Cervicocephalic kinesthetic sensibility and postural balance in patients with nontraumatic chronic neck pain – a pilot study
© Palmgren et al; licensee BioMed Central Ltd. 2009
Received: 15 December 2008
Accepted: 30 June 2009
Published: 30 June 2009
Although cervical pain is widespread, most victims are only mildly and occasionally affected. A minority, however, suffer chronic pain and/or functional impairments. Although there is abundant literature regarding nontraumatic neck pain, little focuses on diagnostic criteria. During the last decade, research on neck pain has been designed to evaluate underlying pathophysiological mechanisms, without noteworthy success. Independent researchers have investigated postural balance and cervicocephalic kinesthetic sensibility among patients with chronic neck pain, and have (in most cases) concluded the source of the problem is a reduced ability in the neck's proprioceptive system. Here, we investigated cervicocephalic kinesthetic sensibility and postural balance among patients with nontraumatic chronic neck pain.
Ours was a two-group, observational pilot study of patients with complaints of continuous neck pain during the 3 months prior to recruitment. Thirteen patients with chronic neck pain of nontraumatic origin were recruited from an institutional outpatient clinic. Sixteen healthy persons were recruited as a control group. Cervicocephalic kinesthetic sensibility was assessed by exploring head repositioning accuracy and postural balance was measured with computerized static posturography.
Parameters of cervicocephalic kinesthetic sensibility were not reduced. However, in one of six test movements (flexion), global repositioning errors were significantly larger in the experimental group than in the control group (p < .05). Measurements did not demonstrate any general impaired postural balance, and varied substantially among participants in both groups.
In patients with nontraumatic chronic neck pain, we found statistically significant global repositioning errors in only one of six test movements. In this cohort, we found no evidence of impaired postural balance.
Head repositioning accuracy and computerized static posturography are imperfect measures of functional proprioceptive impairments. Validity of (and procedures for using) these instruments demand further investigation.
Current Controlled Trials ISRCTN96873990
Cervical pain is common, affecting many people to varying degrees. It rarely is serious, and is often a consequence of several interacting factors with unknown etiology . Neck pain can be acute, subacute, or chronic, pain or functional disability lasting for 0–4 weeks (acute), 4–12 weeks (subacute), or more than 12 weeks (chronic). Curing neck pain is challenging, but several therapies can help . Chiropractic care and manipulative therapy has been shown to reduce soreness and improve function in patients with chronic neck pain of nontraumatic origin [2–4].
Over the last decade, functional impairment of suboccipital and deep cervical flexor muscles, and cervical mechanoreceptive dysfunction, have been thought to affect proprioception in necks of patients with chronic cervical pain . Ability to reposition the head to a previous position is dependent on cervicocephalic kinesthetic sensibility , and a method for evaluating it was introduced by Revel et al. . Movement of the head relative to the trunk involves information from the cervical proprioceptive apparatus and the vestibular system, the former perhaps playing a primary role . Pinsault et al.  recently suggested that the vestibular system is probably not involved in returning the head to a neutral position in the cervicocephalic relocation test, and supported this test as a measure of cervical proprioceptive acuity. Disturbed kinesthetic sensitivity has been implicated in functional instability of joints, and their susceptibility to re-injury, chronic pain, and even degenerative disease . Evidence also suggests that removal of deleterious or abnormal afferent input at the site of articulation alone may result in improved proprioception and motor response . Some studies [3, 7, 12–17], although not all [5, 18, 19], have reported that impaired position sense, quantified by reduced head relocation accuracy and increased cervical joint position errors, is present in patients with traumatic and idiopathic (nontraumatic) neck pain.
While neck pain may alter proprioceptive function, there is no clear consensus in the literature. Furthermore, no general agreement has been reached on how to perform head repositioning tests, or dichotomize results. In a recent study of intra- and inter-examiner reliability, Strimpakos et al.  concluded that researchers measuring neck proprioception have failed to provide reliable measures and conclusive observations.
Chronic neck pain may be linked to reduced cervicocephalic kinesthetic sensibility and postural balance [21, 22]. From a manual therapeutic viewpoint, this is appealing, as many manual diagnostic and therapeutic procedures detect these phenomena.
