
A prospective study of the long-term efficacy of local methyl prednisolone acetate injection in the management of mild carpal tunnel syndrome
V. Agarwal,
R. Singh,
A. Sachdev,
Wiclaff,
S. Shekhar and
D. Goel1
Department of Medicine, Government Medical College Chandigarh and 1 Department of Neurology, Himalayan Institute Hospital Trust, Dehradun, India.
Correspondence to: V. Agarwal, Department of Clinical Immunology, SGPGIMS, Lucknow 226014, India. E-mail: vikasagr{at}sgpgi.ac.in
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Abstract
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Objective. Local glucocorticoid injections are used to treat carpal tunnel syndrome (CTS). However, this treatment is associated with frequent relapses. An important limitation of studies with higher relapse rates is that no attempt has been made to identify patients with mild or severe disease. We evaluated the efficacy of local glucocorticoid injection in patients with mild CTS.
Method. Mild CTS was defined as intermittent symptoms without absence of sensations, muscle atrophy or weakness of the thenar muscles. Forty-eight patients with idiopathic mild CTS were evaluated before and 3 and 12 months after a single local injection of 40 mg methyl prednisolone acetate. Outcome was assessed by overall satisfaction on a 100 mm visual analogue scale, the Boston self-administered questionnaire for symptom severity and functional scores and improvement in the electrophysiological parameters.
Results. At 3 months, 93.7% of the patients reported marked improvement in their symptoms, with significant improvement in the mean values of the nerve conduction parameters distal motor latency at the wrist (DML) (P = 0.00001), distal sensory latency at mid-palm (DSL MP) (P = 0.014) and distal sensory latency at the wrist (DSL W) (P = 0.0003), and symptom severity (P = 4.96 x 108) and the functional scores (P = 3.56 x 105). Significant improvement was still present for DML (P = 1.39 x 105) at 12 months. Almost 50% of the patients achieved normalization in the electrophysiological study. At a median follow-up of 16 months, 79% patients continued to have improvement in their symptoms. Eight patients (16.6%) relapsed following the initial response.
Conclusions. Local glucocorticoid injection results in long-term improvement in nerve conduction parameters, symptom severity and functional scores in patients with mild CTS.
KEY WORDS: Local glucocorticoid, Electrophysiology, Outcome assessment
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Introduction
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Carpal tunnel syndrome (CTS) is the most frequent entrapment neuropathy of the median nerve. Surgical decompression is the most definitive form of therapy [1]. However, its high cost and limited access is an undermining factor. Non-surgical modalities like non-steroidal anti-inflammatory drugs, diuretics, pyridoxine, wrist splints and oral steroids have been studied in small, randomized trials, with no evidence of long-term efficacy [13]. Local glucocorticoid injection improves symptoms in more than 75% of patients [414] and has been superior to placebo in randomized clinical trials [5, 6, 9]. Giannini et al. have reported that local triamcinolone (40 mg) not only provides symptomatic relief but also improves distal motor (DML) and sensory (DSL) latencies of the median nerve at the wrist [7]. Other studies have reported similar observations [5, 6, 8, 14]. Dammers et al. have assessed the effect of a 40 mg methyl prednisolone injection proximal to the carpal tunnel in patients with the carpal tunnel syndrome in a randomized, double-blind, placebo-controlled trial [9]. Most of the responders maintained their response until 12 months without any additional therapy. They concluded that a single injection of steroids close to the carpal tunnel may result in long-term improvement and should be considered before surgical decompression. However, most studies, in contrast, report higher relapse rates, ranging from 8 to 94% (Table 1) within first 12 months after local glucocorticoid injection. Patients with severe CTS had a higher (89%) relapse rate [6] compared with mild CTS (60%) [4].
A number of studies have attempted to identify predictive factors, both clinical and electrophysiological, which can suggest response to local glucocorticoid therapy. Kaplan and colleagues [15] identified five factors that were associated with poor outcome: age over 50 yr, symptoms in excess of 10 months, constant paraesthesia, triggering of digits, and a positive Phalen's test in 30 s or less. Goodman and Foster [16] reported that patients with electrophysiologically mild CTS (DML 57 ms) had better outcome compared with moderate to severe CTS at 18 months of follow-up. Gelberman and colleagues reported that patients with symptoms of <12 months duration, intermittent numbness, normal two-point discrimination, without evidence of weakness or atrophy, and 12 ms delay of distal latencies had the most satisfactory response to triamcinolone injection and splinting [6]. Mortier et al. correlated motor terminal latency time of the median nerve and the result of methyl prednisolone injection in carpal tunnel syndrome in 45 patients. Twelve of the 15 patients who underwent surgery had DML >5.5ms. Only three out of 29 patients with DML <5.5 ms required surgery [17]. Schuchmann et al. [18], in contrast, reported that electrophysiologically worse cases responded better to injection. Irwin et al. concluded that the only factor that correlated with the outcome was the duration of symptoms [19]. However, there is no universal acceptance of these results.
