Comparison of carpal tunnel injection techniques: a cadaver study

The safety and accuracy of various carpal tunnel injection techniques

PURPOSE

Carpal tunnel (CT) syndrome continues to be a commonly treated hand pathology. We aimed to evaluate several CT injection techniques for (1) spatial accuracy within the CT and (2) risk of median nerve (MN) injury. Our purpose was to evaluate for any significant differences in accuracy of needle placement within the carpal tunnel and final distance between the needle tip and the MN with each technique.

METHODS

Fifteen fresh frozen cadaveric arms were used for this study. Six different injection techniques for CT injection were performed on each specimen, including palmaris longus, ulnar to flexor carpi radialis, trans-flexor carpi radialis, volar radial, volar ulnar, and direct through the palm techniques. After needle placement, a standard open CT release was performed to assess for accuracy of placement within the CT and measure needle position in relation to the MN and other anatomic structures.

RESULTS

Accurate intra-CT needle placement was seen in 91% of injections. While there was no significant difference between injection techniques for distance to nearest tendon (p = 0.1531), the trans-flexor carpi radialis (tFCR), volar radial (VR), and volar ulnar (VU) techniques consistently provided the greatest intra-CT distance from needle tip to median nerve (p = 0.0019). The least incidence of intraneural needle placement was found with the tFCR and VR approaches.

CONCLUSION

All six injection techniques reliably enter the CT space. The lowest risk to the MN was found with tFCR and VR techniques, and we recommend these techniques for safe and effective needle placement to avoid iatrogenic intraneural injection.

LEVEL OF EVIDENCE

Level V: Cadaveric Study.

Comparison Between Distal and Proximal Approaches for Local Corticosteroid Injection in Carpal Tunnel Syndrome Management: A Randomized Controlled Trial

BACKGROUND

The present, open-labeled study aimed to compare the distal approach (DA) for local corticosteroid injection (LCI) with the conventional proximal approach (PA) in alleviating the symptom and improving the electrodiagnostic parameters of the patients with carpal tunnel syndrome (CTS).

METHODS

A total of 60 participants with nonsevere CTS were included in the present randomized controlled trial (RCT), of which 29 and 31 were assigned to the DA and PA groups, respectively. Each group received a single, landmark-guided injection of local methylprednisolone. The participants were assessed preintervention and 3 months later using the measures of visual analog scale (VAS), Boston Carpal Tunnel Questionnaire (BCTQ), hand grip strength, and nerve conduction study (NCS).

RESULTS

Following a 3-month follow-up, both groups had significant improvements in VAS, both functional and severity subscales of BCTQ, hand grip strength, and some electrodiagnostic parameters (all P-values < .05). Moreover, the DA group had a significantly lower procedure duration than the PA group (9.80 ± 1.12 vs. 27.61 ± 1.77; P < .001).

CONCLUSIONS

LCI using the DA should be considered a feasible, safe, and effective therapeutic method in patients with mild to moderate CTS. It had a shorter procedure duration than conventional PA, while their clinical and electrophysiological results were similar.

Nonsurgical Treatment for Symptomatic Carpal Tunnel Syndrome: A Randomized Clinical Trial Comparing Local Corticosteroid Injection Versus Night Orthosis

PURPOSE

For carpal tunnel syndrome (CTS), local corticosteroid injection (corticosteroid), and/or wrist immobilization with night orthosis (orthosis) are commonly prescribed and are supported by strong evidence. The aim of this study was to compare orthosis versus corticosteroid for patients with CTS.

METHODS

A CTS diagnosis was made clinically and supported by electrodiagnostic study. Patients were randomly allocated to either orthosis or corticosteroid. Clinical assessments were performed before the intervention, within the first week of the intervention, and 1, 3, and 6 months after the intervention. Primary outcomes were improvement in nocturnal paresthesia and Boston-Levine questionnaire (BLQ) score. Secondary outcomes were pain assessed by visual analog scale and complications.

