Cervicogenic Headaches - Research Review and Integrated Treatment Approach

Cervicogenic Headaches - Research Review and Integrated Treatment Approach

by Brent Brookbush MS, PES, CES, CSCS, ACSM H/FS

Etiology:

“Bogduk11 has proposed that the pathophysiology of CGH results from a convergence of sensory input from the upper cervical spine into the trigeminal spinal nucleus, including input from:

• Upper cervical facets
• Upper cervical muscles
• C2-3 intervertebral disc
• Vertebral and internal carotid arteries
• Dura mater of the upper spinal cord
• Posterior cranial fossa”

The quote above is from an article by Phil Page – this is a wonderful reference for understanding the etiology, symptomatology, prevalence, diagnosis and evidence-based treatment of cervicogenic headaches –http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3201065/

Interesting Note: Often cervicogenic headaches occur in individuals with normal findings on imaging of the cervical spine; however, there may be connective tissue changes that explain the effectiveness of mobilizations in the treatment of CGH.

Knackstedt, Heidi ; Kråkenes, Jostein ; Bansevicius, Dalius ; Russell, Michael. Magnetic resonance imaging of craniovertebral structures: clinical significance in cervicogenic headaches. (J HEADACHE PAIN), 2012 Jan; 13 (1): 39-44.

Quoted from Abstract:

“This paper aims to investigate the relevance of morphological changes in the main stabilizing structures of the craniocervical junction in persons with cervicogenic headache (CEH)… …The site of CEH pain was not correlated with the site of signal intensity changes of the alar and transverse ligaments. In fact, very few had moderate or severe signal intensity changes in their ligaments. MRI shows no specific changes of cervical discs or craniovertebral ligaments in CEH”

Alix ME , Bates DK , A proposed etiology of cervicogenic headache: the neurophysiologic basis and anatomic relationship between the dura mater and the rectus posterior capitis minor muscle. J Manipulative Physiol Ther. 1999 Oct;22(8):534-9.

Quoted from Abstract:

“RESULTS:

Connective tissue bridges were noted at the atlanto-occipital junction between the rectus capitis posterior minor muscle and the dorsal spinal dura. The perpendicular arrangement of these fibers appears to restrict dural movement toward the spinal cord. The ligamentum nuchae was found to be continuous with the posterior cervical spinal dura and the lateral portion of the occipital bone. Anatomic structures innervated by cervical nerves C1-C3 have the potential to cause headache pain. Included are the joint complexes of the upper 3 cervical segments, the dura mater, and spinal cord.

CONCLUSION:

A sizable body of clinical studies note the effect of manipulation on headache. These results support its effectiveness. The dura-muscular, dura-ligamentous connections in the upper cervical spine and occipital areas may provide anatomic and physiologic answers to the cause of the cervicogenic headache. This proposal would further explain manipulation's efficacy in the treatment of cervicogenic headache. Further studies in this area are warranted to better define the mechanisms of this anatomic relationship.”

Diagnosis of Cervicogenic Headache:

O. Sjaastad1, T.A. Fredriksen2, V. Pfaffenrath3, Cervicogenic Headache: Diagnostic Criteria, Headache: The Journal of Head and Face Pain, Volume 30, Issue 11, pages 725–726, November 1990

“Criteria for the diagnosis of cervicogenic headache are proposed, which include unilateral head pain, symptoms and signs of neck involvement, non-clustering episodic moderate pain originating in the neck then spreading to the head, and response to root or nerve blockade; plus rarer and non-obligatory features such as autonomic disturbances, dizziness, phonophotophobia, monocular visual blurring, and difficulty swallowing.”

The two most widely used diagnostic criteria for cervicogenic headache:

• Cervicogenic Headache International Study Group (CHISG)
• International Headache Society (IHS) Diagnostic Criteria

Interesting Note - Historical Perspective:

J M Pearce - Cervicogenic Headache an Early Description:

Despite the controversies surrounding the clinical sources and pathological basis for cervicogenic headache, this term was used by, and often is attributed to Otto Sjaastad2, although Barre and Riff had earlier described headache and vertigo, related to cervical arthritis, ascribed to stimulation of the vertebral nerve3. However, an impressive, but little known description is found in the fourth of 18 lectures given between 1860 and1862 on Rest and Pain, in John Hilton's classical text4:"Suppose a person to complain of pain upon the scalp, is it not very essential to know whether that pain is expressed by the 5th nerve or by the great or small occipital? Thus pain in the anterior and lateral part of the head, which are supplied by the fifth nerve, would Suggest that the cause must be somewhere in the area of distribution of the other portions of the fifth nerve. So if the pain be expressed, the cause must assuredly be connected with the great or small occipital nerve, and in all probability depends on disease of the spine between the first and second cervical vertebrae."

