Murray Valley encephalitis: Case report and review of neuroradiological features

Abstract

We report on a child with diffuse symmetrical thalamic enlargement and signal increase on MRI, representing changes caused by Murray Valley encephalitis (MVE). Very little has previously been reported on the neuroradiological findings of MVE, also known as Australian encephalitis. It is endemic to tropical North Australia, particularly Western Australia and the Northern Territory, but can occur in other parts of Australia. The last epidemic was in south-eastern Australia in 1974. Australian encephalitis is the second most serious acute viral encephalitis to be encountered in Australia. Clinicians need to be aware of MVE in this era of ever-increasing travel. Our aim is to highlight these finding and further define the neuroradiological features.

Clinical and Radiological Predictors of Outcome for Murray Valley Encephalitis

“…3 This series is the first series detailing laboratory investigations and MRI in hospitalized MVEV and complements the individual cases published to date. [14][15][16][17][18] The clinical prodrome, neurological findings, EEG, CSF, and serological parameters were similar to previous MVEV case series, [4][5][6]13,19 illustrating how MVEV encephalitis can present with or without either a CSF neutrophilic or lymphocytic pleocytosis. In the 54 MVEV cases reported since 1978, seizures have been prominent in children but reported in only two adults.…”

“…Acute liver injury, raised creatine kinase, and peripheral leukocytosis are common features of WNV encephalitis, 22 and raised ALT levels have been reported in JEV infection. 23 Cranial CT scans are often normal at the time of presentation in flavivirus encephalitis, 5,14,15,17,18,24 but they may show reduced attenuation in the thalami 16,17 or temporal lobes 15 or show diffuse cerebral edema. 25 Only one of our patients had an abnormal CT scan early in the illness, confirming that this modality lacks the sensitivity to detect the early changes of MVEV encephalitis.…”

“…Five recent MVEV cases [15][16][17][18]25 had variable acute MRI changes of thalamic, basal ganglia, brainstem, subcortical structures, and temporal lobe focal T2 hyperintensity. All of our encephalitic patients had bilateral cerebral peduncle MRI involvement and when found in isolation or with leptomeningeal enhancement, correlated with mild to moderate neurological deficits.…”

West Nile Virus (Kunjin Subtype) Disease in the Northern Territory of Australia—A Case of Encephalitis and Review of All Reported Cases

“…5,17,21,22 The MRI changes showed in the current case are consistent with the inflammatory deep white matter changes typically found in the thalamus and brain stem in encephalitis caused by infection with other WN subtypes and the closely related flaviviruses, including MVEV and JEV. 13,[23][24][25] The cerebellar, brainstem, and thalamic changes seen were consistent with the movement disorder in the presented case. Myoclonus, parkinsonism, and opsoclonus have been described in other flavivirus infections, including WNV/NY99, MVEV, and JEV.…”

Flavivirus Encephalitis

“…3). 33,44,46,59,65,66,[68][69][70][71][72] In some patients, intention tremors and ataxia may suggest cerebellar involvement. 27 Attempts to isolate virus from the blood of patients with flavivirus encephalitis are usually unsuccessful because viremia is transient and titers are low.…”