Can axial pain be helpful to determine surgical level in the multilevel cervical radiculopathy?

Introduction

Magnetic resonance imaging (MRI) has become widely accepted as a valuable imaging study in the investigation of spinal disorders. ¹ Asymptomatic radiographic compression of nerve root is frequently found in the MRI of the cervical spine. ² Spine surgeons are often required to differentiate the target level of cervical disc herniation with asymptomatic radiographic disc herniation. Findings from physical examinations and symptoms provided by the patients are the clues to differentiate the target level of cervical disc herniation. Unfortunately, most physical examinations used to find cervical target level do not have high diagnostic accuracy. ³ Symptoms may be classified into sensory dysfunctions of pain, sensory paresthesia, numbness, and motor dysfunction of motor weakness. Sensory dysfunction is more important than motor dysfunction in assessing target cervical levels for surgery. For an example, the weakness of wrist flexors can cause secondary weakness of wrist extensors, which are antagonistic muscles of wrist flexors. Axial pain including cervicogenic headache and parascapular pain might be helpful in deciding cervical target level because axial pain occurred with cervical root compression and got relieved after decompression of cervical root. ⁴ However, there is no review article regarding the axial pain originated from cervical spondylotic radiculopathy and relieved by surgical decompression. We have reviewed the literatures about the axial pain, which can be utilized in determining surgical target level to be decompressed in the patients with cervical spondylotic radiculopathy at multiple levels.

Review

A detailed computerized literature search using the PubMed search engine was employed using medical subject headings of “radiculopathy” and “cervical vertebrae” and “decompression, surgical” or “cervicogenic headache” or “scapular.” This database consists of literature published from 1980 through 2014. We included English language articles regarding cervical radiculopathy with spondylosis. Articles about radiculopathy with fracture and/or dislocation or ossification of posterior longitudinal ligament were excluded. Review articles were excluded. We reviewed all articles and categorized them into randomized clinical trial, nonrandomized prospective study, and retrospective study.

We identified 215 articles regarding cervical spondylotic radiculopathy treated with surgical decompression, among which 12 articles were about axial pain from cervical spondylotic radiculopathy. One article was excluded because it is about the cervical myelopathy due to disc herniation at C2–C3. ⁵ Another article was excluded because it did not explain about the specific pathology behind the cervical radiculopathy. ⁶ We found 10 retrospective studies that met the study criteria (Tables 1 to 3). ^{7 –16} There were no prospective randomized controlled clinical trials and no prospective nonrandomized studies that met the study criteria.

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Table 1.

Literature review about the cervicogenic headache relieved surgically in the patients with C2, C3, and C4 radiculopathies.

	Patients number	Symptom	Radiculopathy	Treatment
Pikus and Phillips 7	35	Suboccipital pain with radiation to retro-auricular region or retro-orbital region	C2	C2 ganglion soft tissue release
Park et al. 8	2	Suboccipital pain with or without radiation to retro-auricular or retro-orbital region	C3	Surgerya
Chen 9	8	Suboccipital pain with perioral numbness	C3	Surgery
Park et al. 8	17	Suboccipital pain with or without radiation to retro-auricular or retro-orbital region	C4	Surgery
Jenis and An 10	12	No suboccipital pain, pain at the base of the posterior neck, upper trapezius, scapular, and peri-clavicular regions	C4	Surgery
Slipman et al. 11	4	Same as above	C4	Nerve root stimulation

^aSurgery: Anterior cervical discectomy and fusion or posterior decompression and fusion.

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Table 2.

Literature review about the distribution of pain around scapula associated with C5, C6, C7, and C8 radiculopathies.

	Patients number	Symptom	Nerve roots	Confirm
Tanaka et al. 12	50	Suprascapular region (C5), suprascapular region (C6), interscapular region (C7), interscapular and scapular region (C8)	C5, 6, 7, 8	Posterior foraminotomy
Mizutamari et al. 13	11	Same as above	Same as above	Cadaveric dissection

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Table 3.

Literature review about subscapular pain or scapular winging specific for C7 radiculopathy.

	Patients number	Symptom and sign
Ozgur and Marshall 14	28	Subscapular pain without pain radiating to arm
Makin et al. 15	6	Scapular winging
Cast and Jamjoom 16	1	Scapular winging

