Shaun O'Leary

Clinical assessment of the deep cervical flexor muscles: The Craniocervical Flexion Test

BACKGROUND The craniocervical flexion test (CCFT) is a clinical test of the anatomical action of the deep cervical flexor muscles, the longus capitis, and colli. It has evolved over 15 years as both a clinical and research tool and was devised in response to research indicating the importance of the deep cervical flexors in support of the cervical lordosis and motion segments and clinical observations of their impairment with neck pain. SPECIAL FEATURES The CCFT could be described as a test of neuromotor control. The features assessed are the activation and isometric endurance of the deep cervical flexors as well as their interaction with the superficial cervical flexors during the performance of five progressive stages of increasing craniocervical flexion range of motion. It is a low-load test performed in the supine position with the patient guided to each stage by feedback from a pressure sensor placed behind the neck. While the test in the clinical setting provides only an indirect measure of performance, the construct validity of the CCFT has been verified in a laboratory setting by direct measurement of deep and superficial flexor muscle activity. SUMMARY Research has established that patients with neck pain disorders, compared to controls, have an altered neuromotor control strategy during craniocervical flexion characterized by reduced activity in the deep cervical flexors and increased activity in the superficial flexors usually accompanied by altered movement strategies. Furthermore, they display reduced isometric endurance of the deep cervical flexor muscles. The muscle impairment identified with the CCFT appears to be generic to neck pain disorders of various etiologies. These observations prompted the use of the craniocervical flexion action for retraining the deep cervical flexor muscles within a motor relearning program for neck pain patients, which has shown positive therapeutic benefits when tested in clinical trials.

Muscle Dysfunction in Cervical Spine Pain: Implications for Assessment and Management

SYNOPSIS There is irrefutable evidence of an association between mechanical neck pain (MNP) and dysfunction of the muscles of the cervical spine. A myriad of impairments have been demonstrated that include changes in the physical structure (cross-sectional area, fatty infiltration, fiber type), as well as changes in behavior (timing and activation level), of the cervical muscles. Such changes suggest an impaired capacity of the cervical muscles to generate, sustain, and maintain precision of the required levels of torque needed for optimal function. In the context of physical support, these changes potentially have deleterious consequences for the cervical region, which relies heavily on its muscles for mechanical stability. While interventions focused on the retraining of cervical muscle function have shown favorable responses in alleviating MNP, the development of best practice strategies for the assessment and management of cervical muscle dysfunction is still a work in progress. One obstacle in researching the efficacy of cervical muscle training is that, as yet, we do not possess the capacity to optimally measure and classify those patients most likely to respond to different methods of training that would enrich clinical practice. While gains in this area are emerging, the ability of a clinician to best identify the need and implement the most appropriate method of training cervical muscle function is still largely dependent on a comprehensive examination of the patient that considers all aspects of the patients disorder and functional requirements. LEVEL OF EVIDENCE Level 5.

Magnetic resonance imaging findings of fatty infiltrate in the cervical flexors in chronic whiplash.

Study Design. Retrospective investigation of muscle changes in patients suffering from chronic whiplash-associated disorders (WAD). Objectives. To quantitatively compare the presence of muscle alterations (fatty infiltrate [MFI] and cross-sectional area [CSA]) in the anterior musculature of the cervical spine in a cohort of chronic whiplash patients (WAD II) and healthy control subjects across muscle and cervical segmental level. Summary of Background Data. Magnetic resonance imaging can be regarded as the gold standard for muscle imaging. There is little knowledge about in vivo features of anterior neck muscles in patients suffering from chronic WAD and how muscle structure differs across the factors of muscle, vertebral level, age, self-reported pain and disability, body mass index, and duration of symptoms. Methods. Reliable magnetic resonance imaging measures for MFI and CSA were performed for the anterior cervical muscles bilaterally in 109 female subjects (78 WAD, 31 healthy control; 18–45 years, 3 months to 3 years postinjury). The measures were performed on all subjects for the longus capitis and colli and the sternocleidomastoid muscles. Results. The WAD subjects had significantly larger MFI and CSA for the anterior muscles compared to healthy control subjects (all P < 0.0001). In addition, the amount of MFI varied by both cervical level and muscle, with the longus capitis/colli having the largest amount of fatty infiltrates at the C2–C3 level (P < 0.0001). MFI was inversely related to age, self-reported pain/disability, and body mass index but directly proportional to duration of symptoms. Conclusion. There is significantly greater MFI and CSA in the anterior neck muscles, especially in the deeper longus capitis/colli muscles, in subjects with chronic WAD when compared to healthy controls. Future studies are required to investigate the relationships between muscular morphometry and symptoms in patients suffering from acute and chronic WAD.

