Original Article http://dx.doi.org/10.12972/The .2015.01.01.011 www.thenerve.net

The Effect of Cervical Radiculopathy on the Outcome of Carpal Tunnel Release in a Patient with

Heui Seung Lee1, Sung Bae Park2, Sang Hyung Lee2, Young Seob Chung2, Hee-Jin Yang2, Young-Je Son2

1Department of , Seoul National University Hospital, Seoul National University College of Medicine, Seoul, 2Department of Neurosurgery, Seoul National University Boramae Medical Center, Seoul National University College of Medicine, Seoul, Korea

Objective: The aim of this cross-sectional study was to elucidate the incidence of cervical radiculopathy among patients who have been diagnosed with carpal tunnel syndrome (CTS) and to evaluate the outcome of carpal tunnel release (CTR) in CTS patients with clinically diagnosed cervical radiculopathy. Methods: Eighty-five patients who underwent CTR for their electrophysiologically and ultrasonographically diagnosed CTS from January 2013 to July 2015 were evaluated according to the presence of cervical radiculopathy or any condition proven by a radiological assessment of the cervical region. The outcome of CTR was graded from 1 to 4 by the degree of relief and evaluated according to clinical factors including cervical radiculopathy. Results: CTR was shown to be effective in 70 (82.4%) patients, whereas 14 (16.5%) were categorized as a non-effective group. The outcome of CTR was significantly different in the presence of ipsilateral cervical radiculopathy, which was documented by an electrophysiological assessment (p=0.05). However, there was no significant difference in the outcome of CTR between patients with normal and abnormal findings in the cervical region in the radiological assessments. Conclusion: CTR seemed less effective for the patients who had cervical radiculopathy. An electrophysiological study to identify cervical radiculopathy before performing a CTR is necessary to increase the success rate of the treatment by selecting the most appropriate patients.

Key Words: Carpal tunnel syndromeㆍCarpal tunnel releaseㆍCervical radiculopathy

drome and patients with coexisting cervical radiculopathy5). However, the correlation between co-existing double crush INTRODUCTION syndrome and the outcome of CTR still remains controversial. The aim of this study is to elucidate the incidence of electro- Carpal tunnel syndrome (CTS) is one of the most frequent physiologically proven cervical radiculopathy and its effect on compressive neuropathies of the upper extremities, accounting the postoperative prognosis of CTR. for 90% of all entrapment neuropathies2,12). In a recent sur- veillance study by Bland et al., the annual incidence was 139.4 cases per 100,000 in females and 67.2 cases per 100,000 in MATERIALS AND METHODS males, with a female to male ratio of 2.07173). Carpal tunnel release (CTR), which consists of the division 1. Study Population of the transverse carpal ligament to increase the space in the carpal tunnel, is indicated in patients with moderate to severe All patients with CTS admitted to our hospital to undergo CTS. The success rate of CTR in patients with CTS has been CTR were recruited to this cross-sectional study from January 9,12) reported to be 70 to 90% . The outcome of CTR can be 2013 to July 2015. We enrolled patients whose diagnosis of different between patients with isolated carpal tunnel syn- CTS was made by an electrophysiological assessment such as Corresponding author: Sung Bae Park, MD, PhD a (NCS) or electromyelography (EMG) Department of Neurosurgery, Seoul National University Boramae to document the presence and the severity of the CTS. The Medical Center, Seoul National University College of Medicine, 20, preoperative severity of the CTS was graded by using the Boramae-ro 5-gil, Dongjak-gu, Seoul 07061, Korea 8) Tel: +82-2-870-3301, Fax: +82-2-870-3863 following neurophysiologic grading suggested by Bland : grade E-mail: [email protected] 1, very mild CTS, detected only in two sensitivity tests (e.g.,

