Experimental Endoscopic Cordotomy in the Sheep Model

Interventional pain therapies are usually based on destruction of the related pain-conducting pathways. Current procedures targeting pain have replaced conventional pain treatment modalities while being less invasive. In this study, we investigated the feasibility of the endoscopic percutaneous cordotomy process on the sheep cervical spinal cord.

Seven male sheep, Akkaraman® genus, were operated on in the study. The guide was introduced at C1 to C2 vertebrae. The interlaminar area was exposed by a dilator, the dura was identified, and then the working cannula was inserted into the subarachnoid space. The target point of cordotomy was defined by endoscopic visualization as the midpoint between the dentate ligament and ventral root entry zone. After determination of the target point, a carbon dioxide laser (CDL) probe was introduced through the cannula. Ablative lesioning was performed by CDL. Hindlimb withdrawal thresholds were measured using the "Sample Pain Scale". The lesion was demonstrated by magnetic resonance imaging and histopathological examination.

Three sheep had ipsilateral hemiparesis and the response to firm pressure test was not performed on them. Among the remaining four sheep, the pain tolerance test showed that one sheep was at stage 0, two at stage 1, and the last one at stage 3.

Cordotomy might be successfully performed with the endoscopic technique in the sheep model and this should encourage future studies regarding minimal invasive procedures for intractable pain.