Accepted Manuscript The neck extensor endurance test: An inter-rater reliability study Deepak Sebastian, DPT, ND, PhD, OCS, FAAOMPT Raghu Chovvath, DPT, OCS, FAAOMPT Ramesh Malladi, DPT, OCS, FAAOMPT PII:

S1360-8592(14)00066-7

DOI:

10.1016/j.jbmt.2014.04.014

Reference:

YJBMT 1122

To appear in:

Journal of Bodywork & Movement Therapies

Received Date: 12 February 2014 Revised Date:

14 March 2014

Accepted Date: 9 April 2014

Please cite this article as: Sebastian, D., Chovvath, R., Malladi, R., The neck extensor endurance test: An inter-rater reliability study, Journal of Bodywork & Movement Therapies (2014), doi: 10.1016/ j.jbmt.2014.04.014. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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THE NECK EXTENSOR RELIABILITY STUDY

ENDURANCE

TEST:

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INTER-RATER

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* Deepak Sebastian DPT, ND, PhD, OCS, FAAOMPT + Raghu Chovvath DPT, OCS, FAAOMPT # Ramesh Malladi DPT, OCS, FAAOMPT

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*Program director and clinical faculty, + Clinical faculty, # Clinical faculty, Institute of Therapeutic Sciences, Residency in Orthopaedic Physical Therapy, Fellowship in Orthopaedic Manual Physical Therapy, Alternative Rehab Inc, 20319 Farmington road, Livonia, MI 48152 Corresponding author: [email protected] 248-808-3792

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Background & Purpose : The purpose of this study was to determine the interrater reliability in detecting the presence of weakness of the neck extensors and differentiate the presence of weakness of the superficial versus the deep neck extensors in a symptomatic population. The presence of weakness of the neck extensors has been described to cause pain and dysfunction in the cervical region. Methods: 30 patients with a diagnosis of neck pain were randomly assigned and examined by two musculoskeletal physical therapists at a time, in order to determine the presence of weakness of the superficial versus the deep neck extensors. With the patient lying prone and head and neck past the edge of the table and the cervico-thoracic junction stabilized, the ability of the individual to sustain a chin tick position in neutral for 20 seconds was evaluated. A positive finding for weakness of the deep neck extensors is the ‘chin length’ increasing with neck extension, as observed on the inclinometer, indicating a dominance of the superficial extensors of the neck. Weakness of both deep and superficial neck extensors was identified by the presence of neck flexion indicating an inability to hold the head up. Inter-rater reliability was determined using the Cohen’s un-weighted kappa statistic. Results: For the neck extensor endurance test, the inter-rater reliability was ‘very good’ (k=0.800,SE of kappa = 0.109, 95% CI). Conclusion: The neck extensor endurance test may be incorporated as a simple yet effective test to determine the presence weakness of the neck extensors and differentiate the presence of weakness of the superficial versus the deep neck extensors in a symptomatic population. The accuracy of the NEET as a test is still debatable, as it has not been compared to a diagnostic gold standard. Based on the results of this study, we speculate the NEET may still offer an initial sense of direction for clinicians treating neck dysfunction.

Key Words: special test, neck extension, endurance, neck pain, reliability

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INTRODUCTION: Dysfunction of the supporting musculature of the neck has been described in patients

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with neck pain and the deep neck flexors have received attention in this regard (Cagnie B et al, 2010). They have been described to exhibit difficulty in performing and sustaining a task called cranio-cervical flexion, which is the neutral position of the cervical spine. The

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deep cervical extensor muscle group is also considered to be important in performing this task (O’Leary et al, 2009), however poorly documented. It is only recently that the

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activation pattern of cervical extensors and the change in activation pattern of these muscles in patients with neck pain are being discussed (Cagnie et al, 2011 ; Schomacher and Falla, 2013).

A distinct anatomic division has been described between the neck extensors as a

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superficial and deep group (Elliot JM et al, 2010). The superficial neck extensors being the Splenius Capitis (SpC) and Semispinalis Capitis (SCa) and the deep neck extensors the Multifidus (Mul) and Semispinalis cervicis (SCe). The superficial group has been

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described to be best activated in cranio-cervical extenstion (CCE) while the deep group in cranio-cervical flexion (CCF) (Lee JP et al, 2006; Schomacher and Falla, 2013; Elliot JM

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et al, 2010).

Clinically, CCF is the activity that has been encouraged in therapeutic intervention as

this has been described to optimize the load distribution and functional ability of the cervical region, thereby minimizing risk for dysfunction (Jull G et al, 2007). Deconditioning of the deep cervical flexors are described as contributors to the inability to perform this activity. The Mul and SCe are also at risk for de-conditioning due to their

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complementary stabilizing function, potentially contributing to dysfunction in weakened states (Cagnie et al, 2011). A clinical test has been instituted to identify the presence of weakness of the deep cervical flexors (Arumugam, Mani and Raja, 2011), which has

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aided in indicating appropriate therapeutic (strengthening) intervention (Falla et al, 2007). Appropriate identification of dysfunctional states of the deep neck extensors may similarly be necessary to indicate appropriate therapeutic intervention in subjects with

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neck dysfunction.

