A novel method for making dorsal horn lesions.

OBJECTIVE

Dorsal root entry zone (DREZ) lesioning for intractable pain currently requires a multi-level laminectomy for direct access to all spinal cord segments intended to be lesioned. The hypothesis is that a silastic rubber catheter can be inserted into the dorsal horn (through a single laminectomy site) and advanced down several spinal cord segments, while staying exclusively in the dorsal horn.

METHODS

A cervical laminectomy was performed in four sheep. Standard cerebrospinal fluid drainage catheters were introduced into the dorsal horn through a small incision in the DREZ. The catheters were advanced caudally along the longitudinal cord axis for a distance of 8-11 cm. Neurophysiological monitoring was done. The cord was excised from the spinal canal, fixed in formalin and cut in serial axial slices at 1 cm intervals to assess the position of the catheter within the spinal cord.

RESULTS

The catheter stayed within the grey column of the spinal cord dorsal horn, along the entire length of its insertion. Electrophysiological data confirmed that dorsal horn activity was totally ablated after catheter passage in three sheep, and partially ablated in the fourth.

CONCLUSION

The intrinsic architecture of the spinal cord tissue allows the predictable passage of the catheter through the column of dorsal horn grey matter. Dorsal horn lesioning can be accomplished without direct access to the cord segments selected for surgery.