RESULTS

Of 100 patients enrolled in the study, 95 completed the planned follow-up (45 in the orthosis arm and 50 in the corticosteroid arm). Corticosteroid injections were superior to orthosis in remission of nocturnal paresthesia (remission rates at 1 month, 84.6% versus 43.83%; 3 months, 71.1% versus 40.4%; and 6 months, 80.3% versus 28.8%). The BLQ scores (functional and symptom subscales) were also more favorable for corticosteroid at 1, 3, and 6 months (minimal clinically important differences for Function > 0.5 and Symptom > 0.16). Pain scores were lower and favored the corticosteroid group. There were no complications in either group.

CONCLUSIONS

Both options are effective in the short term. Corticosteroid is superior to orthosis for improving CTS-related nocturnal paresthesia, BLQ scores, and pain.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic I.

Accuracy of Carpal Tunnel Injection: A Prospective Evaluation of 756 Patients

Background: Corticosteroid injection into the carpal tunnel is both a diagnostic test and a therapeutic modality in the treatment of carpal tunnel syndrome. Many injection techniques are described in the literature. Improper placement of injection may result in damage to neurovascular structures in the carpal canal or decrease efficacy of the test and/or therapy. The purpose of this study is to determine if carpal tunnel injection using anatomic landmarks is reproducible and safe. A review of the senior author's injection technique is presented. Methods: Over 8 years, there were 756 attempted placements of a 25-gauge needle into the carpal tunnel in a simulated carpal tunnel injection prior to open carpal tunnel release. The needle was inserted at the wrist crease, just ulnar to palmaris longus. Open carpal tunnel release was subsequently performed, and position of the needle was recorded. Results: In 572 patients (75.7%), the needle was found to be in the carpal tunnel without penetration of contents. The needle was in the carpal tunnel but piercing the median nerve in 66 attempts (8.7%). The carpal tunnel was missed in 118 attempts (15.6%). Conclusions: This is the largest study looking at accuracy of carpal tunnel injection using anatomic landmarks. Our injection accuracy (75.7%) is less than reported in previous studies, which note 82% to 100% accuracy using the same injection technique. This may indicate that carpal tunnel injection is less reliable than previously thought. Safety of carpal tunnel injection remains an important concern. The median nerve was penetrated in 8.7% of attempts.

Electrophysiological responsiveness and clinical outcomes of local corticosteroid injection in the treatment of carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common mononeuropathy caused by entrapment of the median nerve at the wrist. Common treatment options for CTS include oral analgesics, splinting, hand therapy, local injections with steroids or surgery. OBJECTIVE The aim of the present study was to assess the short-term clinical and electrophysiological outcomes of local corticosteroid injection (LCI) in patients with symptomatic CTS. METHODS Electrophysiological parameters were evaluated before and three months after LCI. Moreover, the Numeric Rating Scale (NRS), the Boston Symptom Severity Scale (SSS) and the Functional Status Scale (FSS) were administered before and after the injection. A mixture of 1 mL (40 mg) of methylprednisolone and 1 mL of 0.5% bupivacaine were injected blindly on the volar side of the forearm between the tendons of the radial carpal flexor muscle and long palmar muscle. RESULTS A total of 25 patients (45 hands) were enrolled in the study. Twenty women and five men with a mean age of 49.28 ± 11.37 years were included. A statistically significant difference was noted for improvement of sensory conduction velocities, sensory peak latency, and motor distal latency (p = 0.001) after LCI. A significant difference was recorded between pre- and post-injection for NRS, SSS and FSS scores (p = 0.000). CONCLUSION Local corticosteroid injection for CTS provides a short-term improvement in neurophysiological and clinical outcomes such as pain intensity, symptom severity and functional ability.

Comparison of Ultrasound-Guided Versus Landmark-Based Corticosteroid Injection for Carpal Tunnel Syndrome: A Prospective Randomized Trial

PURPOSE

Although a local corticosteroid injection for carpal tunnel syndrome (CTS) is frequently performed by palpation using anatomical landmarks, ultrasound (US) allows physicians to visualize and confirm placement of the injectate close to the median nerve, possibly improving the efficacy of the injection. The aim of this study was to compare the effectiveness and complications of US-guided steroid injections with landmark-based injections for CTS.

