Sixth nerve palsy affects the lateral rectus muscle, limiting outward movement of the eye. It causes horizontal double vision, especially when looking toward the affected side.
Causes and presentation
Onset can be sudden or gradual.
- Common causes include microvascular ischaemia, trauma, raised intracranial pressure, and tumours
- Esotropia worse on gaze toward the palsied side and at distance
- Compensatory head turn toward the affected side to reduce diplopia
- In children, may present with strabismus and risk of amblyopia
Management
Treatment addresses both cause and symptoms.
- Investigation for underlying systemic or neurological disease, especially in younger patients
- Observation for spontaneous recovery in microvascular palsies over 3-6 months
- Temporary prisms or occlusion to relieve diplopia
- Strabismus surgery or botulinum toxin if deviation becomes stable but persistent
