Cortical Blindness: Etiology, Diagnosis, and Prognosis Michael S. Aldrich, MD," Anthony G. Alessi, MD," Roy W. Beck, MD,$ and Sid Gilman, MDI We examined 15 patients with cortical blindness, reviewed the records of 10 others, and compared these 25 patients to those in previous studies of cortical blindness. Although cerebrovascular disease was the most common cause in ow series, surgery, particularly cardiac surgery, and cerebral angiography were also major causes. Only 3 patients denied their blindness, although 4 others were unaware of their visual loss. Electroencephalograms (EEGs) were performed during the period of blindness in 20 patients and all recordings were abnormal, with absent alpha rhythm. Visual evoked potentials recorded during blindness were abnormal in 15 of 19 patients, but did not correlate with the severity of visual loss or with outcome. Bioccipital lucencies were found in computed tomographic (CT) scans of 14 patients; none of the 14 regained good vision. Recovery of vision was poor in all 8 patients who had a spontaneous stroke, but fair or good in 11 of the other 17 patients. Prognosis was best in patients under the age of 40 years, in those without a history of hypertension or diabetes mellitus, and in those without associated cognitive, language, or memory impair- ments. We conclude that (1) the prognosis in cortical blindness is poor when caused by stroke; (2) EEGs are more useful than visual evoked potentials for diagnosis; and (3) bioccipital abnormalities shown on CT scan are associated with a poor prognosis. Aldrich MS, Alessi AG, Beck RW, Gilman S: Cortical blindness: etiology, diagnosis, and prognosis. Ann Neurol 21:149-158, 1987 Cortical or cerebral blindness (CB) refers to loss of vision been a change in the distribution of causes of CB in produced by lesions affecting geniculocalcarine visual the last 10 years; (2) the frequencies of specific fea- pathways. Complete CB is much less common than tures of CB and their relation to etiology, including incomplete blindness. denial and unawareness of blindness, visual distortions Six series of patients with CB have been reported and hallucinations, and electrophysiological abnor- IS, 7, 19, 32, 35, 441. Reese 1351 reported that the malities; (3) whether these features are helpful in the prognosis was better for CB occurring after ven- diagnosis of CB; and (4) whether specific clinical, ra- triculography than for CB caused by vascular disease. diological, or electrophysiological findings can be used Symonds and Mackenzie 1441 noted that in CB due to to predict prognosis. vascular causes, loss of vision was usually sudden; blindness was permanent in a quarter of the patients; Methods and denial, hallucinations, visual agnosia, and spatial We reviewed the charts of all adult inpatients with a dis- disorientation were inconstant features. Bergman E51 charge diagnosis of CB, central visual disturbance, or noted the absence of alpha activity in the electroen- unclassified visual disturbance who were seen at the Univer- cephalogram (EEG) and its reappearance with recovery sity of Michigan Hospitals between 1974 and 1984. Between of vision. Nepple and colleagues [32] described 15 June 1982 and June 1984, patients with CB were examined patients with bilateral homonymous hemianopia; the by one or more of the authors, as were previously diagnosed patients who returned for follow-up. Patients were consid- most common causes were vascular disease, uncal her- ered to have had cortical blindness if severe bilateral niation, and migraine. Bogousslavsky and associates homonymous visual deficits had developed that lasted longer [71 prospectively followed 58 patients with unilateral than 24 hours, and if there were reactive pupils and no evi- homonymous hemianopia and found that 13 devel- dence of an ocular or psychogenic cause of blindness. From a oped cortical blindness. total of 351 chart reviews and patient examinations, we In this study we report the clinical characteristics identified 25 patients with CB. An additional 11 patients had and laboratory results in 25 patients with cortical blind- cortical blindness for less than 24 hours due to transient ness in an attempt to determine: (1) whether there has ischemic attacks (n = 5), migraine (n = 3), angiography (n From the Departments of *Neurology, ?Neurosurgery, and Address reprint requests to Dr Aldrich, Department of Neurology, $Ophthalmology, University of Michigan Medical Center, Ann Ar- 1920/03 16 Taubrnan Center, University of Michigan Hospitals, Ann bor, MI. Arbor, MI 48109-0316. Received Mar 25, 1986, and in revised form June 17. Accepted for publication June 18, 1986. 