1. 1. _Sjaastad 0., Headache and the influence of stress. A personal view. _ Ann Clin Res 1987;19:122-8.
2. 2. Sjaastad 0. Cervicogenic headache: the controversial headache. Clin Neurol Neurosurg 1992;94(suppl):S 147-9. 3
3. 3. Barre JA, Riff P. Le vertige qui fait entendre de Lermoyez: etude des fonctions vestibulaires a propos d'un cas typique; role possible de l'irritation du nerf vertebral par arthrite cervicale. Revue Oto-neuro ophthalmology 1926; 4:498-501.
4. 4. Hilton J. Rest and pain. Walls EW, Phillips EE, eds. London: Bell, 1950:77. doi: 10.1136/jnnp.58.6.698 1995 58: 698 J Neurol Neurosurg Psychiatry

Annotated Bibliography:

Piekartz, H ; Lüdtke, K, Effect of treatment of temporomandibular disorders (TMD) in patients with cervicogenic headache . Manuelle Therapie (MANUELLE THERAPIE), 2011 Jul; 15 (3): 124-34. (62 ref)

Reason for Study: Study compared the effectiveness of cervical manual therapy (normal treatment) to cervical and temperomandibilar manual therapy for the treatment of cervicogenic headaches - both immediately post treatment and after a 6 month treatment free period.

Dependent Variable: Headache Intensity and Neck Function

Independent Variable: Temperomandibular Disorder Treatment (both groups received manual therapy techniques for the cervical spine)

Number of Patients: 43 (16 men)

Time Period: Evaluation pre treatment, evaluation after 6 treatment sessions, and 6 month follow-up

Outcomes: There was a statistically significant differences between groups in headache intensity and neck function both immediately post treatment and during follow-up The TMD treatment group had better outcomes then those individuals receiving neck treatment alone.

Protocols: Subjects were randomly assigned to either cervical manual therapy or cervical and TMD manual therapy groups. Each group was evaluated, received 6 sessions of treatment, and follow-up after 6 months.

• Inclusion Criteria:
  • Patients diagnosed according to the International Classification of Diagnostic Criteria of Headaches (ICDH-II)
  • Outcome criteria included:
    • Intensity of headache using a colored analog scale
    • Neck Disability index
    • Conti Anamnestic Questionare
    • Noise registration at the mandibular joint
    • Graded Chronic Pain Stutus,
    • Mandibular deviation,
    • Range of Mouth Opening
    • Pressure/pain threshold of the masticatory muscles.

Researchers Perspective: Based on the results of this study the researchers believe the assessment and treatment of TMD in cervicogenic patients is beneficial, even in the long-term.

Potential Issues with the Study: 44.1% of the cervicogenic headache patients in this study had TMD. Is this a normal percentage based on research and clinical observation, or did the subjects in this study have more to gain from this treatment plan?

Recommendation for Physical Therapists: Assessment of TMD (and treatment when necessary) should be part of protocols for the treatment of cervicogenic headache patients.

Nilsson N ; Christensen HW ; Hartvigsen J, The effect of spinal manipulation in the treatment of cervicogenic headache. Journal of Manipulative & Physiological Therapeutics (J MANIPULATIVE PHYSIOL THER), 1997 Jun; 20 (5): 326-30.

Reason for Study: This study aimed to determine whether isolated intervention of high velocity low amplitude manipulation of the cervical spine has any effect on cervicogenic headache.

Dependent Variable: Number of headaches, intensity/episode, and use of analgesics

Independent Variable: High velocity – low amplitude mobilization of cervical spine

Number of Patients: 53 subjects randomly assigned to experimental or control group with blinded observer.

Time Period: 5 weeks (treatment weeks 2-4)

Outcomes: The manipulation group faired significantly better in all 3 monitored variables.

Protocols: 2 treatments per week for 3 weeks. Experimental group received high intensity, low amplitude cervical manipulation (toggle recoil for upper cervical region and diversified technique for mid and lower), the control group received low level laser in the upper cervical region and deep tissue massage on the lower cervical and upper thoracic region including trigger points.

