[Quadruple sectoranopia]. / Quadruple sectoranopie.

Quadruple sectoranopia is a rare campimetric syndrome involving upper and lower, homonymous, congruent field blind sectors sparing a horizontal zone. Ischemia or infarction of the lateral parts of the lateral geniculate body, supplied by the distal part of the anterior choroidal artery, accounts for the visual field defect. Ganglionic nerve fiber atrophy matched to the visual field defect may be found if the lateral geniculate body dysfunction involves infarction. The four cases reported so far involve the following etiologies: a case of surgical ligation of the distal part of the anterior choroidal artery during cerebral meningioma removal, two cases of stroke with anterior choroidal artery infarction, and a case of vascular steal with anterior choroidal artery blood flow being shunted away from the lateral geniculate body by an arteriovenous malformation. If lateral geniculate body infarction is not solely involved, partial recovery may occur, ischemic quiescent neuronal areas being able to resume their activity following ischemia resolution.

[Congenital achromatopsia: electroretinogram in early diagnosis]. / Achromatopsie congénitale: interêt de l'électrorétinogramme pour le diagnostic précoce.

PURPOSE: Achromatopsia is a hereditary disease responsible for congenital low vision. Patients present with nystagmus, abnormal visual behavior or photophobia. Only the electroretinogram (ERG) can confirm the diagnosis in infants. PATIENTS AND METHODS: Thirty children referred for nystagmus or low vision were included in this retrospective study. A complete ophthalmological examination, an ERG and when possible a color vision test (Ishihara, Farnsworth 15 Hue test) was done. A Ganzfeld ERG was performed in accordance with ISCEV standards in patients more than 6 years of age. In younger patients, a simplified method using electroluminescent diode stimulation was used and a comparative ERG in accordance with ISCEV standards was performed when the patients were old enough. RESULTS: The ERG response was identical in children and adults. It confirmed the diagnosis of achromatopsia: the scotopic components obtained in dark adapted conditions were normal, (scotopic a-wave, b2 wave). The photopic components, recorded in light-adapted conditions, in order to inhibit the scotopic response (photopic wave, b1 wave), were not recordable. The color vision tests confirmed color blindness; however, in some patients color denomination was correct. CONCLUSION: The simplified ERG procedures performed in our series were reliable in detecting achromatopsia. However, it may not be sufficient to discriminate complete from incomplete achromatopsia.

[Quantitive evaluation of metamorphopsia in macular disease]. / Evaluation quantitative des métamorphopsies dans la pathologie maculaire.

INTRODUCTION: Visual acuity loss and scotoma are not the only functional consequence of macular disease. Frequently, patients also complain of metamorphopsia. Such visual distortion should be taken into account when evaluating the potential benefit of surgical procedures in macular disease. The Amsler grid does not allow any quantified analysis. In addition, a precise confrontation of the macular lesion with its functional consequences is not possible by this test. We present a new method for analyzing metamorphopsia in macular disease. METHODS: Opto-acustic modulation controlled laser emission allowed to generate a retinal image of 256 squares with an angular size of 1 degrees each. The subject was instructed to fixate the center of the grid and to push a handheld button every time he perceived abnormalities within the presented pattern. At the end of the procedure, the responses were represented on graph superimposed on the fundus image. 15 eyes of 15 successive patients complaining of metamorphopsia were included in this preliminary study. Informed consent was obtained prior to inclusion. All patients reported abnormalities on standard Amsler testing. The test-retest reliability was evaluated by repeating the same procedure between 2 hours and 7 days after the first procedure. RESULTS: The evaluation of 3 patients did not provide reliable information on metamorphopsia because of instable fixation. In 12 patients, a coherent response was obtained. In 9 eyes, the result was unchanged when repeating the procedure, concerning both the number of abnormal elements and their spatial distribution. CONCLUSION: The preliminary results appear to be encouraging, indicating a good reproducibility of the results of this method. They should be confirmed on a larger scale. Further work is necessary to evaluate the interest of this method in assessing functional results of macular surgery.