Journal of the Korean Society of Peripheral Nervous System 11 Cervical Radiculopathy and Carpal Tunnel Syndrome inching, palm/wrist median/ulnar comparison, ring finger “dou- among the different groups according to each radiological ble peak”); grade 2, mild CTS (orthodromic sensory condu- abnormal finding was evaluated by chi-square test. SPSS 20 ction velocity from index finger to wrist <40 m/s with motor (IBM SPSS Inc., Armonk, NY) was used for statistical analysis, terminal latency from wrist to abductor pollicis brevis [APB] and significance was defined as p≤0.05. <4.5 ms); grade 3, moderately severe CTS (motor terminal latency >4.5 ms and <6.5 ms with preserved index finger SNAP); grade 4, severe CTS (motor terminal latency >4.5 ms and RESULTS <6.5 ms with absent SNAP); grade 5, very severe CTS (motor terminal latency >6.5 ms); and grade 6, extremely severe CTS During the study period, 85 patients were treated by either (surface motor potential from APB <0.2 mV, peak-to-peak). open or endoscopic CTR for CTS. Of the study population, An institutional database was reviewed according to sex, 79 were women and 6 were men. The mean age of the patients age, past medical history and degree of pain relief. was 58.86±10.94 years (range, 31 to 86 years). The demogra- phics of the patients are listed in Table 1. The preoperative 2. Radiologic Evaluation of the Cervical Region clinical diagnosis of CTS was made in all 85 patients according to their history and the results from the combination of NCS, EMG and ultrasonographic evaluation of the carpal tunnel. For some patients in our study, an MRI or X-ray was per- Forty-six (54.1%) of the 85 patients had an MRI or X-ray formed on the cervical spine to evaluate the symptoms. The of the cervical region. The patients were divided into the follo- results of abnormal radiological findings fell into the following wing three groups based on the findings of the radiographic 3 groups: neural foraminal stenosis, central canal stenosis, and assessments of the cervical region: neural foraminal stenosis cervical . (26 patients), central canal stenosis (2 patients) and spondylosis (10 patients). Of the 85 patients, 17 were proven to have cervi- 3. Outcome Assessment cal radiculopathy on NCS and EMG. The difference in the outcome between endoscopic and All patients who underwent a CTR for their CTS were follo- open CTR was not considered to be different for long-term wed up in the outpatient clinic at least one week after the 12) pain relief based on a previous study . first procedure. The degree of pain relief was graded from The outcome of CTR was available for assessment in 84 1 to 4 in the following order: “Excellent” (improvement >75 of 85 patients. Among these patients, CTR was shown to be %), “Good” (50-70%), “Fair” (25-50%), and “Poor” (<25%). effective for 70 (83.3%) of 84 patients. We defined the outcome of CTR to be effective when the The effect of CTR was assessed based on the patient’s clini- patients reported that the pain was relieved by more than cal characteristics (Table 2 and 3). The mean age of the patients 50%. These were classified as the “Excellent” or “Good” pain was not significantly different between the effective and non- relief groups. Non-effective was defined as pain relief of less effective groups. There was no significant difference in the than 50%. preoperative severity of CTS between the effective and non-

4. Statistical Analysis Table 1. Demographic and clinical data of the study population The degree of pain relief after CTR was graded from 1 to Gender 4, and, using ANOVA methods and independent t-test, the Male 6 (7.1%) mean values of the grades were compared among patients Female 79 (92.9%) based on the radiological findings of the cervical region and Age (years)±SD 58.86±10.94 the presence of co-existing mellitus, which were con- Male 60.83±8.68 sidered to affect the outcome of the treatment. The preopera- Female 58.71±11.12 tive severity of CTS was also evaluated according to co-exis- Underlying conditions ting diabetes mellitus and cervical radiculopathy by comparing diabetes mellitus 13 (15.3%) the mean value of the severity of CTS. The mean value of rheumatoid arthritis 1 (1.2%) the preoperative severity of CTS was compared between effe- C6, 7, 8 radiculopathy 17 (20%) ctive and non-effective groups after CTR. The outcome of foraminal stenosis 26 (30.6%) CTR was also evaluated between the groups with and without central canal stenosis 2 (2.4%) cervical radiculopathy using chi-square methods. The outcome cervical spondylosis 11 (12.9%)