Each group was evaluated, had one week of recording in a diary pre-treatment, received 6 sessions of treatment (2/week), and then continued recording in a diary for an additional week. Results were compared using non-parametric, unpaired two-sided statistical analysis throughout (Chi-square) test.

• Inclusion Criteria
  • Those headache sufferers who answered a newspaper advertisement and fulfilled the International Headache Society Criteria for Cervicogenic Headache
  • Outcome criteria included:
    • Use of analgesics
    • Headache intensity/episode
    • Number of headaches
      • Recorded in diary by subjects

Researchers Perspective: The researchers mentioned that the control was not a true placebo and that the combination of soft tissue techniques and manipulation should be studied. However, the study did provide significant evidence that spinal manipulation is not only effective as a means of treating cervicogenic headaches, but more effective than soft tissue on the lower cervical and thoracic spine combined with low energy laser therapy.

Potential Issues with the Study: As mentioned by the researchers the choice of techniques used for the control implies that these techniques may not be effective, or may not be more effective if used in conjunction with manipulation. I would like to see a study comparing soft tissue AND manipulation versus manipulation alone. Further, in my reading I came across several articles that mentioned research on the effective use of low energy laser at the CO – C2 region. A more “true” placebo may need to be devised in further studies.

Recommendation for Physical Therapists: Physical therapists treating this patient population should be proficient in cervical manipulation and should include this treatment approach in practice.

Robert Fleming, Sara Forsythe, Chad Cook, Influential Variables Associated with Outcomes in Patients with Cervicogenic Headache Journal of Manual & Manipulative Therapy2007, Vol. 15 Issue 3, p155-164. 10p.

Reason for Study: The study aimed determine characteristics of patients that are associated with outcomes of physical therapy treatment of cervicogenic headaches

Dependent Variable: Outcomes

Independent Variable: Physical Therapy Treatment

Number of Patients: 44 patients charts were reviewed (average – 11 treatments in 6.9 weeks)

Time Period: Retrospective analysis of primary authors patient database.

Outcomes: The majority of individuals reported improvements in function, headache frequency, and headache intensity. However, patients who were older, working full time, and those whose headache could be made better or worse through movement of the head neck had better outcomes.

Protocols: Patients received a specific program based on physical therapy assessment that included soft tissue release, mobilization, stretching, deep cervical flexor strengthening and a home exercise program. Hierarchical multivariate statics were use to outline which variables were associated with the change scores of frequency, intensity, and function.

Database Search:

• Inclusion Criteria
  • Those assessed with cervicogenic headache, but without coexisting conditions that could effect outcomes (example: positive VBI test).
  • Exclusion criteria included:
    • Records were excluded if pertinent information was missing from documentation.

Researcher’s Perspective: As cervicogenic headaches have a significant impact on function it is important to determine the patient specific variables that contribute to prognosis. This study builds on the growing body of research in this field of study.

Potential Issues with the Study: Accuracy of patient records.

Recommendation for Physical Therapists: The techniques used are supported by research, but physical therapists should be aware of multiple factors that will influence the chance of positive outcomes.

Lin Y., Lai, C., Chang W., Tu L., Lin J., Chou S., Immediate Effects of Ischemic Compression on Neck Function in Patients With Cervicogenic Cephalic Syndrome. Journal of manipulative and physiological therapeutics yr:2012 vol:35 iss:4 pg:301

Reason for Study: This study aimed to determine whether ischemic compression was an effective treatment for cervicogenic headache

Dependent Variable: Sensory organization test, ROM, and isometric strength

Independent Variable: Ischemic Compression

Number of Patients: 27 subjects with chronic neck pain and 26 healthy volunteers

Time Period: 1 treatment

Outcomes: Ischemic pressure significantly improved ROM, isometric strength and postural stability

Protocols: ROM, Sensory organization test scores, and isometric strength were measured

• Exclusion Criteria: Individuals with organic lesion of the ear, nose, throat, eye or CNS were excluded
• Inclusion: Subjects with chronic neck pain persisting for 3 months or more with at least 1 CEH symptom (headache, dizziness, etc.), and/or radiographic images that showed “kinking, fanning , or sponylolisthesis in the AP or lateral views in the neutral flexion or extension positions.”

