Neck pain is a common musculoskeletal problem. Occasionally

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1 Performance of the Craniocervical Flexion Test in Subjects With and Without Chronic Neck Pain Thomas Tai Wing Chiu, PhD 1 Ellis Yuk Hung Law, MSc 2 Tony Hiu Fai Chiu, MSc 2 Journal of Orthopaedic & Sports Physical Therapy Study Design: Cross-sectional comparative study. Objective: To compare the performance of the deep cervical flexor muscles on the craniocervical flexion test (CCFT) in individuals with and without neck pain. Background: Significant weakness of the superficial neck muscles is often found in patients with neck pain. However, there is scant work on deep cervical flexors performance in subjects with chronic nonspecific neck pain. Methods and Measures: Twenty asymptomatic subjects and 20 subjects with chronic neck pain (duration, 3 months) were recruited. The CCFT was performed with the subject supine and required performing a gentle head-nodding action of craniocervical flexion (indicating yes) for 5 incremental stages of increasing difficulty. Each stage was held for 10 seconds, as guided by the pressure biofeedback unit. The data used for analysis were the highest pressure level that each subject was able to hold for 10 seconds, up to a maximum of 30 mmhg. Results: Reliability data obtained on 10 asymptomatic subjects indicated that the CCFT was reliable, with a kappa coefficient equal to Subjects with chronic neck pain had significantly poorer (P.001) performance on the CCFT (median pressure achieved, 24 mmhg) when compared with those in the asymptomatic group (median pressure achieved, 28 mmhg). Conclusions: The results of this study demonstrated that patients with chronic neck pain had a poorer ability to perform the CCFT when compared with asymptomatic subjects. The study adds to the evidence that poor ability to perform the CCFT may be clinical evidence of an impairment that characterizes neck pain, regardless of origin. J Orthop Sports Phys Ther 2005;35: Key Words: cervical spine, pressure biofeedback, strength Neck pain is a common musculoskeletal problem. Occasionally neck pain may be related to a severe pathology such as nerve compression, a prolapsed intervertebral disc, or a fracture. However, most often neck pain has no specific and identifiable cause and is regarded as nonspecific neck pain. 2 Neck pain is considered chronic if it lasts for more than 3 months. 22 Panjabi et al 19 estimated that the neck musculature contributes 80% to the mechanical stability of the cervical spine while the os- 1 Associate Professor, Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong. 2 Physiotherapist, Physiotherapy Department, The United Christian Hospital, Hong Kong. We affirm that we have no financial affiliation (including research funding) or involvement with any commercial organization that has a direct interest in any matter included in this manuscript. This protocol was approved by the Ethical Committee of The Hospital Authority in Hong Kong. Address correspondence to Dr Thomas TW Chiu, Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Hong Kong. rstchiu@polyu.edu.hk seoligamentous system contributes the remaining 20%. A number of studies have demonstrated a reduction in the strength and endurance capabilities of both deep and superficial cervical flexor and extensor muscles in patients with neck pain. 1,3,9,17,23 Hallgrenetal 9 and McPartland et al 17 determined that subjects with chronic head and neck pain showed atrophy and fatty infiltration of the suboccipital skeletal muscle tissues. Jull et al 12 found that muscular performance for the deep neck flexors was significantly reduced in a group of patients with cervical headaches. Exercise interventions are important for effective management of patients with neck pain. However, there has been a lack of consensus on optimal exercise prescription. This results in part from a lack of studies to quantify the precise nature of impairment in both the deep and superficial cervical muscles in patients with neck pain. 4 A low-load craniocervical flexion test (CCFT) has been developed by Jull et al 10,11 to investigate the anatomical action of the deep cervical flexors, specifically of the longus colli in synergy with the longus capitis. The CCFT is a clinical test used to assess an individual s ability to slowly perform and hold a precise upper cervical flexion action without flexion of Journal of Orthopaedic & Sports Physical Therapy 567