Multiple sclerosis with normal neuro-ophthalmological work-up: results of focal stimulations induced by a scanning laser ophthalmoscope.

OBJECTIVE: Visual evoked potentials (VEPs) are a very useful tool in diagnosis of multiple sclerosis (MS). Nevertheless, in some cases of the disease, VEPs are normal. The aim of this study was to evaluate the diagnostic value of focal checkerboard reversal stimulation based on opto-acoustic modulation generated by a scanning laser ophthalmoscope (SLO) in patients whose standard neuro-ophthalmological work-up was normal. METHODS: We prospectively studied 185 MS patients. In this cohort we found 30 patients with definite MS and normal neuroophthalmological work-up and we studied the diagnostic yield of focal visual stimulation in these patients. We performed focal SLO-elicited VEPs with two different spatial distributions: a central 8 x 8 degrees square field and a central 8 x 8 degrees exclusion square. The results were analysed in terms of age of the patient, course of the disease, and disability evaluated on the Expanded Disability Status Scale (EDSS). RESULTS: Mean latencies of focal VEPs were increased in MS patients compared to controls. In MS, focal stimulation allowed dysfunction of the visual system to be detected in 50% of patients who have been classified as normal according to conventional VEPs. VEP abnormalities were found to be correlated with the EDSS score (P<0.001) and the course of the disease (P<0.05). CONCLUSION: We have demonstrated the value of focal VEPs in MS diagnosis using SLO-based techniques. Further prospective work in patients with possible and probable MS should enable an evaluation of the sensitivity and specificity of this method in the early diagnosis of MS.

Outer retinal dysfunction in patients treated with vigabatrin.

OBJECTIVE: To assess early visual impairment related to vigabatrin prospectively in patients with and without visual symptoms. BACKGROUND: Vigabatrin acts as an inhibitor of gamma-aminobutyric acid (GABA) transaminase. GABA-induced ion transport changes in the retinal pigment epithelium have been described. The electro-oculogram (EOG) is a clinical test that reflects photoreceptor and pigment epithelium function. PATIENTS AND METHODS: Of the 22 consecutive patients presenting with a history of partial seizures currently treated with vigabatrin, 20 were included in the study. A complete clinical ophthalmologic and neurologic examination was performed, including static 100-point perimetry, EOG, and electroretinogram (ERG). RESULTS: In 14 of 20 patients, the light/dark ratio (Arden ratio) of the standard EOG was reduced in at least one eye. The a- and b-wave amplitudes and implicit time of the ERG were within the normal range in all patients; however, ERG oscillatory potentials could not be recorded in 10 patients. Twelve patients had visual field constriction; five complained of visual symptoms. The most severe visual impairment was observed in patients treated with both vigabatrin and valproate. CONCLUSIONS: There is some evidence of outer retinal dysfunction in the patients treated with vigabatrin. EOG, a more sensitive diagnostic tool than ERG for screening vigabatrin-treated patients, also appears to be more specific.

Creutzfeldt-Jakob disease: neurophysiologic visual impairments.

OBJECTIVE: The predictive value of electrophysiologic visual testing in Creutzfeldt-Jakob disease (CJD) was investigated, and the retinal pathologic findings in three cases are reported. BACKGROUND: The fatal prognosis of CJD, its transmissibility, and the lack of treatment make early diagnosis essential in averting human-to-human transmission. Electroretinogram and visual evoked potentials have been studied in few cases of CJD. METHODS: A visual electrophysiologic examination was performed in 41 consecutive patients referred with suspected CJD. The disease had been diagnosed in 24 patients (CJD group; 15 were confirmed neuropathologically and 9 by clinicolaboratory methods in accordance with diagnostic criteria). The remaining 17 patients were diagnosed with other neurologic disorders, and served as a control group. RESULTS: Flash electroretinogram revealed a significant decrease in the amplitude of the B1 wave (<60 microV) and the B/A ratio (<2) in the CJD group compared with those in the control group. Flash visual evoked potentials revealed no significant difference in latency, but amplitude was increased (>10 microV) in the CJD group, especially in patients with myoclonus. CONCLUSIONS: The visual electrophysiologic abnormalities provide an interesting noninvasive diagnostic tool in idiopathic CJD. The B1-wave decrease is closely correlated with the outer plexiform layer abnormalities observed on neuropathologic examination.