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Table 2. Degree of pain relief according to the ipsilateral cervical radiculopathy Grade of the outcome 1 (Excellent) 2 (Good) 3 (Fair) 4 (Poor) total ipsilateral C6, 7, 8 radiculopathy 1 9 7 0 17 p=0.05* no radiculopathy 12 48 7 0 67 *Statistical analysis was performed by Chi-square test between effective (Excellent and Good) and non-effective groups (Fair and Poor).

Table 3. Degree of pain relief according to radiologically proven co-existing conditions Grade of the outcome 1 (Excellent) 2 (Good) 3 (Fair) 4 (Poor) total ipsilateral neural foraminal stenosis 3 15 8 0 26 p=0.17* central canal stenosis 1 1 0 0 2 cervical spondylosis 0 10 0 0 10 *Statistical comparison was performed by ANOVA among the radiologically proven conditions (neural foraminal stenosis, central canal stenosis and cervical spondylosis). effective groups (p=0.186). The presence of cervical radiculo- radiculopathy4). pathy, which was proven by neurophysiological assessments The results of previous studies have shown discrepancies (NSC and EMG), was the only factor that was significantly in the relationship between cervical pathology that can cause different between the effective and non-effective groups (p= double crush syndrome and CTS. 0.05). The degree of pain relief that was graded from 1 to In the one of the largest studies by Hurst et al., there was 4 based on each patient’s response was not significantly diffe- a significant correlation of bilateral carpal tunnel syndrome rent among the groups with different findings on the radio- with cervical arthritis (p<0.05), whereas a recent study by logical cervical evaluation (p=0.17). Abnormal findings in Kwon et al. showed that double crush syndrome in CTS did radiological assessment did not give the significant difference not explain the correlation between the level of cervical radi- in outcome of CTR to both groups with and without cervical culopathy and motor or sensory responses. In radiculopathy (p=0.571 and p=0.165, respectively). The out- their study, the frequency of coexisting CTS was not signifi- come of CTR was not significantly different according to the cantly different according to the level of radiculopathy10). presence of diabetes mellitus (p=0.13). The mean value of the Of the neuropathic factors, it has been suggested that pa- preoperative severity of CTS in patients with diabetes mellitus tients with diabetes mellitus have a higher tendency to develop was not significantly different from those without diabetes CTS without necessarily increasing interstitial pressure within mellitus (p=0.81). the carpal tunnel, due to a lower threshold for nerve damage7,11). Hurst et al. also showed a tendency for an increased inci- DISCUSSION dence of bilateral CTS in patients with co-existing diabetes mellitus, although this increase was not statistically significant6). Upton and McComas first described double crush syndrome In our study, 13 (15.3%) of 85 patients had co-existing in 1973 based on their clinical observation that the majority diabetes mellitus; however, neither the preoperative seve- of patients had median or associated with rity of CTS nor the postoperative outcome of CTR was signi- evidence of cervicothoracic root lesions, suggesting that com- ficantly different from patients without diabetes mellitus (p= pression of an axon at one location makes it more sensitive 0.81 and 0.13). to the effects of compression in another location because of Although the presence of ipsilateral cervical radiculopathy impaired axoplasmic flow. They also observed a high associa- at C6, C7 or C8 did not have a significant correlation with tion between diabetes and CTS13). the preoperative severity of CTS in our study, it was signifi- Based on the fact that median nerve sensory fibers primarily cantly related to a poorer postoperative outcome for CTR. use C6 and C7 roots and that motor fibers primarily use C8 However, our study showed that there was no significant diffe- and T1, some authors have tried to corroborate the hypothesis rence in the outcome of CTR according to each radiological that abnormal sensory conduction of the median nerve would diagnosis in the cervical region, including neural foraminal be found more frequently in those patients with C6 or C7 stenosis, central canal stenosis and cervical spondylosis.

