Magnetic resonance imaging findings in dogs with steroid-responsive meningitis-arteritis in the UK and their clinical significance: 53 cases (2013-2021)

Abstract

Objectives: To describe the MRI findings in a UK referral population of dogs with steroid-responsive meningitis-arteritis and to determine if they were associated with any specific clinical features or outcomes.

Materials and methods: We performed a multi-centre retrospective case series of dogs diagnosed with steroid-responsive meningitis-arteritis in the UK that underwent MRI. Blinded consensus review of the MRI studies was performed and the findings described. The presence or absence of specific MRI abnormalities were analysed for significant associations with presenting signs, results of investigations or case outcomes.

Results: Fifty-three dogs were included. The most common MRI findings were paravertebral muscle changes (30/53; 56.6%), meningeal contrast enhancement (13/41; 31.7%) and spinal cord parenchymal T2-W hyperintensity (15/53; 28.3%). Haemorrhage was observed in five of 53 (9.4%) cases - three intradural-extramedullary, one intramedullary and one extradural. Following binary logistic regressions, T2-W spinal cord parenchymal hyperintensity had a significant positive association with paresis/paralysis (odds ratio 14.86, 95% confidence interval 1.42 to 154.99) as did haemorrhage (odds ratio 16.12, confidence interval 2.05 to 126.73). Fifty-two (98.1%) dogs survived to discharge. Relapse occurred in nine of 29 (31.0%) dogs with sufficient follow-up, and no MRI finding had a significant relationship with its occurrence.

Clinical significance: Magnetic resonance imaging findings for steroid-responsive meningitis-arteritis can be severe and extensive, as can the clinical presentation. The presence of paresis/paralysis should raise concern for haemorrhage, though most dogs still have a good prognosis.

FIG 1

Dorsal T2‐W fat‐suppressed Dixon sequence of the caudal head, neck and cranial thorax demonstrating paravertebral muscle changes (arrow).

FIG 2

(A) Transverse T2‐W sequence at the level of the caudal thorax showing evidence of intramedullary haemorrhage (long arrow) and paravertebral muscle changes (short arrow). (B) Transverse T2*GE sequence at the same location as (A) confirming presence of an intramedullary susceptibility artefact consistent with haemorrhage (white arrow).

FIG 3

Transverse T1‐W post‐contrast image of the cervical spinal cord at the level of the atlas. There is marked meningeal contrast enhancement surrounding the spinal cord (white arrow).