METHODS

A total of 102 patients with CTS were randomized into 2 groups: landmark-based injection and US-guided injection. The response to treatment, including grip strength and the Boston Carpal Tunnel Questionnaires (BCTQ) was assessed at baseline and at 4, 12, and 24 weeks after the injection.

RESULTS

The BCTQ symptom and function scores were similar in the 2 groups throughout the 24-week follow-up period, with the exception of significantly lower (better) symptom scores at 4-week follow-up in the US-guided injection group. The grip strength was similar in the 2 groups throughout the 24-week follow-up period. After 24 weeks, 12 patients (24%) in the landmark-based injection group and 9 patients (18%) in the US-guided injection group had undergone carpal tunnel surgery. Symptoms of median nerve irritation were more likely to occur in patients with landmark-based injections (14%) than in those with US-guided injection (2%).

CONCLUSIONS

A US-guided steroid injection for CTS produces pain and functional results similar to those of landmark-based injection.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic I.

Influence of Injection Volume on Rate of Subsequent Intervention in Carpal Tunnel Syndrome Over 1-Year Follow-Up

PURPOSE

The optimal volume and dose of corticosteroid injections for treatment of carpal tunnel syndrome (CTS) have not yet been established. It is unknown whether the volume of injectate influences the outcome of carpal tunnel injection. The purpose of this study was to assess whether there is an association between the volume of injectate and subsequent intervention in the treatment of CTS.

METHODS

This study evaluated residents of Olmsted County, MN, who were treated with a corticosteroid injection for CTS between 2001 and 2010. Failure of treatment was the primary outcome, defined as a subsequent intervention: either a second injection or carpal tunnel release within 1 year of initial injection. General estimating equations logistic regression was used to assess the association between injectate volume and rate of treatment failure, adjusting for age, sex, effective dose of steroid, type of steroid injected, electrodiagnostic severity, and the presence of comorbidities such as rheumatoid arthritis, diabetes mellitus, peripheral neuropathy, and radiculopathy.

RESULTS

There were 856 affected hands in 651 patients. A total of 56% (n = 484) of treated hands received subsequent treatment within 1 year. Multivariable analysis showed that a larger injectate volume was significantly associated with reduced rate of treatment failure within 1 year. Rheumatoid arthritis and ultrasound-guided procedures were also associated with a reduced rate of treatment failure, whereas severe electrodiagnostic results were associated with an increased rate of failure.

CONCLUSIONS

This study showed that a larger volume of corticosteroid injection is associated with reduced odds of subsequent intervention after a single corticosteroid injection in CTS. Further research is needed to determine the optimal volume for steroid injections in the treatment of CTS.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Comparing the effectiveness of ultrasound-guided versus blind steroid injection in the treatment of severe carpal tunnel syndrome

Background/aim: This study aimed to compare the effectiveness of ultrasound (US)-guided injection versus blind injection of corticosteroids in the treatment of carpal tunnel syndrome (CTS). Materials and methods: This prospective, randomized clinical trial included patients with severe CTS based on clinical and electrophysiological criteria. The patients were evaluated for clinical and electrophysiological parameters at baseline and 4 weeks after treatment. Symptom severity and hand function were assessed by the Boston questionnaire. The patients underwent blind injection or US-guided injection. Results: When compared with baseline, both groups showed significant improvement in Boston questionnaire scores and all electrophysiological parameters. Significant differences were observed between the groups for clinical parameters (Boston Symptom Severity Scale: P = 0.007; Functional Status Scale: P < 0.001) in favor of the US-guided group. Conclusion: This study demonstrated that both US-guided and blind injections were effective in reducing symptoms and improving hand function. US-guided injections may yield more effective clinical results in the short-term than blind injections in the treatment of patients with severe CTS.

