Diabetic neuropathy should not be a barrier to carpal tunnel release surgery, because diabetic patients with carpal tunnel syndrome experience the same degree of neurophysiologic recovery after the procedure as do nondiabetic patients, according to Swedish investigators.
In a prospective case-control study, there were virtually no significant differences in neurophysiologic recovery after carpal tunnel syndrome (CTS) release between diabetic patients and controls, or among diabetic patients with or without peripheral neuropathy.
“We therefore recommend that diabetic patients with CTS are offered the same opportunities for surgical carpal tunnel release as nondiabetic patients,” wrote Dr. Niels O.B. Thomsen of Malm (Sweden) University Hospital and his colleagues.
The authors looked at pre- and postoperative data on 35 consecutive diabetic patients and 31 age- and sex-matched nondiabetic controls treated for CTS during 2004–2007. All cases and controls also had nerve conduction studies 1 year after surgery.
Diabetic patients were diagnosed with peripheral neuropathy if they had abnormal preoperative neurophysiologic values in sural nerve sensory conduction velocity (SCV), sensory nerve action potential (SNAP), and peroneal nerve motor conduction velocity studies.
At 1-year follow-up, there were significant differences in neurophysiologic recovery between diabetic patients and controls in only two categories: The SNAP values from digit III improved significantly more in nondiabetic patients, at a mean change from baseline of 2.1 mcV vs. 4.8 mcV, respectively. In contrast, diabetic patients had significantly greater antidromic elbow-wrist improvement, at a mean of 17.6 m/sec vs. 6.9 m/sec for nondiabetic patients.
There were no significant between-group differences in distal motor latency, motor conduction velocity, compound muscle action potential, wrist-palm SCV, or palm–digit III SCV (Clin. Neurophysiol. 2010 April 21 [doi:10.1016/j.clinph.2010.03.014]).
The investigators also looked at whether preoperative nerve conduction values could predict whether patients would improve following surgery, and found that in general, patients with the greatest presurgical disability had the highest postsurgical improvement. Still, few patients had nerve conduction values within the normal range at 1 year.
“The clinical implication … is that even though diabetic patients with CTS have significantly impaired nerve conduction parameters compared to nondiabetic patients with CTS, they obtain the same degree of neurophysiologic recovery after surgical carpal tunnel release. This result even applies to diabetic patients with evidence of peripheral neuropathy,” the researchers wrote.
The study was supported by the Swedish Research Council (Medicine), Crafoord's Fund for Medical Research, Svenska Diabetesförbundet, Diabetesföeningen Malmö, Konsul Thure Carlsson Fund for Medical Research, Region Skåne, and Funds from the Malmö (Sweden) University Hospital. The authors had no conflicts of interest to declare.