The role of fenestration in the management of canine thoracolumbar intervertebral disc disease

Abstract

Intervertebral disc fenestration is a surgical procedure performed in neurosurgery since decades, specifically in management of Thoracolumbar Intervertebral Disc Herniation (TIVDH). During this procedure a window in the annulus fibrosus is opened and evacuation of the nucleus pulposus is attempted in order to eliminate the possibility of degenerative material extrusion into the spinal canal. This is a process which takes place mostly in chondrodystrophoid breed dogs that suffer from Hansen Type I Intervertebral Disc Disease. The idea of fenestration initially appealed a lot of surgeons and it was used even as monotherapy in TIVDH patients. However, development of diagnostic imaging demonstrated the need for a more substantial decompressive intervention e.g., hemilaminectomy – mini-hemilaminectomy) on the exact site of disc herniation especially in crucial cases with severe neurological deficits. One of the most challenging issues about TIVDH management is not only the effectiveness of the initial surgical or conservative treatment, but also early and late recurrence episodes prevention. The role of prophylactic fenestration remains a very controversial issue among specialists today. Many of them support that in combination with decompressive surgery, the extruded disc and/or the immediately adjacents or even more distant discs should be fenestrated to avoid future extrusions and clinical relapses. A number of authors conducted studies in order to assess follow up evidence and clinical parameters after surgical decompression with or without fenestration. The goal was to eventually obtain the answer about whether or not fenestration is rightly considered as preventive measure. It is difficult though, to objectively evaluate these data due to variability in patients (breed, sex, age, neurological stage), different surgical methods performed and limited follow up examination. Older data supported that recurrence rate was lower after fenestration of degenerative discs. Today, taking into account results of more thorough studies and meta-analyses, the fact that prophylactic fenestration reduces the rate of recurrences is strongly questionable.
Possible postsurgical complications after fenestration are either iatrogenic or they are associated with spinal instability provoked due to supportive structure alterations. Nevertheless, the frequency of those complications seems to be low in clinical practice.