The Potential Benefit of Intracarpal Pressure Measurement in Endoscopic Carpal Tunnel Syndrome Surgery – An Analysis of EMG Findings and Pressure Values

Abstract

Several methods of carpal tunnel syndrome (CTS) surgery have been described. The open approach is regarded as the gold standard, however there are also many critics of this technique. Due to the fact that results of open surgery are often quite disappointing -about 60 % of patients have scar pain or so called pillar pain in the hypothenar and thenar eminences following surgery, we have therefore, turned our interests to less invasive techniques. In the past 12 years, we have accumulated vast experience in CTS surgery, which is a very frequent procedure in our department. Other than the classic open approach, we have obtained experience in the so called "twin incision technique" (1) "flexor carpi radialis approach" (20) and the uniportal (single portal) endoscopic approach (9). Endoscopy is our favoured technique (system Wolf). In most cases of mild or moderate EMG findings, using the endoscopic technique we were able to achieve superior patient satisfaction rates.Intracarpal pressure (ICP) measurement has a long history. The accepted normal ICP range in healthy individuals is between 3-6 mmHg in the neutral wrist position and up to 20-60 mmHg during extension (21). The positive results of certain groups, especially studies done by Japanese authors have led us to further improve our results. In our study, a Codman sensor, typically used for the measurement of intracranial pressure was used to measure intracarpal pressure. The main reason for ICP measurement was to evaluate the relationship between peroperative intracarpal pressure, the level of decompression and pre/postoperative EMG findings. In addition, the effect of different hand positions and anatomical location on ICP was assessed. Summary: Endoscopic carpal tunnel syndrome surgery is a modern minimally invasive method of carpal tunnel decompression. However, the method does also have its critics, who emphasize that there is an increased rate of complications in comparison to open procedures. To further improve and optimize results of endoscopic surgery we used an intracarpal pressure sensor to verify the effect of carpal tunnel decompression. The endoscopic single portal approach was used in all cases. Median nerve conduction studies were performed prior to and 3 months after surgery. Two groups, those with pressure studies and those without, were then compared according to several EMG parameters such as: median nerve distal motor latency, amplitude of motor response, sensory nerve conduction velocity to the index finger, and amplitude of sensory nerve action potential. In both groups, we observed similarly significant improvements in all conduction parameters, except the amplitude of motor response, which did not change in either group, i.e. no difference in postoperative EMG between the two groups was observed. Despite this fact, intracarpal pressure measurement is still useful in localising the point in which the median nerve is compressed and provides valuable functional information on the level decompression achieved. Material and Methods Surgery TH...

A coupled electro-mechanical approach for early diagnostic of carpal tunnel syndrome

“…al. in their studies[91,[96][97][98][99][100][101] presented results of experimental intracarpal pressure determination. Comparison of the results obtained in this study with the relevant experimental results from these works are presented in (Table5).…”