2 the mid and lower cervical spine. It is based on the anatomical interrelated action of the deep muscles (the longus colli and capitis) to support and stabilize the cervical spine as well as produce a flattening of the normal cervical spine lordosis. 12 An inflatable air-filled pressure sensor is used to guide an individual through the 5 test stages. The pressure sensor is placed behind the neck and is inflated to 20 mmhg, which is sufficient to fill the space between the testing surface and the neck without pushing the neck into further lordosis. Clinical use of the test suggests that an ideal controlled performance of the deep cervical flexors can increase the pressure to 30 mmhg and hold this pressure for 10 seconds. 12 Moreover, in a recent study to quantify craniocervical flexion for the 5 incremental stages of the CCFT, Falla et al 8 demonstrated that on average 24.9% of the full range of craniocervical flexion was used to reach the first target of the CCFT (22 mmhg), followed by linear increments up to 80% for the last stage of the test (30 mmhg). Some subjects could achieve higher pressure values, but compensated by a movement of retraction of the cervical spine (not a pure craniocervical flexion movement). This test has been used extensively to examine subjects with cervicogenic headache and those with whiplash injury. 10,12,13 As a result, low-load therapeutic exercise emphasizing motor control rather than muscle strength has been advocated for effective rehabilitation of these patients. 14 However, there is scant work, especially using a clinically applicable test, on quantifying deep cervical flexors muscular performance in subjects with chronic nonspecific neck pain. The aim of this study was to compare the low-load action of the deep cervical flexors in subjects with and without neck pain by using the CCFT, as suggestedbyjulletal. 4,10,11 Results of this study may add to the evidence that a lesser ability to perform the CCFT is clinical evidence of an impairment that characterizes neck pain, regardless of origin. METHODS Subjects A total of 40 subjects were recruited for the study. The asymptomatic group consisted of 12 females and 8 males (mean ± SD age, 37.7 ± 10.6 years) recruited from the United Christian Hospital of Hong Kong. Subjects were excluded if they had a history of cervical or upper thoracic pain in the previous 12 months, or if they had participated in any form of specific strengthening of the neck and upper extremities musculature over the past 12 months. Subjects with chronic neck pain were recruited from the physiotherapy outpatient department of the same hospital. Chronic neck pain was defined as having persistent neck pain for at least 3 months. The chronic neck pain group consisted of 13 females and 7 males (mean age, 43.4 ± 10.9 years) who were suffering from mechanical neck pain that had no specific identifiable etiology. They did not have any history of trauma or surgery to the upper quarter and had not participated in any form of specific strengthening of the neck and upper extremities musculature in the previous 12 months. Subjects who had claims for compensation, neurological deficit, cervical myelopathy, fractures, or psychological problems, or were considered mentally unfit, were excluded. Subjects presented with histories of neck pain from 4 to 60 months (mean ± SD, 17.4 ± 15.2 months). Results of the independent t test for age showed that there was no statistically significant difference between the 2 groups (P =.106). Informed consent was obtained and rights of the subjects were protected. The Ethical Committee of Hospital Authority in Hong Kong granted ethical approval for this study. Instrumentation and Measurement Before performance of the CCFT, subjects were asked to rate their maximum level of pain over the 24 hours prior to the testing. Pain was assessed using a visual analog scale consisting of a 10-cm horizontal line with endpoints labeled no pain and worst pain ever. The subject was required to place a mark on the 10-cm line, and the distance in centimeters from the low end of the visual analog scale to the patient s mark was used as a numerical index of the severity of pain. Average (±SD) pain rating was 5.57 ± The CCFT was performed with the subject supine and required performing a gentle head-nodding action of craniocervical flexion (an action indicating yes) for 5 incremental stages of increasing range, each stage being held for 10 seconds. 6 Performance was guided by feedback from a pressure biofeedback unit (Chattanooga Group, Inc, Hixson, TN) placed suboccipitally to monitor the flattening of the cervical lordosis that results from the contraction of the deep neck flexors. 15,16 The linear relationship between the incremental pressure targets of the CCFT and the craniocervical flexion range of motion has been demonstrated by Falla et al. 8 Moreover, the results of a recent electromyographic analysis of the deep cervical flexor muscles revealed that each stage of the test was accompanied by increasing electromyographic amplitude in the deep cervical flexor muscles, which is consistent with the anatomical action of these muscles. 6 The dependent variable was the performance on the CCFT as measured by the highest level of pressure the individual could hold for 10 seconds up to a maximum value of 30 mmhg. 568 J Orthop Sports Phys Ther Volume 35 Number 9 September 2005

