Poliomyelitis-like syndrome, or polio-like paralysis, is an uncommon form of myelitis that presents similar to polio, due to non-poliovirus pathologies which selectively involve the anterior horn cells of the spinal cord and result in an anterior horn syndrome. Although it usually has an infective etiology, there are rare non-infective etiologies too.
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 1-7.
There are many causes:
- infective: enterovirus 71 considered a leading cause, but there are many other implicated viruses (e.g. coxsackie A9 and A23, coxsackie B viruses, West Nile virus, Japanese encephalitis virus, Epstein-Barr virus, Murray Valley encephalitis virus, respiratory syncytial virus, etc.) 1-5
- post-vaccination 6
- Hopkins syndrome: exceedingly rare myelitis following an asthma attack 7
MRI of the spine is the modality of choice for assessing for signal abnormality of the anterior horn cells.
T2: hyperintense anterior horn cells 1-5
- on axial imaging this has the characteristic owl's eyes sign, which appears as thin anterior 'pencil like' linear T2 hyperintensities 5
- T1 C+ (Gd): generally no enhancement unless there is radicular involvement 1,3
Depending on the underlying etiology, there may also be imaging findings related to concurrent encephalitis.
- 1. J.A. Maloney, D.M. Mirsky, K. Messacar, S.R. Dominguez, T. Schreiner, N.V. Stence. MRI Findings in Children with Acute Flaccid Paralysis and Cranial Nerve Dysfunction Occurring during the 2014 Enterovirus D68 Outbreak. (2015) American Journal of Neuroradiology. 36 (2): 245. doi:10.3174/ajnr.A4188 - Pubmed
- 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
- 4. 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
- 5. Joy Zhuo Ding, Hugh J. McMillan. “Owl’s Eye” Sign in Acute Flaccid Paralysis. (2019) Canadian Journal of Neurological Sciences. 46 (6): 756. doi:10.1017/cjn.2019.250 - Pubmed
- 6. José Roberto Lopes Ferraz-Filho, Ulysses dos Santos Torres, Eduardo Portela de Oliveira, Antonio Soares Souza. MRI findings in an infant with vaccine-associated paralytic poliomyelitis. (2010) Pediatric Radiology. 40 (1): 138. doi:10.1007/s00247-010-1650-6
- 7. Nihei K, Naitoh H, Ikeda K. Poliomyelitis-like syndrome following asthmatic attack (Hopkins syndrome). (1987) Pediatric neurology. 3 (3): 166-8. doi:10.1016/0887-8994(87)90085-3 - Pubmed