Thoracic vertebral canal stenosis due to articular process hypertrophy in two cats treated by hemilaminectomy with partial osteotomy of the spinous process

Abstract

Case summary A 9-year-old neutered female British Shorthair cat (case 1) and a 13-year-old neutered male domestic shorthair cat (case 2) showed signs of chronic T3–L3 myelopathy, which progressed over 6 and 12 months, respectively. On presentation, case 1 had moderate pelvic limb proprioceptive ataxia and ambulatory paraparesis, and case 2 was non-ambulatory paraparetic and had urinary incontinence. Bilateral enlargement of the articular process joints at T11–T12 in case 1 and T3–T4 in case 2 causing dorsolateral extradural spinal cord compression was shown on MRI. Surgical decompression by a unilateral approach through hemilaminectomy with partial osteotomy of the spinous process was performed in both cases. The side of the approach was chosen based on the severity of the cord compression. Surgery resulted in a satisfactory outcome with short hospitalisation times. On discharge, case 1 showed mild postural reaction deficits on both pelvic limbs. Case 2 had regained urinary continence and could ambulate unassisted, although it remained severely ataxic. The 6 month follow-up showed very mild paraparesis and proprioceptive ataxia in both cats. No chronic medical treatment was required. Relevance and novel information This is the first report to describe clinical presentation, imaging features, surgical treatment and outcomes of thoracic vertebral canal stenosis owing to bilateral articular process hypertrophy in cats with no adjacent spinal diseases. Thoracic articular process hypertrophy should be included in the differential diagnosis of adult cats with chronic progressive myelopathy. Hemilaminectomy with partial osteotomy of the spinous process might be an appropriate surgical technique in these cases.

Thoracic vertebral canal stenosis in cats: clinical features, diagnostic imaging findings, treatment and outcome

“…A good outcome 6 months after surgery has been reported for two cats with TVCS secondary to articular process hypertrophy. 4 Similarly, of the three cats that underwent surgery in the present study, all demonstrated a good outcome 1–2 months postsurgery and two demonstrated a good long-term outcome.…”

“…A recent case report described thoracic vertebral canal stenosis in two cats, secondary to bilateral articular process hypertrophy. 4 It is unclear if this report describes a different disease process to that seen in the current study, given the appreciable articular process hypertrophy on imaging. However, in agreement with the current study, both cats were middle-aged or older at presentation and demonstrated a chronic, progressive T3–L3 myelopathy.…”

“…In contrast to the present study, both cats had evidence of ventral spondylosis deformans at the site of vertebral stenosis, suggesting chronic vertebral instability and secondary articular process hypertrophy as the pathophysiology. 4…”

“…The most frequent sites of stenosis were the T3–T4 and T11–T12 intervertebral disc spaces, consistent with the sites affected in the aforementioned case report. 4 It is unclear why the sites of stenosis varied and it may be expected for degenerative changes to primarily occur in the caudal thoracic vertebral column, which shows a higher degree of flexibility and is subject to increased biomechanical forces compared with the cranial thoracic compartment. 14,15 Equally, it is possible relative stenosis is limited to selected regions of the vertebral canal.…”

“…3 Thoracic vertebral canal stenosis (TVCS) was recently documented to be among the 10 most common causes of spinal disease in the cat, 3 and a recent report described the successful surgical management of two cats with articular process hypertrophy causing TVCS. 4 However, there is little known about the clinical presentation, imaging findings and outcome of cats with this disease.…”