[Retinochoroidal involvement of type II membranoproliferative glomerulonephritis. An angiographic study with indocyanine green]. / Atteinte rétinochoroïdienne dans les glomérulonéphrites membrano-prolifératives de type II (GNMP II). Une étude angiographique au vert d'indocyanine.

PURPOSE: Type II measangiocapillary glomerulonephritis is related to dense deposits within the glomerular basal membrane and the basal membrane of the pigment epithelium (Bruch's membrane). Being a vasculitis, an angiographic study by indocyanine green (ICG) could possibly enlarge the semiologic features of this disease. METHODS: The indocyanine green angiographic changes in 3 patients with predialitic renal failure due to type II measangiocapillary glomerulonephritis (MCGN II) (dense deposit disease) are reported. A complete ophthalmologic examination, electroretinography, electro-oculography, fluorescein and indocyanine green angiography (ICG) were performed for each patient. RESULTS: Abnormal hyperfluorescent dots were seen on the same part of the fundus on both fluorescein and ICG angiography, though these locations were different for each of the three patients. These results seem to link the deposits to vascular changes within the choriocapillaris, which opposes them to drusen encountered in age related macular degeneration (ARMD). It appears that the choriocapillary lesions could be similar to the glomerular disease. CONCLUSION: Beyond the diagnostic challenges related to the nephrologic disease, it is known that subretinal neovascularization occurs in some cases of MCGN II, although the pathophysiologic mechanism of the deposits is probably not the same as in ARMD. Therefore, ICG angiography should be performed when MCGN II is first known, serving as an initial examination for further follow-up.

The mechanism of spinal cord injury after simple and double aortic cross-clamping.

Ischemic spinal cord injury after cross-clamping of the descending aorta can occur independently of aortic disease. In a previous study we had shown a precipitous uniform fall of spinal surface oxygen tension downstream to the clamping site irrespective of level. In the present paper, the hemodynamic changes in the spinal and aortic collateral circulation were investigated. Pressures were measured in the proximal, distal, and excluded aortic segments (descending thoracic and lumbar aorta) as well as in the intercostal and the lumbar arterial beds. Before high aortic occlusion, pressures in the intercostal and lumbar arterial beds were lower than aortic pressure. Along with the postclamping fall in distal arterial pressure, intercostal and lumbar arterial bed pressure decreased further but remained above aortic pressure. Exclusion of the thoracic aorta by double clamping restored intercostal bed pressure almost to control, whereas exclusion of the abdominal aorta hardly affected lumbar bed pressure. We conclude that spinal collateral circulation is more highly developed in the thoracic than in the lumbar region. After aortic cross-clamping, blood tends to drain away from the spinal cord rather than supplying it longitudinally. Under clinical conditions, therefore, retrograde bleeding into the opened aorta as well as into the aorta downstream to the distal clamp should be minimized and larger vessels originating from the aorta should promptly be anastomosed to the graft.

Direct measurements of oxygen tension on the spinal cord surface of pigs after occlusion of the descending aorta.

Spinal cord injury is the most dreaded complication of operative procedures on the descending aorta. Our previous experimental study on pigs indicated that an increase in the cerebrospinal fluid pressure after aortic cross-clamping did not influence the occurrence of spinal cord injury. We therefore concluded that the cause of spinal cord injury after aortic cross-clamping is due to primary oxygen deficiency in the spinal cord distal to the occlusion site, especially in the area supplied by the artery of Adamkiewicz. The aim of the present study is to examine the primary ischemic cause of spinal cord injury after aortic cross-clamping by directly measuring the oxygen tension on the spinal cord surface in pigs. During the occlusion phase, oxygen tension decreased significantly distal to the clamping site and especially in the areas supplied by the artery of Adamkiewicz both after occlusion of the high thoracic (Group I) and the lumbar aorta (Group II). The marked decrease in oxygen tension proves that hypoxia is the primary reason for spinal cord injury. The presence of a "steal phenomenon" should be discussed.

