Although subacute ascending paralysis without sensory involvement is typically evocative of Guillain-Barré syndrome, it can alternatively be due to infection or inflammation of the spinal cord. We describe a 16-month-old female who presented with ascending flaccid paresis after an upper respiratory tract infection. She then developed signs of upper motor neuron involvement of the lower limbs associated with upper motor neuron involvement of the upper limbs. Motor nerve conduction and electromyographic studies of upper limbs demonstrated anterior horn cell involvement. Neuroimaging was consistent with cervical myelitis, and cerebrospinal fluid polymerase chain reaction was positive for herpesvirus-1. Although association with the primary infection of the respiratory tract may be fortuitous, possible neurotropic or hematogenous spread of herpesvirus-1 to the cervical spinal cord cannot be excluded.