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Visual Field Defects in Vascular Lesions of the Lateral Geniculate Body

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Visual Field Defects in Vascular Lesions of the Lateral Geniculate Body 12 Journal ofNeurology, Neurosurgery, and Psychiatry 1992;55:12-15 Visual field defects in vascular lesions of the J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.1.12 on 1 January 1992. Downloaded from lateral geniculate body Cristian Luco, Arnold Hoppe, Mariana Schweitzer, Ximena Vicufia, Aldo Fantin Abstract minimal in optic tract lesions.' A vascular Corresponding retinal nerve fibres begin lesion of the lateral geniculate body (LGB) is their path in the eyes and end in a single an exception to the relationship between con- visual cortical cell. Because of this gruency of the visual field defect and the arrangement, lesions in the anterior anteroposterior localisation. Even though the visual pathway produce incongruent LGB is on the anterior third of the retrochias- visual field defects and in the posterior matic visual pathway and a lesion just in front pathway congruent field defects. The or behind this nucleus produces incongruent lateral geniculate body is on the anterior field defects, the visual field defect found in third of the visual pathway. A lesion of these cases is a congruent wedge-shaped this nucleus produces moderately to homonymous hemianopia or the sparing of a completely congruent visual field symmetrical wedge-shaped area, and loss of defects. Five patients with ischaemic upper and lower quadrants. These visual field lesions of the lateral geniculate body are defects are infrequent in lesions in other sites reported. Two patients had a wedge- of the visual pathway and anatomically almost shaped homonymous hemianopia, two impossible in a vascular lesion of the visual other cases had congruent superior cortex. Another type of field defect found with homonymous quadrantic defects and the LGB lesions is congruent quadrantic contrac- Department of fifth a quadruple sector defect. The tion of the upper or lower visual field.2 Neurology, School of lateral geniculate body has a dual blood Lesions of this nucleus are infrequent and the Medicine, Universidad from the anterior Cat6lica de Chile, supply choroidal use of CT enables a more accurate diagnosis. Santiago artery (branch from internal carotid We report on five patients with vascular C Luco artery) and from the lateral choroidal lesions of the LGB. Two had the typical A Hoppe artery (branch from the posterior wedge-shaped homonymous hemianopia, two A Fantin cerebral artery). A schematic diagram other cases had superior congruent homo- Department of Neurology, School of has been devised which shows that a nymous quadrantic defects (quadrantanopsia) Medicine, Universidad knowledge of the visual field disrupted and the last one a quadruple sectoranopia. In de Chile, and Neuro- can identify the arterial system involved. four cases CT scan revealed a vascular lesion Ophthalmology Unit, Instituto de of the LGB and in one case the test was Neurocirugia, The fibres of the visual pathway that carry negative. Santiago, Chile information from the retina to the calcarine http://jnnp.bmj.com/ C Luco cortex M Schweitzer have a systematic spatial arrangement. X Vicufia Lesions in this pathway produce characteristic Case reports Correspondence to: visual field defects whose analysis frequently Case 1 Dr Luco, Department of allows localisation of the lesion, especially in Neurology, Universidad This patient was a 62 year old male with an Cat6lica de Chile, Marcoleta the anteroposterior axis. One of the most unremarkable past medical history. In 387, Santiago, Chile frequently used features in diagnosis is con- December 1986 he had a severe headache and Received 4 October 1990 and gruency-that is, the similarity between the on September 29, 2021 by guest. Protected copyright. in revised form 7 March "visual disturbance". On examination, a few 1991. visual field defect of one eye and the other. hours later the only abnormality was high Accepted 26 March 1991 Congruency is maximal in cortical lesions and blood pressure (160/100 mm Hg). The neurological examination was normal except for the visual fields. The neurophthalmo- logical examination showed a normal visual acuity, pupillary reaction, ocular motility and ocular fundus. A right congruent, wedge- shaped homonymous hemianopia (fig 1) was detected. A brain CT scan disclosed an ischaemic lesion of the posterolateral area of the left thalamus, enhanced by contrast (fig 2). Eight months later the visual field was normal, and the patient had no visual complaints. Case 2 This patient was a 49 year old male with moderate arterial hypertension, who suddenly noticed a disturbance of his left visual field with no other general or ophthalmological Figure Wedge-shaped, right homonymous hemianopia. Case 1. complaints. On neurophthalmological Visualfield defects in vascular lesions of the lateralgeniculate body 13 Figure 2 Brain CT scan pupil reactions and eye movements. The fun- J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.1.12 on 1 January 1992. Downloaded from with a left posterolateral dus examination