Jacqueline M.S. Winterkorn

Anterior ischemic optic neuropathy in children: Case reports and review of the literature

Anterior ischemic optic neuropathy, infarction of the optic nerve head owing to inadequate perfusion through the posterior ciliary arteries, is a common cause of visual loss in adults but is rarely reported in children, in part because the diagnosis is overlooked. We report two cases of young children undergoing chronic peritoneal dialysis, who suffered bilateral visual loss from anterior ischemic optic neuropathy. Predisposing local anatomic and multiple systemic factors included a small optic nerve head with little cupping, possible intraocular hypertension, and systemic hypotension, hypovolemia, and anemia. The literature on anterior ischemic optic neuropathy is reviewed.

Resolution of chronic cluster headache after resection of a tentorial meningioma: case report.

Cluster headache is almost always idiopathic, but, in rare cases, associated intracranial lesions have been found. We describe a patient who had chronic cluster headache for more than 20 years. The headache immediately resolved upon resection of a tentorial meningioma. Prior reports of cluster headache as a manifestation of structural disease are briefly reviewed. In the patient described, the pain was referred from the right tentorium cerebelli to the right side of the face, in accordance with reported studies on the subjective localization of pain referred from posterior fossa structures. The accompanying abnormalities of autonomic function may have been mediated by central autonomic reflexes that are also involved in the pathogenesis of idiopathic cluster headache.

Distractibility of cats with lesions of the superior colliculus-pretectum during performance of a 4-choice visual discrimination

(1) Intact cats and cats with bilateral lesions of the superior colliculus-pretectum were trained on 4-choice, luminous flux discriminations in an apparatus consisting of a 6-foot square open field with 4 stimulus panels along one wall. After cats attained a high performance criterion on a 4-choice dark-light discrimination they were tested for distractibility by flashing a light behind one of the stimulus panels. (2) All intact cats and cats with lesions of the superior colliculus-pretectum learned the 4-choice luminous flux discriminations. Cats with lesions of the superior colliculus-pretectum, however, followed longer paths and had longer latencies to the correct door, even after attaining criterional performance. (3) All intact cats and cats with lesions of the superior colliculus-pretectum were distracted by the flashing light, as indicated by increased commission of errors, increased path lengths and increased response latencies on trials in which the distracting stimulus was presented. However, both intact cats and cats with lesions of the superior colliculus-pretectum habituated to the distracting stimulus. (4) These results are consistent with previous findings that cats with lesions of the superior colliculus-pretectum have difficulty in withholding incorrect responses or in shifting attention or response tendencies from the incorrect to the correct stimulus. (5) These results do not support the hypothesis that lesions of the superior colliculus produce deficits in attention as measured by distractibility to novel stimuli.

Resolution of Chronic Cluster Headache after Resection of a Tentorial Meningioma

ABSTRACTCLUSTER HEADACHE IS almost always idiopathic, but, in rare cases, associated intracranial lesions have been found. We describe a patient who had chronic cluster headache for more than 20 years. The headache immediately resolved upon resection of a tentorial meningioma. Prior reports of clust

Visual discrimination between spatially separated stimuli by cats with lesions of the superior colliculus-pretectum

(1) This study was designed to test the ability of cats with lesions of the superior colliculus-pretectum to discriminate between stimuli which are widely separated in space. (2) Intact cats and cats learning or relearning after lesions of the superior colliculus-pretectum, were trained on light-dark (LD) and horizontal-vertical stripe (HV) discriminations in a V-maze, where the stimuli were widely separated in space, or in a divided straight maze, where the stimuli were side by side. (3) Two types of errors were scored: door-push errors when the cat pushed open the incorrect door; alley-entrance errors when the cat entered the incorrect alley, but turned and entered the correct alley without having pushed the incorrect door. (4) In the V-maze as well as in the straight maze, cats with lesions of the superior colliculus-pretectum achieved criterional performance by alley-entrance and door-push scoring on LD and HV discriminations. Thus, cats with lesions of the superior colliculus-pretectum can locate or orient to widely separated visual stimuli well enough to discriminate between them from a distant choicepoint. (5) Cats with lesions of the superior colliculus-pretectum generally committed a larger number and higher percentage of alley-entrance errors during learning than unoperated cats in either maze. However, commission of alley-entrance errors was not further increased in the V-maze, where the stimuli were widely separated in space. (6) All unoperated cats committed alley-entrance errors as well as door-push errors suggesting that commission of alley-entrance errors may reflect a normal process in two-choice learning.

Deficits in luminous flux discrimination by cats with lesions of the superior colliculus-pretectum

(1) Intact cats and cats relearning or initially learning after bilateral ablation of the superior colliculus-pretectum were trained on a simple flux discrimination in a straight maze where the stimuli were either immediately side by side at the end of the runway or were separated by an opaque barrier. (2) After ablation of the superior colliculus-pretectum, each preoperatively trained cat had a significant deficit in retention of the luminous flux discrimination regardless of whether or not the stimuli were separated by a barrier or whether the correct stimulus was darker or lighter than the incorrect stimulus. (3) Under each of the different training conditions, every cat learning the flux discrimination initially after ablation of the superior colliculus-pretectum was retarded in comparison with intact cats. (4) The severity of the postoperative learning deficit correlated highly with the total extent of the lesion in the superior colliculus and pretectum.

Deficits in visual learning by cats with lesions of the visual cortex

Cats were trained for food reward in a divided straight maze or in a V-maze on a light-dark discrimination and on a series of horizontal-vertical stripe discriminations. Errors were scored by both door-push and alley-entrance criteria. After lesions of the visual cortex, cats could relearn or initially learn the light-dark discrimination but were not successfully trained to shift from brightness to pattern cues when learning the series of horizontal-vertical stripe discriminations, using a modified method of limits procedure. Both unoperated cats and cats with lesions of the visual cortex committed alley-entrance errors when learning the light-dark discrimination.