Volume 88, Issue 10, Pages 1256-1259 (October 2007)

8 of 126

ABSTRACT

FULL TEXT

FULL-TEXT PDF (77 KB)

Musculoskeletal Disorders in Referrals for Suspected Cervical Radiculopathy

These results were presented in part to the American Association of Electromyography and Electrodiagnosis, 1997, and the American Academy of Physical Medicine and Rehabilitation, 1998.

Abstract

Cannon DE, Dillingham TR, Miao H, Andary MT, Pezzin LE. Musculoskeletal disorders in referrals for suspected cervical radiculopathy.

Objectives

To determine (1) the prevalence of selected common musculoskeletal disorders in patients referred for electrodiagnosis when cervical radiculopathy is suspected and (2) whether these findings predict electrodiagnostic study outcome.

Design

Prospective study.

Setting

Electrodiagnostic laboratories in departments of physical medicine and rehabilitation at 5 participating institutions.

Participants

A total of 191 subjects undergoing electrodiagnostic evaluations for upper-limb symptoms when cervical radiculopathy was suspected.

Interventions

Not applicable.

Main Outcome Measures

Prevalence of certain musculoskeletal disorders (myofascial pain, shoulder impingement, lateral epicondylitis, de Quervain’s tenosynovitis) and outcomes of electrodiagnostic testing (normal study, cervical radiculopathy, or another electrodiagnostically confirmed diagnosis).

Results

The total prevalence of musculoskeletal disorders was 42%. The prevalence in those with a normal study was 69%, compared with 29% in those with cervical radiculopathy (P<.001) and 45% in those with another diagnosis (P=.02).

Conclusions

Musculoskeletal disorders are common in patients with suspected cervical radiculopathy. Although the presence of certain musculoskeletal disorders makes having a normal electrodiagnostic evaluation significantly more likely, the high prevalence among both patients with normal studies and those with radiculopathy and other disorders limits the usefulness of this information in precisely predicting study outcome. The presence of musculoskeletal disorders should not preclude electrodiagnostic testing when otherwise indicated.

Key Words: Electrodiagnosis, Musculoskeletal diseases, Radiculopathy, Rehabilitation

Article Outline

• Abstract

• Methods

• Participants

• Data Collection

• Data Analysis

• Results

• Discussion

• Conclusions

• References

• Copyright

FOR PERSONS WITH NECK and upper-limb symptoms referred to an electrodiagnostic lab, the clinician considers the diagnostic possibilities and structures the study accordingly. Suspected radiculopathy is a common reason patients are referred for electrodiagnostic evaluation.1, 2, 3 Cervical radiculopathy is a pathologic condition of the cervical spinal nerve roots. It usually presents with pain in the neck and radiating down the arm and numbness and parasthesia distally.4 The distribution of symptoms depends on the nerve root(s) affected.5 Likewise, musculoskeletal disorders are common causes of upper-limb symptoms,6, 7 and they can be mistaken for radiculopathy.8, 9, 10

This study examined the following musculoskeletal disorders of the upper-limb: myofascial pain, shoulder impingement syndrome, de Quervain’s tenosynovitis, and lateral epicondylitis. Although other disorders that mimic radiculopathy could have been considered, these were included because they are common conditions and can be diagnosed based on physical exam findings.

Myofascial pain is characterized by pain in skeletal muscles that originates from trigger points, areas within the muscle that are highly sensitive and reproduce the patient’s symptoms when palpated.11, 12 The pattern of symptoms seen could mimic radiculopathy at several levels, depending on the muscles and fascia involved. Shoulder impingement occurs when there is excessive dynamic tendon overuse and inflammation resulting in painful overhead arm movement from compression of these tendinous structures by the coracoacromial arch. Positive shoulder impingement signs are diagnostic for this syndrome. The pain is exacerbated by abducting and internally rotating the glenohumeral joint, which can occur when sleeping with the arm overhead or combing one’s hair.13, 14 The presence of symptoms at the shoulder could mimic a C5 radiculopathy, for example. De Quervain’s tenosynovitis is caused by narrowing of the first dorsal compartment of the wrist (containing the abductor pollicis longus and extensor pollicis brevis tendons). It presents with pain on the radial side of the wrist (potentially mimicking a C6 radiculopathy) and impairment of thumb function and is identified through a Finkelstein manuver.15, 16 Lateral epicondylitis (also known as tennis elbow) is characterized by pain at the lateral aspect of the elbow that can radiate into the forearm, similar to the pattern of symptoms one may see with a C6 radiculopathy. The pain is reproduced with palpation of the extensor muscles over the lateral epicondyle.17, 18

At present, the prevalence of musculoskeletal disorders in patients referred for electrodiagnostic evaluation is unknown. The purpose of this study was to determine the prevalence of these selected common upper-limb musculoskeletal disorders in patients referred for electrodiagnostic testing. Further, although there are studies examining the predictive ability of physical exam on electrodiagnosis,19, 20, 21 in this study the influence of these specific musculoskeletal disorders on electrodiagnostic study outcome prediction was examined.

