Introduction of Disc Material into the Vertebral Canal by Fenestration of Thoracolumbar Discs Following Decompressive Surgery

Abstract

Objective Intervertebral disc extrusion is a common disease affecting chondrodystrophic dogs. It has been reported that fenestration of thoracolumbar intervertebral discs reduces recurrence of disc extrusion and is associated with a low complication rate. One complication reported is iatrogenic introduction of disc material into the canal directly following fenestration. This study aimed to ascertain if, and at what frequency, additional disc material may be introduced into the vertebral canal by fenestration of the affected disc following decompressive surgery. Study Design Twenty-one dogs that underwent hemilaminectomy and disc fenestration for the treatment of thoracolumbar intervertebral disc extrusion had intraoperative assessment of the vertebral canal before and after fenestration. The spinal cord was first decompressed by hemilaminectomy and removal of all visible extruded disc material within the vertebral canal. Once no further material was visible, manual fenestration of the affected disc was performed. The vertebral canal was re-inspected, and the presence or absence of additional material was noted and included in the surgery report. Results Seven dogs showed the presence of new disc material in the vertebral canal post fenestration.This preliminary study shows that additional disc material can be forced into the vertebral canal by fenestration following decompressive surgery, with a frequency of 7/21. Conclusion This illustrates the importance of checking the vertebral canal after fenestration of an extruded intervertebral disc.

Approach to and Practice of Disc Fenestration in the Management of Intervertebral Disc Extrusions in Dogs: A Questionnaire Survey

“…There is little evidence regarding the incidence of complications in disc fenestration, although introduction of further material into the vertebral canal may occur in as many as 33% of cases. 4 A larger proportion indicated that they did not regularly fenestrate because they did not feel fenestration was effective however, so it is clear that the evidence for this procedure is not universally accepted, and this may have a further effect on resident training. Interestingly, a similar number of respondents said they have changed their habits for (14%) or against (12%) fenestration.…”

“…2 Many publications report the effect of fenestration on recurrence, optimum sites for fenestration, 2 surgical methods, 3 disadvantages and complications. 4 A previous publication aimed to identify approaches to treatment of intervertebral disc extrusion in dogs. 5 This survey involved respondents from North America only, and we felt it would be interesting to survey a wider geographical area and also ask further questions specifically regarding habits and issues around fenestration, including questions on complications encountered, whether habits have changed, and cervical fenestration.…”

Current Approaches to the Management of Acute Thoracolumbar Disc Extrusion in Dogs

“…In the context of acute canine IVDE, fenestration is performed “always” or “most of the time” by 69% of board-certified neurologists and 36% of board-certified surgeons ( 26 ). Clinicians who do not routinely fenestrate cite concerns including questionable efficacy; prolonged surgical time; complications such as hemorrhage, pneumothorax or nerve root injury; variable success in removal of in situ nucleus pulposus; potential for introduction of additional disc material into the vertebral canal; induction or worsening of degenerative changes to non-herniated discs, and the concern for adjacent segment disease ( 70 , 71 ). Clinicians who do routinely fenestrate cite a recurrence rate as high as 40% for IVDE and the fact that dogs who present for a second bout of surgical IVDE have a rate of euthanasia as high as 44%, often due to financial concerns of the owner ( 34 , 72 ).…”

Prophylactic Effect of Fenestration on the Recurrence of Thoracolumbar Intervertebral Disc Disease in Dogs

“… Type of study: case report (7) [ 36 , 37 , 38 , 39 , 40 , 41 , 42 ]; cadaveric study (9) [ 16 , 17 , 25 , 43 , 44 , 45 , 46 , 47 , 48 ]; review study (9) [ 1 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ]; questionnaire (1) [ 57 ]. Recurrence was not investigated (35) [ 7 , 14 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , …”

“…Recurrence was not investigated (35) [ 7 , 14 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 ].…”