The objective of this study was to describe the incidence and types of @entity227 after posterior globus pallidus internus (GPi) pallidotomy for @entity191 . The creation of the @entity75 carries a risk of damaging neighboring structures such as the optic tract. The reported frequency of @entity227 in @entity1 after pallidotomy varies from 0 to 40%. Goldmann visual field testing was performed on 40 @entity1 who underwent microelectrode-guided posterior GPi pallidotomy. The optic tract was identified during the procedure by listening during microelectrode recording for the evoked responses to light flashes and by assessing stimulation-induced subjective responses. After the first 18 @entity1 , lesioning thresholds were increased from 0.5 to > or =1.0 mA so that the lesion was placed more distant from the optic tract. The location of individual lesions was determined on postsurgical MRI. Three @entity1 (7.5%) had @entity227 likely related to the pallidotomy. These were contralateral homonymous superior @entity1805 , associated in two @entity1 with small paracentral @entity1019 . The incidence of @entity227 with the early technique was 11% (2/18) and decreased to 4.5% (1/22) after thresholds for lesioning were increased. Except for the location of the lesion relative to the optic tract (more ventral, adjacent to or extending into the optic tract), no other variable correlated with a post-pallidotomy @entity227 . Microelectrode-guided GPi pallidotomy is a relatively safe procedure as regards visual function even when the optic tract is used as a guide for lesion placement.

Visual fields in XXXX with posterior GPi pallidotomy.

@entity1 :: ('9606', 'Species') :: ['patients'] @entity227 :: ('MESH:D014786', 'Disease') :: ['visual field defect', 'visual field defects'] @entity75 :: ('MESH:D001927', 'Disease') :: ['pallidotomy lesion'] @entity191 :: ('MESH:D010300', 'Disease') :: ["Parkinson's disease"] @entity1805 :: ('MESH:D006423', 'Disease') :: ['quadrantanopias'] @entity1019 :: ('MESH:D012607', 'Disease') :: ['scotomas']
@entity1 :: (9606,Species) :: ['patients']