From our experience, we believe that patients with clinically mild CTS and DML <7.5 ms at the wrist and without absence of the nerve action potential will have prolonged and lasting remission with local glucocorticoid injection compared with patients with clinically severe CTS or DML >7.5 ms. We undertook a prospective study of the long-term efficacy of methyl prednisolone acetate (MPA) injected locally into the carpal tunnel in patients with clinically mild CTS.
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Patients and methods
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Subjects aged >18 yr attending the medical out-patient department with a confirmed diagnosis of CTS were enrolled in the study. Written/verbal consent was obtained from each subject prior to the injection. The ethical committee of the institute approved the study protocol.
Clinical diagnosis was made on the basis of presence of pain and paraesthesias in the distribution of the median nerve, nocturnal exacerbation of symptoms and positive Phalen's manoeuvre and/or Tinel's sign. Electrophysiological diagnosis was made according to the American Association of Electrodiagnostic Medicine (AAEM) 1993 guideline [20] and our electrophysiological methods conformed to AAEM recommendations.
The Boston self-administered questionnaire [21], measuring symptom severity score and functional score for CTS, was analysed prior to, and 3 and 12 months following the MPA injection.
Clinical examination was carried out at intervals of 46 weeks. Nerve conduction studies (NCS) (sensory and motor median, ulnar and radial nerves) were carried out prior to and 3 and 12 months after the MPA injection. Nerve conduction studies were conducted at 3335°C room temperature with a Spirit Nicolet electromyograph using OS 2 software.
Mild CTS was defined as intermittent symptoms without atrophy or weakness of the thenar muscles and absence of sensations.
The electrophysiological severity of CTS was assessed according to Bland [22] with minor modification. Grades 4 and 5 were combined together as severe CTS.
Under aseptic conditions, 40 mg MPA plus 0.5 ml of 2% xylocaine was injected into the carpal tunnel using a 40 mm 24 gauge needle entering at the anterior wrist flexion crease just ulnar to the palmaris longus tendon; the angle of the needle during insertion was 45° distally and 45° radially. The needle was advanced approximately 1 cm, with puncture of the transverse carpal ligament.
The following patients were excluded: (i) those with thenar atrophy, muscle weakness or spontaneous activity (fibrillation potentials and positive sharp waves) on EMG of the abductor muscle; (ii) those with rheumatic diseases, cervical radiculopathy, and peripheral neuropathies; (iii) those who had previously undergone an injection of glucocorticoid into the carpal tunnel, had prior carpal tunnel surgery or had sustained distal radius fracture; and (iv) those with attending conditions like diabetes mellitus, hypothyroidism, pregnancy, rheumatoid arthritis and amyloidosis.
The primary outcome was overall satisfaction with therapy, i.e. relief of symptoms (pain, numbness, tingling, nocturnal awakening). Secondary outcomes were normalization of the electrophysiological parameters and the Boston self-administered questionnaire for symptom severity and functional scores. Overall satisfaction with the therapy was assessed with a 100-mm visual analogue scale (VAS), 0 representing no relief/worsening and 100 representing being completely asymptomatic. Greater than 70% overall satisfaction with the therapy, with no difficulty in functional mobility and without the need for further therapy, as judged by the patient, was considered to constitute improvement. Anything less than this was considered failure.
Statistical analysis
Paired two-tailed Student's t test was applied for numerical and the
2 test for categorical variables.
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Results
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The study period was from October 2001 to May 2003. Forty-eight patients (67 hands), 40 females, with mean age 45 yr (range 2470) and mean duration of symptoms 6 months (range 112), were enrolled in the study. Most of the patients had tingling and nocturnal worsening of symptoms as the initial presentation (Table 2). Almost 60% patients had numbness in the distribution of the median nerve. Phalen's manoeuvre (positive in 79% cases) had higher sensitivity than Tinel's sign (positive in 54.1% cases).
