Outcome of carpal tunnel release surgery in patients with diabetes

Effects of decompression on behavioral, electrophysiologic, and histomorphologic recovery in a chronic sciatic nerve compression model of streptozotocin-induced diabetic rats

Purpose

To determine susceptibility to decompression surgery in diabetic and nondiabetic peripheral neuropathy using a chronic compression neuropathy model.

Materials and methods

Twenty-four streptozotocin-induced diabetic rats were randomly divided into three groups: group I, chronic compression of the left sciatic nerve for 4 weeks with decompression; group II, similar without decompression; and group III, sham exposing the sciatic nerve only. The other 24 nondiabetic rats were assigned to groups IV–VI, which received compression–decompression, compression, and the sham operation, respectively. Mixed-nerve-elicited somatosensory evoked potentials (M-SSEPs) and compound muscle action potentials (CMAPs) were measured to verify the compression neuropathy in the posttreatment follow-up. Behavioral observations in thermal hyperalgesia tests were quantified before electrophysiologic examinations. Treated and contralateral nerves were harvested for histomorphologic analysis.

Results

Chronic compression of sciatic nerve induced significant reduction of amplitude and increment of latency of M-SSEP and CMAP in both diabetic and nondiabetic rats. Diabetic group changes were more susceptible. Decompression surgery significantly improved both sensory and motor conduction, thermal hyperalgesia, and the mean myelin diameter of the rat sciatic nerve in both diabetic and nondiabetic groups. Near full recovery of motor and sensory function occurred in the nondiabetic rats, but not in the diabetic rats 8 weeks postdecompression.

Conclusion

Behavioral, electrophysiologic, and histomorphologic findings indicate that decompression surgery is effective in both diabetic and nondiabetic peripheral neuropathy.

Minimal clinically important difference of carpal tunnel release in diabetic and nondiabetic patients

BACKGROUND

Establishing the minimal clinically important difference for patient-reported outcomes questionnaires is essential in outcomes research to evaluate the patient's perspective of treatment effectiveness. The authors aim to determine the minimal clinically important difference after carpal tunnel release in diabetic and nondiabetic patients using the Boston Carpal Tunnel Questionnaire.

METHODS

The authors prospectively evaluated 114 patients (87 nondiabetic and 27 diabetic patients) undergoing carpal tunnel release. In addition to standard history and physical examination, the authors obtained preoperative electrodiagnostic studies to confirm carpal tunnel syndrome. The Boston Carpal Tunnel Questionnaire was administered before and after surgery at 3 and 6 months. Patients were asked about their level of satisfaction at the final follow-up visit. The authors applied the receiver operating characteristic curve approach to determine the minimal clinically important difference of symptom and function severity scales of the questionnaire. The authors used patient satisfaction as the reference standard to compare against the standardized change in scores after surgery for the two groups.

RESULTS

For both diabetic and nondiabetic patients, symptom and function severity scales showed large effect sizes of greater than 0.8 at 3 and 6 months after surgery. At 6 months after surgery, to be satisfied, diabetic patients required a minimal clinically important difference of 1.55 and 2.05 for symptom and function scales, respectively, whereas nondiabetic patients required 1.45 and 1.6, respectively.

CONCLUSIONS

Diabetic patients needed a greater improvement in Boston Carpal Tunnel Questionnaire score to be satisfied on functional and symptom severity scales than nondiabetic patients. Overall, diabetic patients had less improvement in Boston Carpal Tunnel Questionnaire final scores compared with nondiabetics.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.