Researcher’s Perspective: The researchers in this study determined that the increase in ROM, isometric strength, and increase in postural stability are evidence of the effectiveness of ischemic pressure in the treatment of cervicogenic headache.

Potential Issues with the Study: The researchers did not track the most relevant variables to patients suffering from cervicogenic headache – namely intensity of symptoms and loss of function related to pain and dizziness.

Recommendation for Physical Therapists A more accurate statement than that expressed in the “Researcher’s Perspective” would be, “Ischemic compression is effective for improving neck function, and these changes may have an impact on the intensity and frequency of cervicogenic headaches.”

Hall T , Chan HT , Christensen L , Odenthal B , Wells C , Robinson K ., Efficacy of a C1-C2 self-sustained natural apophyseal glide (SNAG) in the management of cervicogenic headache.

J Orthop Sports Phys Ther. 2007 Mar;37(3):100-7.

Reason for Study: This study aimed to determine the efficacy of using self-administered “sustained natural apophyseal glide (SNAG) techniques” as described by Mulligan for the long-term management of cervicogenic headaches.

Dependent Variable: ROM (Flexion Rotation Test – FRT) and Headache Index Score

Independent Variable: Self-administered SNAG

Number of Patients: 32 subjects

Time Period: Initial instruction, practice session, immediate evaluation post treatment, follow-up using headache index score at 4 weeks and 12 months.

Outcomes: Immediate change in FRT increased by an average of 15 degrees in the Self-SNAG group over 5 degrees in the control. Headache index scores were substantially less in the C1-C2 self-SNAG group compared to the placebo group (mean 31% to 24% reduction) at 4 weeks, 12 months (mean 54% to 41% reduction).

Protocols: Double-blind, randomized, placebo-controlled trial design. 122 recruited from advertisement and medical clinics - inclusion and exclusion criteria were based on the guidelines set by the Headache Classification Subcommittee of the IHS, and the Cervicogenic Headache International Study Group. The experimental group received an initial instruction session and a practice session of the Self-SNAG using Mulligan strap as described by Mulligan, the placebo used the same strap and were given the same amount of instruction but were only asked to apply pressure with the strap and no movement of the head – essentially creating a “sham” mobilization technique. Scores were analyzed using an independent T-test.

Researcher’s Perspective: These results provide evidence for the efficacy of the C1-C2 self-SNAG technique in the management of individuals with cervicogenic headache.

Potential Issues with the Study: The sham technique may have been effective at producing a posterior to anterior mobilization at the C2 level masking some of the gross effectiveness of the Self-SNAG technique. Further, there was no follow-up on ROM. Although this may not have been necessary given the intent of the study, it would have been interesting to compare improvements in cervical function to Headache Index scores.

Recommendation for Physical Therapists: Self-administered mobilization techniques, specifically self-SNAG techniques should be included in a home exercise program for the long-term care of cervicogenic headaches.

Summary of Research and Suggestions for Treatment:

Several studies cited an IHS report claiming 15-20% of all recurrent headaches are of cervicogenic origin. Conditions of the neck should be considered when patients present with vertigo, lightheadedness, dizziness, an uneasy feeling, trouble focusing, trouble with balance, headache and or neuralgia in the trigeminal sensory nerve distribution. It is hypothesized that altered signal intensity from sensory afferents stemming from nerve roots C1 to C3 converge at the trigemenocervical nucleus, resulting in the symptoms mentioned above. In all studies cited in this review, the change in afferentation is thought to relate to changes in upper cervical spine function. This may include degenerative change and/or dyskinesis of upper cervical facets, changes in neuromuscular activity (ex., hypertonicity of the occipitals, sternocleidomastoid, scalenes), degenerative changes to intervertebral disk C2-3, vertebral and internal artery compromise, cross-bridging of upper cervical fascia and dura mater (specifically the rectus posterior capitis minor muscle), and postural dysfunction (ex. hypotonicity of deep cervical flexors)1-6

The studies above examine various treatment strategies including mobilization of C1-C2 and lower cervical vertebrae, soft tissue ischemic compression (trigger point release), stretching, treatment for TMD, and exercises for improving the strength and endurance of deep cervical flexors. All modalities show some level of effectiveness1,3,4 with mobilization techniques specific to the upper cervical spine being the most effective treatment when combined with other therapies.2,5,8 Although mobilization may be of particular efficacy, in a review by the Cochrane Library, combined therapeutic treatments (manual therapy, soft tissue, and exercise) was effective, and manipulation alone was not beneficial for mechanical neck disorders.8

Therapists should consider the prognostic indicators of age, working status, and those whose headache could be made better or worse through movement of the head and neck. Although age and working status may not be adjustable by the physical therapist, the positive prognostic indicator of “provocation with movement” deserves further study. Starting with the Maitland Upper Cervical Quadrant tests, the Cyriax’ Active Movements with Overpressure, or a combination of movement including the FRT, may be refined by further research, and developed into a testing cluster with high specificity, sensitivity, and reliability.

