neurologic disorders
Sixth Cranial (Abducens) Nerve Palsy
Key Points
Sixth cranial (abducens) nerve palsy typically results from small-vessel disease, particularly in diabetics, but the cause is often unidentified. This palsy causes impaired abduction and horizontal diplopia. To identify the cause, do neuroimaging (preferably MRI), followed by lumbar puncture if imaging results are normal and benign intracranial hypertension is suspected; if vasculitis is suspected, start with erythrocyte sedimentation rate (ESR), antinuclear antibodies, and rheumatoid factor. If increased intracranial pressure is excluded in children, consider an upper respiratory infection. Sixth cranial nerve palsy commonly resolves when the cause is nontraumatic and may do so posttrauma; treatment of infection, inflammation, or tumor, when present, may result in improvement. 