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Current evidence based practice suggests clinical tests to have ‘diagnostic utility’ prior to administration in clinical practice (Tweed and Wilkinson, 2012). It suggests that a clinical test should first have an operant definition based on it’s clinical need and be reliably reproducible between examiners. Subsequently, the sensitivity, specificity, likelihood and odds ratios are calculated. It is obvious that when an operant definition of

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a clinical test has been established based on the clinical need, studying it’s reliability would be an essential precedent.

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In the presence of neck dysfunction, ideally the test should identify the presence of neck extensor weakness and be able to differentiate between weakness of the superficial

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and deep group weakness, or both, as it may suggest the type of intervention needed. The neck extensor endurance test (NEET) aims to be able to identify weakness of both superficial and deep neck extensors. As the test has not been previously described, it does not have a published, agreed upon operant definition. The aim of this study was to identify an operant definition for the potentially, clinically useful, neck extensor endurance test (NEET). Subsequently the intent was to test the reproducibility of the test between raters.

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METHODS: Three orthopaedic board certified and orthopaedic manual therapy fellowship trained

conducted a

pilot training

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physical therapists, with 22 years of experience in orthopaedic physical therapy, on students. The intention was to first familiarize the

methodology of performing the NEET and subsequently establish an operant definition.

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With the subject lying prone and head and neck past the edge of the table and the cervicothoracic junction stabilized, the ability of the individual to sustain a chin tuck position in

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neutral for 20 seconds was evaluated (fig. 1a). A positive finding for weakness of the deep neck extensors is the ‘chin length’ increasing with neck extension, as observed on the inclinometer, indicating a dominance of the superficial extensors of the neck (fig. 1b). The inclinometer has been described to be a valid tool for measuring active range of motion in the cervical region (De Koning CH et al, 2008; Balou M et al, 2014). A

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physiological neutral is difficult to establish in the maximal cranio-cervical flexion position owing to the varying degrees of tightness in the sub-occipital musculature, atlanto-occipital joint capsule and ligamentum nuchae. Hence a deflection of 5 to 10

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degrees from a maximal cranio-cervical flexion position to a relative cranio-cervical

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extension position for the deep cervical test and a flexion deflection of more than 10 degrees for the global test were considered a positive finding. While the inclinometer helps to visually quantify the amount of deflection seen for purposes of establishing reproducibility, it may not be required in routine clinical practice as the direction of cranial movement can be visualized by a trained eye. Weakness of both deep and superficial neck extensors (global weakness) was identified by the presence of neck flexion indicating an inability to hold the head up (fig. 1c). A statistical analysis was not

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done for the pilot training as the intent was to simply understand the methodology for consistency of performing the test, prior to conducting the study. Once the ‘operant

clinicians, the study proceeded.

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Fig 1a, 1b, 1c. Test positions for the NEET

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definition’ for consistency of performance was clearly understood by the participating

Upon the approval of the 5 member Institutional Review Board of the Institute of Therapeutic Sciences, 30 patients with a diagnosis of neck pain were randomly assigned

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and independently examined by 2 musculoskeletal physical therapists at a time, in order to determine the presence of deep and superficial neck extensor weakness, or both. The individuals tested were both male and female, age groups ranging 30-75 years, with

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complaints of neck pain secondary to degeneration, overuse, muscle and joint mechanical dysfunction, radiculopathy and post cervical surgery. The exclusion criteria included

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upper cervical ligamentous instability, vertebral artery compromise, acute trauma, systemic pathology and infectious states of the cervical region. The physical therapists were orthopaedic board certified and orthopaedic manual therapy fellowship trained, with 22 years of experience in orthopaedic physical therapy. The patients signed an informed consent before being tested. The patients with neck pain were assigned by the clinic office administrator to the respective clinicians’ daily schedule, as a routine. While the

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treating clinician performed the initial evaluation, the other testing clinician was called in by an associate when the NEET was to be performed. The test was performed once while the two clinicians simultaneously observed and recorded their findings. The results of the

findings.

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RESULTS:

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findings were recorded separately and provided to an associate who tabulated the

The clinicians were considered to be in agreement when they agreed individually on

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weakness of the deep and the global components of the test, identified as positive or negative. Inter-rater reliability was determined using the kappa statistic (Raghavan, Fosler and Lai, 2012). Since the scale for measurement was nominal, with no levels of seriousness of agreement or disagreement, the Cohen’s un-weighted kappa statistic was used (Hallgren KA, 2012). The software used was the GraphPad Software, Inc., La Jolla,

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CA. For the NEET, the inter-rater reliability was ‘substantial’ (k=0.800, SE of kappa =

Table 1

B

Total

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A

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0.109, 95% CI). (Table 1).

A

14

1

15

B

2

13

15

Total

16

14

30

AA BB AB BA

Number of agreements deep Number of agreements global and normal Number of disagreements global and normal Number of disagreements deep and normal

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Kappa= 0.800 SE of kappa = 0.109 95% confidence interval: From 0.586 to 1.014 The strength of agreement is considered to be 'very good'.

