dorsal midbrain syndrome
Neurological syndrome affecting vertical gaze and pupillary function due to lesions in the dorsal midbrain region.
Full Definition
Dorsal midbrain syndrome, also known as Parinaud syndrome, is a constellation of eye movement and pupillary abnormalities resulting from lesions affecting the dorsal midbrain, particularly the pretectal region and posterior commissure. The classic features include impaired vertical gaze (especially upward), convergence-retraction nystagmus on attempted upgaze, light-near dissociation of the pupils (pupils that respond to accommodation but not to light), and eyelid retraction (Collier sign). The syndrome can result from various causes including pineal region tumors, hydrocephalus, brainstem infarction, or inflammatory conditions. Additional features may include skew deviation, accommodative spasm, and vertical diplopia. The condition is named after Henri Parinaud, who first described the clinical features. Early recognition is crucial as some causes, particularly those causing acute hydrocephalus, require urgent neurosurgical intervention.
Usage
Usage note: Also called Parinaud syndrome; specify which eye movement findings are present.
In Context
- "The patient's upgaze palsy and light-near dissociation were consistent with dorsal midbrain syndrome." — Neuro-ophthalmology examination
- "MRI revealed a pinealoma causing dorsal midbrain syndrome with characteristic eye movement abnormalities." — Imaging correlation