Rosh Emergency Medicine Practice Test 2025 - Free Emergency Medicine Practice Questions and Study Guide

In a patient with a fracture-dislocation at the C3-C4 vertebral level, respiratory paralysis would be expected due to the involvement of the cervical spinal cord that impacts the phrenic nerve. The phrenic nerve, which originates from the cervical roots C3 to C5, is responsible for innervating the diaphragm, the primary muscle involved in respiration. Damage to this area can lead to significant respiratory impairment or paralysis.

Considering the other options, ipsilateral hemiplegia would typically be associated with lesions affecting one side of the brain or the brainstem, rather than isolated cervical spine injuries. Muscle fasciculations might suggest lower motor neuron involvement but do not directly correlate with isolated upper cervical spine injury at the C3-C4 level. Upward plantar reflexes indicate upper motor neuron lesions, which would not be a primary manifestation of injuries localized to the cervical spine itself unless there were additional components of neurological injury considering the level of involvement. Thus, respiratory failure is the most direct and significant consequence of such an injury, highlighting why this is the expected finding.