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Show Journal of Clillical Neuro-ophthaimoioxy 8(2): 85. 1988. Editorial Comment Exercise-Induced Visual Hallucinations © 1988 Raven Press. Ltd., New York The paper by Drs. Lessell and Kylstra in this issue of The Journal raises the interesting question of exercise-induced visual hallucinations, as documented in two patients with occipital lobe tumors. Case one showed an extraxial left occipital lobe meningioma but had no visual field defect on examination. Case two was a young man with a low-grade left occipital lobe astrocytoma who had a complete right hemianopia, splitting fixation. I was interested in the optokinetic responses in these patients and wrote Dr. Lessell about that point. He noted that he had repeatedly tested the optokinetic responses in case one with a striped drum and that they were always symmetrical (i.e., she had a "negative" a.N. sign as defined by Kestenbaum). He did not see the young man (case two) in the acute phase and no mention was made of his optokinetic responses at that time. When Dr. Lessell saw case two, he was on medication and he did not show good optokinetic responses in either horizontal direction. The reason these points are made is for the following reason: Dr. Cogan pointed out years ago that in patients with occipital lobe field defects the presence of horizontally intact and symmetrical optokinetic responses (the "negative" a.N. sign) was most commonly seen with vascular lesions, whereas in a patient with an occipital lobe field defect, if a consistently asymmetrical optokinetic response was found, this made one think of the possibility of a neoplastic lesion of the occipital lobe. For example, if in a patient with a right hemianopia (as case two here) targets were taken from the patient's left to his right, an intact response would be seen, whereas if targets were taken from the patient's right to his left (i.e., starting from the defective field and moving targets towards the intact field), a depressed to absent optokinetic response would be found. This asymmetry is called the "positive" a.N. sign. Dr. Lessell is quite correct that the optokinetic responses can be quite dampened to essentially absent in patients who are sedated, obtunded, on large doses of dilantin and phenobarbital, and the like, and, indeed, Dr. Fisher used to tell me years ago that if a patient had been given 200-250 mg nembutal, they would have totally abolished opto- 85 kinetic responses, an important point to remember. The point I'm trying to make is that you not only should not put the patient in a large cylindric chamber as is done with animals in research facilities, but that one can use the striped drum and in some cases a simple red-and-white striped optokinetic flag is even better because of the large sized targets subtended by that simple device. I have found that in some patients optokinetic responses are better with a drum-that in others the responses are better with a large optokinetic flagand that in other circumstances a simple cloth tape measure as is used to measure head circumference in infants is a better device, for the latter requires rather good acuity (perhaps 20/40-20/70) and one can get an objective measure of the visual acuity to some degree with it. If one has an occipital lobe tumor or a temporal lobe tumor with a negative a.N. sign, then the optokinetic responses are a particularly important clinical parameter to follow. If on a return visit the optokinetic responses have now become asymmetrical (i.e., a negative a.N. sign has become a positive a.N. sign), that is a very good clinical sign pointing to parietal lobe extension in that patient and points to recurrence or progression of the tumor. In the meantime, let us thank Drs. Lessell and Kylstra for bringing these important observations to our attention and let us be on the lookout for exercise-induced visual hallucinations in other cases. ane hearing that historical point before this paper might have even wondered if that might not be a "cerebral Uhthoff's sign" and could have mistakenly thought of a demyelinizing lesion, but that would be less likely because of the fact that seizures are commonly considered as arising in the cortical gray mantle, and multiple sclerosis would certainly be thought of as associated with white matter lesions; however, there is no question but that true seizures may occur in patients with multiple sclerosis and that has been documented in the literature. Thank you, Drs. Lessell and Kylstra, for reporting these interesting cases! J. Lawton Smith, M.D. |