Following MPA injection, improvement was seen in 93.7 and 81% of patients at 3 and 12 months, respectively. However, only 18 and seven patients were completely asymptomatic at 3 and 12 months, respectively. None of the patients had a positive Phalen's manoeuvre or Tinel's sign. Two patients continued to complain of paraesthesias in the affected median nerve despite improvement in the electrophysiological variables. One of these patients underwent open surgical release of the carpal tunnel and the other dropped out from the study after declining surgery. Clinical relapse was seen in eight patients (12 hands) at an interval varying from 7 to 15 months. Four patients (six hands) were administered a second MPA injection locally into the carpal tunnel at 7, 9, 15 and 7 months, respectively. Two of these patients had transient symptomatic improvement without any improvement in the NCS. They declined further MPA injection and were advised to undergo surgery. The other two did not improve with reinjection and surgery was advised. The remaining patients declined to have a second injection as the symptoms were not troublesome and did not hamper their functional mobility. At a median follow-up of 16 months, 79% (n = 38) patients continued to report improvement and eight patients (16.6%) continued to have symptoms.
At 3 months, the Boston symptom severity and functional scores showed significant improvement (Table 2), 17 and 26 patients achieving normal symptom severity and functional scores respectively. Both these scores, however, continued to show significant improvement at 12 months (P = 0.0006 and 0.01, respectively), eight and 18 patients reporting normalization of the symptom severity and functional scores respectively.
There were 23, 35 and nine hands graded mild (grade 2), moderate (grade 3) and severe (grade 4), respectively. Following MPA injection at 3 months, 64% of the hands had normalized, 23.8% had improved but not normalized, and 12% and had shown worsening of the NCS (Table 3). At 12 months, 50% of the hands had normalized, improved but not normalized, or shown worsening of the NCS. Electrophysiological parametersdistal motor latency (DML), distal sensory latency mid-palm (DSL-MP) and distal sensory latency wrist (DSL-W) (Table 4)showed significant improvement at 3 months. NCS available for 35 patients (52 hands) 12 months after the MPA injection showed continued significant improvement in DML (Table 5).
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TABLE 3. Outcome of hands at 3 (n = 67) and 12 (n = 52) months according to electrophysiological grading of the severity of CTS.
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We did not observe any major adverse effects due to local injection of glucocorticoid into the CTS. Mild discoloration of the skin over the site of injection was observed in four hands.
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Discussion
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Since the first report of use of glucocorticoid injection in the management of CTS by Phalen and Kendrick in 1957 [23], many studies have reported a highly satisfactory response, varying from 51 to 94% at 412 weeks, but a high recurrence rate subsequently (Table 1). A lot of emphasis has been placed on failures of glucocorticoid injection therapy; however, there have been reports of number of patients (6.584%) remaining asymptomatic at 12 months. No data emerge regarding these patients. This wide variability in response to local glucocorticoid injection is due to the heterogeneity of patients in terms of their symptoms, disease severity, functional impairment, natural history and outcome assessment. So far there are no universally acceptable scales for grading the severity of the CTS, either clinically or electrophysiologically, or for assessing the outcome in terms of subjective, objective and electrophysiological parameters.
Recently, Padua et al. [24] have studied the natural history of untreated CTS in a multicentre trial recruiting a large cohort of patients with idiopathic CTS. They observed that more than one-quarter of the hands (73 of 274) improve spontaneously without any therapy over a period of 1015 months. The main positive prognostic indicators were short duration of symptoms and young age, whereas bilateral symptoms and a positive Phalen's test were indicators of a poorer prognosis. In view of this report, surgical release of CTS should not be recommended early and as the first-line therapy.
In the present prospective study, we carefully chose patients with mild CTS and assessed their outcome according to precisely defined clinical (subjective and objective) and electrophysiological parameters. The cut-off value, DML <7.5 ms, was chosen in view of experience at our centre. Nineteen out of 23 patients with DML >7.5 ms required surgical release within 36 months of presentation during the year before the study (V. Agarwal, R. Singh, D. Goel, A Sachdev, unpublished data). In the present study, local glucocorticoid injection was found to have long-term efficacy in patients with mild CTS. It improved not only symptoms but also the NCS. Our results at 3 months are in agreement with the existing literature; however, outcome at 12 months was much better compared with earlier reports (Table 1). It appeared from our data that, below a DML of 7.5 ms, electrophysiological severity did not appear to influence the outcome of local MPA injection. Thus, long-term relief of symptoms, as evidenced in our study, will support the case for a policy of treating mild CTS patients with local glucocorticoid injections rather than surgical release.
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Acknowledgments
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This work was partially funded by Indian Council of Medical Research grant as part of an MBBS student's summer vacation project.
The authors have declared no conflicts of interest.
