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Show Jou17Ul1 of Clinical Neuro-ophthalmology 7(3):151-154, 1987. Transient Postictal Cortical Blindness Stephanie A. Skolik, M.D., Thomas R. Mizen, M.D., and Ronald M. Burde, M.D. © 1987 Raven Press, Ltd., New York An 8-year-old boy with insulin-dependent diabetes mellitus and a seizure disorder demonstrated transient visualloss after severe seizure activity. The role of hypoglycemia in relation to his transient cortical blindness remains indeterminate. The nature of the cortical involvement, the rate of visual recovery, and prior reports of postictal phenomena emphasize the relatively benign nature of this condition in children. Key Words: Cortical blindness-Seizure disorder. From the Departments of Ophthalmology (S.A.S., T.R.M., R.M.B.) and Neurology and Neurological Surgery (R.M.B.), Washington University School of Medicine, St. Louis, Missouri. Dr. Skolik is currently a Resident in Ophthalmology at Alton Ochsner Clinic, New Orleans, Louisiana; Dr. Mizen is currently with the Department of Ophthalmology, Rush-Presbyterian- St. Luke's Medical Center, Chicago, Illinois. Supported in part by an unrestricted grant from Research To Prevent Blindness, Inc., New York, New York (Department of Ophthalmology, Washington University School of Medicine). Address correspondence and reprint requests to Ronald M. Burde, M.D., Department of Ophthalmology, Box 8096, 660 South Euclid Avenue, St. Louis, MO 63110, U.S.A. 151 The diagnostic criteria for cortical blindness include subjective visual loss, loss of reflex lid closure to threat, normal pupillary responses to direct and consensual stimulation, normal ophthalmoscopic findings, and retention of normal extraocular movements. In adults, cortical blindness has been reported following trauma, carbon monoxide poisoning, Schilder's disease, cerebral angiography, corticotropin therapy, blood transfusions, hemodialysis, electroshock therapy, eclampsia, and uremia and also in the postpartum period (1). Cerebral ischemia and hypoxia are postulated to contribute to the pathophysiology of cortical blindness in adults. With transtentorial herniation, direct compression of the posterior cerebral arteries occurs. Laminar necrosis in "border zone" areas between the distribution of major cerebral blood vessels occurs as a result of tissue hypoxia, especially with concurrent hypotension (2). In children, the syndrome of cortical blindness is rare and may be transient (3,4). Childhood cortical blindness has been reported following respiratory or cardiac arrest, head trauma (1,4), meningitis (5), profound hypoglycemia (6), and as a postictal phenomenon (7). We observed a child with transient cortical blindness following sustained seizures. CASE REPORT This 7-year, ll-month-old developmentally delayed boy had insulin-dependent diabetes mellitus diagnosed at age 3lf2 years, at which time he was hospitalized for 1 week to begin insulin therapy. One week after returning home from the hospital, the patient experienced an episode of head drop, which the pediatrician felt was related to an insulin reaction. The insulin dosage was adjusted, and the patient continued to be observed at home. Episodes of head dropping continued to occur on 152 S. A. SKOLIK ET AL. a weekly basis over the next 3 months, at which time the patient was readmitted to the hospital. The diagnosis of a petit mal seizure was made, and the patient was started on clonazepam (0.5 mg, three times per day), mephobarbital (dosage unclear), and ethosuximide (250 mg, three times per day). The frequency of seizures decreased to approximately one time each month. The mother, who was a school teacher, said her child was achieving the developmental milestones normally until the advent of the seizures and seizure medication; since they had started, no further developmental milestones were seen. The patient's seizure activity remained controlled at this level until 7 months prior to being seen (age 7 years, 4 months) when the seizure activity increased in frequency over the course of 1 week to about 20 seizures per day. The nature of the disorder remained the same. The patient was hospitalized for a prolonged period of time as his seizure disorder was refractory to multiple drug therapy. Eventually, reasonable control was achieved with a combination of valproic acid (2,500 mg in divided doses), ethosuximide (200 mg, three times per day), and adrenocorticotropic hormone (800 IJ..g, once a day). On this regime, the patient experienced only occasional "focal twitches" and chewing movements, and he was discharged after 13 weeks in the hospital. Four days after this discharge, the patient had his first tonic-clonic-type grand mal seizure, lasting 2-3 min. These seizures increased in frequency over the next month to three to five per week. During the seizure, the