MRI findings in children with acute flaccid paralysis and cranial nerve dysfunction occurring during the 2014 enterovirus D68 outbreak

Abstract

Background and purpose: Enterovirus D68 was responsible for widespread outbreaks of respiratory illness throughout the United States in August and September 2014. During this time, several patients presented to our institution with acute flaccid paralysis and cranial nerve dysfunction. The purpose of this report is to describe the unique imaging findings of this neurologic syndrome occurring during an enterovirus D68 outbreak.

Materials and methods: Patients meeting a specific case definition of acute flaccid paralysis and/or cranial nerve dysfunction and presenting to our institution during the study period were included. All patients underwent routine MR imaging of the brain and/or spinal cord, including multiplanar T1, T2, and contrast-enhanced T1-weighted imaging.

Results: Eleven patients met the inclusion criteria and underwent MR imaging of the brain and/or spinal cord. Nine patients presented with brain stem lesions, most commonly involving the pontine tegmentum, with bilateral facial nerve enhancement in 1 patient. Ten patients had longitudinally extensive spinal cord lesions; those imaged acutely demonstrated involvement of the entire central gray matter, and those imaged subacutely showed lesions restricted to the anterior horn cells. Ventral cauda equina nerve roots enhanced in 4 patients, and ventral cervical nerve roots enhanced in 3, both only in the subacute setting.

Conclusions: Patients presenting with acute flaccid paralysis and/or cranial nerve dysfunction during the recent enterovirus D68 outbreak demonstrate unique imaging findings characterized by brain stem and gray matter spinal cord lesions, similar to the neuroimaging findings described in previous outbreaks of viral myelitis such as enterovirus 71 and poliomyelitis.

Fig 1.

Noncontrast FLAIR images through the dorsal pons demonstrate a variety of types of T2 hyperintensity. A, In patient 4, T2 hyperintensity in the dorsal pons (arrow) extends into the dentate nuclei. B, In patient 2, more focal and intense T2 signal is localized in the dorsal pons (arrow). C, In patient 6, ill-defined and less intense signal in the dorsal pons extends to the dentate nuclei (arrow). D, In patient 10, more focal and T2 hyperintensity is seen within the dorsal pons (arrow).

Fig 2.

Atypical appearance of CNS disease includes T2 hyperintensity localized to the substantia nigra in patient 3 (white arrows, A and B). In patient 7, the facial nerves abnormally enhance bilaterally (white arrows, C) and the left ventral pons has an atypical T2 hyperintense focus (black arrow, D). There is also more ill-defined hyperintensity in the dorsal pons (white arrow, D).

Fig 3.

A–C, In Patient 2 scanned at 2 days, the central cord hyperintensity is more ill-defined and involves the entire central gray matter (black arrows, A; white arrow, B). Nerve roots do not enhance (white arrows, C). D–F, Patient 8, scanned at 25 days, demonstrates T2 hyperintensity confined to the anterior horn cells asymmetric to the left (black arrow, D; white arrow, E) and nerve root enhancement (white arrows, F).

Fig 4.

A–D, Acute imaging performed at 2–3 days in patient 1 demonstrates T2 hyperintensity in the right dorsal pons (white arrow, A) and more ill-defined central gray matter hyperintensity seen more commonly in the acute phase (white arrows, B and C; black arrows, D). E–I, Subacute imaging of the spine performed in the same patient at 38 days demonstrates contraction of the cord T2 hyperintensity to focally involve the anterior horn cells (black arrows, E; white arrows, F and H) and nerve root enhancement of ventral cervical roots (white arrows, G) and the cauda equina (white arrows, I).