Of particular excitement for myself, was the study showing effective long-term management of cervicogenic headaches using a self-administered mobilization technique5. As a human movement professional whose primary occupation has been personal training, I am often rendered helpless when treatment requires mobilization of a joint. There are very few effective self-administered mobilization techniques. Although my personal impetus to expand this facet of exercise may have started with a limit of scope, the importance of this potential modality extends far beyond the effective management of compensation patterns by unlicensed professionals (I know this is controversial territory, but please read on).

Insurance company reimbursement limits not only the number of treatments, but low payouts force more treatments-per-therapist-per-hour, effectively limiting the length of treatment per session as well. Every physical therapist knows that treatment is not effective without continued management (An analogy: Once the body learns to cheat (compensate), it will try to cheat again when things get tough). Effective home exercise programs must become the hallmark of all great human movement professionals. Studies examining this necessary addition to the home exercise program may ensure better long-term results for all human movement professionals. Those self-administered mobilization techniques with a high level of efficacy and low risk may be added to the elite fitness professional’s skill-set, providing individuals with access to quality instruction after insurance companies fail to provide additional benefits. Admittedly, the use of these techniques by personal trainers would likely require advanced credentialing.

An integrated, multi-level approach to treatment of cervicogenic headaches is proposed below. Exercise interventions were created considering all the techniques above, predictive models of compensation for cervical dysfunction9 (forward head translation, downward rotation and anterior tipping of scapula, thoracic kypophosis, elevation of 1st and 2nd rib), and exercise selection based on my work as a human movement professional.

Level 1: Physician

Differential Diagnosis

• Imaging
  • Rule-out
    • Primary Headache
    • CNS Impairment
    • Vestibular System Involvement
    • Vertebrobasilar Insufficiency (VBI)
    • Facet Joint Hypertrophy
    • Fracture
    • Spondylosis
    • Spondylolysis
    • Spondiolisthesis
    • Advanced DDD
    • Osteoperosis
    • Etc.

Intervention

• Diagnosis
• Pharmacological
• Injection
• Surgical

Level 2: Physical Therapy Intervention

Assessment

• Subjective Criteria (IHS Diagnostic Criteria)
• Posture (Forward Head, Scapular position, Thoracic Kyphosis)
• Cyriax (AROM with Over-pressure, Passive ROM, Resisted Motion)
• Cervical Upper Quadrant and Lower Quadrant Exam
• Arthokinematic Motion (PA bilateral, unilateral)
• Strength (Deep Cervical Flexor Endurance)
• ROM
• Temporomandibular Joint Dysfunction (Not included in the treatment plan below – beyond the scope of this article)

Treatment

Note the suggested treatment below highlights all of the structures commonly involved in cervical compensation patterns. Assessment should refine the treatment approach to only dysfunctional structures and significantly reduce the number of techniques performed in a single session.

• Pain and Inflammation Management
  • Modalities (Laser, E-stim, Ultrasound, etc.)
  • Therapeutic Heat and Cold
  • Effleurage
• Manual Release:
  • Subocciptal Muscles (Obliquus capitis superior, rectus capitis posterior minor, recuts capitis posterior major, obliquus capitis inferior)
  • Splenius Capitis
  • Splenius Cervicis
  • Scalenes
  • Levator Scapulae
  • Sternocliedomastoid
  • Upper Trapezius
  • Rhomboid
  • Pec Minor
• Mobilization
  • C1-C2
  • C2-C3
  • Lower Cervical Spine
  • Upper Thorcic Spine
  • AC Joint
  • SC Joint
  • First Rib
  • Second Rib
• Stretch
  • Cervical Extensors
  • Levator Scapulae
  • Trapezius
  • Scalenes
  • SCM
  • Pec Minor
• Activation
  • Deep Cervical Flexors - Longus coli, longus capitis, rectus capitis anterior
  • Serratus Anterior
  • Lower Traps
• Integration
  • Chest Out/Thumbs Out - With cervical retraction used to maintain a stability ball against wall
  • Prone Cobra – With maintained Cervical Retraction
• Reactive Integration
  • Prone Bench/Ball Scaption with gentle rhythmic perturbation applied to hands (watch for cervical extension compensation, cervical flexion compensation, and elevation of scapulae)

Level 3: Self-Administered Techniques

Home Exercise Program and Corrective Routine (Warm-Up) for use by other Human Movement Professionals (ATC, CPT, LMT, etc.)