Methods

Participants

We conducted a prospective study between May 1996 and May 1998 at the following medical centers that treat diverse patient populations and have high volume physical medicine and rehabilitation (PM&R) electrodiagnostic services: The Johns Hopkins University, Baltimore, MD; Ingham Regional Medical Center affiliated with Michigan State University, East Lansing, MI; Madigan Army Medical Center, Tacoma, WA; Womack Army Medical Center, Fort Bragg, NC; and Walter Reed Army Medical Center, Washington, DC. Patients who were referred to the electrodiagnostic laboratories in the department of PM&R at one of these medical centers for upper-limb symptoms when cervical radiculopathy was suspected were asked to participate. Subjects participated on a voluntary basis after signing written informed consent. The institutional review committee at each of the participating institutions approved the study protocol.

Data Collection

We implemented standardized procedures and data collection sheets at all participating institutions. Patients completed a questionnaire, which collected detailed information and medical history. A standardized physical examination, performed on all subjects, consisted of the following: (1) a neurologic examination, including manual muscle testing, sensation (vibration and pinprick), and reflex assessments; (2) a musculoskeletal examination; and (3) special tests, such as the Tinel sign and Phalen maneuver. After the questionnaire and physical examination, electrodiagnostic evaluations conducted by attending physicians and/or supervised resident physicians were performed for all patients. All co-investigators were certified by the American Board of Electrodiagnostic Medicine and were skilled musculoskeletal physicians. Such expertise was sought to ensure that electrodiagnostic and physical exam findings across participating centers were consistently interpreted.

We administered a standard set of physical examination tests for all patients to identify the presence of musculoskeletal disorders of interest. Myofascial pain was diagnosed for the purposes of this study if palpation of the neck or shoulder region reproduced symptoms.11, 22 Shoulder impingement was deemed present if crossed adduction, forward flexion, or abduction with internal rotation of the shoulder reproduced symptoms.23 Lateral epicondylitis was diagnosed if palpation of the wrist extensor muscles reproduced pain.24 De Quervain’s tenosynovitis was diagnosed if a Finkelstein test was positive.24 Each subject had these specific musculoskeletal examination tests performed as a standardized part of the study along with the neurologic testing described above. Other clinical assessments were done as part of the overall consultation at the discretion of the electrodiagnosticians, who used their clinical expertise and experience to guide the course of the exam and make the final diagnostic conclusions.

The standardized electrodiagnostic study consisted of at least the following: (1) 1 upper-limb motor nerve conduction study, (2) 1 upper-limb sensory nerve conduction study, and (3) needle electromyography with either monopolar or concentric needles of a standard set of 10 muscles. Additional tests were used to evaluate the suspected condition at the discretion of the physician performing the evaluation. The electrodiagnostic conclusions and study outcomes were classified in 3 mutually exclusive categories: (1) normal study, (2) cervical radiculopathy, or (3) other diagnosis established by electrodiagnostic testing. A stratified data collection strategy was used to recruit sufficient persons in each category because these proportions in the referral population were different.

Cervical radiculopathy was diagnosed using previously established methods.25 Specifically, cervical radiculopathy was considered present if electromyographic findings (spontaneous activity, increased polyphasics, complex repetitive discharges, or reduced recruitment) were found in 2 or more muscles innervated by the same nerve root but with different peripheral nerves, or if the paraspinal muscles showed spontaneous activity. Other diagnoses included plexopathy, median neuropathy (carpal tunnel syndrome), ulnar neuropathy, radial neuropathy, and polyneuropathy. These conditions were identified using nerve conduction and electromyographic findings by the electrodiagnostic consultant.

For all analyses, electrodiagnostic outcomes—normal study, radiculopathy, or other diagnosis—were then analyzed as they related to the presence of the musculoskeletal disorders of interest.

Data Analysis

We used SASa for Windows to compare the prevalence of musculoskeletal disorders between study groups using chi-square analysis or the Fisher 2-sided exact test. To further examine the influence of musculoskeletal conditions on study outcome, a multivariate analysis was undertaken using Stata.b Age, sex, and duration of symptoms were controlled for to eliminate any potential confounding effect that these variables may have had on the outcome of the analysis. Study outcomes were defined as normal study (reference category), cervical radiculopathy, or other diagnosis.