patient frequently had urinary incontinence and occasionally fecal incontinence. Two days prior to admission, the patient experienced three violent grand mal seizures lasting 4-5 min each. On the day prior to admission, the patient had four such seizures. On the morning of admission, somnolence, odd behavior, and searching eye movements were noted, and the mother felt the child was blind. Initial evaluation revealed a somnolent 7-year, 11-month-old boy with subjective visual loss, no light perception bilaterally, no fixation behavior, and loss of reflex eyelid closure to threat. The pupils responded normally to light and near stimuli. Volitional eye movements were conjugate and full; doll's head maneuver was normal, as was the remainder of the ocular motor examination. The anterior segments were normal. Fundus examination demonstrated normal optic nerves, maculas, and vessels; the retinas were normal. J Gill Neuyo-op1lthalmol, Vol. 7, No.3, 1987 The patient was oriented only to person with fluctuating attention, No focal neurologic motor or sensory deficits were appreciated; gait was narrow-based, Height, weight, and head circumference were slightly below the mean; cafe-au-lait spots were noted on the dorsum of the left hand, the right cheek, the buttocks, and groin. Laboratory study abnormalities included a white blood cell count of 14,000/mm3, a blood glucose of 184 mg/dl, and a urinalysis demonstrating glucose and ketones, Electroencephalography revealed a slow spike and wave pattern, Computerized tomography (CT) showed cortical atrophy without focal infarction. Forty-eight hours after medication for seizure control, the patient's mental status improved and vision was "light perception," Visual examination at 72 h revealed that objects were perceived at a distance of 2 feet, and by 96 h "finger-counting" vision was recorded bilaterally. Over the next 3 weeks, control of the seizure activity proved difficult, and the visual acuity correlated with the seizure activity; i,e" with increased seizure activity, visual acuity was poor, but it would rapidly recover as the seizures resolved, No hemianopic visual field deficit could be identified at any time. At the end of 3 weeks, the seizures were controlled, and visual acuity was recorded as 20/40 bilaterally with the remainder of the ocular exam remaining normal. DISCUSSION Amaurosis following convulsions in infants was reported by Nettleship (8) in 1884 and by Gay (9) in 1893 and discussed by Ashby and Stephenson (10) in 1903. Ashby and Stephenson reported 11 cases of postictal amaurosis, most of which demonstrated other signs of neurologic dysfunction. They concluded that (a) amaurosis occurs in infants and children postictally; (b) the amaurosis is usually transient; and (c) convulsions prior to amaurosis are usually severe, Pritchard (11) subsequently described a case of a child with fever, convulsions, unreactive pupils, and amaurosis whose vision recovered in several months as the systemic symptoms resolved. Kosnik and associates reported that in children with seizure disorders there is an occipital focus occurring in approximately 50% of patients (7), They wrote that the occipital cortex is relatively immature in children and thus is characterized by unstable electrical activity, The high incidence of occipital lobe foci in children TRANSIENT POSTICTAL CORTICAL BLINDNESS 153 would provide a reason for postictal blindness to be more common in children. Todd's paralysis is a term used to denote focal neurologic deficits, usually motor, following convulsive seizures. Sensory deficits may occur. Amaurosis is rarely seen, but it is more commonly seen in children. The mechanisms underlying Todd's paralysis remain speculative. Todd (12) and Jasper (13) suggested a theory of "neuronal exhaustion," which Miller (1) felt is the best explanation in this type of case. Efron (14) postulated that a postparoxysmal electric silence occurs due to active inhibition with hyperpolarization. Greenblatt (3) classified posttraumatic transient cerebral blindness into three groups, revealing a significant association with migraine and seizure diatheses. The first group is juveniles up to age 8 years who exhibit the usual postconcussive symptoms of somnolence, irritability and vomiting, and whose visual loss is of short duration measured in hours; prognosis for visual recovery is good. The second group is adolescent through teenage years, where visual loss may be delayed minutes to hours, and the prognosiS for visual recovery is good. The third group is adults who sustain severe trauma accompanied by other neurologic dysfunction and sudden visual loss, which may be of long duration; recovery of vision is variable and dependent on the insult. Greenblatt noted that there is a significant association of transient visual loss with migraine and seizure