Correlation of Clinical and Neuroimaging Findings in a Case of Rabies Encephalitis

Abstract

Rabies is an uncommon cause of fatal encephalitis. Anatomic imaging studies such as computed tomographic and magnetic resonance scans have generally been negative in confirmed cases of rabies. We report a case of confirmed rabies with extensive brainstem and hypothalamic-pituitary abnormalities on magnetic resonance imaging. Although these findings are nonspecific, they should raise the clinical suspicion of rabies in the setting of aggressive encephalitis of unclear cause, and appropriate diagnostic tests should be performed.

Neuroimaging Findings in Rabies Encephalitis

“…Various other authors have described the involvement of the same brain and spinal cord structures in different combinations on MRI in rabies patients 2,4,5,10,11 . In our series, too, the basal ganglia demonstrated T2/FLAIR hyperintensities in six patients (Fig 1A), and brainstem signal changes were noted in four patients.…”

“…Imaging findings in rabies encephalitis is limited to a few case reports 2,4,5,9–11 . The deep gray nuclei have been the most frequently afflicted, followed by the brainstem.…”

“…The limbic system's involvement is also seen in herpes simplex encephalitis but for the absence of basal ganglionic involvement. Also, in herpes simplex encephalitis, petechial hemorrhagic lesions are common, whereas it has been rarely reported in rabies 4 …”

Neuroimaging Findings in Rabies Encephalitis

“…Various other authors have described the involvement of the same brain and spinal cord structures in different combinations on MRI in rabies patients 2,4,5,10,11 . In our series, too, the basal ganglia demonstrated T2/FLAIR hyperintensities in six patients (Fig 1A), and brainstem signal changes were noted in four patients.…”

“…Imaging findings in rabies encephalitis is limited to a few case reports 2,4,5,9–11 . The deep gray nuclei have been the most frequently afflicted, followed by the brainstem.…”

“…The limbic system's involvement is also seen in herpes simplex encephalitis but for the absence of basal ganglionic involvement. Also, in herpes simplex encephalitis, petechial hemorrhagic lesions are common, whereas it has been rarely reported in rabies 4 …”

Diagnosis, management and post-mortem findings of a human case of rabies imported into the United Kingdom from India: a case report

“…However, the marked brainstem involvement recently described in studies of viral antigen distribution and magnetic resonance imaging (MRI) in rabies patients [53-55] and implicated as potentially relevant to centrally-mediated dysautonomia was not seen here.…”

Magnetic resonance imaging in rabies

“…3 Pleasure and Fischbein describe extensive magnetic resonance abnormalities in the brainstem and hippocampus in a patient with rabies encephalitis that had been proved at necropsy. 4 Awasthi et al report hyperintensities in the globus pallidi, putamen, and thalami bilaterally on both T1 and T2 weighted images in a case of rabies encephalitis diagnosed antermortem. 5 They attribute the hyperintensity on the T1 image to extracellular methaemoglobin.…”

Neuroimaging Findings in Rabies Encephalitis

“…Various other authors have described the involvement of the same brain and spinal cord structures in different combinations on MRI in rabies patients 2,4,5,10,11 . In our series, too, the basal ganglia demonstrated T2/FLAIR hyperintensities in six patients (Fig 1A), and brainstem signal changes were noted in four patients.…”

“…Imaging findings in rabies encephalitis is limited to a few case reports 2,4,5,9–11 . The deep gray nuclei have been the most frequently afflicted, followed by the brainstem.…”

“…The limbic system's involvement is also seen in herpes simplex encephalitis but for the absence of basal ganglionic involvement. Also, in herpes simplex encephalitis, petechial hemorrhagic lesions are common, whereas it has been rarely reported in rabies 4 …”

Diagnosis, management and post-mortem findings of a human case of rabies imported into the United Kingdom from India: a case report

“…However, the marked brainstem involvement recently described in studies of viral antigen distribution and magnetic resonance imaging (MRI) in rabies patients [53-55] and implicated as potentially relevant to centrally-mediated dysautonomia was not seen here.…”

Magnetic resonance imaging in rabies

“…3 Pleasure and Fischbein describe extensive magnetic resonance abnormalities in the brainstem and hippocampus in a patient with rabies encephalitis that had been proved at necropsy. 4 Awasthi et al report hyperintensities in the globus pallidi, putamen, and thalami bilaterally on both T1 and T2 weighted images in a case of rabies encephalitis diagnosed antermortem. 5 They attribute the hyperintensity on the T1 image to extracellular methaemoglobin.…”

Neuroimaging Findings in Rabies Encephalitis

“…Various other authors have described the involvement of the same brain and spinal cord structures in different combinations on MRI in rabies patients 2,4,5,10,11 . In our series, too, the basal ganglia demonstrated T2/FLAIR hyperintensities in six patients (Fig 1A), and brainstem signal changes were noted in four patients.…”

“…Imaging findings in rabies encephalitis is limited to a few case reports 2,4,5,9–11 . The deep gray nuclei have been the most frequently afflicted, followed by the brainstem.…”

“…The limbic system's involvement is also seen in herpes simplex encephalitis but for the absence of basal ganglionic involvement. Also, in herpes simplex encephalitis, petechial hemorrhagic lesions are common, whereas it has been rarely reported in rabies 4 …”

Diagnosis, management and post-mortem findings of a human case of rabies imported into the United Kingdom from India: a case report

“…However, the marked brainstem involvement recently described in studies of viral antigen distribution and magnetic resonance imaging (MRI) in rabies patients [53-55] and implicated as potentially relevant to centrally-mediated dysautonomia was not seen here.…”

Magnetic resonance imaging in rabies

“…3 Pleasure and Fischbein describe extensive magnetic resonance abnormalities in the brainstem and hippocampus in a patient with rabies encephalitis that had been proved at necropsy. 4 Awasthi et al report hyperintensities in the globus pallidi, putamen, and thalami bilaterally on both T1 and T2 weighted images in a case of rabies encephalitis diagnosed antermortem. 5 They attribute the hyperintensity on the T1 image to extracellular methaemoglobin.…”