Assessment

• Posture
• Passive ROM (Limited, Normal, Pain scale)
• Strength (Janda Active Cervical Flexion Test)

Treatment

Note the suggested treatment below highlights all of the structures commonly involved in cervical compensation patterns. Assessment should refine the treatment approach to only dysfunctional structures and significantly reduce the number of techniques performed in a single session.

• Self-Administered Release (Linked to Video when Available):
  • Splenius Capitis & Splenius Cervicis with Tennis Ball
  • Levator Scapulae with Training Soft Ball
  • Upper Trapezius with Training Soft
  • Rhomboids With Training Soft ball
  • Pec Minor
  • Crucifixion Stretch with Suboccipital Release on Foam Roll
• Mobilization
  • C1-C2 Self-SNAG
  • Thoracic Spine
• Stretch
  • Pec Minor (Stretched During Crucifixion Stretch)
  • Levator Scapulae
  • Trapezius
• Activation
  • Deep Cervical Flexors - Longus coli, longus capitis, rectus capitis anterior
  • Serratus Anterior & Lower Traps (Wall Angels/Scaption)
• Integration
  • Chest Out/Thumbs Out - With cervical retraction used to maintain a stability ball against wall
  • Prone Cobra – With maintained Cervical Retraction
• Reactive Integration
  • Bodyblade IR/ER with maintained scapular retraction and cervical retraction, may be attempted using the cervical retraction against ball on wall technique.

Bibliography:

1. Piekartz, H ; Lüdtke, K, Effect of treatment of temporomandibular disorders (TMD) in patients with cervicogenic headache . Manuelle Therapie (MANUELLE THERAPIE), 2011 Jul; 15 (3): 124-34. (62 ref)
2. Nilsson N ; Christensen HW ; Hartvigsen J, The effect of spinal manipulation in the treatment of cervicogenic headache. Journal of Manipulative & Physiological Therapeutics (J MANIPULATIVE PHYSIOL THER), 1997 Jun; 20 (5): 326-30.
3. Robert Fleming, Sara Forsythe, Chad Cook, Influential Variables Associated with Outcomes in Patients with Cervicogenic Headache Journal of Manual & Manipulative Therapy2007, Vol. 15 Issue 3, p155-164. 10p
4. Lin Y., Lai, C., Chang W., Tu L., Lin J., Chou S., Immediate Effects of Ischemic Compression on Neck Function in Patients With Cervicogenic Cephalic Syndrome. Journal of manipulative and physiological therapeutics yr:2012 vol:35 iss:4 pg:301
5. Hall T , Chan HT , Christensen L , Odenthal B , Wells C , Robinson K ., Efficacy of a C1-C2 self-sustained natural apophyseal glide (SNAG) in the management of cervicogenic headache. J Orthop Sports Phys Ther. 2007 Mar;37(3):100-7.
6. Phil Page, Cervicogenic headaches: An evidence-Led approach to Clinical Management, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3201065/
7. Aleksander Chaibi, Bichael Bjorn Russel, Manual Therapies for Cervicogenic Headache: A Systematic Review. J Headache Pain (2012) 13:351-339
8. Gross A., Hoving J., Haines T., Goldsnith C., Kay T., Aker P. , Gert Bonfort and the Cervical Overview Group. A Cochrane Review of Manipulation and Mobilization for Mechanical Neck Disorders. http://www.nhwc.ca/files/7re_Cochrane_Review.cca.pdf
9. Shirley Sahrmann and Associates, Movement System Impairment Syndromes: of the Extremities, Cervical and Thoracic Spine. © 2011 by Mosby, Inc., an affiliate of Elsevier Inc.

© 2013 Brent Brookbush

Questions, comments, and critique are welcome and encouraged!