Results

There were 191 subjects included in the study, with 52% having a radiculopathy, 24% a normal study, and 25% another condition identified through electrodiagnosis. The mean age ± standard deviation was 49±16 years and 54% were men. The average duration of symptoms reported by the subjects was 20±34 months. The prevalence of the selected musculoskeletal disorders in the study sample by diagnostic category is shown in table 1. Among those diagnosed with radiculopathy, only 2% were diagnosed based on paraspinal findings alone; the majority had electromyographic findings in 2 or more muscles consistent with the diagnostic criteria.

Table 1.

Prevalence of Musculoskeletal Disorders in Patients With Suspected Cervical Radiculopathy


Musculoskeletal Disorder	Normal Study (n=45)	Cervical Radiculopathy (n=99)	Other Electrodiagnosis Diagnosis‡ (n=47)	Total Sample (N=191)
Myofascial pain syndrome	53	17⁎	19⁎	26
Shoulder impingement	31	9⁎	30†	19
Lateral epicondylitis	9	9	11	9
De Quervain’s tenosynovitis	7	2	0	3
One or more of the above	69	29⁎	45⁎	42

NOTE. Values are percentages.

⁎

Significant at P<.05 compared with normal study

†

Significant at P<.05 compared with cervical radiculopathy

‡

Other diagnoses included plexopathy, median neuropathy (carpal tunnel syndrome), ulnar neuropathy, radial neuropathy, polyneuropathy.

The total prevalence of the musculoskeletal disorders was 42%. The prevalence in those with a normal study was 69%, compared with 29% in those with cervical radiculopathy (P<.001) and 45% in those with another diagnosis (P=.02). Multivariate analyses revealed that the presence of myofascial pain meant about one fourth the likelihood of having cervical radiculopathy compared with a normal study (P=.002), the presence of shoulder impingement meant about one fifth the likelihood of having cervical radiculopathy compared with a normal study (P=.007), and the presence of myofascial pain meant about one third the likelihood of having another diagnosis compared with a normal study (P=.017), given that other variables in the model were held constant.

Discussion

Musculoskeletal disorders are common in patients suspected of having a cervical radiculopathy. However, within the study sample there were significant differences in the prevalence of musculoskeletal disorders when subjects were grouped according to the outcome of their electrodiagnostic studies. Over two thirds of patients (69%) with normal studies had a musculoskeletal disorder diagnosed based on physical exam findings. In comparison, 29% of those with a confirmed cervical radiculopathy (P<.001) and 45% of those with other electrodiagnostic diagnoses (P=.02) had a musculoskeletal disorder.

Although the presence of a musculoskeletal disorder suggests that a patient will have a normal study, the fairly high prevalence of musculoskeletal disorders in those with a confirmed cervical radiculopathy or another electrodiagnostic condition limits the usefulness of this information in predicting the results of an electrodiagnostic study. A study should not be curtailed solely on the basis of finding a musculoskeletal disorder on physical exam. In patients referred to the electrodiagnostic laboratory it is common to have these separate problems.

Myofascial pain in particular was common among those with a normal study (53%), and significantly more common than in those with a confirmed cervical radiculopathy (17%, P<.001) or other electrodiagnostic conclusions (19%, P<.001). This result could be an indication of the difficulty in distinguishing between myofascial pain and cervical radiculopathy or other neurologic disorders and the degree to which they mimic each other. The referred pain patterns seen in myofascial pain can be very similar to the dermatomal patterns of the spinal nerve roots.9 Therefore, it is possible that many patients being referred for electrodiagnostic evaluations actually have myofascial pain, either alone or along with radiculopathy. In such cases, an electrodiagnostic evaluation can help clarify the nature of the problem.

Shoulder impingement had a similar prevalence both in those subjects with a normal study (31%) and those with other electrodiagnostic conclusions (30%), but was significantly less common in those with a cervical radiculopathy (9%, P<.001) compared to those with a normal study. This finding may be a reflection of the difficulty in distinguishing pain due to shoulder disorders from referred pain to the shoulder due to cervical radiculopathy,26 similar to the difficulty in distinguishing between myofascial pain and radiculopathy proposed earlier. Both cases emphasize the importance of electrodiagnostic testing in helping to distinguish between upper-limb musculoskeletal disorders and cervical radiculopathy when evidence is present for both conditions and treatment strategies for the musculoskeletal disorder are not effective. However, electrodiagnostic studies are not advocated for all patients with musculoskeletal disorders. Rather, the clinician should consider the possibility of radiculopathy or other disorders even in the presence of such conditions.

