Neurobrucellosis

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Neurobrucellosis refers to central nervous system involvement by brucellosis and occurs secondary to ingestion or contact with gram-negative, facultative intracellular coccobacilli of the Brucella species. Up to 10% of infections are complicated by neurological involvement .

The remainder of this article is a discussion of CNS brucellosis. For a general discussion on systemic infection, please refer to the article on brucellosis.

Epidemiology

Brucella is found worldwide. High-risk areas include countries surrounding the Mediterranean Sea, Eastern Europe, Mexico, South and Central America, Africa, Asia, the Caribbean and the Middle East .

Clinical presentation

Onset is insidious; undulant, low-grade fever, headache, fatigue and malaise may precede any neurological findings by a number of months. A study of 128 patients with brucellosis found that central nervous symptom involvement is more likely if the following signs and symptoms are present :

  • blurred vision
  • sensorineural hearing loss
  • disorientation
  • recent behavioral change
  • agitation
  • muscle weakness
  • neck stiffness
  • deep tendon reflex change
  • paresthesia
  • diplopia
  • ataxia
  • pseudotumor cerebri
  • facial paralysis

Brucella may be isolated from blood cultures and/or cerebrospinous fluid (CSF). Additional CSF abnormalities include the presence of anti-Brucella antibodies, pleocytosis, high protein and low glucose levels .

Pathology

Transmission occurs secondary to direct contact with infected animals or the consumption of unpasteurised dairy products. In addition to the four main species causing brucellosis, ​B. ceti and B. pinnipediae have more recently been isolated in the context of neurobrucellosis .

Radiographic features

In just under half of brucellosis cases with neurological findings, imaging of the CNS is unremarkable . Abnormal neuroimaging may involve the meninges, cranial nerves, white and grey matter, vasculature, and spinal nerve roots .

CT

Diffuse white matter changes, meningeal enhancement, lacunae and hemorrhages within the basal ganglia, hydrocephalus and cerebral edema may be demonstrated.

MRI
  • T1: arachnoiditis
  • T2/FLAIR: ​arachnoiditis; diffuse, hyperintense lesions affecting the white matter, with an appearance of focal demyelination
  • T1/T2 C+ (Gd): brain abscess or granuloma with ring enhancement; leptomeningeal, basal meningeal, perivascular and/or spinal root enhancement

Differential diagnosis

The heterogenous presentation and imaging findings of neurobrucellosis warrant a thorough history and risk-stratification. Clarification of recent travel and exposure to unpasteurised dairy is important, remembering that both acute and chronic presentations are possible.

Differentials are therefore numerous, but include: