Surgical treatment of dorsal hemivertebrae associated with kyphosis by spinal segmental stabilisation, with or without decompression

Abstract

This retrospective case series examined the effectiveness of spinal segmental stabilisation, with or without decompression, in nine dogs with neurological deficits associated with dorsal hemivertebrae. Data on signalment, preoperative neurological status, imaging findings, surgical techniques and outcome were evaluated. All cases occurred in young or adult, small-breed dogs with neurological signs ranging from progressive moderate pelvic limb ataxia to non-ambulatory paraparesis. Six dogs also showed urinary and faecal incontinence. In each dog, one or more dorsal thoracic hemivertebra(e) were detected by radiography and MRI. In all dogs, hemivertebra(e) were associated with kyphosis and reduced vertebral canal diameter. All dogs were surgically managed with spinal segmental stabilisation, using Steinmann pins and orthopaedic wires and/or sutures attached to the spinous processes. Three dogs also underwent additional decompressive surgery. Post-operative follow-up ranged from 1.5 to 5.5 years. Immediate or delayed post-operative complications occurred in three dogs, including implant migration or loosening. Eight dogs showed long-term gait improvement, with resolution of incontinence if previously present. At 2-6 years post-surgery, four dogs were neurologically normal, three had mild residual ataxia, one had moderate ambulatory paraparesis, and one dog relapsed 3.5 years after surgery, resulting in severe paraparesis. Spinal segmental stabilisation techniques, with or without decompression, can result in satisfactory outcomes in small dogs with hemivertebrae and mild to moderate neurological signs. Further adaptations might be required to avoid implant loosening and allow continued growth in immature dogs.

Ventral stabilization of thoracic kyphosis through bilateral intercostal thoracotomies using SOP (String of Pearls) plates contoured after a 3‐dimensional print of the spine

“…Five of the 6 dogs in our case series had concomitant spinal compression of 20%‐50% that was not further addressed. Similarly, Charalambous et al reported 6 dogs with varying degrees of vertebral canal stenosis (27%‐88%) that did not undergo decompressive surgery but underwent only stabilization of the kyphotic segment and reached a satisfactory outcome. Findings of our case series combined with Charalambous and colleagues’ experience could indicate that instability of the kyphotic segment is an important component in the chronic progression of the clinical signs in dogs with thoracic kyphosis and secondary myelopathy.…”

“…All dogs underwent a full neurological examination at initial presentation and several times postsurgery. A grading scale created by Charalambous et al was applied to assess gait abnormalities and neurological deficits in each dog, allowing comparisons among various consultations (Table ). The same neurologist (RC) assessed the neurological function of each dog from initial presentation to the last follow‐up examination.…”

“…All MRI studies were reviewed by a board‐certified radiologist (AG). T2‐weighted MR images were used to assess stenosis of the vertebral canal, defined by a reduction in height (distance between the dorsal and ventral surface of the vertebral canal), when comparing the canal height at the site of most severe compression to canal height at the second thoracic vertebra …”

“…Clinical signs are related to the neuroanatomical localization of the disease, often consisting of a chronic, progressive T3‐L3 myelopathy with varying degrees of proprioceptive paraparesis and pelvic limb ataxia. Deterioration may be acute or chronic, leading to nonambulatory paraparesis or paraplegia and urinary retention …”

“…[1][2][3]5,7 In a few published articles authors have described the surgical management of vertebral instability and compression caused by thoracic kyphosis in dogs, including segmental spinal stabilization and vertebral body pin and polymethylmethacrylate (PMMA) fixation. [7][8][9] Aikawa et al 8 and Jeffery et al 9 published case series of 9 and 3 small breed dogs, respectively, treated with vertebral body pin and PMMA fixation and dorsal-hemi or hemilaminectomy (except for 1 dog). Eleven of the 12 dogs reached a good outcome postsurgery, but postoperative complications included implant failure and complications related to PMMA.…”