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Rabies encephalitis

Case contributed by Dr Sara Alharbi

Presentation

Acute agitation, hypersalivation, tachypnea, dysphagia as well as oromandibular and neck dystonia three months post cadaveric liver transplant.

Patient Data

Age: 20 years
Gender: Male
MRI

Coronal and axial FLAIR images show hyperintense signal and mild swelling of the bilateral frontal cortex, hippocampi, dorsal thalami as well as focal hyperintensities in the left caudate and lentiform nuclei.  Axial T2-weighted images demonstrate an additional small focal pontine hyperintensity. Diffusion-weighted images and ADC maps demonstrate corresponding diffusion restriction in the bilateral frontoparietal cortex, thalami and hippocampi.

The case is submitted by Dr. Sara Alharbi and Dr. Manal Nicolas-Jilwan.

Case Discussion

The patient's condition deteriorated rapidly including a decreased level of consciousness and generalized tonic-clonic seizures, further worsening into a comatose state with loss of brainstem reflexes. Rabies encephalitis was suspected as the liver donor was reported to have a history of dog bite and possible meningoencephalitis prior to his death. Rabies antibodies were positive in blood and CSF.  Polymerase-chain-reaction for rabies was positive in the saliva, brain biopsy and CSF.  The patient died one month after admission.

Rabies is a fatal CNS infection caused by an RNA virus of the rhabdovirus family, transmitted to humans via infected animal (dog or bat) bite. None-bite transmission can occur through open wounds, laboratory accidents, inhalation in bat-infested caves and organ transplantation.

Human rabies manifests in two clinical forms:

  1. Classic encephalitic form is the most common, begins with non-specific prodromal symptoms of autonomic dysfunction and progresses to hydrophobia, aerophobia, hypersalivation, fluctuating level of consciousness and eventually coma.
  2. Paralytic form presents with flaccid paralysis and relative sparing of consciousness and sensory system.

The key MRI imaging features include increased T2/FLAIR signal intensity preferentially involving brainstem, hippocampi, thalami, basal ganglia and frontal and parietal lobes. Encephalitic and paralytic forms have similar imaging patterns, however, the involvement of medulla and spinal cord is more prevalent in the paralytic form.

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Case information

rID: 66201
Published: 18th Feb 2019
Last edited: 4th Mar 2020
Inclusion in quiz mode: Included

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