Short- and long-term outcome and magnetic resonance imaging findings after surgical treatment of thoracolumbar spinal arachnoid diverticula in 25 Pugs

Abstract

Background: There is a successful outcome after surgical management of spinal arachnoid diverticula (SAD) in up to 82% of cases.

Hypothesis/objectives: We hypothesized that Pugs have favorable short-term and poor long-term prognosis after surgical treatment of thoracolumbar SAD. The aim of the present investigation was to describe clinical findings, short- and long-term outcomes, and follow-up magnetic resonance imaging (MRI) findings in Pugs with thoracolumbar SAD.

Animals: Twenty-five client owned Pugs with 12-month follow-up information after surgical treatment of thoracolumbar SAD.

Methods: Multicenter retrospective case series. All medical records were searched for Pugs diagnosed with SAD. Data regarding signalment, history, surgical procedure, outcome, histopathology, and follow-up MRI results were extracted.

Results: Mean age at presentation was 7.32 (range 2-11) years, 80% were males. Short-term outcome was available in 25 dogs, and improvement was confirmed in 80% of dogs. Long-term outcome was available in 21 dogs, and deterioration was confirmed in 86% of cases, with late-onset recurrence of clinical signs after initial postsurgical improvement affecting 85% of Pugs. A moderate correlation (r = 0.50) was found between duration of clinical signs and outcome. In 8 dogs with deteriorating clinical signs, follow-up MRI revealed regrowth of the SAD in 2 cases, new SAD formation in 2 cases, and intramedullary T2W hyperintensity/syringomyelia in 6 cases.

Conclusions and clinical importance: This study suggests that Pugs with thoracolumbar SAD do not have a favorable long-term prognosis after surgical treatment for reasons yet to be determined.

Keywords: Pugs; SAD; spinal cyst; surgical treatment of SAD.

Figure 1

Pug, 7 years old, male, suffering from SAD at the T11 vertebral level. Histological section of the diverticula wall. The diverticula wall is composed of mature collagenous connective tissue and lined in places by flattened epithelium. There is mild inflammatory reaction consisting of neutrophils and lymphocytes (arrow). Hematoxylin and eosin staining. ×20 magnification

Figure 2

Pug, 7 years old, male. Initial mid‐sagittal (A), transverse T2W (B), and T1W transverse (C) magnetic resonance images (MRI) demonstrating a spinal arachnoid diverticula (SAD) at T12‐13 vertebral level. A follow‐up MRI 7 months after surgery, demonstrating recurrence of the SAD in T2W mid‐sagittal (D) and transverse (E) MRI images. Please note intramedullary hyperintensity which is already present in presurgical MR images (arrow) (A). Advanced intramedullary T2W hyperintensity in postsurgical MR images (arrowhead) (D)

Figure 3

Pug, 6 years old, male. Initial mid‐sagittal (A) and transverse T2W (B) magnetic resonance images demonstrating a multilobular spinal arachnoid diverticula (SAD) at T12 vertebral level. A follow‐up magnetic resonance imaging (MRI) 20 months after surgery, demonstrating a new SAD formation originating from 1 part of the multilobular SAD (arrow), which was not addressed during the surgery, in mid‐sagittal (C), transverse T2W (D), and T1W transverse (E) MR images. Advanced intramedullary T2W hyperintensity is present (arrowhead)

Figure 4

Pug, 5 years old, female. Initial mid‐sagittal (A), transverse T2W (B), and T1W transverse (C) MRI images demonstrating a spinal arachnoid diverticula (SAD) at T9‐10 vertebral level. A follow‐up magnetic resonance imaging (MRI) 8 months after surgery demonstrating advanced T2W intramedullary hyperintensity (arrow) in T2W mid‐sagittal (D), transverse (E), and T1W transverse (F) MRI images. Please note intramedullary hyperintensity which is already present in presurgical MR images (arrow) (A). Advanced intramedullary T2W hyperintensity in postsurgical MR images (arrowhead) (D)