History and Physical
An 8-year-old boy presented with acute-onset and progressive lower extremity weakness in the setting of a rhinovirus/enterovirus positive respiratory test. On the day of admission, he developed difficulty walking and urge incontinence, without sensory symptoms. Weakness progressed and he developed respiratory failure requiring bilevel positive airway pressure (BiPAP). Neurologic exam revealed mild weakness in the distal upper extremities and more significant weakness in the lower extremities. Sensation and reflexes were intact and symmetric throughout. He was unable to stand without support and could not take any steps.
Diagnostic workup
MRI of the spine was significant for mild focal T2 hyperintensity at the cervicothoracic junction. MRI brain was normal. Repeat MRI of the spine 3 days later revealed a larger and clearly demarcated lesion from C6 to T1, primarily involving the central cord ( Fig. 53.1 ). There was no associated mass effect or abnormal enhancement.
Transverse myelitis. Spine MRI, (A) sagittal T2 shows focal cord hyperintensity from C6-T1 without associated enhancement or edema. (B) Axial T2 shows preferential involvement of the central gray matter.
Within 24 hours, the patient developed hypotonia, worsening distal weakness (left greater than right), areflexia in all extremities, and diffuse pain. Over the subsequent 3 days, a sensory level was identified around T5 to T8. Workup was significant for negative MOG and AQP-4 antibodies. CSF was without pleocytosis or protein elevation. He was initially treated with high-dose IV steroids, followed by intravenous immunoglobin (IVIG) after his weakness progressed. His exam improved and he was discharged on a steroid taper. At 3-month follow up, his residual deficits were mild intrinsic hand weakness, mildly decreased sensation to temperature in the lower extremities, hyperreflexia, and bilateral ankle clonus.
Clinical Differential Diagnoses
The initial neurologic exam suggested an upper motor neuron process within the cervical cord, such as autoimmune myelitis (given weakness in the setting of preserved reflexes). The differential includes CNS demyelinating disorders (MOGAD, NMOSD, MS) and systemic autoimmune disorders (lupus Sjogren syndrome, antiphospholipid antibody syndrome, mixed connective tissue disease, sarcoidosis). Infectious causes of myelitis include EBV, CMV, poliovirus, herpes simplex virus (HSV), HIV, human T-lymphotropic virus type 1 (HTLV-1), Lyme, syphilis, tuberculosis, and schistosomiasis.
As the patient’s course progressed, he developed areflexia more suggestive of lower motor neuron involvement, as can be seen in Guillain-Barré syndrome ( Fig. 53.2 ) and acute flaccid myelitis (AFM). His asymmetric weakness and spinal MRI findings were concerning for possible AFM, particularly in the setting of a recent upper respiratory infection with positive entero/rhinovirus testing. While polio is the classic cause of acute flaccid paralysis, many nonpolio infections can cause lower motor neuron presentations (including enterovirus D-68 ( Fig. 53.3 ) and A-71, coxsackievirus, echovirus, West Nile virus, adenovirus, herpesvirus, and flaviviruses). A clear sensory level is more suggestive of inflammatory myelitis than AFM. Of note, both myelitis and AFM are expected to have associated pleocytosis, but this finding may be delayed from clinical presentation.
Guillain-Barré syndrome. Spine MRI, (A) sagittal cervical and (B) axial and (C) sagittal lumbar postcontrast T1, shows smooth thickening and enhancement of nerve roots with preferential involvement of ventral motor roots.
Enterovirus D-68 rhombencephalomyelitis. Cervical spine MRI, (A) sagittal T2, shows longitudinally extensive myelitis with ill-defined brainstem and cord involvement ( arrows ). (B) Axial T2 shows asymmetric hyperintensity of the dorsal brainstem ( arrowhead ).
Other diagnoses less likely given clinical history and exam include trauma, ischemic and hemorrhagic myelopathy, spinal cord tumor, and abscess.
Imaging Differential Diagnoses
Edema involving spinal cord gray and white matter in children is suggestive of transverse myelitis. However, there is a wide differential diagnosis with few reliable biomarkers. Nutritional deficiencies (vitamins E and B 12 , copper) can affect the dorsal and lateral columns. Spinal cord ischemia can be associated with vascular anomalies such as arteriovenous shunts, vasculitis such as Behcet disease, and fibrocartilaginous embolism. MRI reveals pencil-like T2 hyperintensities of the anterior horns of gray matter (“snake eye” or “owl eye” appearance) ( Fig. 53.4 ). Diffusion-weighted imaging (DWI) changes are not sensitive or specific for distinguishing ischemia from infection.