The change in deep cervical flexor activity after training is associated with the degree of pain reduction in patients with chronic neck pain

Objectives: Altered activation of the deep cervical flexors (longus colli and longus capitis) has been found in individuals with neck pain disorders but the response to training has been variable. Therefore, this study investigated the relationship between change in deep cervical flexor muscle activity and symptoms in response to specific training. Methods: Fourteen women with chronic neck pain undertook a 6-week program of specific training that consisted of a craniocervical flexion exercise performed twice per day (10 to 20 min) for the duration of the trial. The exercise targets the deep flexor muscles of the upper cervical region. At baseline and follow-up, measures were taken of neck pain intensity (visual analogue scale, 0 to 10), perceived disability (Neck Disability Index, 0 to 50) and electromyography (EMG) of the deep cervical flexors (by a nasopharyngeal electrode suctioned over the posterior oropharyngeal wall) during performance of craniocervical flexion. Results: After training, the activation of the deep cervical flexors increased (P<0.0001) with the greatest change occurring in patients with the lowest values of deep cervical flexor EMG amplitude at baseline (R2=0.68; P<0.001). There was a significant relationship between initial pain intensity, change in pain level with training, and change in EMG amplitude for the deep cervical flexors during craniocervical flexion (R2=0.34; P<0.05). Discussion: Specific training of the deep cervical flexor muscles in women with chronic neck pain reduces pain and improves the activation of these muscles, especially in those with the least activation of their deep cervical flexors before training. This finding suggests that the selection of exercise based on a precise assessment of the patients’ neuromuscular control and targeted exercise interventions based on this assessment are likely to be the most beneficial to patients with neck pain.

Differential changes in muscle composition exist in traumatic and nontraumatic neck pain

Study Design. A population based cross-sectional study. Objective. To clarify relative constituents of viable muscle in 2-dimensional cross-sectional area (CSA) measures of ventral and dorsal cervical muscles in patients with chronic whiplash-associated disorders (WAD), idiopathic neck pain, and healthy controls. Summary of Background Data. Previous data using T1-weighted magnetic resonance image demonstrated large amounts of neck muscle fat infiltration and increased neck muscle CSA in patients with chronic WAD but not in idiopathic neck pain or healthy controls. Methods. Magnetic resonance images were obtained for 14 cervical muscle regions in 136 females, including 79 with chronic whiplash, 23 with chronic idiopathic neck pain, and 34 healthy controls. Results. Without fat removed, relative CSA of 7 of 14 muscle regions in the participants with chronic WAD was larger, 3 of 14 smaller and 4 of 14 similar to healthy individuals. When T1-weighted signal representing the lipid content of these muscles was removed, 8 of 14 relative muscle CSA in patients with whiplash were similar, 5 of 14 were smaller and only 1 of 14 was larger than those observed in healthy controls. Removal of fat from the relative CSA measurement did not alter findings between participants with idiopathic neck pain and healthy controls. Conclusion. These findings clarify that previous reports of increased relative CSA in patients with chronic whiplash represent cervical muscle pseudohypertrophy. Relative muscle CSA measures reveal atrophy in several muscles in both patients with WAD and idiopathic neck pain, which supports inclusion of muscle conditioning in the total management of these patients. Level of Evidence: 3

Is There Altered Activity of the Extensor Muscles in Chronic Mechanical Neck Pain? A Functional Magnetic Resonance Imaging Study

OBJECTIVE To compare the pattern of neck extensor muscle use in participants with chronic mechanical neck pain to that of healthy controls during 2 different extension exercises by use of muscle functional magnetic resonance imaging (mfMRI). DESIGN Cross-sectional. SETTING University laboratory. PARTICIPANTS Data recorded from subjects with chronic mechanical neck pain (n=12; 10 women, 2 men) were compared with previously recorded data from healthy subjects (n=11; 7 men, 4 women). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES mfMRI measures of shifts in T2 relaxation were made for the multifidus, semispinalis cervicis, semispinalis capitis, and splenius capitis muscles, at C2-3, C5-6, and C7-T1 levels, prior and immediately after 2 different exercises: cervical extension in craniocervical neutral (CCN) and cervical extension in craniocervical extension. T2 shift values (difference between pre- and postexercise T2 relaxation values) for each muscle and exercise condition were used for analysis. RESULTS While there were observed differences in differential activation of the extensor muscles in participants with mechanical neck pain compared with controls, these differences were only evident for the CCN exercise condition and were only observed for 3 out of the 7 muscle regions of interest during this exercise. CONCLUSIONS Results of this study suggest some alteration in the differential activation of the cervical extensors in patients with mechanical neck pain and indicate that further investigation of this muscle group in mechanical neck pain disorders is warranted.