Lumbar and thoracic spinal cord oxygen tension during aortic cross-clamping.

In order to investigate the changes in tissue oxygen and the efficiency of the collateral circulation in the different regions of the spinal cord (SC) during aortic occlusion, surface PO2 (sPO2) was measured on the exposed SC in the pig in the lumbar (L3-5) as well as in the thoracic (Th6-8) parts before, during and after a 45 minute occlusion. The pigs were divided into two groups: group IA: cross-clamping of the aorta immediately below the left subclavian artery; group II: occlusion of the aorta immediately above the arteria radicularis magna anterior (ARMA). In response to occlusion, the sPO2 distal to the occlusion always decreased significantly (group IA: mean lumbar sPO2 from 42.3 mm Hg to 3.2 mm Hg, mean thoracic sPO2 from 34.9 mm Hg to 3.9 mm Hg; group II: mean lumbar sPO2 from 28.0 mm Hg to 7.9 mm Hg). Mean thoracic sPO2 in group II remained constant. No statistically significant differences between the distal regions could be established. The collateral circulation in the thoracic as well as in the lumbar region was insufficient at least during occlusion.

The arteria radicularis magna anterior as a decisive factor influencing spinal cord damage during aortic occlusion.

Cross-clamping of the descending aorta immediately below the subclavian artery may result in damage to the spinal cord. Despite various protective procedures, the risk of such damage cannot be entirely eliminated. In an experimental study with 47 pigs, the influence of various factors on the genesis of spinal cord damage was examined. The pigs were divided into five groups: Groups I to IV--occlusion of the descending aorta for 45 minutes; Group I--no reduction in arterial blood pressure proximal to the site of occlusion; Group II--like Group I, plus drainage of the cerebrospinal fluid; Group III--reduction in arterial blood pressure; Group IV--like Group III, plus drainage of the cerebrospinal fluid; Group V--permanent ligation of the artery of Adamkiewicz. The degree of permanent spinal cord damage was 85.7% (Groups I to IV, six animals) and 71.4% (Group V, five animals). Thus there were no significant differences among the various groups. The frequency of spinal cord damage was independent of arterial blood pressure, intracranial pressure, and intraspinal pressure. The intracranial pressure and the intraspinal pressure were significantly dependent upon the central venous pressure but were independent of the arterial blood pressure.

Response of spinal cord oxygen tension to aortic occlusion.

In order to study the factors influencing spinal cord injury resulting from occlusion of the descending aorta, the local surface PO2 (sPO2) was measured in the lumbar region (L4-5) of the exposed spinal cord after laminectomy in the pig. This is the area supplied by the arteria radicularis magna anterior (ARMA). The following aspects were considered: duration of occlusion, blood supply by the ARMA, distribution and width of spinal cord collaterals. The animals were divided into two groups. In group I (n = 7) the descending aorta was occluded immediately below the left subclavian artery; in group II (n = 7) the abdominal aorta was occluded immediately superior to the ARMA. Occlusion induced a rapid sPO2 decrease in all animals, from 29 to 3 mm Hg in group I (-14 mm Hg/min) and from 28 to 8 mm Hg in group II (-12 mm Hg/min). After 45 minutes of occlusion the blood flow through the aorta was released giving a pronounced sPO2 overshoot (36 mm Hg) about 10 minutes later. After 20 minutes there had been a return to initial sPO2 values. The results of this study confirm the hypothesis that spinal cord injury during occlusion of the descending aorta is primarily due to ischemic hypoxia/anoxia.