Acute flaccid paralysis in infants and young children with enterovirus 71 infection: MR imaging findings and clinical correlates

Abstract

Background and purpose: Enterovirus 71 (EV71) infection is now considered an important cause of childhood acute flaccid paralysis. The purpose of our study was to determine whether EV71-infection-related acute flaccid paralysis in infants and young children has characteristic MR imaging patterns.

Methods: Seven infants and young children with acute paralysis of the upper or lower extremities and positive EV71 cultures underwent spinal MR studies during an outbreak of hand-foot-and-mouth disease in Taiwan in 1998.

Results: Acute paralysis was observed in one upper extremity in two patients, in one lower extremity in three patients, and in both lower extremities in two patients. None of the patients had sensory impairment or bulbar palsy. MR studies showed unilateral or bilateral hyperintense lesions in the anterior horn regions of the cord on T2-weighted images in six patients. No abnormal signal was present in one patient. Two of three patients who received intravenous injections of contrast material had ventral root enhancement on T1-weighted images. One of them also had enhancement of the unilateral anterior horn cells. At clinical follow-up, both patients with bilateral anterior horn abnormalities had residual motor weakness, whereas only one of the five patients with unilateral involvement had residual weakness.

Conclusion: EV71 radiculomyelitis tends to be unilateral and to specifically involve both the anterior horn cells of the cord and the ventral roots. MR imaging allows early detection of spinal cord and root lesions.

fig 1.

Unilateral AFP and transient urinary retention in 18-month-old girl with lumbosacral radiculomyelitis. A, Contrast-enhanced axial T1-weighted image (752/15/1) at L1 level shows strong enhancement of the left ventral root (arrowhead) and mild enhancement of the left anterior horn cells (arrow) of the sacral cord. B, Left anterior horn lesion (arrow) is inconspicuous on gradient-echo T2-weighted image (808/18/20).

fig 2.

Radiculomyelitis causing bilateral AFP and urinary retention. A, Unenhanced axial T1-weighted image (752/15) shows hypointense lesions (arrowheads) in the anterior horn cells of spinal cord bilaterally at T11 level. B, Contrast-enhanced T1-weighted image at the same level as in A shows predominant enhancement of the ventral roots (arrowheads). The anterior horn cell lesions do not enhance. C, Contrast-enhanced T1-weighted image at the conus level clearly shows the predominant ventral root enhancement. The slightly hyperintense dot at the left dorsal root region (arrowhead) is probably due to enhancement of the radicular vein. D, The anterior horn cell lesions are hyperintense and more conspicuous on gradient-echo T2-weighted image (808/15/20) as compared with T1-weighted image (A). E, Sagittal fast spin-echo T2-weighted image (2300/103/2) shows the extent of the anterior horn cell lesions (arrowheads) from midthoracic to conus levels.

fig 3.

Persistent weakness of right lower limb 2 months after EV71 infection in a 16-month-old infant. A, Axial fast spin-echo T2-weighted image (4000/80/3) at lumbosacral cord 2 months after acute paralysis shows a hyperintense lesion in the right anterior horn region (arrow). B, Sagittal fast spin-echo T2-weighted image shows a long-segment hyperintense lesion (arrowheads) extending from the lower thoracic to the lumbosacral levels.