Among participants with chronic neck pain, investigators have used different static and dynamic measurements of balance to show significant abnormalities in standing vertical posture [16, 21–23]. Persons suffering chronic neck pain tended toward joint dysfunction, muscle atrophy, and standing imbalance . Reduced balance and amplified sway have also been reported in studies of patients with chronic neck pain with severe etiology, such as trauma or whiplash-associated disorders [23, 25–27]. A number of mechanisms involved in neck pain might cause distorted cervical somatosensory input to the postural control system. Field et al. enumerated these as direct trauma, inflammatory mediators, and effects of pain on nociceptors and mechanoreceptors .
However, few studies have investigated sensorimotor control in nontraumatic neck pain, using head repositioning accuracy (as described by Revel et al. ), and vertical standing balance. This reflects a gap in understanding of cervical pain. Therefore, we aimed to investigate cervicocephalic kinesthetic sensibility and postural balance among patients with nontraumatic chronic neck pain. We hypothesized that they would show disturbed cervicocephalic kinesthetic sensibility (as measured by HRA), and altered postural control (measured using computerized static posturography).
The study was performed at the Scandinavian College of Chiropractic in Stockholm, Sweden, using a two-group, observational design, with repeated measures. Participants were given oral and written information before agreeing to participate. The project was approved by the Research Ethical Board of the Chiropractic Association of Sweden, and the Scandinavian College of Chiropractic Scientific Council (board of ethical approval), in accordance with the Declaration of Helsinki.
Criteria for patient inclusion and exclusion
1. Age 30–55 years
2. Neck pain prolonged more than 12 weeks1
1. Neck trauma
2. Received manual treatment within one week prior to the investigation
3. Chronic low back pain (> 3 months)
4. Arthrodesis in foot or ankle
5. Evidence of impaired function/pain in foot or ankle
6. Evidence of impaired function/pain in knee
7. Evidence of impaired function/pain in hip
8. Diastolic pressure > 110 mm Hg
10. Drug abuse
11. Aid for walking or standing
12. Known disease that affects nervous system (e.g., multiple sclerosis, stroke, Parkinson disease)
13. Known disease that affects vestibular apparatus (e.g., Meniére disease, benign paroxysmal positional vertigo)
Outcome Measures: head repositioning accuracy
Head repositioning accuracy (HRA) measures the ability of the neuromusculoskeletal system to reposition the head to a neutral posture, after movements in different planes. A cervical joint positioning error is considered to mainly reflect disturbed afferent input from articulations of the neck, and muscle receptors . The test assesses the ability to perceive both movement and position of the head, relative to the trunk. Joint positioning error results in an angular difference between the starting position and the resumed neutral head posture. This angle can be measured as the distance between the starting point and the final position of a laser spot on a target sheet, projected from a subject's head. The dependent variable that reflects accuracy during head repositioning is most commonly measured in angular units (degrees) or linear metric units .
Outcome Measures: computerized static posturography
Computerized static posturography (CSP) was used to assess balance. Under altered visual conditions, a stable force platform (model FP4, HUR labs Force Platform, Tampere, Finland, http://www.hurlabs.com) measured postural sway and changes in standing balance. The force platform measured 60 × 60 cm, with industrial grade force transducers at each corner. Ground reaction forces were registered, and changes over time were measured in both medial-lateral and anterior-posterior directions. Sensors had a measuring range of 0–200 kg. Force changes were sent by USB connection to a laptop computer (recorded using Windows 2000 [Microsoft, Seattle, WA]), and raw traces were produced both numerically and graphically. Accompanying software (Finsole Orthothic Analyzing Suite, HUR, Balance Software 1.23, Tampere, Finland) provided easy data acquisition and immediate analysis of results.
The CSP measured how the participant's center of pressure changed with time. Two values were collected for each registration: the total trace length/distance covered by the projection of the center of gravity (measured in millimeters), and 90% of the area enclosed by the track of the same projection (measured in millimeters squared).
To check for the possibility that individual measurements of postural balance would provide unreliable values, we examined procedural reliability by comparing values from one test sequence with means from three to five test sequences (with all conditions). When comparing groups, no significant differences could be detected that would indicate low procedural reliability that averaging of a greater number of repeat measurements would give more reliable results.
