Outcomes of extensive hemilaminectomy with durotomy on dogs with presumptive progressive myelomalacia: a retrospective study on 34 cases

Abstract

Background Progressive myelomalacia (PMM) is a fatal complication of progressive ascending and descending necrosis of the spinal cord after acute spinal cord injury. A recent study suggested that extensive hemilaminectomy with durotomy (EHLD) at the intramedullary T2-hyperintense region which performed immediately after magnetic resonance imaging (MRI) improved the survival rate in dogs with presumptive PMM. The objective of this retrospective study was to evaluate the effects of EHLD on halting the progression of PMM in dogs presumptively diagnosed with PMM which had the interval between MRI and surgery. Results Thirty-four dogs with presumptive PMM which had undergone EHLD with the delay following MRI examination (range, 0 to 3 days) were included. The cranial side of EHLD was set depending on the delay time after MRI, MRI findings, neurological examination and intraoperative macroscopic appearance. Two weeks after surgery, the perioperative survival rate was 97% (33/34). During follow-up with a median time period of 82.5 weeks (range, 0-290 weeks), the postoperative survival rate was 91% (31/34). At the end of the follow-up period, 31 out of 34 dogs were alive without severe postoperative complications while the remaining 2 dogs died from causes not directly attributable to the surgery. There was no improvement in the pelvic limb function of all dogs. Conclusions EHLD appears to be effective in halting the progression of presumptive PMM and preventing morbidity even in dogs which had the interval between MRI and EHLD. Our algorithm of determining the range of EHLD may enable to set the appropriate ranges of EHLD in the cases which develop signs consistent with PMM after MRI examination.

ACVIMconsensus statement on diagnosis and management of acute canine thoracolumbar intervertebral disc extrusion

“…Postoperative survival rate was 61% for 18 dogs with focal hemilaminectomy alone, and EHLD was identified as the independent variable associated with increased survival using multivariate analysis. In a retrospectively reported case series of 34 dogs with presumed PMM and treated with EHLD of variable length, postoperative survival rate was 91% with a median follow‐up of 82.5 weeks 234 . No dogs in this series regained ambulation, but the authors attributed the high rate of postoperative survival to EHLD and attenuated PMM progression.…”

“…Conventional wisdom suggests that removal of numerous consecutive articular processes and their soft tissue attachments can result in decreased vertebral column stability, and, a recent retrospective study identified a negative association between prolonged anesthetic time and neurologic outcome in paraplegic DPN dogs 235 . However, a study describing very extensive laminectomy and durotomy for some animals (often >10 vertebral segments) reported that no dogs required spinal stabilization or developed serious complications or radiographic signs of instability 234 . One study did report a single case with short‐term severe allodynia that resolved within 10 days after treatment with PO gabapentin 99 …”

“…235 However, a study describing very extensive laminectomy and durotomy for some animals (often >10 vertebral segments) reported that no dogs required spinal stabilization or developed serious complications or radiographic signs of instability. 234 One study did report a single case with shortterm severe allodynia that resolved within 10 days after treatment with PO gabapentin. 99 Durotomy can lead to spinal cord herniation, meningeal scarring and adhesion formation.…”

Dysphonia in a dog with cervical spinal cord injury and suspected progressive myelomalacia caused by a C4‐C5 hydrated nucleus pulposus extrusion

“…Surgical confirmation of myelomalacia by visual inspection of the spinal cord after durotomy and palpation with a probe may be considered sufficient to definitively diagnose myelomalacia. 34,35 Although irreversible, myelomalacia may remain focal from the start or halt after initial ascending/descending progression for largely unknown reasons, though measures to lower intraspinal pressure seem promising.…”

“…• The effect of extensive decompressive surgery and durotomy in dogs with severe SCI or myelomalacia is a subject of interest in recent literature. [34][35][36][37] • Dural surgery as a measure to lower intrathecal pressure and monitoring thereof are two of the key points of…”