midbrain signs
Last reviewed 07/2021
Ocular abnormalities are a prominent feature of space- occupying lesions in the midbrain. Presentation includes:
- lesions of the upper midbrain - weakness of conjugate deviation upwards and ptosis
- lesions of the lower midbrain - weakness of conjugate deviation downwards - often accompanied by ptosis and weakness of convergence
- pupils unequal and dilated
- reactions to light and to convergence-accommodation may be both lost, or just the former may be absent
- nuclear ophthalmoplegia may be asymmetrical
- headache, papilloedema, vomiting from hydrocephalus
- nystagmus and ataxia may result from injury to cerebellar pathways
- compression of lateral lemniscus may cause unilateral or bilateral deafness
- tremors, tonic convulsions, loss of consciousness may occur