Outcome Measures: both HRA and CSP
To help interpret sensorimotor function tests (HRA and CSP), a Visual Analogue Scale (VAS) was used to quantify participant pain at the time of investigation. All participants completed a VAS questionnaire regarding intensity of pain in their cervical region, by marking continuous, 100 mm, linear scales, with two extremes: no pain and worst imaginable pain. Test-retest reliability for the VAS has been reported (r = 0.99; p < .05) [29, 30], and it may be a better psychometric instrument than the McGill Pain Questionnaire . We collected no data on pre-investigation pain levels, such as pain during the preceding week, worst pain, or pain during specific tasks.
All persons invited to participate agreed to do so, and inclusion and exclusion criteria were confirmed (Table 1). Exclusion criteria were designed to eliminate confounding ailments and injuries that might influence balance ability or the proprioceptive system in the neck.
To minimize participation selection bias, participants also underwent a brief, clinical investigation, consisting of a history and a clinical orthopedic screening: toe/heel walk for distal muscle function and movement; squat-test for proximal muscle function and movement; blood pressure; and vascular auscultation. This clinical investigation complemented exclusion criteria, clarified clinically functional status, and helped purge conditions that might influence outcome measures.
The main variables compared between experimental and control groups were those deriving from HRA and CSP. Following testing for normal distribution (D'Agostino-Pearson normality test), socio-demographics and pain characteristics were compared using Fisher's exact test. For HRA, projections of the laser on the coordinate system (following movement) were measured (X, Y), and each coordinate was given a positive or negative value, according to its location in relation to the point of origin before repositioning. Using these two values, the participant's global HRA (radius) in centimeters was calculated trigonometrically. The mean value and standard deviation of the global error from zero for each component in the repositioning task was calculated for the 10 consecutive trials in each test movement, and used for data analysis. We used absolute value (magnitude only) in measuring deviation from the origin, rather than a positive or negative value; thus, no distinction was made between over- and underestimation of the original neutral position. The difference between the smallest measured distance from the origin to the final position after movement, and the largest measured distance from the origin were measured in both groups. Data from HRA and CSP were normally distributed, and differences were studied using an unpaired t test (2-tailed). Statistical analyses were performed using GraphPad Prism (version 5.00), and power calculations were done using GraphPad StatMate (version 2.00; GraphPad Software, San Diego, California, USA). Data analysis was performed by an independent statistician. Probability values less than 0.05 (5%) were considered statistically significant.
Cervicocephalic kinesthetic sensibility (HRA)
Minimum and maximum values (cm) of the distance from the origin following different neck movements.
Postural balance (CSP)
Lengths and ellipse areas associated with postural sway displayed extensive variations in all tests, both within and between groups.
Some results of tests with tandem stance and closed eyes were not obtainable, because participants stepped off the platform or lost their balance, which resulted in drop-outs from both groups. From the control group, data from 12 participants could be used, and from the experimental group, only seven.
Compared to participants without neck pain, our limited sample did not indicate a general reduction of cervicocephalic kinesthetic sensibility among patients with chronic neck pain of nontraumatic origin. However, for flexion, global repositioning errors were significantly larger in the experimental group than in the control group (p < .05). For other movements, there were no significant differences in HRAs. Results from CSP measurements did not demonstrate any general impaired static posture among participants. Only one of eight parameters tested–ellipse area in tandem stance with closed eyes–showed significant differences between groups (p < .05). However, substantial variations were seen within and between groups.
Lack of statistically significant differences in five of six HRA tests and nearly all CSP tests may be due to the small number of study participants. Following the study, analysis indicated that the power was only about 30% (range, 30% to 60%) for HRA and about 3% to 40% for CSP. Compared to a more desirable 80%, these values indicate that groups were not large enough to ensure that differences would be detected in our study, if present. Thus, we cannot be sure that so few differences exist between groups in HRA and CSP.
Another limitation was that we did not assess functional performance. Therefore, the experimental group may not have had a sufficient degree of pain and functional impairment to result in a detectable difference between groups.
Comparison with Findings of Others
Although our sample was small, and HRA and CSP results varied among participants, one of six test movements for HRA showed significant differences, suggesting a possible interaction of some or several underlying mechanisms.
