Minimally Invasive, Integrated Endoscopic Hemilaminectomy for Hansen Type I Intervertebral Disc Extrusion in Chondrodystrophic Dogs

The objective of this prospective pilot study is to assess the feasibility of a minimally invasive, integrated endoscopic hemilaminectomy in chondrodystrophic dogs with clinically relevant Hansen type 1 intervertebral disc extrusion (IVDE). Study subjects included five client-owned chondrodystrophic dogs under 15kg with an acute, single site IVDE between T10 and L5 of less than 90 days duration and no loss of deep pain perception. The extent of the extrusion could not exceed 2/3 the diameter of the cannula to be used as defined by magnetic resonance imaging (MRI). A postoperative MRI was performed to assess remaining spinal cord compression. If significant compression remained, patients returned to surgery for a standard, open hemilaminectomy. Only the first dog required conversion to an open approach which resulted in adequate decompression. The same dog had a significant surgical complication of iatrogenic damage to the spinal cord during the minimally invasive approach. The other 4 dogs had no complications and achieved adequate spinal cord decompression. Three dogs eventually returned to normal neurologic status and another was improved compared to presentation. One dog was euthanized for reasons unrelated to IVDE. The authors conclude that a minimally invasive, integrated endoscopic hemilaminectomy is a feasible approach and can allow for adequate decompression of the spinal cord secondary to acute, single-site extrusion. Endoscopic approaches have a steep learning curve and extra care is required in the learning phase to avoid complications. Further studies are warranted to compare the safety and efficacy of this technique to a standard approach.