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Optic neuritis is pathologically very similar to multiple sclerosis. The myelin sheaths which surround and insulate the nerve fibers are gradually destroyed by a pathological process of unknown origin. However, in optic neuritis this demyelinating process occurs in the optic nerve. With the advent of modern imaging techniques, particularly magnetic resonance imaging (MRI), it has become clear that the optic nerve may be affected near the eye, within the canal which leads into the skull, or inside the skull. There have been suggestions based on imaging studies that the optic chiasm might also be affected in some cases of optic neuritis. However, in these reports, the involvement of the optic chiasm, an anatomical crossing point in which optic nerve fibers split up to travel to their destination in the left or right brain hemisphere, has not been correlated with any actual clinical symptoms. Six cases are presented in which the patients had symptoms which were suggestive of optic neuritis lesions in the optic chiasm. In four of these six cases, the expected lesions could be confirmed using magnetic resonance imaging. In most cases, however, demyelinating lesions in the optic chiasm do not occur alone; additional lesions are present elsewhere along the optic nerve. In the present series, the presence of additional lesions in the optic nerve probably explains the ocular pain experienced by three of the patients. In general, optic chiasmal neuritis responds to treatment with steroids and the prognosis is generally favorable. However, in some cases, the appearance of optic chiasmal neuritis is the first indication of the development of more serious disease. Similarly, optic neuritis may be the first indication of multiple sclerosis in a patient. (Consumer Summary produced by Reliance Medical Information, Inc.)

The authors have observed two cases of neurologic disease occurring in a brother and sister. They presume that the ailment is inherited as a recessive trait, and attempts to classify it with known genetic disorders suggest that the syndrome shared by these siblings is probably a distinct clinical entity. The sister developed blinking and abnormalities of movement at the age of 17. The problems with movement worsened. She developed visual difficulties, and the development of pigment clumping in the retina was observed. Her speech became unintelligible. Her brother was documented as having severe hearing loss at 20 months of age and fell frequently as a child. A full evaluation was conducted when he was 23 years of age; pigmented retinopathy and intermittent severe blinking were observed. The two patients displayed a syndrome that most closely resembles Hallervorden-Spatz syndrome. However, Hallervorden-Spatz syndrome usually involves both early onset and a relentless progression to death in early adulthood. These siblings are continuing to function in society long after the appearance of symptoms. Magnetic resonance imaging did not reveal evidence of brain atrophy, which is common in Hallervorden-Spatz syndrome. In addition to a discussion of the symptoms of the two patients, the authors provide a detailed table of the known genetic disorders in which abnormal retinal pigmentation is known to be a feature. (Consumer Summary produced by Reliance Medical Information, Inc.)

Horner's syndrome results from the paralysis of cervical (in the neck) sympathetic nerves. The symptoms include drooping of the eyelid and a sinking in of the eyeball. There is often flushing on the affected side of the face. The lesion causing Horner's syndrome may be located at any point along the pathway from the hypothalamus to the eye socket. Horner's syndrome is probably caused most commonly by lesions in the brainstem. The authors now report a case in which Horner's syndrome resulted from an infarction (reduction in blood flow) of the hypothalamus. When Horner's syndrome results from a hypothalamic lesion, the cause is usually a tumor or a hemorrhage. Because of the rich blood supply to this part of the brain, infarctions are rare. In this case (a 62-year-old woman), nuclear magnetic imaging demonstrated a hypothalamic infarction, which extended into the posterior internal capsule. While some symptoms such as dysarthria (impaired speech) were present which could be attributed to the lesion in the internal capsule, there were no other symptoms indicative of hypothalamic damage except the Horner's syndrome. In up to 30 percent of all individuals, a fetal pattern of circulation can persist into adulthood; in this pattern, the entire blood supply of the hypothalamus derives from the carotid artery. Therefore, the hypothalamus is sensitive to disruptions in carotid blood flow in these subjects. In the current patient, however, arteriography revealed no such persistent fetal circulation. The patient was placed on aspirin and sent home; she remains asymptomatic and a follow-up at four weeks revealed only a narrow furrowing of the left eyelid. (Consumer Summary produced by Reliance Medical Information, Inc.)

The occlusion of an artery serving the eye can lead to sudden and irreversible loss of vision; such an event may well be called an ''ocular stroke.'' Two cases illustrate that the occurrence of a rapid loss of vision in one eye may be indicative of the presence of a carotid artery dissection. In an arterial dissection, the inside wall of the artery cracks and high-pressure arterial blood is forced in. The blood forces itself along a significant length of the artery between the layers of the arterial wall. Splitting the layers as it forces its way, the blood literally ''dissects'' the arterial wall. The blood within the arterial wall can then force the inner wall into the normally open arterial lumen, thus cutting off normal blood flow. Such dissection of the carotid arteries, which carry blood into the head, is a major cause of cerebrovascular symptoms, especially in young patients. In both presented cases, the loss of vision in one eye was apparently the consequence of a previously unrecognized carotid dissection. The authors suggest that the possibility of carotid dissection should be considered in cases of sudden unilateral vision loss or impairment. (Consumer Summary produced by Reliance Medical Information, Inc.)