revealed a tilted disc with thalamic lesions. Case 1. atrophy of peripapillary pigment epithelium. The contrast enhanced brain CT scan showed "..t.A a right thalamic and inferotemporal (hip- pocampus) ischaemic lesion (fig 4). The visual field disclosed a congruent left superior quadrantic defect (fig 5). Six months later the visual field had returned to normal. Case 4 This patient was a 56 year old male with a two .1 year history of gastrectomy for a peptic ulcer, without arterial hypertension or diabetes mellitus, who, after bending down, experi- enced a slight dizziness and a strange visual feeling. General and neurological examination were normal. Neurophthalmological examina- tion showed normal visual acuity, pupillary reaction, ocular motility and fundus. On visual field examination there was a congruent left superior quadrantanopsia (fig 6). Brain CT scan showed a right posterolateral thalamic infarct (fig 7). A year later, the neurophthal- mological control was normal and CT scan revealed a small hypodense lesion of the same examination his visual acuity was 6/6 in both area. eyes, the pupil reaction, ocular motility and fundus examination were normal. The visual Case S field had an incomplete wedge-shaped left This patient was a 56 year old woman with homonymous hemianopia (fig 3). The chronic arterial hypertension who had been neurological examination was otherwise nor- treated with propranolol and diuretics. Her mal. A second generation CT scan did not current illness began with a sudden onset right disclose a definite lesion. Based on the visual hemiparesis and a right visual field deficit. On field defect and a negative CT scan, an general examination her blood pressure was ischaemic lesion of the LGB was suggested. 130/90, with no other abnormality. On neurological examination there was a mild right Case 3 hemiparesis and a right visual field defect on This patient was a 71 year old female with a confrontation. The hemiparesis partially clinical history of pulmonary tuberculosis, recovered in four hours, but the field defect moderate arterial hypertension and cardiac showed no change. A brain CT on admission an arrythmia due to auricular flutter. Her was normal. The neurophthalmological http://jnnp.bmj.com/ present illness began suddenly one night with examination two days later showed normal tachycardia followed by significant polyuria vision in both eyes, with normal ocular and a mild left hemiparesis of sudden onset. On examination, a few hours later, the blood pressure was 150/90, with normal cardiac rhythm. On neurological examination she had a mild left sensory motor deficit. Neur- ophthalmological examination showed right on September 29, 2021 by guest. Protected copyright. visual acuity 6/18 and left 6/12, with normal __ ~W__ Figure 4 Brain CT scan with a right thalamic and Figure 3 Wedge-shaped, left homonymous hemianopia. Case 2. inferotemporal ischaemic lesion. Case 3. 14 Luco, Hoppe, Schweitzer, Vicufia, Fantin The LGB is a wedge-shaped structure J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.1.12 on 1 January 1992. Downloaded from situated at the posterolateral aspect of the thalamus, which receives information from the second neuron of the visual pathway. Fibres from the ipsilateral retina end in layers 2, 3 and 5 and those from the contralateral retina in layers 1, 4 and 6, without interaction between them. The LGB is on the anterior third of the retrochiasmatic visual pathway receiving the output of the optic tract. Different authors34 have suggested that visual field defects in patients with LGB lesions are incongruent. However, when analysing the literature, as well as our own cases, we conclude that field defects in a vascular LGB lesion appear to have moderate to complete congruency. This is an Figure 5 Left superior quadrantopsia. Case 3. exception to the rule that the nearer the lesion is to the calcarine cortex the greater the con- gruency ofthe visual field defect. On analysing visual fields this exception should be taken into motility, pupillary light reaction and ocular account, even though LGB lesions are so fundus. Her visual field revealed a right infrequent that they are not mentioned in superior and inferior homonymous quandran- reports of a large series of homonymous tic defect with sparing of a wedge-shaped area hemianopias.5 symmetrically located along the horizontal The LGB has a dual blood supply: from the meridian (fig 8). A second CT carried out five anterior choroidal artery (branch ofthe internal days later showed a left basal temporal lobe carotid artery) and from the lateral choroidal ischaemic lesion (fig 9). Four vessel cerebral artery (branch ofthe posterior cerebral artery). angiograms were normal. Frisen et al6 have reported two patients with a wedge-shaped congruent homonymous hemi- anopia showing that the lesion was due to an Discussion occlusion of the lateral choroidal artery. The The arrangement of the nerve fibres along the same author7 reported another patient with a visual pathway enables us to have a single brain superior and inferior homonymous defect image because retinal receptors, which receive which he called a quadruple sectoranopia.
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