Brain abscess in seven cats due to a bite wound: MRI findings, surgical management and outcome

Abstract

PRESENTATION AND LESION LOCALISATION: Seven adult domestic shorthair cats were presented with a 1- to 6-day history of progressive neurological signs. A focal skin puncture and subcutaneous swelling over the dorsal part of the head were detected on physical examination. Neurological examination indicated lesion(s) in the right forebrain in four cats, multifocal forebrain in one cat, left forebrain in one cat, and multifocal forebrain and brainstem in the remaining cat. In all cats, magnetic resonance imaging revealed a space-occupying forebrain lesion causing a severe mass effect on adjacent brain parenchyma. CLINICAL APPROACH AND OUTCOME: All cats were managed with a combination of medical and surgical treatment. At surgery a small penetrating calvarial fracture was detected in all cats, and a tooth fragment was found within the content of the abscess in two cats. The combination of surgical intervention, intensive care and intravenous antimicrobials led to a return to normal neurological function in five cats.

Practical relevance: As this series of cases indicates, successful resolution of a brain abscess due to a bite injury depends on early recognition and combined used of antimicrobials and surgical intervention. A particular aim of surgery is to remove any skull and foreign body (tooth) fragments that may represent a continuing focus of infection.

FIG 1

Magnetic resonance (MR) images from case 1 — T1WI before and after gadolinium (GAD) administration, T2WI and FLAIR. The images reveal an intra-axial space-occupying lesion with well-defined margins in the right frontoparietal lobe, with an isointense core in FLAIR, hyperintense on T2WI and hypointense on T1WI with marked ring enhancement. The perilesional oedema is moderate in this case. The muscles and subcutaneous tissue above the brain lesion and the skull are hyperintense on T2WI and show diffuse contrast uptake on T1WI

FIG 2

MR images from case 2 — tranverse T1WI before and after gadolinium administration, T2WI and FLAIR. The images reveal an intra-axial lesion in the right frontoparietal lobe, with an isointense core surrounded by hypointense margins on T1WI, hyperintense on T2WI and on FLAIR, with marked contrast enhancement on T1WI. The mass is surrounded by a diffuse perilesional oedema which contributes to the mass effect on the brain parenchyma, causing a subfalcine brain herniation and midline shift. The muscles and subcutaneous tissue over the visible skull lesion are hyperintense on T2WI and show diffuse contrast uptake on T1WI

FIG 3

Surgical treatment of cat 1. (a) Presurgical appearance of the skin lesion. (b) Intraoperative view of the skull defect; purulent material is arising from the abscess. (c) Drainage and retrieval of pus from the brain abscess

FIG 4

MR images from case 6 before and 7 weeks after surgery — transverse T1WI before and after gadolinium (GAD) administration, and T2WI. The preoperative images reveal an intra-axial lesion in the right parietal lobe, hyperintense on T2WI and hypointense on T1WI, with strong ring enhancement after gadolinium administration. The right temporalis muscle and the subcutaneous tissue above the brain lesion are hyperintense on T2WI and T1WI and show contrast uptake. The perilesional oedema is severe in this case, with midline shift. Post-surgery MRI scans of the brain reveal a CSF fluid cavity at the site of the previous resected abscess, with no contrast enhancement or parenchymal oedema