Poliomyelitis-like syndrome

Poliomyelitis-like syndrome is an uncommon infective myelitis by pathogens which selectively involve the anterior horn cells of the spinal cord and results in a anterior horn syndrome.  

Patients with poliomyelitis-like syndrome present with selective neurological deficits due to anterior horn involvement; flaccid paralysis and areflexia of the involved limb without sensory impairment 2

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 3 to be implicated.  Other picornaviruses and flaviviruses such as coxsackie A and B viruses, Japanese encephalitis virus, respiratory syncytial virus (RSV)1, Epstein-Barr virus (EBV)2 and Murray Valley virus are rare causes of poliomyelitis-like syndrome, with encephalitic presentations far more common than anterior horn cell involvement.

MRI of the spine is the modality of choice for assessing for signal abnormality of the anterior horns. 

MRI

The typical MRI appearance is long segment T2 hyperintensity centred on the anterior horns, usually non enhancing. On axial imaging this has the characteristic owl's eyes sign, which on sagittal appears as thin anterior 'pencil like' linear T2 hyperintensity. 

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

The differential diagnosis is largely that of other causes of anterior horn syndrome / owl's eyes sign and includes: 

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rID: 44689
Synonyms or Alternate Spellings:

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