It is possible that there was some level of overcall for these musculoskeletal conditions given the nature of the prospective study and the careful and systematic examination for these conditions. In addition, there are interrater differences in physical examination even for skilled practitioners that could influence our findings. For example, the exact finger pressure used to elicit findings during palpation was not standardized. Further, the study design allowed for some subjectivity in the diagnosis of musculoskeletal conditions, relying on the expertise of the participating examiners. More specific pre-established diagnostic criteria would have made the diagnosis more objective.

Also, it is possible that the musculoskeletal conditions diagnosed were unrelated to the reason prompting the electrodiagnostic referral. Further studies examining the relationship between referral reasons, musculoskeletal disorders present, and electrodiagnostic outcomes would help clarify the clinical significance of this issue. However, whether or not the referral reasons were related to the musculoskeletal and electrodiagnostic conclusions, the main purposes of the study (namely, to determine the prevalence of the musculoskeletal conditions in the referral population and whether they predict the electrodiagnostic conclusions) are unaffected.

Finally, the underlying pain system and peripheral nervous system physiology is quite complex and interrelated. These systems may augment the pain responses and perceptions in persons with radiculopathies or entrapment neuropathies such that physical exam maneuvers are perceived as more painful than they otherwise might be in persons without these conditions.

Neither lateral epicondylitis nor de Quervain’s tenosynovitis showed any significant differences across study groups. However, the prevalence of each of these 2 disorders in the study sample was higher than the prevalence in the general population,7 as one would expect in a sample of patients being referred for evaluation of upper-limb symptoms.

The multivariate analysis showed that the presence of myofascial pain lowers the probability of finding a cervical radiculopathy or another condition through electrodiagnostic testing, and that the presence of shoulder impingement syndrome makes finding a cervical radiculopathy less likely. These findings provide some indication about the outcome of electrodiagnostic testing in patients diagnosed with these conditions, but not enough to accurately predict the results.

These findings are in line with what was concluded in other studies on the predictive ability of physical exam on electrodiagnostic outcome. Physical exam findings are important and helpful in guiding the course of an electrodiagnostic study, but are not sufficient to predict what the outcome of the study will be.19, 20 Similarly, the presence of musculoskeletal disorders gives some indication about the outcome of an electrodiagnostic study but does not provide enough information to definitively predict the results of the study.

Conclusions

Musculoskeletal disorders are common in patients referred for electrodiagnostic assessment of cervical radiculopathy. However, the presence of a musculoskeletal problem does not accurately predict who will have a normal electrodiagnostic study or an electrodiagnostically confirmed cervical radiculopathy with sufficient discriminative ability to curtail the electrodiagnostic evaluation. Although there is a significantly higher prevalence in those with a normal study compared to those with cervical radiculopathy and other electrodiagnostic conclusions, the fairly high prevalence in all groups makes it difficult to predict the outcome of electrodiagnostic testing based on the presence of musculoskeletal disorders.

Supplier

References

1. 1Dumitru D, Zwarts MJ. Radiculopathies. In: Dumitru D, Amato AA, Zwarts MJ editor. Electrodiagnostic medicine. 2nd ed.. Philadelphia: Hanley & Belfus; 2002;p. 713–776.

2. 2Levin KH. Electrodiagnostic approach to the patient with suspected radiculopathy. Neurol Clin N Am. 2002;20:397–421.

3. 3Podner S. Critical reappraisal of referrals to electromyography and nerve conduction studies. Eur J Neurol. 2005;12:150–155. MEDLINE | CrossRef

4. 4Cohen I, Jouve C. Cervical radiculopathy. In: Frontera W, Silver J editor. Essentials of physical medicine and rehabilitation. Philadelphia: Hanley & Belfus; 2002;p. 19–24.

5. 5Carette S, Fehlings MG. Cervical radiculopathy. N Engl J Med. 2005;353:392–399. CrossRef

6. 6Bot SD, van der Waal JM, Terwee CB, et al. Incidence and prevalence of complaints of the neck and upper extremity in general practice. Ann Rheum Dis. 2005;64:118–123. MEDLINE | CrossRef

7. 7Walker-Bone K, Palmer KT, Reading I, Coggon D, Cooper C. Prevalence and impact of musculoskeletal disorders of the upper limb in the general population. Arthritis Rheum. 2004;51:642–651. MEDLINE | CrossRef

8. 8Facco E, Ceccherelli F. Myofascial pain mimicking radicular syndromes. Acta Neurochir Suppl. 2005;92:147–150. MEDLINE

9. 9Lauder TD. Musculoskeletal disorders that frequently mimic radiculopathy. Phys Med Rehabil Clin N Am. 2002;13:469–485. Full Text | Full-Text PDF (535 KB) | CrossRef

10. 10Woodward TW, Best TM. The painful shoulder: part 1. clinical evaluation. Am Fam Physician. 2000;61:3079–3088.