The Accuracy of Common Hand Injections With and Without Ultrasound: An Anatomical Study

BACKGROUND

The aim of the study is to determine the accuracy of hand injections with and without the aid of ultrasound (U/S) into the carpal tunnel, thumb carpometacarpal (CMC) joint, first dorsal compartment (DC) and the radiocarpal (RC) joint.

METHODS

Four participants of various level of experience injected the carpal tunnel, thumb CMC, first DC, and RC joint into 40 fresh frozen cadaver specimens with blue dye and radiographic contrast. Participants 1 and 2 were injected without U/S guidance, and participants 3 and 4 were injected with U/S guidance. A successful injection was determined by both fluoroscopy and dissection/direct observation. Additional information was recorded for each injection such as median nerve infiltration and evidence of thumb CMC arthrosis.

RESULTS

The overall accuracy for carpal tunnel, thumb CMC, first DC, and RC injections were 95%, 63%, 90%, and 90%, respectively. Success was compared with and without U/S guidance. Success rates were similar for each injection site, except the thumb CMC joint, where U/S participants had 25% higher accuracy. In the setting of thumb CMC arthrosis, the incidence of success was 38% for participants with no U/S aid and 72% for participants with U/S aid. There was a significant difference between participants who used U/S with the participant with more U/S experience being more successful.

CONCLUSION

Carpal tunnel, first DC, and RC injections had an accuracy of greater than 90%. Thumb CMC injections have a lower accuracy (63%) and one can improve accuracy with U/S. The accuracy of U/S-guided injections is dependent on the user and their experience.

Corticosteroid Injections for Carpal Tunnel Syndrome: Long-Term Follow-Up in a Population-Based Cohort

BACKGROUND

Corticosteroid injection is a recommended treatment option for carpal tunnel syndrome, before considering surgery. Nevertheless, injections remain controversial because there is strong evidence of only short-term benefits. This study aimed to determine the reintervention rate and to identify prognostic indicators for subsequent treatment after corticosteroid injection for carpal tunnel syndrome.

METHODS

This study evaluated residents of Olmsted County treated with a corticosteroid injection for carpal tunnel syndrome between 2001 and 2010. Treatment failure was the primary outcome of interest. Two definitions for failure were examined: (1) the patient receiving subsequent procedural intervention and (2) the patient undergoing carpal tunnel release. Survival was estimated using Kaplan-Meier methods, and association of covariates with increased failure was modeled using Cox proportional hazards regression.

RESULTS

The study included 774 affected hands in 595 patients. The median follow-up period was 7.4 years. Reintervention was performed in 68 percent of cases, of which 63 percent resulted in eventual surgery. Injectate volume was significant for the outcome of any retreatment [hazard ratio, 0.879 (95 percent CI, 0.804 to 0.96)] and surgery [hazard ratio, 0.906 (95 percent CI, 0.827 to 0.99)]. Rheumatoid arthritis was also significant in both models, with a hazard ratio of 0.627 (95 percent CI, 0.404 to 0.97) for any retreatment and 0.493 (95 percent CI, 0.292 to 0.83) for surgery.

CONCLUSIONS

In this cohort, 32 percent of patients did not receive subsequent treatment after a single injection, which indicates that there is a therapeutic role for corticosteroid injections in treating carpal tunnel syndrome. Further research is necessary to identify those patients who will benefit from an injection, to provide more individually tailored treatment.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Corticosteroid Injections for Carpal Tunnel Syndrome: Long-Term Follow-Up in a Population-Based Cohort

BACKGROUND

Corticosteroid injection is a recommended treatment option for carpal tunnel syndrome, before considering surgery. Nevertheless, injections remain controversial because there is strong evidence of only short-term benefits. This study aimed to determine the reintervention rate and to identify prognostic indicators for subsequent treatment after corticosteroid injection for carpal tunnel syndrome.

METHODS

This study evaluated residents of Olmsted County treated with a corticosteroid injection for carpal tunnel syndrome between 2001 and 2010. Treatment failure was the primary outcome of interest. Two definitions for failure were examined: (1) the patient receiving subsequent procedural intervention and (2) the patient undergoing carpal tunnel release. Survival was estimated using Kaplan-Meier methods, and association of covariates with increased failure was modeled using Cox proportional hazards regression.