The Nerve 1(1) September 2015 13 Cervical Radiculopathy and Carpal Tunnel Syndrome

Hence, the results from our study support the concept of Ball: Can the outcome of open carpal tunnel release be predi- double crush syndrome in CTS patients. Based on the results cted?: a review of the literature. ANZ J Surg 80:50-54, 2010 of our study, preoperative neurophysiologic studies such as NCS 2. American Academy of Orthopaedic Surgeons Work Group Panel. Clinical guidelines on diagnosis of carpal tunnel syndrome, 2007 and EMG are necessary to identify the patients with cervical 3. Bland JD, Rudolfer SM: Clinical surveillance of carpal tunnel radiculopathy who may be less likely to benefit from CTR for syndrome in two areas of the United Kingdom, 1991-2001. J their symptom relief. In contrast to the utility of preoperative Neurol Neurosurg Psychiatry 74 (12):1674-1679, 2003 electrophysiological assessments to identify cervical radiculo- 4. Brent S Russell: Carpal tunnel syndrome and the “double crush” pathy, radiological evaluation seems insufficient to predict a hypothesis: a review and implications for . Chiro- patient’s prognosis after surgical decompression of carpal tunnel. practic & Osteopathy 16:2, 2008 Thus, taking cost-effectiveness into consideration, preopera- 5. Choi S.J., Ahn D.S.: Correlation of clinical history and electo- diagnostic abnormalities with outcome after for carpal tive neurophysiologic evaluation to determine the severity of tunnel syndrome. Plat. Reconstr. Surg 102(7):2374-2380, 1998 CTS and evidence of cervical radiculopathy would occur prior 6. Hurst LC, Weissberg D, Carroll RE: The relationship of the to cervical radiographic evaluation, and radiologic evaluation double crush to carpal tunnel syndrome (an analysis of 1000 may be omitted if cervical radiculopathy is not proven by neu- cases of carpal tunnel syndrome). J Hand Surg 10:202-204, 1985 rophysiologic assessments. 7. I. Ibrahim, W.S. Khan, N. Goddard, P. Smitham: Carpal Tunnel Syndrome: A Review of the Recent Literature. The Open Ortho- paedics Journal 6 (Suppl 1:M8):69-76, 2012 CONCLUSION 8. Jeremy D.P. Bland, FRCP: A neurophysiological grading scale for carpal tunnel syndrome. Muscle Nerve 23:1280-1283, 2000 9. Jimenez DF, Gibbs SR, Clapper AT: Endoscopic treatment of The limitation of our study is that the factors of confoun- carpal tunnel syndrome: a critical review. J Neurosurg 88(5): ding potential that are known to be associated with poor sur- 817-826, 1998 gical prognosis1 such as patient occupation, repetitive work 10. Kwon HK, Hwang M, Yoon DW: Frequency and severity of and of the abductor pollicis brevis muscle were not carpal tunnel syndrome according to level of cervical radiculo- considered in the preoperative evaluation. pathy: double crush syndrome? Clin Neurophysiol 117(6):1256- Therefore, further clinical study should be performed while 1259, 2006 11. MacDermid JC, Doherty T: Clinical and electrodiagnostic testing controlling for possible confounding factors. of carpal tunnel syndrome: a narrative review. J Orthop Sports. Phys Ther 34(10):565-588, 2004 REFERENCES 12. Somaiah Aroori, Roy AJ Spence: Carpal tunnel syndrome. Re- view. Ulster Med J 77(1):6-17, 2008 13. Upton ARM, McComas AJ: The double crush in nerve entrap- 1. Alexandra Turner, Frank Kimble, Károly Gulyás and Jennifer ment syndromes. Lancet 2:359-362, 1973

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