11. 11Borg-Stein J, Simons DG. Myofascial pain. Arch Phys Med Rehabil. 2002;83(3 Suppl 1):S40–S47. Abstract | CrossRef

12. 12Gerwin RD. Myofascial pain syndromes in the upper extremity. J Hand Ther. 1997;10:130–136. MEDLINE

13. 13Koester MC, George MS, Kuhn JE. Shoulder impingement syndrome. Am J Med. 2005;118:452–455. Abstract | Full Text | Full-Text PDF (349 KB) | CrossRef

14. 14Chang WK. Shoulder impingement syndrome. Phys Med Rehabil Clin N Am. 2004;15:493–510. Full Text | Full-Text PDF (268 KB) | CrossRef

15. 15Moore JS. De Quervain’s tenosynovitis: stenosing tenosynovitis of the first dorsal compartment. J Occup Environ Med. 1997;39:990–1002. MEDLINE | CrossRef

16. 16Kay NR. De Quervain’s disease (Changing pathology or changing perception?). J Hand Surg [Br]. 2000;25:65–69. MEDLINE | CrossRef

17. 17Whaley AL, Baker CL. Lateral epicondylitis. Clin Sports Med. 2004;23:677–691. Abstract | Full Text | Full-Text PDF (361 KB) | CrossRef

18. 18Nirschl RP, Ashman ES. Elbow tendinopathy: tennis elbow. Clin Sports Med. 2003;22:813–836. Full Text | Full-Text PDF (645 KB) | CrossRef

19. 19Lauder TD. Physical examination signs, clinical symptoms, and their relationship to electrodiagnostic findings and the presence of radiculopathy. Phys Med Rehabil Clin N Am. 2002;13:451–467. Full Text | Full-Text PDF (97 KB) | CrossRef

20. 20Lauder TD, Dillingham TR, Andary M, et al. Predicting electrodiagnostic outcome in patients with upper limb symptoms: are the history and physical examination helpful?. Arch Phys Med Rehabil. 2000;81:436–441. Abstract | Full Text | Full-Text PDF (38 KB) | CrossRef

21. 21Wainner RS, Fritz JM, Irrgang JJ, Boninger ML, Delitto A, Allison S. Reliability and diagnostic accuracy of the clinical examination and patient self-report measures for cervical radiculopathy. Spine. 2003;28:52–62. CrossRef

22. 22Tough EA, White AR, Richards S, Campbell J. Variability of criteria used to diagnose myofascial trigger point pain syndrome—evidence from a review of the literature. Clin J Pain. 2007;23:278–286. MEDLINE | CrossRef

23. 23Andrews JR. Diagnosis and treatment of chronic painful shoulder: review of nonsurgical interventions. Arthroscopy. 2005;21:333–347. Abstract | Full Text | Full-Text PDF (194 KB) | CrossRef

24. 24Piligian G, Herbert R, Hearns M, Dropkin J, Landsbergis P, Cherniack M. Evaluation and management of chronic work-related musculoskeletal disorders of the distal upper extremity. Am J Ind Med. 2000;37:75–93. MEDLINE | CrossRef

25. 25Dillingham TR, Lauder TD, Andary M, et al. Identification of cervical radiculopathies: optimizing the electromyographic screen. Am J Phys Med Rehabil. 2001;80:84–91. MEDLINE | CrossRef

26. 26Manifold SG, McCann PD. Cervical radiculitis and shoulder disorders. Nov Clin Orthop Relat Res. 1999;368:105–113.

a Medical College of Wisconsin, Milwaukee, WI

b Department of Physical Medicine and Rehabilitation, Medical College of Wisconsin, Milwaukee, WI

c Department of Medicine, Medical College of Wisconsin, Milwaukee, WI

d Department of Physical Medicine and Rehabilitation, Michigan State University College of Osteopathic Medicine, East Lansing, MI.

Reprint requests to Timothy R. Dillingham, MD, Dept of Physical Medicine and Rehabilitation, 9200 W Wisconsin Ave, Milwaukee, WI 53226-3596

No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.

a Version 9.1; SAS Institute Inc, 100 SAS Campus Dr, Cary, NC 27513.

b Version 9.0; StataCorp, 4905 Lakeway Dr, College Station, TX 77845.

PII: S0003-9993(07)01281-6

doi:10.1016/j.apmr.2007.07.010

8 of 126