diathesis. He concluded that both vasomotor instability and neuronal instability are contributing factors in all cases. When dealing with a child who has cortical blindness, the question of the value of electrophysiologic testing as a diagnostic and prognostic tool is always raised. Over the past few years, numerous investigators have attempted to answer this question by developing neurophysiologic testing strategies to reflect the underlying cortical dysfunction; however, the results of such testing have been less than encouraging. For example, Bodis-Wollner and co-workers (15) found normal visual evoked responses to flash, pattern, and sinusoidal gratings in a blind child who was shown to have a loss of visual association cortex by CT scanning. Spehlmann and associates (16) reported normal visual evoked responses in a patient with extensive bilateral posterior cerebral infarction. Using visual evoked responses, Frank and Torres (17) examined 30 "cortically blind" children and compared them with 30 children with similar cen-tral nervous system disease without blindness. Even though some degree of abnormality existed in all the responses, no significant difference existed between the two groups. Other inconsistencies and difficulties are reported, further questioning the value of visual evoked response testing in the evaluation of cortical blindness (18,19). At the present time, depending on the location of the injury, the patient may exhibit no vision, minimal vision with denial of visual loss, or bilateral hemianopias with a preserved central island of vision with either a normal or abnormal evoked response. Whiting and associates (20) reported that visual evoked potential mapping might be more valuable than traditional visual evoked responses in the diagnosis of cortical blindness. In their study of 50 children with permanent cortical visual impairment, the visual evoked potential map was always abnormal and correlated with the CT scan results, whereas the visual evoked response was abnormal in only one-half of the cases. Visual evoked potential mapping may appear to be a predictive modality but must be tested in future studies. REFERENCES I. Miller NE, ed. Walsh alld Hoyt's clillical Ileum-ophthalmology (vol. I.). 4th ed. Baltimore: Williams & Wilkins, 1982;142-9. 2. Hoyt WF, Walsh FB. Cortical blindness with partial recovery following acute cerebral anoxia from cardiac arrest. Arch Ophthalmo/1958;60:1061-9. 3. Greenblatt SH. Posttraumatic transient cerebral blindness. Association with migraine and seizure diatheses. JAMA 1973;225:1073-6. 4. Griffith JF, Dodge PRo Transient blindness following head injury in children. N Ellgl JMed 1968;278:648-51. 5. Olurin O. Cortical blindness following convulsions and fever in Nigerian children. Pediatrics 1970;46:102-7. 6. Mukamel M, Weitz R, Nissenkorn L Yassur I, Varsano I. Acute cortical blindness associated with hypoglycemia. J Pediatr 1981;98:583-5. 7. Kosnik E, Paulson GW, Laguna JF. Postictal blindness. Neurology 1976;26:248-50. 8. Nettleship E. On cases of recovery from amaurosis in young children. TrailS Ophthalmol Soc UK 1883-1884;4:24366 9. Gay W. Acute cerebral amaurosis of infancy. ROlf Land Ophthal Hosp Rep 1890-1893;13:404-14. . 10. Ashby H, Stephenson S. Acute amaurosis following infantile convulsions. Lallcet 1903;1:1294-6. 11. Pritchard E. Case of amaurosis following violent convulsions. Proc R Soc Med 1918;11:1-2. 12. Todd R. Clillical lectures all paralysis, disease of the bra ill alld other affectiolls of the llert'OIlS system. London, 1854. 13. Jasper H. Electrical activity in the depths of the cortex as compared to that on the surface. TrailS Am Neural Assoc 1955;80:21-2. I Clin Nel/ro-ophtha/lllol. Vol. 7, No.3. 1987 154 S. A. SKOLIK ET AL. 14. Efron R. Post-epileptic paralysis: theoretical critique and report of a case. Brain 1961;84:381-94. 15. Bodis-Wollner 1, Atkin A, Raab E, Wolkstein M. Visual association cortex and vision in man: pattern-evoked occipital potentials in a blind boy. Science 1977;198:629-30. 16. Spehlmann R, Gross RA, Ho SU, Leetsma JE, Norcross KA. Visual evoked potentials and postmortem findings in a case of cortical blindness. Ann Neural 1977;2:531-4. 17. Frank Y, Torres F. Visual evoked potentials in the evaluation of "cortical blindness" in children. Ann Neural 1979;6:126-9. I Clill Nellro-ophthalmol, Vol. 7. No.3, 1987 18. Barnet AB, Manson JI, Wilner E. Acute cerebral blindness in childhood. Six cases studied clinically and electrophysiologically. Neurology 1970;20:1147-56. 19. Kupersmith MJ, Nelson JI, Carr EE. The visual evoked potential as a prognosticator in childhood cortical blindness [Abstract]. Ann Neural 1983;14:146. 20. Whiting 5, Jan JE, Wong PKH, Flodmark 0, Farrell K, McCormick AQ. Permanent cortical and visual impairment in children. Oev Med Child Neural 1985;27:730-9. |