3 TABLE 1. Results of test-retest reliability of the craniocervical flexion test. There is 80% agreement between the first and second test values (kappa coefficient = 0.72). Highest Values Achieved Over the Serial Testing (mmhg) Subject First Test Second Test Journal of Orthopaedic & Sports Physical Therapy FIGURE. The starting position for the craniocervical flexion test. The subject s head was positioned on a towel and the pressure sensor was placed behind the cervical spine below the occiput. Procedure Subjects were first taught how to perform the CCFT by viewing a 3-minute video to standardize the instructions and the content of information about the test. The subject was positioned in a supine lying position. The cervical spine was supported in a neutral position, which was determined visually by maintaining a horizontal plane between the forehead and the chin, ensuring that a line bisecting the neck longitudinally was parallel to the treatment plinth. 10,12,14 The pressure biofeedback unit was placed between the plinth and the posterior aspect of the neck just below the occiput and inflated to a baseline of 20 mmhg (Figure). Subjects were given sufficient time to practice the craniocervical flexion movement with the pressure biofeedback unit. A trained examiner observed and corrected any substitution movements to insure that all subjects could perform the test correctly. Signs of incorrect performance, such as posterior retraction of the chin to push the neck directly back onto the sensor, were corrected by the trained examiner during the practice phase. The examiner closely monitored the subjects during the CCFT and superficial neck flexor muscle recruitment was discouraged by verbal feedback. Each subject was reminded to relax the neck musculature and to concentrate on performing a gentle, nodding head movement. Each subject was instructed to perform the neck craniocervical flexion movement at 5 different pressure levels (22, 24, 26, 28, and 30 mmhg) and to hold each level for 10 seconds. A 30-second rest period was provided between each level. 6 The testing procedure ended when the subject could not hold a specific pressure level for 10 seconds or the maximum level of 30 mmhg was achieved. The highest level each subject achieved was recorded. Each subject was tested only once by 1 of the researchers, who was blinded to the group assignment of the subjects. Reliability The measurement procedure was tested for its reliability with asymptomatic subjects only. An additional 10 asymptomatic subjects (5 males and 5 females; age range, years; mean age, 37.7 years) were tested with the measurement procedure as described above. Testing was repeated 1 week later by the same researcher. Statistical Analysis Kappa statistic was used to determine the reliability of the measurement. An independent sample t test was used to detect any difference in age between the symptomatic and the asymptomatic groups. The Mann-Whitney test was used to investigate the difference of performance on the CCFT between the 2 groups, with the highest pressure level that could be maintained for 10 seconds as the dependent variable. This test was selected based on the limited range of values of the dependent variable (22-30 mmhg) and the fact that the data were not normally distributed. All the data were analyzed by using the computerized statistical program SPSS RESULTS Test-retest data on 10 asymptomatic subjects indicated good reliability of the CCFT measurement, with an 80% agreement between the first and the second test values (kappa coefficient = 0.72) (Table 1). Performance on the CCFT The results of this study revealed that there was a significant difference between the 2 groups in the J Orthop Sports Phys Ther Volume 35 Number 9 September