149 = 2), or seizures (n = 1).The most common diagnoses in Three developed a partial field loss, followed several the remaining 3 15 patients were homonymous hemianopia, days later by loss of the remaining vision, and 3 de- amaurosis fugax, and optic neuritis. All patients had been scribed a period of gradual visual deterioration over examined by a neurologist or an ophthalmologist; 15 of several minutes or hours. Three patients had perma- the patients had been examined by one or more of the nent complete blindness and several others described a authors. period of complete visual loss but had some percep- For each of the 25 patients, we reviewed the clinical tion of light or motion at the time of examination days course, findings from neurological and ophthalmological ex- or weeks later. Two patients complained of a more aminations, and the results of computed tomographic (CT) brain scans, EEGs, flash visual evoked potentials (FVEPs) severe visual loss than was indicated by objective test- and pattern reversal visual evoked potentials (PRVEPs). We ing. Frank denial occurred in only 3 patients and was evaluated cognitive, language, and memory functions with variably accompanied by complaints of poor lighting bedside tests of the ability to: (1) recall three objects at 1 and and by confabulated descriptions of objects and faces. 3 minutes; (2) recall names of presidents of the United Four other patients, all of whom had experienced vi- States; (3) repeat strings of digits forwards and backwards; (4) sual disturbance after cardiac surgery, appeared inat- subtract sevens serially from 100; (5) perform simple arith- tentive to their visual loss or were not fully aware of it. metic; (6) discriminate right and left; (7) follow one- and two- Five patients complained of visual difficulty apparently step commands; (8) repeat and write short sentences; and (9) within minutes of the onset. These included 2 patients name objects. For the purpose of this study, we defined whose blindness developed during radiological pro- preexisting visual field deficits as those present for at least 1 cedures. month prior to the onset of blindness. We rated the outcome as good (when vision returned to the previous level), fair Two patients had partial seizures with visual halluci- (when visual acuity was 20/100 or better in both eyes and nations during the onset of blindness, documented by there was a consistent ability to count fingers in at least one ictal EEG recordings. One had a prolonged hallucina- hemifield), or poor (when visual acuity was less than 20/100 tion of ffashing red lights in the left hemifield [3],and in both eyes and there was no consistent ability to count the other had repeated images of four friends moving fingers in more than one quadrant). from left to right across his visual field. Four other CT brain scans were obtained in 19 patients. In all cases, patients experienced illusions or hallucinations, 1 dur- the slice image width was 10 mm, and the slice angle was 15 ing the onset of blindness and the other 3 during re- degrees from the canthomeatal line (except for Patient 17 in covery. whom the slice angle was 0 degrees). For each CT slice image, the region of abnormality was plotted on a standard- ized slice template C21, 30). Diagnostic Studies EEGs were assessed for the presence of: (1) a visually CT brain scans were obtained in 19 patients (Figs 1 detectabie alpha rhythm, defined as a posterior dominant 8- to 13-Hz rhythm present during wakefulness and responsive through 3). Unilateral abnormalities were present in 2, to eye opening; (2) photic driving, defined as any visually and bilateral abnormalities were present in 14. Two detectable posterior rhythm, time-locked to stimulation de- patients had normal CT scans done on the day of onset livered by conventional EEG photic stimulators; and (3) focal of blindness, but follow-up CT scans were not ob- or diffuse slow-wave abnormalities or epileptiform abnor- tained. In 1 patient (No 16), who regained full vision malities. Visual evoked potentials (VEPs) were assessed for after several weeks, a CT scan done 4 months later was the presence of abnormalities of amplitude or latency. Op- normal. tokinetic responses were defined as any reproducible eye The variability of the CT appearance in the 14 pa- movement that could be elicited with a striped tape or tients with bilateral abnormalities suggested that not all striped drum. The Wilcoxon rank order method was used to cases were due to bilateral posterior cerebral artery assess statistical significance. thrombosis. Cerebellar involvement in Patients 1 and 2 suggested basilar artery occlusion, while relatively Results small areas of infarct suggested posterior cerebral Clinical features of the 25 patients are presented in branch artery occlusions or watershed infarctions in Table 1. The most common causes of CB were spon- Patients 19 and 20. In all 14 patients, the occipital pole taneous ischemic stroke (32%), cardiac surgery (20%), was involved bilaterally. Involvement of the parietal and cerebral angiography (12%) (Table 2). Of the 5 lobe was usually associated with additional cognitive patients with CB following cardiac surgery, 2 suffered deficits but not with worsened vision. cardiac arrests (Patients 12 and 13) and 1 had CT evi- EEGs were performed in 20 patients during the pe- dence of multiple cerebral emboli (Patient 10).