RESULTS

The study included 774 affected hands in 595 patients. The median follow-up period was 7.4 years. Reintervention was performed in 68 percent of cases, of which 63 percent resulted in eventual surgery. Injectate volume was significant for the outcome of any retreatment [hazard ratio, 0.879 (95 percent CI, 0.804 to 0.96)] and surgery [hazard ratio, 0.906 (95 percent CI, 0.827 to 0.99)]. Rheumatoid arthritis was also significant in both models, with a hazard ratio of 0.627 (95 percent CI, 0.404 to 0.97) for any retreatment and 0.493 (95 percent CI, 0.292 to 0.83) for surgery.

CONCLUSIONS

In this cohort, 32 percent of patients did not receive subsequent treatment after a single injection, which indicates that there is a therapeutic role for corticosteroid injections in treating carpal tunnel syndrome. Further research is necessary to identify those patients who will benefit from an injection, to provide more individually tailored treatment.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Effectiveness of Ultrasound-Guided Compared to Blind Steroid Injections in the Treatment of Carpal Tunnel Syndrome

OBJECTIVE

To compare the effectiveness of ultrasound-guided injections to blind injections in the treatment of carpal tunnel syndrome (CTS) in a large community-based cohort.

METHODS

This study evaluated residents of Olmsted County, Minnesota, treated with a corticosteroid injection for CTS between 2001 and 2010. The proportion of patients receiving retreatment and the duration of retreatment-free survival between blind and ultrasound-guided injections were compared. Propensity score matching was used to control for confounding by indication.

RESULTS

In the matched data set consisting of 234 (of 600) hands treated with a blind injection and 87 (of 89) ultrasound-guided injection cases, ultrasound guidance was associated with a reduced hazard of retreatment (hazard ratio 0.59 [95% confidence interval (95% CI) 0.37-0.93]). In addition, ultrasound guidance was associated with 55% reduced odds of retreatment within 1 year compared to blind injections (adjusted odds ratio 0.45 [95% CI 0.24-0.83]).

CONCLUSION

This study indicates that ultrasound-guided injections are more effective in comparison to blind injections in the treatment of CTS.

Assessing the variability of injectate distribution following carpal tunnel injection--a cadaveric study

This anatomical study was designed to assess the distribution of a solution (injectate) made up using local anesthetic, steroid and dye into the carpal tunnel using a commonly used injection technique. Dissections were undertaken in 29 embalmed cadaveric wrists. The cadaveric specimens were dissected 24 hours after injection to observe the effect of time on diffusion patterns in both superficial and deep planes. Eighteen of the 29 specimens showed the presence of the injectate in the superficial plane and three preferential patterns of distribution were noted in the deep plane: free in the carpal tunnel, exclusively in the tendon sheath and mixed. This is the first study investigating the delayed diffusion pattern of injectate in the carpal tunnel and illustrates its variability. The findings of variable degree of superficial diffusion and different patterns of intracarpal spread help to offer some explanation regarding the variability of the response following carpal tunnel injection.

MRI-Based Identification of an Appropriate Point of Needle Insertion for Patients with Idiopathic Carpal Tunnel Syndrome to Avoid Median Nerve Injury

To identify a safe entry point for needle insertion in patients with idiopathic carpal tunnel syndrome (CTS), cross-sectional images of the wrist MRI of 45 normal volunteers and 180 consecutive patients with idiopathic CTS were reviewed. Insertion of the needle from the five different entry points into the carpal tunnel was simulated by drawing a 1-pixel line, and the incidence of contact with the median nerve was compared. In the CTS patients, the lowest incidence was 3% when inserted at one-third of the length between the FCR and FCU tendons on the ulnar side at the level of the distal part of the distal radioulnar joint and 4% at the mid point between the palmaris longus tendona and the flexor carpi ulnaris tendon. It was greater in the advanced stage of CTS than the less severe CTS. We recommend those two entry points.