Immediate features of paralysis
The acute features of oculomotor nerve palsy may include:
- divergent strabismus:
- the paralysed eye is rotated outwards and downwards when the normal eye fixates - due to intact actions of lateral rectus and superior oblique muscles
- concurrent trochlear nerve palsy is indicated by absence of intorsion on attempted down-gaze
- only lateral movement is possible
- pupil may be fixed and dilated, and accommodation lost:
- however the pupil is spared in 75% of cases due to diabetes since the inner pupillary fibres are more affected than the outer ones
- however the pupil is spared in 75% of cases due to diabetes since the inner pupillary fibres are more affected than the outer ones
- ptosis of the upper eyelid - may cover the pupil due to loss of action of levator palpebrae superioris
- ipsilateral oculomotor nerve palsy may feature as part of Benedikt or Weber syndromes
- there may be a mild proptosis arising from loss of tone of three of the four recti muscles
Reference
- Libreros-Jiménez HM, Manzo J, Rojas-Durán F, et al. On the cranial nerves. NeuroSci. 2024 Mar;5(1):8-38.
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