Acute flaccid myelitis associated with enterovirus D68 in a non-epidemic setting

Abstract

Acute flaccid myelitis (AFM) is a recently defined clinical disease accompanied by the national outbreak of enterovirus D68 (EV-D68) in the United States during the late summer/fall of 2014; 258 cases of EV-D68 and 59 cases of AFM were reported in Japan during the late summer/fall of 2015. Subsequently, there have been no epidemics of AFM or EV-D68. However, we encountered a patient who had AFM associated with EV-D68 in 2017. This is the first case of AFM caused by EV-D68 after the 2015 epidemic, and the only reported case in 2017. This report indicates that AFM caused by EV-D68 can arise even in non-epidemic situations. If a patient presents with paralysis, AFM caused by EV-D68 should be included in the differential diagnosis, regardless of the absence of an epidemic of EV-D68 infection.

Keywords: AFM, acute flaccid myelitis; AFP, acute flaccid paralysis; Acute flaccid myelitis; EV-D68, enterovirus D68; Enterovirus D68; GBS, Guillain-Barré Syndrome; MMT, manual muscle testing; MRI, magnetic resonance imaging.

Fig. 1

a) Spinal magnetic resonance imaging (MRI) scan obtained on the day of admission (day 4). T2-weighted images of the lumber spinal cord show that longitudinal lesions are ill-defined and involve the central gray matter (arrow). Gadolinium-enhanced T1-weighted images show abnormal enhancement of the cauda equina, predominantly in the ventral roots (arrowheads). b) Spinal magnetic resonance imaging (MRI) scan obtained on day 27. In this second MRI scan, spinal lesions appeared to have become well-defined and were confined to the anterior horn (arrow). The anterior dominant enhancement of the cauda equina remained (arrowheads).

Fig. 2

Follow-up of motor function and treatment. The upper part shows the development of motor function over time. The motor function of the upper limbs improved, but the weakness of the lower limbs remained. Rehabilitation continued after discharge from the hospital. The bladder and rectal disorders had improved before the discharge. The lower part shows the treatment course. Gamma globulin and steroid pulse were administered as shown.