Although chronic neck pain can be defined in clinical terms, underlying pathophysiological mechanisms are still primarily unidentified. As with chronic low back pain, investigations have failed to demonstrate a consistent relation linking structural pathology and neck-related pain [32–37]. There are no clear criteria for how chronic neck pain should be diagnosed and classified . Furthermore, large inherent variations in functional proprioceptive impairment and pain within one group of patients with nontraumatic neck pain might contribute to the variety of results.
Our findings are consistent with studies reporting no significant impairment of kinesthesia in patients with nontraumatic neck pain, or whiplash-associated disorders with mild disability [5, 18, 38]. However, our results contrast with some findings involving chronic cervical pain in which the cause was not controlled  or involved trauma [12, 17, 39–41]. In a group of 30 patients with chronic neck pain, Revel et al.  noted error scores almost double in magnitude (compared with an age-matched group of healthy individuals), indicative of significant impairments. Heikkilä and Åström  and Heikkilä and Wenngren  found significantly larger HRA errors in whiplash groups than in healthy controls. Overall, differences observed were not as great as those reported originally by Revel and colleagues . Using a different measuring device, Loudon et al.  examined a small whiplash group with chronic symptoms, and reported that they had larger mean position-sense errors than did healthy individuals. In a study of patients with idiopathic or traumatic neck pain by Sjölander et al. , larger repositioning errors were found in patients with chronic neck pain than among asymptomatic subjects. These effects were more pronounced for patients with trauma than for those with insidious neck pain. The authors did not find any systematic over- or under-estimation among patients. They suggested that increased repositioning errors observed in chronic neck pain are a result of poor position sense due to disturbed proprioceptive input, rather than of systematic bias in motor control systems at central levels.
In contrast, and in concordance with our findings, Rix and Bagust  observed no significant differences in repositioning accuracy between groups with chronic, nontraumatic neck pain, when compared with control groups, except for mean global error scores following flexion. Also, Teng et al. , who investigated 20 patients with chronic neck pain, reported that history of chronic neck pain did not correlate with cervicocephalic kinesthetic sensibility in middle-aged adults. Edmondston et al.  investigated 21 subjects with postural neck pain, and 22 who were asymptomatic. They assessed subjects' ability to replicate self-selected 'good' posture. No significant differences in posture repositioning errors between groups were observed. The authors concluded that individuals with postural neck pain may have a different perception of "good" posture, but no significant difference in kinesthetic sensibility compared with matched asymptomatic subjects. Armstrong et al.  investigated 23 subjects with whiplash, and compared them with a matched control group. They found no differences in head and neck position sense between individuals with chronic whiplash-associated disorders and the controls. Woodhouse and Vasseljen  investigated 116 patients with traumatic or nontraumatic chronic neck pain. Cervical movements in the associated planes relative to the primary movement plane were reduced among the two groups with neck pain, in comparison with 57 asymptomatic controls. The authors postulated that changes were probably not related to a history of neck trauma, or to current pain, but more likely due to a history of long-lasting pain. They found no differences between groups in cervicocephalic kinesthetic sensibility.
In our study, we did find a statistically significant altered global HRA in the neck pain group for one of the test movements: flexion. However, due to the lack of homogeneity and variations in only one-sixth of the test movements, this might have limited clinical meaning and generalizability.
The relationship between head repositioning acuity and functional performance is clinically important. Investigators have observed larger repositioning errors in persons reporting greater problems with function (higher Neck Disability Index) [14, 43] than in those with milder problems [14, 38, 43]. Larger repositioning errors in patients with chronic whiplash-associated disorders have also been observed, with dizziness and unsteadiness . More recently, Owens et al. , using normal student volunteers, showed that a recent history of cervical extensor muscle contraction could produce HRA errors similar to those reported in patients with whiplash. The authors suggested that this supports the role of paraspinal muscles in sensorimotor dysfunction not necessarily related to trauma.
In patients with chronic neck pain, and under various testing conditions, investigators have observed considerable abnormalities in standing vertical posture [21–23, 45, 46]. There are, however, conflicting reports on characteristics of postural balance during quiet standing in these patients . Others have pointed out large variations in postural performance among patients , or have recommended dynamic posturography on a sway-referenced force plate, for better quantification of postural problems . In terms of postural stability and balance, considerable research is still needed to provide sound diagnostic tests appropriate for use in a routine, clinical setting.