4 TABLE 2. Highest pressure value successfully achieved for each subject during the craniocervical flexion test in both groups. Pressure Level (mmhg) Number of Subjects Able to Achieve Target Pressure (%) Group With Neck Pain* Asymptomatic Group 22 5 (25%) 1 (5%) (55%) 2 (10%) 26 3 (15%) 6 (30%) 28 1 (5%) 5 (25%) (30%) * Median, 24 mmhg. Median, 28 mmhg. The Mann-Whitney test indicated a significant difference in the performance of the craniocervical flexion test between groups (P.001). performance of the CCFT (P.001) (Table 2). The median pressure level achieved by the asymptomatic group was 28 mmhg, as compared to 24 mmhg for the subjects in the chronic neck pain group. The CCFT test emphasized low-load action without the requirement of achieving a maximum force, so no subject stopped the test because of pain. DISCUSSION In this study, we aimed to investigate if there was any difference in the performance on the CCFT between individuals with chronic neck pain and asymptomatic subjects. Craniocervical flexion represents the action of the longus capitis in synergy with the longus colli, which causes a reduction of the cervical lordosis. 15,16 The pressure biofeedback unit, which was placed behind the neck, monitored the flattening of the cervical spine as the deep neck flexors were activated. The results of our study revealed that the highest pressure level successfully achieved during the CCFT was less on average in the subjects with chronic neck pain compared to the asymptomatic group. Subjects in the asymptomatic group could quite accurately perform and control the cranio-flexion action to the target pressures for each level. Similar results were demonstrated by Jull et al 13 in individuals with whiplash-associated disorder and insidious onset of neck pain when compared to healthy subjects. Our results imply poor contractile capacity of the deep neck flexors to reduce cervical lordosis, 16 particularly in the last 3 levels of the test. Individuals in the chronic neck pain group had difficulty achieving the higher pressure levels associated with the CCFT, and none of them were able to achieve the 30 mmhg pressure level. The results may suggest that those patients with chronic neck pain may tend to develop an increased cervical lordotic posture associated with a forward head posture. 21 Further study to investigate the relationship between head posture and cervical flexor strength is indicated. A few studies have demonstrated that neck muscle weakness was common in patients with chronic neck pain. 1,3 There is a growing trend towards the use of exercise in treating neck pain. 14,22 Jull et al 14 found that a treatment approach combining manipulative therapy and exercise led to a 10% better outcome than either manipulative or exercise therapy alone for patients with cervicogenic headaches. The finding of deep cervical flexor impairment in the current study may give support to incorporating the training of these muscles in the management of patients with chronic neck pain. Further studies are warranted to determine clinical effectiveness. The present study demonstrates that CCFT appears to be a satisfactory clinical method to evaluate the deep cervical flexors performance in patients with chronic neck pain. We also observed that the most common signs of incorrect performance during the test were (1) jerking the chin down with a fast movement and (2) performing a chin retraction to push the neck onto the sensor. Both compensation patterns could be corrected by proper training. Result of this study may give support to using the CCFT as an objective outcome measure in clinical assessment of patients with neck pain. The technique can also be used as a biofeedback system for the patient to monitor the progression of their cervical flexor performance in a rehabilitation program. The CCFT is useful to identify deficits in the deep neck flexors, as no direct strength measure of these muscles could be made clinically. However, further investigations are needed to study the sensitivity and specificity of the CCFT, along with its correlation with other outcome measures. Ideally, reliability data on patients with chronic neck pain should be collected and reported, because the reason for termination of the test may not be the same for asymptomatic subjects compared to patients with neck pain. Reliability in the asymptomatic group could be inflated due to the ceiling effect. Use of surface electromyographic biofeedback to detect activity of the superficial neck flexor muscles during the CCFT should be considered in future similar studies. 5,7,18,20 A large scale normative study using the CCFT is warranted to provide further support of what is the normal range of pressure values for the test. CONCLUSIONS Performance on the CCFT by subjects with neck pain of greater than 3 months was significantly lower than that of a matched asymptomatic control group. Results of the study add to the evidence that poor ability to perform the CCFT may be clinical evidence of an impairment that characterizes neck pain, regardless of origin. Further investigation is warranted to determine the optimal management and strategy to address this specific muscle impairment. 570 J Orthop Sports Phys Ther Volume 35 Number 9 September 2005

