tailieunhanh - Chapter 029. Disorders of the Eye (Part 23)

Parinaud's Syndrome Also known as dorsal midbrain syndrome, this is a distinct supranuclear vertical gaze disorder from damage to the posterior commissure. It is a classic sign of hydrocephalus from aqueductal stenosis. Pineal region tumors, cysticercosis, and stroke also cause Parinaud's syndrome. Features include loss of upgaze (and sometimes downgaze), convergence-retraction nystagmus on attempted upgaze, downwards ocular deviation ("setting sun" sign), lid retraction (Collier's sign), skew deviation, pseudoabducens palsy, and light-near dissociation of the pupils. Nystagmus This is a rhythmical oscillation of the eyes, occurring physiologically from vestibular and optokinetic stimulation or pathologically in a wide variety of diseases (Chap. 22) | Chapter 029. Disorders of the Eye Part 23 Parinaud s Syndrome Also known as dorsal midbrain syndrome this is a distinct supranuclear vertical gaze disorder from damage to the posterior commissure. It is a classic sign of hydrocephalus from aqueductal stenosis. Pineal region tumors cysticercosis and stroke also cause Parinaud s syndrome. Features include loss of upgaze and sometimes downgaze convergence-retraction nystagmus on attempted upgaze downwards ocular deviation setting sun sign lid retraction Collier s sign skew deviation pseudoabducens palsy and light-near dissociation of the pupils. Nystagmus This is a rhythmical oscillation of the eyes occurring physiologically from vestibular and optokinetic stimulation or pathologically in a wide variety of diseases Chap. 22 . Abnormalities of the eyes or optic nerves present at birth or acquired in childhood can produce a complex searching nystagmus with irregular pendular sinusoidal and jerk features. This nystagmus is commonly referred to as congenital sensory nystagmus. It is a poor term because even in children with congenital lesions the nystagmus does not appear until several months of age. Congenital motor nystagmus which looks similar to congenital sensory nystagmus develops in the absence of any abnormality of the sensory visual system. Visual acuity is also reduced in congenital motor nystagmus probably by the nystagmus itself but seldom below a level of 20 200. Jerk Nystagmus This is characterized by a slow drift off the target followed by a fast corrective saccade. By convention the nystagmus is named after the quick phase. Jerk nystagmus can be downbeat upbeat horizontal left or right and torsional. The pattern of nystagmus may vary with gaze position. Some patients will be oblivious to their nystagmus. Others will complain of blurred vision or a subjective to-and-fro movement of the environment oscillopsia corresponding to their nystagmus. Fine nystagmus may be difficult to see upon gross examination of