and their functions through pain reduction than any other kind of intervention15).  Cassidy et al.16) independently conducted
both manipulation and joint mobilization for patients with mechanical neck pain, and
reported the two groups showed significant improvements in pain and ROM after the
interventions.  Joint mobilization conducted for the patients with chronic RA helped to increase their pain
threshold17). Another hypothesis
regarding pain reduction after manipulation is that beta-endorphins are expressed and that
this alleviates pain18). According to
Vernon et al.19), after manipulation,
beta-endorphins increased for five minutes, but 15 minutes later, their level had returned
to its original state. According to the results of the present study, proprioception and
pain were significantly reduced after UTM, a result that is consistent with the empirical
evidence of previous studies.  Another proposal is that spine manipulation activates type I (static movement) and type II
(dynamic movement) mechanoreceptors, which are distributed in passive and active structures,
sending signals through the CNS to the periaqueductal grey area, the pain control system
around the cerebral aqueduct of mid-brain, which increases the pain threshold to control
pain20).  The results of this study show that the thoracic manipulation group displayed more
significant differences in pain reduction than the cervical stability group, and that CST
also improved proprioception and pain. According to the study of Panjabi21), cervical stability is maintained by the
stability passive and active tissues and the capability of neuromuscular control. The
purpose of the passive system is to use the elasticity of passive tissues including
ligaments, joint capsules, and tendons to stabilize the neutral position. The purpose of the
active system is to use the force generated by active tissues like muscles to maintain the
neutral position. In addition, the neuromuscular control system controls and amplitude of
the overall range and mobility. The CST result was consistent with the theory that training
improves the stability the neutral position and its maintenance through the activation of
the active tissues of muscles.  Despite these results, this study had several limitations. For example, the number of study
subjects small, and there was no long-term intervention of manipulation or CST. Therefore,
we consider that it will be necessary to increase the number of study subjects and lengthen
the intervention period to prove the effects of manipulation. In the present study, the
repositioning test was conducted to measure the propriocetive deficit. However, this is an
indirect method, not a direct one, of measuring proprioception. For that reason, it is
impossible to generalize the results. Therefore, we think that a more objective tool and
measurement method will be needed to investigate proprioception.  In summary, the UTM group showed significant improvements in cervical proprioception, and
significant reduction in pain, which were larger than those of the CST group. The findings
of this study indicate that combine stability training and thoracic manipulation for
patients with neck pain improves proprioception and reduces pain level.

Question: Compared to cervical stability training (CST) what was the result of upper thoracic manipulation (UTM) on reduction in pain?
Evidence: The UTM showed
significantly smaller repositioning error in flexion and right and left side-bending and
greater reduction in pain than the CST group (p<0.01). 
Answer: significantly increased