5 ACKNOWLEDGMENT The authors wish to specially thank Mrs E. Chan, department manager of the physiotherapy department of United Christian Hospital in HKSAR, for her support of the venue and equipment for data collection, and Mr Peggo Lam for his expert statistical advice. The authors would also like to express their appreciation to Mr M. Yeung, Ms F. Lam, and Mr R. Choi for their helpful support in taking videos and photographs. REFERENCES 1. Barton PM, Hayes KC. Neck flexor muscle strength, efficiency, and relaxation times in normal subjects and subjects with unilateral neck pain and headache. Arch Phys Med Rehabil. 1996;77: Borghouts JA, Koes BW, Bouter LM. The clinical course and prognostic factors of non-specific neck pain: a systematic review. Pain. 1998;77: Chiu TT, Lo SK. Evaluation of cervical range of motion and isometric neck muscle strength: reliability and validity. Clin Rehabil. 2002;16: Falla D. Unravelling the complexity of muscle impairment in chronic neck pain. Man Ther. 2004;9: Falla D, Dall Alba P, Rainoldi A, Merletti R, Jull G. Location of innervation zones of sternocleidomastoid and scalene muscles a basis for clinical and research electromyography applications. Clin Neurophysiol. 2002;113: Falla D, Jull G, Dall Alba P, Rainoldi A, Merletti R. An electromyographic analysis of the deep cervical flexor muscles in performance of craniocervical flexion. Phys Ther. 2003;83: Falla D, Rainoldi A, Merletti R, Jull G. Myoelectric manifestations of sternocleidomastoid and anterior scalene muscle fatigue in chronic neck pain patients. Clin Neurophysiol. 2003;114: Falla DL, Campbell CD, Fagan AE, Thompson DC, Jull GA. Relationship between craniocervical flexion range of motion and pressure change during the craniocervical flexion test. Man Ther. 2003;8: Hallgren RC, Greenman PE, Rechtien JJ. Atrophy of suboccipital muscles in patients with chronic pain: a pilot study. J Am Osteopath Assoc. 1994;94: Jull G. Deep cervical flexor muscle dysfunction in whiplash. J Musculoskelet Pain. 2000;8: Jull G. Physiotherapy management of the cervical spine. In: Giles L, Singer K, eds. Clinical Anatomy and Management of Cervical Spine Pain. London, UK: Butterworth-Heinemann; 1998: Jull G, Barrett C, Magee R, Ho P. Further clinical clarification of the muscle dysfunction in cervical headache. Cephalalgia. 1999;19: Jull G, Kristjansson E, Dall Alba P. Impairment in the cervical flexors: a comparison of whiplash and insidious onset neck pain patients. Man Ther. 2004;9: Jull G, Trott P, Potter H, et al. A randomized controlled trial of exercise and manipulative therapy for cervicogenic headache. Spine. 2002;27: ; discussion Mayoux-Benhamou MA, Revel M, Vallee C. Selective electromyography of dorsal neck muscles in humans. Exp Brain Res. 1997;113: Mayoux-Benhamou MA, Revel M, Vallee C, Roudier R, Barbet JP, Bargy F. Longus colli has a postural function on cervical curvature. Surg Radiol Anat. 1994;16: McPartland JM, Brodeur RR. Rectus capitis posterior minor: a small but important suboccipital muscle. J Bodywork Mov Ther. 1999;3: Nederhand MJ, Hermens HJ, Ijzeman MJ, Turk DC, Zilvold G. Cervical muscle dysfunction in chronic whiplash-associated disorder grade 2: the relevance of the trauma. Spine. 2002;27: Panjabi MM, Cholewicki J, Nibu K, Grauer J, Babat LB, Dvorak J. Critical load of the human cervical spine: an in vitro experimental study. Clin Biomech (Bristol, Avon). 1998;13: Sommerich CM, Joines SM, Hermans V, Moon SD. Use of surface electromyography to estimate neck muscle activity. J Electromyogr Kinesiol. 2000;10: Szeto GP, Straker L, Raine S. A field comparison of neck and shoulder postures in symptomatic and asymptomatic office workers. Appl Ergon. 2002;33: Taimela S, Takala EP, Asklof T, Seppala K, Parviainen S. Active treatment of chronic neck pain: a prospective randomized intervention. Spine. 2000;25: Watson DH, Trott PH. Cervical headache: an investigation of natural head posture and upper cervical flexor muscle performance. Cephalalgia. 1993;13: ; discussion 232. J Orthop Sports Phys Ther Volume 35 Number 9 September