Influence of vibration on cervicocephalic kinesthetic sensibility in patients with non-specific neck pain and healthy subjects

Several clinical signs are seen in research with neck pain patients, for
example a reduced range of motion (ROM), jerky movement (JERK) and a reduced
joint position sense (Sjölander et al., 2008). The jerky movement and reduced
joint position sense are probably caused by sensorimotor disturbances
(Sjölander et al., 2008). Sensorimotor disturbances play a role in the
development, existence and return of several signs and symptoms in neck pain
patients (Sterling et al., 2003; Treleaven et al., 2003; Heikkila and Astrom,
1996).


In particular, the contraction of the deep neck flexors is reduced in patients
with chronic neck pain (Falla et al., 2004). Falla et al. (2011) showed that at
a higher intensity of the pain occurs less contraction of the deep neck
flexors. However, there is no correlation between the duration of pain and the
degree of tensioning (Falla et al., 2011).
It has been showed that pain can bring a change on multiple levels of the
nervous system. The influence of pain can have an impact on the sensitivity of
muscle spindles and provide an altered cortical representation and modulation
of cervical afferent input (Armstrong et al, 2008;. Treleaven 2008).
A change of cervical somatosensory activity can lead to disturbance in the
sensorimotor function (Armstrong et al, 2008;. Treleaven 2008).

Critical to effective motor control is accurate sensory information (Riemann
and Lephart 2002). The ability to sense position, known as proprioception, is
essential in repositioning of the cervical spine (Kristjansson and Treleaven
2009; Armstrong et al., 2008). The proprioception is determined by a complex
mechanism inside and outside the cervical spine. The vestibular system,
muscular and arthrogenic receptors in combination with the central en
peripheral nervous system play a key role in this process (Kristjansson and
Treleaven 2009; Armstrong et al., 2008; Treleaven 2008). Multiple studies have
demonstrated that the density of the muscle spindles, which are muscular
receptors, in the cervical spine are highest in the suboccipital and mid
cervical part of cervical muscles (Banks 2006; Boyd-Clark et al., 2002;
Kulkarni et al., 2001; Amonoo-Kuofi 1983).
The smoothness of movement can be measured by the jerk index and the joint
position sense (Lee et al., 2008; Pinsault et al., 2008; Sjölander et al.,
2008; Lee et al., 2006). The joint position sense make use of the
repostioningtest head-to-neutral or head-to-target and has the joint position
error (JPE) as an outcome (Lee et al., 2008; Pinsault et al., 2008; Sjölander
et al., 2008; Lee et al., 2006). The smoothness of movement and the joint
position sense can be measured to get an impression of the proprioception of
the cervical spine (Sjölander et al., 2008).
In earlier studies the joint position sense is measured in a two-(2-D) and
three-dimensional(3-D) manner (Roren et al., 2009). Research by Cattrysse et
al. (2009) showed that the reproducibility of a 3-D motion analysis is moderate
to good (Cattrysse et al., 2009).
In a study in patients with a fusion of an anterior cervical segment measured
in three-dimensional manner has been found that this three-dimensional method
is a way to gain insight in the ROM and coupled movements, but also in the
smoothness of movements (JERK) of the cervical spine (Cattrysse et al., 2012).

It is known pain has a bad influence on JPE in the cervical spine. Malmström et
al., 2013 have investigated the effect of a unilateral pain stimulus in the
cervical spine on the JPE. This shows that after the unilateral pain stimulus
the JPE for the head-to-target repositioning is significantly greater on the
side of the pain stimulus (p <0.001). To the opposite side, no significant
difference has been found.

Treleaven et al., 2011 examined the sensory disorders in four different groups.
The four groups include: low traumatic cervical pain, traumatic upper cervical
pain, nontraumatic low cervical pain and non-traumatic upper cervical pain.
From this study it can be concluded that people with non-traumatic low cervical
pain have less sensory disorders.

Two contradicting studies researched the effect of aging on the joint position
error. In the study of Demaille - Wlodyka et al., 2007 neither age nor sex
influenced the ability to bring the head back to neutral. In the study of
Vuillerme et al., 2008, 18 healthy young adults (average age 23 years) compared
to 18 healthy adults older (average age 68 years) in the execution of the
relocation cervicocephalic test. This study shows that older adults are less
accurate and less consistent compared to younger adults.

Excercise, mobilisation and manipulation can improve the repositioning
accuracy.
Vibration on the neck muscles in healthy subjects lead to a change in postural
control to the opposite side.
Vibration has an opposite effect between neck patients and healthy subject.
Neck patients show a decrease of the JPE and a reduced postural sway after
vibration. Healthy subjects show an increased joint position error.

In conclusion. There is a tendency that vibration on the neck muscles in neck
pain patiens leads to improvement of the JPE, however this is until now only
been studied within the 2-D study of Beinert et al 2014.
There are no studies known in which the JPE, ROM, coupled movements and JERK
3-D have been measured after the administration of vibration on the neck
muscles.

With vibration on the sub-occipital muscles is attempted to influence the
proprioception. The expectation is that the effect of vibration in healthy
subjects leads to a larger deviation in the JPE. The expectation in patients
with non-specific neck pain is that vibration leads to an improvement in the
JPE.
A positive effect of vibration on the JPE in non-specific neck pain patients
shows that therapeutic goals and interventions should focus on proprioception.

The purpose of this study is to research the influence of vibration on the neck
muscles on JPE and the effect of aging on this parameter in patients with
a-specific neck pain. The second purpose is to research the influence of
vibration on the neck muscles on JPE in healthy subjects.

The study consists of a four phase procedure. In the first phase all patients
will be aksed to make five movements according a standardized procedure within
their maximum comfortable range of motion. The five movements are:
Axial rotation
Lateral bending
Flexion / Extension
Flexion/left rotation to Extension/right rotation = 3DL
Flexion/ right rotation to Extension/left rotation = 3DL

The procedure without vibration will be carried out twice; the first
measurement can be seen as a warming-up and as a backup and the second
measurement will be used as the actual registration for the study.
All movements start and end in the neutral position and every motion will be
done three times in every direction (e.g. rotation left - rotation right -
rotation left - rotation right - rotation left - rotation right).
After finishing all 5 movements the procedure will be carried out again.

In the second phase the joint position error shall be measured according to a
standardized instruction. The subject is blindfolded and tries to remember the
neutral position. Then the subject moves over the maximum comfortable range of
motion and returns as accurately as possible back to the neutral position. The
subject will be asked to return to the neutral position after the following
three movements:
Axial rotation
Lateral bending
Flexion / Extension
All movements are carried out six times to both sides. In several studies is
demonstrated that 6 trials are needed to derive stable estimates (Swait et al.,
2007; de Vries et al., 2015).

In the third phase of the procedure the joint position error will be measured
with vibration on the sub-occipital muscles. All movements in this procedure
shall be carried out six times as well for the same reasons as described above.

In the fourth phase the movements of the first phase will be repeated with the
application of vibration on the sub-occipital muscles. All movements start and
end in the neutral position and every motion will be done three times in every
direction. After finishing all 5 movements this procedure will be carried out
again.

Vibration on the sub-occipital muscles with a frequency of 100hz

In this study there is no risk of damage. All movements that are carried out
(cervical flexion, extension, rotation and lateralflexion) are part of the
normal movements in the daily life and are accepted in the diagnostic and
therapeutic interventions. The use of electromagnetic trackers is non-invasive
and extremely appropriate to analyse this motions. The application of vibration
is already being used in several studies without harmful or side effects.