Poliomyelitis-like syndrome

Case contributed by Dr Christine Goh


4 days weakness and hyporeflexia on background of diarrhoeal illness.

Patient Data

Age: 37
Gender: Male

MRI spinal cord

Abnormal T2 hyperintensity involving most of the length of the cord has bilaterally symmetric appearance, with signal abnorrmality centred on the anterior horns.  There was no pathological enhancement within the cord, and no abnormally enhancing nerve roots.

Minimal disc protrusions at a few levels do not result in spinal canal stenosis or cord compression.  No abnormal vascular flow voids or areas of susceptibility artefact within the cord.

In the context of febrile/diarrhoeal illness, an infective or postinfectious aetiology was considered likely, and the combination of acute flaccid paralysis with anterior horn changes favours poliomyelitis-like syndrome.

The MRI findings were not consistent with the initial clinical diagnosis of Guillain-Barre syndrome, which is characterised by normal cord appearance, with variable nerve root enhancement.

Grey matter signal abnormality with anterior horn predominance can be seen in cord ischaemia, however this would usually have a more abrupt onset of neurological deficit.


MRI brain

MR imaging of the brain  demonstrated T2 and FLAIR signal abnormality centred on the dentate nuclei and circumferentially involving the brainstem.  There was no basal ganglia or thalamic involvement, and no parenchymal or leptomeningeal enhancement.

Findings are compatible with a rhombencephalitis.

Case Discussion

CSF analysis demonstrated a mild lymphocytosis with normal protein level.

Poliomyelitis-like syndrome (resulting in anterior horn syndrome) is an infective myelitis by pathogens which selectively involve the anterior horn cells to cause an acute flaccid paralysis.  

The archetypical infective agent is poliomyelitis, although due to high rates of vaccination it is now more common for outbreaks of enterovirus 71 or West Nile virus to be implicated.  Other picornaviruses and flaviviruses such as coxsackie A and B viruses, Japanese encephalitis virus and Murray Valley virus are rare causes of poliomyelitis-like syndrome, with encephalitic presentations far more common than anterior horn cell involvement.

The typical MRI appearance is long segment T2 hyperintensity centred on the anterior horns, usually non enhancing.

There may also be imaging findings related to concurrent encephalitis.  Bilateral thalamic and brainstem involvement is the classic distribution of findings in encephalitis due to flaviviruses such as Japanese encephalovirus and West Nile virus.

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Case information

rID: 34623
Published: 5th Mar 2015
Last edited: 2nd May 2016
Inclusion in quiz mode: Included

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