Chemically-induced chronic nerve compression in rabbits--a new experimental model for the carpal tunnel syndrome

In order to create an experimental model for the carpal tunnel syndrome without the use of the commonly applied foreign bodies (silicone or rubber tubes, tourniquets etc.), the present study tried to induce a chemically provoked compression of the median nerve in rabbits. In 9 female rabbits 1 ml of Aethoxskerol 3% (Hydrox-polyethoxy dodecan) was instilled into the carpal tunnel around the median nerve after visualisation of the nerve. The other foreleg served as the control and was treated with the same amount of saline solution. Electroneurophysiologic parameters were registered preoperatively, 1 month and 6 months post surgery and histomorphologic investigations by light and electron microscopy were performed after 6 months. 6 months after treatment with Aethoxysklerol, a statistically significant lengthening of the distal latency period as well as a significant reduction of the compound potential amplitude could be observed. In accordance with these findings, morphological investigation revealed the presence of extensive granulation tissue around the median nerve together with signs of demyelination. Our results indicate that we were able to produce the development of extensive granulation tissue in the carpal tunnel of rabbits with subsequent compression of the median nerve which was confirmed by histomorphologic investigation as well as by measurement of nerve conductive velocity.