Axial pain might be classified into the cervicogenic headache and parascapular axial pain. Cervicogenic headache is characterized by headache referred from a primary pain source in the cervical spine. ^17,18 It is a common diagnosis among the neurologists, but unfamiliar to many spine surgeons. The mechanism of the cervicogenic headache is the convergence at the trigeminocervical nucleus from cervical and trigeminal afferents. In the nucleus, nociceptive afferents from the C1, C2, C3, and C4 spinal nerves converge into the neurons that also receive afferents from the first division of the trigeminal nerve, via the trigeminal nerve spinal tract. ^17,18 It is diagnosed when cervicogenic headache is relieved temporarily by diagnostic blocks of cervical joints or nerves. ¹⁸ Cervicogenic headaches include suboccipital headaches, retro-orbital pain, retro-auricular pain, or temporal pain. Six articles have been dealing with cervicogenic headache relieved from surgical treatment in the patients with C2, C3, and C4 radiculopathies (Table 1). ^{7 –11} Thirty-five patients with C2 radiculopathy, 10 patients with C3 radiculopathy, and 17 patients with C4 radiculopathy had the pain radiating to the retro-auricular or retro-orbital region with suboccipital pain preoperatively. ^{7 –9} Postoperatively they had the relief of suboccipital pain. ^{7 –9} However, no suboccipital pain was reported in the other studies with study population of the patients with C4 radiculopathy. ^10,11

The parascapular axial pain was associated with C5, C6, C7, and C8 radiculopathies in two studies (Table 2). ^12,13 One study deals with axial pain resolved after surgical treatment and the other is a cadaveric dissection study (Table 2). ^12,13 Axial pain was divided into suprascapular pain, interscapular pain, and scapular pain. ¹² The location of the pain improved by posterior foraminotomy was evaluated in 50 patients; the patients with C5 and C6 nerve root showed relief of suprascapular pain, those with C7 nerve root showed that of interscapular pain, and those with C8 nerve root showed that of interscapular and scapular pain. ¹² In the cadaveric study, dissection of the nerve roots revealed the dermatomal distribution of C5 and C6 nerve root at suprascapular region, C7 nerve root at interscapular region, and C8 nerve root at interscapular and scapular region. ¹³

Subscapular pain without radicular pain or scapular winging may be specific for C7 radiculopathy (Table 3). ^{14 –16} Twenty-eight patients of 241 patients with C7 radiculopathy (12% of the study population) had subscapular pains without pain radiating to upper extremity before anterior cervical discectomy and fusion (ACDF) at C6–C7 and they have disappeared postoperatively. ¹⁴ Seven patients with C7 radiculopathy had the relief of preoperative scapular winging after ACDF at C6–C7. ^15,16 It was found when pushing forward against a wall with the hands at the waist level. ¹⁵ Differential diagnosis should include the long thoracic nerve palsy. The patients with C7 radiculopathy showed the scapular winging only when pushing forward against a wall with the hands at the waist level. ¹⁵ In contrast, the patient with an idiopathic long thoracic nerve palsy showed scapular winging when pushing forward against a wall with the hands both at the waist level and at the shoulder level. ¹⁵

Discussion

Reliability of Spurling test and distraction test for cervical radiculopathy was found relatively high (κ = 0.62 and 0.88). ³ Reliability of dermatomal sensory dysfunction, motor weakness of deltoid muscle due to C5 nerve root dysfunction, and motor weakness of biceps brachii muscle was relatively high reliability (κ = 0.67, 0.62, and 0.69). ³ However, other physical examinations used for cervical radiculopthy had relatively low reliability. ³ Axial pain including cervicogenic headache and parascapular pain might be helpful in deciding cervical target level. However, there is no review article regarding the axial pain originated from cervical spondylotic radiculopathy and relieved by surgical decompression. The purpose is to review the literatures about the axial pain, which can be utilized in determining target level to be decompressed in the patients with cervical spondylotic radiculopathy at multiple levels.

Cervicogenic headaches of suboccipital headaches, retro-orbital pain, retro-auricular pain, or temporal pain may be associated with C2, C3, and C4 radiculopathies. The axial pain around scapula may be associated with C5, C6, C7, and C8 radiculopathies.

As with any study, the present investigation has several limitations. First, the literature we reviewed are all retrospective and none are level I studies. Second, they did not show a specific dermatomal distribution of axial pain enough to be used in clinical practice. Third, they did not evaluate the sensitivity, the specificity, and positive and negative predictive values of the axial symptoms for defining surgical levels. Despite these shortcomings, to our knowledge, this is the first review concerning axial pain helpful to determine surgical target level in the patients with cervical spondylotic radiculopathy at multiple levels.

Conclusion

Sensory dysfunction is more important than motor dysfunction for the differentiation of the pathologic level of cervical radiculopathy. While dermatomal distribution of arm pain is useful to evaluate the origin of cervical root compression, the axial pain might be helpful to find the origin of the cervical root compression. However, there is insufficient evidence to make recommendations for the use in clinical practice because they did not show a specific dermatomal distribution of axial pain and did not evaluate the sensitivity, the specificity, and positive and negative predictive values of the axial symptoms for defining surgical levels. In addition, the direction of the disc herniation, the degree of nerve compression, and the duration of the symptoms should be taken into consideration for deciding target surgical level because radiating pain does not always correlate with dermatomal distribution.