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 encephalitis 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.
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.
- 1. Tejada J, Hernández-Echebarria LE, Fernández-López JF et-al. Acute anterior horn cell disease resembling poliomyelitis as a manifestation of respiratory syncytial virus infection. J. Neurol. Neurosurg. Psychiatr. 1996;60 (1): 106-7. Free text at pubmed - Pubmed citation
- 2. Wong M, Connolly AM, Noetzel MJ. Poliomyelitis-like syndrome associated with Epstein-Barr virus infection. Pediatr. Neurol. 1999;20 (3): 235-7. Pubmed citation
- 3. Schafernak KT, Bigio EH. West Nile virus encephalomyelitis with polio-like paralysis & nigral degeneration. Can J Neurol Sci. 2007;33 (4): 407-10. Pubmed citation