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References
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- Dawson DM. Entrapment neuropathies of the upper extremities. N Engl J Med 1993;329:201318.[Abstract/Free Full Text]
- Burke DT, Burke MM, Steward GW, Cambre A. Splinting for carpal tunnel syndrome: in search of the optimal angle. Arch Phys Med Rehabil 1994;75:12414.[CrossRef][ISI][Medline]
- Chang M-H, Chiang H-T, Lee SS-J, Ger L-P, Lo Y-K. Oral drug of choice in carpal tunnel syndrome. Neurology 1998;51:3903.[Abstract]
- Green DP. Diagnostic and therapeutic value of carpal tunnel injection. J Hand Surg 1984;9A:8504.[ISI]
- Girlanda P, Dattola R, Venuto C, Mangiapane R, Nicolosi C, Messina C. Local steroid treatment in idiopathic carpal tunnel syndrome: short- and long-term efficacy. J Neurol 1993;240:18790.[CrossRef][ISI][Medline]
- Gelberman RH, Aronson D, Weismann MH. Carpal tunnel syndrome: results of a prospective trial of steroid injection and splinting. J Bone Joint Surg Am 1980;62:11814.[Abstract]
- Giannini F, Passero S, Cioni R et al. Electrophysiologic evaluation of local steroid injection in carpal tunnel syndrome. Arch Phys Med Rehabil 1991;72:73842.[ISI][Medline]
- Ayhan-Ardic FF, Erdem HR. Long-term clinical and electrophysiological results of local steroid injection in patients with carpal tunnel syndrome. Funct Neurol 2000;15:15765.
- Dammers JWHH, Veering MM, Vermeulen M. Injection with methyl prednisolone proximal to the carpal tunnel: randomised double blind trial. BMJ 1999;319:8846.[Abstract/Free Full Text]
- Weiss A-PC, Sachar K, Gendreau M. Conservative management of carpal tunnel syndrome. A reexamination of steroid injection and splinting. J Hand Surg [Am] 1994;19:4105.[Medline]
- O'Gradaigh D, Merry P. Corticosteroid injection for the treatment of carpal tunnel syndrome. Ann Rheum Dis 2000;59:9189.[Abstract/Free Full Text]
- Demirci S, Kutluhan S, Koyuncuoglu HR et al. Comparison of open carpal tunnel release and local steroid treatment outcomes in idiopathic carpal tunnel syndrome. Rheumatol Int 2002;22:337.[CrossRef][ISI][Medline]
- Akkus S, Kutluhan S, Akhan G, Tunc E, Koyuncuoglu HR. Does fibromyalgia affect the outcomes of local steroid treatment in patients with carpal tunnel syndrome? Rheumatol Int 2002;22:1125.[CrossRef][ISI][Medline]
- Hagebeuk EE, De Weerd AW. Clinical and electrophysiological follow-up after local steroid injection in the carpal tunnel syndrome. Clin Neurophysiol 2004;115:14648.[CrossRef][ISI][Medline]
- Kaplan SJ, Glickel SZ, Eaton RG. Predictive factors in the non-surgical treatment of carpal tunnel syndrome. J Hand Surg [Br] 1990;15:1068.[Medline]
- Goodman HV, Foster JB. Effect of local corticosteroid injection on median nerve conduction in carpal tunnel syndrome. Ann Phys Med 1962;7:287.
- Mortier G, Dijs H, De Ridder A, Driessens M. Correlatie tussen de motoische terminale latentietijd (MTLT) van de nervus medianus en het resultaat van de conservatieve behandeling (cortisone inspuiting) bij het carpaal tunnel syndroom. Acta Belg Med Phys 1989;12:1921.[Medline]
- Schuchmann JA, Melvin JL, Duran RJ, Coleman CR. Evaluation of local steroid injection for carpal tunnel syndrome. Arch Phys Med Rehabil 1971;52:2535.[Medline]
- Irwin LR, Beckett R, Suman RK. Steroid injection for carpal tunnel syndrome. J Hand Surg [Br] 1996;21:3557.[Medline]
- American Association of Electrodiagnostic Medicine Quality Assurance Committee. Literature review of the usefulness of nerve conduction studies and electromyography for the evaluation of patients with carpal tunnel syndrome. Muscle Nerve 1993;16:1392414.[CrossRef][ISI][Medline]
- Levine DW, Simmons BP, Koris MJ, Daltroy LH. A self-administered questionnaire for the assessment of severity of symptoms and functional status in carpal tunnel syndrome. J Bone Joint Surg 1993;11:158592.
- Bland, JDP. A neurophysiological grading scale for carpal tunnel syndrome. Muscle Nerve 2000;23:12803.[CrossRef][ISI][Medline]
- Phalen GS, Kendrick JI. Compression neuropathy of the median nerve in the carpal tunnel JAMA 1957;164:52430.[ISI]
- Padua L, Padua R, Aprile I et al. Multiperspective follow-up of untreated carpal tunnel syndrome: a multicenter study. Neurology 2001;56:145966.[Abstract/Free Full Text]
Submitted 10 July 2004;
revised version accepted 18 January 2005.