Clinical and Research Implications
Because functional and structural cervical pathology underlying chronic neck pain remain largely unclear, continued research is crucial. However, it has been suggested that deficits in proprioception and motor control, rather than chronic pain itself, might be prime factors limiting function and quality of life in affected patients [17, 21].
Subgroups classified objectively, according to proprioceptive or nonproprioceptive etiology, could be the focus of further research. Moreover, future work also might consider whether methods used in our study could contribute to daily clinical care. We would like to see further investigations of measurements of functional proprioceptive impairment, and its association with pain. Future research should combine measures used in the present study with measures of disability (e.g., the Neck Disability Index). This is important, because kinesthetic deficits in the neck have been linked to severity of pain and disability. Furthermore, to support comparison of results among studies, we recommend standardization of hardware and protocols in studies using HRA, force platforms, and CSP. Lastly, we recommend investigation of effects of different treatment modalities on chronic neck pain, as measured by sensorimotor function tests, such as HRA and CSP.
For patients with nontraumatic chronic pain, only one of six test movements showed global repositioning errors significantly larger than for controls. Likewise, postural measurements showed little impaired balance, and substantial variations were present within groups. These results contrast with some other studies of patients with either traumatic or nontraumatic neck pain. However, limiting factors in our own work mean that further investigation will be required to establish whether and how nontraumatic chronic neck pain influences proprioception in the neck.
List of abbreviations
Computerized static posturography
Head repositioning accuracy
Visual analogue scale.
- Nachemson A: Back and Neck Pain. 2000, Stockholm (Sweden): The Swedish Council on Technology Assessment in Health Care (SBU)Google Scholar
- Hurwitz EL, Aker PD, Adams AH, Meeker WC, Shekelle PG: Manipulation and mobilization of the cervical spine. A systematic review of the literature. Spine. 1996, 21: 1746-1759.View ArticlePubMedGoogle Scholar
- Palmgren PJ, Sandstrom PJ, Lundqvist FJ, Heikkila H: Improvement after chiropractic care in cervicocephalic kinesthetic sensibility and subjective pain intensity in patients with nontraumatic chronic neck pain. J Manipulative Physiol Ther. 2006, 29: 100-106.View ArticlePubMedGoogle Scholar
- Gross AR, Kay T, Hondras M, Goldsmith C, Haines T, Peloso P, Kennedy C, Hoving J: Manual therapy for mechanical neck disorders: a systematic review. Man Ther. 2002, 7: 131-149.View ArticlePubMedGoogle Scholar
- Rix GD, Bagust J: Cervicocephalic kinesthetic sensibility in patients with chronic, nontraumatic cervical spine pain. Arch Phys Med Rehabil. 2001, 82: 911-919.View ArticlePubMedGoogle Scholar
- Humphreys BK: Cervical outcome measures: testing for postural stability and balance. J Manipulative Physiol Ther. 2008, 31: 540-546.View ArticlePubMedGoogle Scholar
- Revel M, Andre-Deshays C, Minguet M: Cervicocephalic kinesthetic sensibility in patients with cervical pain. Arch Phys Med Rehabil. 1991, 72: 288-291.PubMedGoogle Scholar
- Mergner T, Maurer C, Peterka RJ: A multisensory posture control model of human upright stance. Prog Brain Res. 2003, 142: 189-201.View ArticlePubMedGoogle Scholar
- Pinsault N, Vuillerme N, Pavan P: Cervicocephalic relocation test to the neutral head position: assessment in bilateral labyrinthine-defective and chronic, nontraumatic neck pain patients. Arch Phys Med Rehabil. 2008, 89: 2375-2378.View ArticlePubMedGoogle Scholar
- Hall MFW, Sturrock R, Hamblen D, Baxendale R: The effect of the hypermobility syndrome on knee joint proprioception. Br J Rheumatol. 1995, 34: 121-125.View ArticlePubMedGoogle Scholar
- McLain RF, Pickar JG: Mechanoreceptor endings in human thoracic and lumbar facet joints. Spine. 1998, 23: 168-173.View ArticlePubMedGoogle Scholar
- Heikkila H, Astrom PG: Cervicocephalic kinesthetic sensibility in patients with whiplash injury. Scand J Rehabil Med. 1996, 28: 133-138.PubMedGoogle Scholar
- Heikkila H, Johansson M, Wenngren BI: Effects of acupuncture, cervical manipulation and NSAID therapy on dizziness and impaired head repositioning of suspected cervical origin: a pilot study. Man Ther. 2000, 5: 151-157.View ArticlePubMedGoogle Scholar
- Treleaven J, Jull G, Sterling M: Dizziness and unsteadiness following whiplash injury: characteristic features and relationship with cervical joint position error. J Rehabil Med. 2003, 35: 36-43.View ArticlePubMedGoogle Scholar
- Sterling M, Jull G, Vicenzino B, Kenardy J: Characterization of acute whiplash-associated disorders. Spine. 2004, 29: 182-188.View ArticlePubMedGoogle Scholar
- Field S, Treleaven J, Jull G: Standing balance: A comparison between idiopathic and whiplash-induced neck pain. Man Ther. 2007Google Scholar
- Sjolander P, Michaelson P, Jaric S, Djupsjobacka M: Sensorimotor disturbances in chronic neck pain-Range of motion, peak velocity, smoothness of movement, and repositioning acuity. Man Ther. 2006, 13 (2): 122-131.View ArticleGoogle Scholar
- Teng CC, Chai H, Lai DM, Wang SF: Cervicocephalic kinesthetic sensibility in young and middle-aged adults with or without a history of mild neck pain. Man Ther. 2007, 12: 22-28.View ArticlePubMedGoogle Scholar
- Woodhouse A, Vasseljen O: Altered motor control patterns in whiplash and chronic neck pain. BMC Musculoskelet Disord. 2008, 9: 90-PubMed CentralView ArticlePubMedGoogle Scholar
- Strimpakos N, Sakellari V, Gioftsos G, Kapreli E, Oldham J: Cervical joint position sense: an intra- and inter-examiner reliability study. Gait Posture. 2006, 23: 22-31.View ArticlePubMedGoogle Scholar
- Michaelson P, Michaelson M, Jaric S, Latash ML, Sjolander P, Djupsjobacka M: Vertical posture and head stability in patients with chronic neck pain. J Rehabil Med. 2003, 35: 229-235.View ArticlePubMedGoogle Scholar
- Treleaven J, Murison R, Jull G, LowChoy N, Brauer S: Is the method of signal analysis and test selection important for measuring standing balance in subjects with persistent whiplash?. Gait Posture. 2005, 21: 395-402.View ArticlePubMedGoogle Scholar
- Sjostrom H, Allum JH, Carpenter MG, Adkin AL, Honegger F, Ettlin T: Trunk sway measures of postural stability during clinical balance tests in patients with chronic whiplash injury symptoms. Spine. 2003, 28: 1725-1734.PubMedGoogle Scholar
- McPartland JM, Brodeur RR, Hallgren RC: Chronic neck pain, standing balance, and suboccipital muscle atrophy–a pilot study. J Manipulative Physiol Ther. 1997, 20: 24-29.PubMedGoogle Scholar
- Brännström H, Malmgren-Olsson EB, Barnekow-Bergkvist M: Balance Performance in Patients with Whiplash Associated Disorders and Patients with Prolonged Musculoskeletal Disorders. Adv Physiother. 2001, 3: 120-127.View ArticleGoogle Scholar
- Madeleine P, Prietzel H, Svarrer H, Arendt-Nielsen L: Quantitative posturography in altered sensory conditions: a way to assess balance instability in patients with chronic whiplash injury. Arch Phys Med Rehabil. 2004, 85: 432-438.View ArticlePubMedGoogle Scholar
- Storaci R, Manelli A, Schiavone N, Mangia L, Prigione G, Sangiorgi S: Whiplash injury and oculomotor dysfunctions: clinical-posturographic correlations. Eur Spine J. 2006, 15: 1811-1816.View ArticlePubMedGoogle Scholar
- Armstrong B, McNair P, Taylor D: Head and neck position sense. Sports Med. 2008, 38: 101-117.View ArticlePubMedGoogle Scholar
