A 39-year-old-male present with morning headaches associated with nausea for the last 2 months and an inability to look upwards. On examination, while upgaze is diminished bilaterally, downgaze is preserve and it is not corrected by the doll’s-head-manoeuvre. On examination of his pupils, his pupils constrict on accommodation but did not constrict on exposure to light. One also notices some mild eyelid retraction bilaterally. Where is the lesion localised to?
Frontal lobe
Dorsal midbrain
Ventral midbrain
Occipital
Cerebellar vermis
Dorsal midbrain
This patient has Parinaud syndrome as a result of a lesion at the dorsal midbrain. Lesions in the other four options do not result in Parinaud syndrome.
Rostral interstitial nucleus of medial longitudinal fasciculus lies at the dorsal midbrain and control vertical gaze. They project to the vestibular nuclei. It results in the following symptoms:
Upward gaze palsy, often manifesting as diplopia
Pupillary light-near dissociation (Pseudo-Argyll Robertson pupils)
Convergence-retraction nystagmus
It’s aetiology include:
Brain tumours in the midbrain or pineal gland (pinealoma)
Multiple sclerosis
Midbrain stroke