Deep Cervical Muscle Dysfunction and Head/Neck/Face Pain–Part 2
Neck pain can be a disabling disorder characterized by periods of remission and exacerbation. It is estimated that in any 6-month period, 54% of adults will experience neck pain.1 There is evidence in the modern literature that changes in deep cervical (neck) muscle (longus capitis, rectus capitis anterior, rectus capitis lateralis, and longus colli) function, as measured by EMG, are associated with neck disorders.2 These changes indicate a reorganization of the motor strategy to perform specific tasks such that neck pain is associated with disturbed neural control of the cervical muscles. These impairments in deep cervical muscle function may result in heightened activity of the superficial muscles (e.g., sternocleidomastoids and anterior scalenes) during craniocervical flexion and upper limb movements.1 Although many muscles of the neck contribute to stabilization and protection of the cervical spine, the deep cervical flexors are critical for the control of intervertebral motion and control of the cervical lordosis.3 The importance of training the core stabilizers in the lumbar spine has been accepted for some time,4 but the importance of core stability in the cervical spine is relatively new. As reported in Part I, cervical dysfunction may be seen in up to 70% of the population suffering from any type of recurring headache.5
In recent years, there has been an increase in the investigation of cervical motor impairment associated with headaches. It is known that cervicogenic headache sufferers present with many neuromuscular changes that are different from those suffering from neck pain only.6 In addition, reduced range of motion is a criterion for cervicogenic headache but not for migraine or tension-type headache.7,8,9
Cervicogenic headache sufferers demonstrate deficits when measuring the strength of the deep cervical flexor muscles, while this is not reported in tension-type and migraine headache.6,10,11 The Head Raise Test provides a simple means of identifying such weakness. During this test, the patient raises his/her head from the table, while the clinician closely observes the direction of chin movement. In optimal firing order during head-neck flexion (longus capitus/rectus capitis anterior, longus colli, anterior scalenes, and sternocleidomastoids) the muscles cause the chin to tuck toward the chest during the first two inches of flexion. In forward head posture (FHP), hypertonic sub-occipitals reciprocally weaken the longus capitus and rectus capitis anterior, causing the sternocleidomastoids (SCMs) to fire first. The chin responds by reaching toward the ceiling, rather than tucking toward the chest.12,13 The Craniocervical Flexion Test (CCFT) has been utilized to suggest that impairment in low-load endurance of the deep cervical flexors is found in individuals with cervicogenic as well as chronic tension-type headache.2,6,14
Despite the growing awareness of the importance of deep cervical muscle strength and endurance, practitioners have few avenues available for in-office testing. In addition to the CCFT, another clinical test of the deep cervical flexor muscles was described by Grimmer in 1994.15 This test was based upon an exercise introduced by Trott in 1988 aimed at “…educating anti-gravity function of the cervical short flexor muscle groups…” It is believed that the use of this type of test for deep cervical muscle performance is useful for practitioners in the assessment of deep cervical flexor endurance. Lastly, Olson et al have demonstrated good inter-tester and intra-tester reliability with the Flexor Endurance Test.16 It is a simple means of assessing endurance capacity of the deep cervical flexor muscles and is the clinical test of choice in this study.
With this in mind, the Physical Therapy Department in the School of Health Professions at the New York Institute of Technology, designed a study to determine the effect of PostureJac®, a postural support and exercise jacket, on endurance of the deep cervical flexors.
Forty-five subjects between the ages of 18 and 40 years in good health were randomly assigned to three groups, consisting of the no-treatment control, the treatment-control, and the experimental (PostureJac) group. The no-treatment control group subjects were placed in the supine position, with hands resting on their abdomen (see Figure 1). The treatment-control group was placed in the supine position, with arms extended and hands holding onto the table for support (see Figure 2). The experimental group was given the PostureJac while in the supine position and engaged the handles in a downward direction (see Figure 3). The outcome measure of deep cervical flexor muscle endurance was based on the results of the Flexor Endurance Test16 and recorded in seconds. The average of four trials for each subject, on different days, was taken as the final measure of deep cervical flexor endurance.
The subjects were asked to raise their heads just enough to allow the tester to slide the widths of the index and middle finger, one on top of the other, under the most posterior aspect of the occiput. The subjects relaxed their heads on the examiner’s fingers. The subjects were instructed to perform a “chin-tuck” and raise the head slightly off the examiner’s fingers. Throughout the test, the examiner moved his/her fingers side to side under the subject’s head in order to provide tactile feedback for proper maintenance of head position.
Timing began when the subject raised his/her head off the examiner’s fingers, and was ended when 1 or more of 4 criteria were met:
- the subject experienced pain and was no longer willing to continue;
- the subject held the test position, but reaching the end of endurance, was unwilling to continue;
- the examiner determined that the subject had lost the chin-tuck position;
- the examiner determined that the subject raised his/her head (flexed the neck while still in chin-tuck) such that the tester’s fingers no longer maintained contact.
Time for the test was recorded to the nearest hundredth of a second.
The average times for each group were calculated using a one-way ANOVA with a Tukey Post Hoc Analysis of the no-treatment control, treatment-control, and experimental groups.