Brain-stem Listeriosis: A Comparison of SPECT and MRI Findings

Sevki Sahin, MD; Ayse S. Arisoy, MD; Aynur E. Topkaya, MD; Sibel Karsidag, MD

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Abstract and Introduction

Abstract

Listeria monocytogenes, although uncommon as a cause of illness in the general population, can result in serious illness when it affects pregnant women, neonates, the elderly, and immunocompromised individuals. Typically, it is a food-borne organism. This report describes a case of brain-stem listeriosis in a previously healthy 51-year-old woman. The diagnosis was based on clinical findings, the results of cerebrospinal fluid (CSF) analysis, CSF culture, and magnetic resonance imaging (MRI) findings. MRI demonstrated upper brain stem and cerebellar peduncle involvement. In addition, Tc-99m exametazime (HMPAO)-labeled single photon emission computed tomography (SPECT) of the brain revealed bilateral cerebellar hypoperfusion. Antibiotic therapy resulted in partial clinical recovery after 3 weeks. At the end of 6 months, brain-stem findings had nearly resolved. However, although minimal residual findings were observed on MRI at 6 months, bilateral diffuse cerebellar hypoperfusion remained on Tc-99m HMPAO brain SPECT.

Introduction

Listeriosis is a serious infection acquired by eating food contaminated with the bacterium Listeria monocytogenes. This bacterium may be found in a variety of raw foods, such as uncooked meats, vegetables, and dairy products made from unpasteurized milk. The organism is a facultative, non-spore-forming, gram-positive bacillus. The risk of a healthy person developing listeriosis after eating contaminated food is very low.[1]

Brain-stem encephalitis caused by L monocytogenes infection is a well-defined entity characterized by progressive brain-stem dysfunction. In humans, brain-stem encephalitis occurs in 10% of the listeriosis cases.[2] In autopsy series, it has been described as inflammatory infiltrates predominantly located in lower cranial nerves.[3]

We present this case because of its unique features, including development of symptomatic listeriosis in an immunocompetent patient, the involvement of upper and mid-brain-stem regions, and the findings in single photon emission computed tomography (SPECT) of the brain.

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