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DISCUSSION:

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Number of observed agreements: 27 ( 90.00% of the observations) Number of agreements expected by chance: 15.0 ( 50.00% of the observations)

In an upright, neutral posture of the cervical spine, passive resistance to motion is

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minimal. Support of the cervical segments is provided by the muscular sleeve formed by the longus colli muscle anteriorly and the semispinalis cervicis and cervical multifidus muscles posteriorly (Falla et al, 2007). The resistance however increases when the neutral position of the cervical spine is altered in the forward head direction thereby increasing the demands on this muscular sleeve. A sustained forward flexion posture of the spine

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has been associated with increased compressive loading and a creep response in the connective tissue and it has long been agreed upon that the forward head posture can

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aggravate, if not initiate, neck pain. While the deep cervical flexors have received the attention on maintaining this neutral position, their co-activators, the deep neck extensors

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have been inadequately recognized in literature. The methods incorporated for measuring the functional ability of the deep cervical extensors are ultrasonography and magnetic resonance imaging (which is the gold standard). Acceptable levels of reliability have been documented (Lee JP, 2007). At the outset, morphological changes in the deep cervical extensors have offered insight to the potential for dysfunctional states in these muscles. Fatty tissue infiltration of the Mul and SCe has been observed in patients with whiplash induced neck pain (Elliot et al, 2006). Studies have examined the spindle

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characteristics of these two groups whose ‘co-activation’ contributed to segmental stability of the cervical spine and not just one group in isolation (Boyd-Clark LC, Briggs CA and Galea MP, 2002). While the CCF position has been documented to show

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activation of the deep cervical extensors (Lee JP et al, 2007), the CCE positions have been observed to show greater activity of the superficial neck extensors, especially the SCa (Elliot JM et al, 2010). The therapeutic carry over to this research finding would be

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to discourage the CCE positions to minimize activity of the superficial extensors. Anecdotal literature suggests progression of deep cervical muscle training from the

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sitting to prone position so as to fire the ‘co-activators’, the deep neck extensors (Magee, Zachazewski, Quillen , 2009 ). Functionally the need may be more obvious as the demands of a cervical neutral position increases as the individual leans forward (as in desk work or driving). Ironically, substantiation of the fact that the deep cervical

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extensors play a vital role in the neutral posture of the cervical spine has already been established but inadequately described and incorporated in clinical practice. The NEET may be utilized as a simple yet effective tool in identifying this neglected entity to direct

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the clinician to the most appropriate clinical intervention when tested positive. In this study, 14 individuals exhibited weakness of the deep muscle groups, and 10

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exhibited global weakness and 6 tested normal. The high prevalence of weak muscle groups correlate to the earlier described findings of a high prevalence of weak deep neck flexor muscle groups in symptomatic individuals (Chiu TT, Law EY and Chiu TH, 2005). As the two groups of muscles have a complementary function, it may be worthwhile to study the presence of deep neck extensor muscle weakness in symptomatic individuals to test positive for deep cervical muscle weakness. 24 of the individuals tested exhibited

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weakness of the deep cervical extensors indicating the need to routinely address the strength of these muscle groups. CONCLUSION:

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The NEET may be incorporated to determine the presence of neck extensor weakness and differentiate between superficial versus the deep neck extensor muscle weakness, or global weakness in a symptomatic population. At this point, the accuracy of the NEET as

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a test is debatable, the reason being that although the test had high agreement among trained raters, the test has not been compared to a diagnostic gold standard with

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calculated statistics. Hence, further research addressing the above stated deficits is required. Based on the speculative analysis from the results of this study, two aspects may appear clinically relevant. Patient with neck pain that test positive for the NEET may be sub grouped within the conditioning classification and clinicians should consider using

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deep neck extensor strengthening on all patients with mechanical neck pain who test positive with this simple and easily administered test. Strengthening for mechanical neck dysfunction should include strengthening the deep neck extensors with almost equal

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importance as the deep neck flexors, due to their complementary stabilizing function. Occipital resistance to the conventional ‘axial extension’ or ‘chin tuck’ activities may be

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the suggested therapeutic intervention to address weakness of the deep cervical extensors.

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Boyd-Clark LC, Briggs CA, Galea MP. Muscle spindle distribution, morphology, and density in longus colli and multifidus muscles of the cervical spine. Spine. 2002;27:694– 701.

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Cagnie B et al. Use of muscle functional magnetic resonance imaging to compare cervical flexor activity between patients with whiplash-associated disorders and people who are healthy. Phys Ther. 2010 Aug;90(8):1157-64. Cagnie B et al. Pain-induced changes in the activity of the cervical extensor muscles evaluated by muscle functional magnetic resonance imaging. Clin J Pain. 2011 Jun;27(5):392-7

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Clin

Cervical extensor endurance test: a reliability study.

The purpose of this study was to determine the inter-rater reliability in detecting the presence of weakness of the neck extensors and differentiate t...
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