Study design: A case report of blunt cervical spine trauma associated with cord oedema at the C3/C4 level with temporary Frankel/American Spinal Injury Association Grade A quadriparesis and motion segment instability without evidence of associated bony lesions (spinal cord injury without radiological abnormality, SCIWORA lesion). Objectives: By means of a rare and illustrative case, the reader's attention is focused on eventual marked cervical motion segment instability in SCIWORA patients. Setting: A department of Neurology in Quito, Ecuador and a department of Neurosurgery in Bern, Switzerland. Method: A 73-year-old man sustained blunt cervical spine trauma. After resolution of paraparesis, dynamic studies of the cervical spine revealed translational instability of C3 over C4. The patient underwent segment fusion by intervertebral cage insertion and plate fixation. Results: The patient had recovered almost completely from tetraparesis under conservative treatment. The postoperative course was uneventful. Solid bony fusion of the C3/C4 motion segment was obtained. Conclusion: Despite normal cervical alignment, the lack of bony lesions and neurological recovery, magnetic resonance imaging and dynamic studies may reveal marked translational cervical motion segment instability requiring segment fusion in order to prevent ongoing damage of the spinal cord.