- Downie WW, Leatham PA, Rhind VM, Wright V, Branco JA, Anderson JA: Studies with pain rating scales. Ann Rheum Dis. 1978, 37: 378-381.PubMed CentralView ArticlePubMedGoogle Scholar
- Scott J, Huskisson EC: Vertical or horizontal visual analogue scales. Ann Rheum Dis. 1979, 38: 560-PubMed CentralView ArticlePubMedGoogle Scholar
- Scrimshaw SV, Maher C: Responsiveness of visual analogue and McGill pain scale measures. J Manipulative Physiol Ther. 2001, 24: 501-504.View ArticlePubMedGoogle Scholar
- Gore DR, Sepic SB, Gardner GM: Roentgenographic findings of the cervical spine in asymptomatic people. Spine. 1986, 11: 521-524.View ArticlePubMedGoogle Scholar
- Boden SD, McCowin PR, Davis DO, Dina TS, Mark AS, Wiesel S: Abnormal magnetic-resonance scans of the cervical spine in asymptomatic subjects. A prospective investigation. J Bone Joint Surg Am. 1990, 72: 1178-1184.PubMedGoogle Scholar
- Liebenson CS: Pathogenesis of chronic back pain. J Manipulative Physiol Ther. 1992, 15: 299-308.PubMedGoogle Scholar
- Marchiori DM, Henderson CN: A cross-sectional study correlating cervical radiographic degenerative findings to pain and disability. Spine. 1996, 21: 2747-2751.View ArticlePubMedGoogle Scholar
- Persson L, Karlberg M, Magnusson M: Effects of different treatments on postural performance in patients with cervical root compression. A randomized prospective study assessing the importance of the neck in postural control. J Vestib Res. 1996, 6: 439-453.View ArticlePubMedGoogle Scholar
- Karlsborg M, Smed A, Jespersen H, Stephensen S, Cortsen M, Jennum P, Herning M, Korfitsen E, Werdelin L: A prospective study of 39 patients with whiplash injury. Acta Neurol Scand. 1997, 95: 65-72.View ArticlePubMedGoogle Scholar
- Armstrong BS, McNair PJ, Williams M: Head and neck position sense in whiplash patients and healthy individuals and the effect of the cranio-cervical flexion action. Clin Biomech (Bristol, Avon). 2005, 20: 675-684.View ArticleGoogle Scholar
- Heikkila HV, Wenngren BI: Cervicocephalic kinesthetic sensibility, active range of cervical motion, and oculomotor function in patients with whiplash injury. Arch Phys Med Rehabil. 1998, 79: 1089-1094.View ArticlePubMedGoogle Scholar
- Loudon JK, Ruhl M, Field E: Ability to reproduce head position after whiplash injury. Spine. 1997, 22: 865-868.View ArticlePubMedGoogle Scholar
- Feipel V, Salvia P, Klein H, Rooze M: Head repositioning accuracy in patients with whiplash-associated disorders. Spine. 2006, 31: E51-58.View ArticlePubMedGoogle Scholar
- Edmondston SJ, Chan HY, Ngai GC, Warren ML, Williams JM, Glennon S, Netto K: Postural neck pain: an investigation of habitual sitting posture, perception of 'good' posture and cervicothoracic kinaesthesia. Man Ther. 2007, 12: 363-371.View ArticlePubMedGoogle Scholar
- Sterling M, Jull G, Vicenzino B, Kenardy J, Darnell R: Development of motor system dysfunction following whiplash injury. Pain. 2003, 103: 65-73.View ArticlePubMedGoogle Scholar
- Owens EF, Henderson CN, Gudavalli MR, Pickar JG: Head repositioning errors in normal student volunteers: a possible tool to assess the neck's neuromuscular system. Chiropr Osteopat. 2006, 14: 5-View ArticleGoogle Scholar
- Karlberg M, Persson L, Magnusson M: Impaired postural control in patients with cervico-brachial pain. Acta Otolaryngol Suppl. 1995, 520 (Pt 2): 440-442.View ArticlePubMedGoogle Scholar
- Field S, Treleaven J, Jull G: Standing balance: a comparison between idiopathic and whiplash-induced neck pain. Man Ther. 2008, 13: 183-191.View ArticlePubMedGoogle Scholar
- Alund M, Ledin T, Odkvist L, Larsson SE: Dynamic posturography among patients with common neck disorders. A study of 15 cases with suspected cervical vertigo. J Vestib Res. 1993, 3: 383-389.PubMedGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.