Altered Trapezius Muscle Behavior in Individuals With Neck Pain and Clinical Signs of Scapular Dysfunction

OBJECTIVE The purpose of this study was to compare the behavior of the trapezius muscle in patients with chronic mechanical neck pain (MNP) and clinical signs of scapula dysfunction to healthy controls. METHODS This is a cross-sectional, between-participant study of trapezius muscle behavior. Eighteen volunteers with chronic MNP and 20 healthy controls participated in the study. Participants performed isometric shoulder abduction, external rotation, and flexion at 3 intensities of effort (maximum voluntary contraction [MVC], 50% MVC, and 20% MVC). Electromyographic signals were recorded unilaterally from the upper, middle, and lower portions of the trapezius muscle during isometric shoulder contractions. RESULTS Significantly greater levels of lower trapezius electromyographic signals were observed in patients with MNP compared with controls for the abduction (P < .027) and external rotation (P < .036) conditions but not for the flexion condition (P > .392). No differences in activity were observed in the upper (P > .248) or middle (P > .052) portions of trapezius between groups during any of the isometric shoulder girdle conditions. CONCLUSIONS These findings represent a change in the behavior of the lower trapezius muscle in individuals with MNP who exhibit clinical signs of scapular dysfunction. Clinicians should consider the potential involvement of the axioscapular muscles when assessing patients with chronic neck pain, as retraining scapular function may be required for the successful management of these patients.

The Effect of Neck-specific Exercise With, or Without a Behavioral Approach, on Pain, Disability, and Self-Efficacy in Chronic Whiplash-associated Disorders: A Randomized Clinical Trial

Objectives:The aim of this study was to compare the effect on self-rated pain, disability, and self-efficacy of 3 interventions for the management of chronic whiplash-associated disorders: physiotherapist-led neck-specific exercise (NSE), physiotherapist-led NSE with the addition of a behavioral approach, or Prescription of Physical Activity (PPA). Materials and Methods:A total of 216 volunteers with chronic whiplash-associated disorders participated in this randomized, assessor blinded, clinical trial of 3 exercise interventions. Self-rated pain/pain bothersomeness (Visual Analogue Scale), disability (Neck Disability Index), and self-efficacy (Self-Efficacy Scale) were evaluated at baseline and at 3 and 6 months. Results:The proportion of patients reaching substantial reduction in pain bothersomness (at least 50% reduction) was more evident (P<0.01) in the 2 NSE groups (29% to 48%) compared with the PPA group (5%) at 3 months. At 6 months 39% to 44% of the patients in the 2 neck-specific groups and 28% in the PPA group reported substantial pain reduction. Reduction of disability was also larger in the 2 neck-specific exercise groups at both 3 and 6 months (P<0.02). Self-efficacy was only improved in the NSE group without a behavioral approach (P=0.02). However, there were no significant differences in any outcomes between the 2 physiotherapist-led NSE groups. Discussion:NSE resulted in superior outcomes compared with PPA in this study, but the observed benefits of adding a behavioral approach to the implementation of exercise in this study were inconclusive.

Pain-induced changes in the activity of the cervical extensor muscles evaluated by muscle functional magnetic resonance imaging

ObjectivesTo investigate the effect of experimental neck muscle pain on the activation of the cervical extensor muscles during the performance of a cervical extension exercise by the use of muscle functional magnetic resonance imaging. MethodsThe activity of the multifidus, semispinalis cervicis, semispinalis capitis, and splenius capitis muscles was investigated bilaterally at 2 cervical levels (C2 to C3 and C7 to T1) in 15 healthy individuals. Measurements were taken at rest and after the performance of a cervical extension exercise without and with induced pain of the right upper trapezius (intramuscular injection of hypertonic saline). ResultsIn the pain condition, the activity of the multifidus/semispinalis cervicis was reduced bilaterally at the C7 to T1 level (P=0.045). For the semispinalis capitis, there were no significant differences between both conditions. The splenius capitis showed a significantly higher T2 shift at the left side at the C2 to C3 level (P=0.008) and a lower T2 shift at the right side at the C7 to T1 level (P=0.023). DiscussionThis is the first study that has shown pain to immediately affect the activity of both deep and superficial cervical extensor muscle layers during a cervical extension exercise. The findings support recommendations for evaluation of cervical extensor muscle function early in the management of painful cervical spine injuries.

Muscle Functional MRI as an Imaging Tool to Evaluate Muscle Activity

Muscle functional magnetic resonance imaging (mfMRI) is an innovative technique that offers a noninvasive method to quantify changes in muscle physiology following the performance of exercise. The mfMRI technique is based on signal intensity changes due to increases in the relaxation time of tissue water. In contemporary practice, mfMRI has proven to be an excellent tool for assessing the extent of muscle activation following the performance of a task and for the evaluation of neuromuscular adaptations as a result of therapeutic interventions. This article focuses on the underlying mechanisms and methods of mfMRI, discusses the validity and advantages of the method, and provides an overview of studies in which mfMRI is used to evaluate the effect of exercise and exercise training on muscle activity in both experimental and clinical studies.