Journal of

Neurology

Short communications

© Springer-Verlag 1991 J Neurol (199l) 238:44-46

Blindness as an ictal phenomenon: investigations with E E G and SPECT in two patients suffering from epilepsy J. B auer 1, P. Schiller I, H. Feistel 2, M.J. Hilz i, and H. Stefan 1 Departments of 1Neurology and =Nuclear Medicine, University of Erlangen-Nuremberg, Schwabachanlage Federal Republic of Germany

6, W-8520 Erlangen,

Received June 1, 1990 / Received in revised form July 26, 1990 / Accepted August 26, 1990

Summary. B l i n d n e s s is a rare ictal p h e n o m e n o n in epileptic seizures. It can occur as an aura, as the seizure itself, or postictally. W e i n v e s t i g a t e d two such patients, in o n e of w h o m b l i n d n e s s m a n i f e s t e das an aura prior to tonic clonic seizures; the interictal E E G exhibited a spikewave focus bioccipitally. I n the second p a t i e n t b l i n d n e s s o c c u r r e d postictally. A n ictal S P E C T , carried out at the o n s e t of the seizure d e m o n s t r a t e d m a r k e d h y p e r p e r f u sion in both occipital regions.

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Introduction

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C3-S B l i n d n e s s m a y be a n ictal, pre- or postictal p h e n o m e n o n of an epileptic seizure. Since this s y m p t o m a t o l o g y is rare, we p r e s e n t o u r findings in two patients. A S P E C T m e a s u r e m e n t carried o u t d u r i n g ictal b l i n d n e s s in o n e of these cases r e v e a l e d h y p e r p e r f u s i o n in both occipital regions.

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Case reports

O2-S Case l A 30-year-old female patient suffered from epilepsy withsimple partial seizures evolving to generalized seizures. The initial symptom of a tonic-clonic seizure was visual loss.Full sight returned postictally within 10min. Figure 1 shows the interictal EEG. It demonstrates a spike-wave focuson the occipital lobe of both hemispheres (01; 02) and on the temporo-occipital right side (T6). Case 2 A 22-year-old female patient suffered from epilepsy with complexpartial seizures sometimes evolving to generalizedseizures. The Off~orint requests to." J. Bauer

01- S Fig.1. Interictal spike-wave focus o[1 the occipital lobe of both hemispheres (01 ; 02) and on the temporo-occipital right side (T6)

interictal EEG occasionally showed paroxysms with generalized spike-wave complexes. During EEG monitoring, a seizure occurred, which led to a disturbance of consciousness and a tonic flexing of the arms. The EEG (Fig. 2a, arrows) exhibited a spike focus in both occipital lobes and in the right temporo-occipital region. While the patient was flexing her arms spike activity became generalized (Fig. 2b). Finally, generalized spike-wave complexes ap-

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Fig. 2a-c. Ictal EEG exhibiting a spike focus on the occipital lobe of both sides and on the temporo-occipital right side (a, arrows). Spike activity became generalized (b) and finally generalized spike-wave complexes appeared (c)

peared (Fig. 2c). During this phase the patient was anxious and consciousness recovered slowly. In the postictal phase the patient mentioned being blind. Within 15 min sight returned completely. An ictal SPECT was carried out after the intravenous injection of technetium 99 m hexamethylene propylene amine oxime (HMPAO) 40 s after seizure onset in EEG (Fig. 2a, b). It showed a marked hyperperfusion on the occipital lobe of both hemispheres (Fig. 3a, horizontal view; Siemens Rota Camera), whereas other brain areas - including the cerebellum - showed no increased perfusion (Fig. 3b, horizontal view).

Fig. 3a, b. Ictal SPECT showing a marked hyperperfusion on the occipital lobe of both hemispheres (a), whereas other brain areas showed no increased perfusion (b)

Discussion

Preictal blindness may precede a seizure, as demonstrated in case 1. The E E G (Fig. 1) showed epileptic loci in the occipital lobes, which seems to be the underlying cause. This rare epileptic p h e n o m e n o n was mentioned by only i out of 1000 patients investigated by Gowers in 1881 [6]. Initial darkening of the visual field is m o r e commonly a s y m p t o m of circulatory collapse [8]. Blindness as an ictalphenomenon was first documented by Ayala in 1929 [2]. In 1946, Bazzi [4] presented another case. H e discussed the pathophysiology in terms of t e m p o r a r y ischaemia produced by the epileptic seizure. In contrast, Penfield and Rasmussen in 1950 [9] demonstrated that the electrical excitement itself caused the blindness. In 1955, Russel and Whitty [10] investigated 24 patients with traumatic epilepsy and visual auras. They discovered negative visual p h e n o m e n a to be m o r e likely associated with damage to the higher visual cortex in patients without interictal dense field deficits. These included posterior and high parietal wounds well above the optic radiations. Patients with lesions in the anterior radiation or calcarine cortex were m o r e likely to experience field cuts and positive visual p h e n o m e n a as part of their seizures. Only in rare cases has true ictal blindness

been confirmed by a simultaneous E E G recording (literature reviewed in [3]). Blindness as a postictal phenomenon is u n c o m m o n . A p a r t from an initial report by A s h b y and Stevenson in 1903 [1] there have been only a few descriptions of such cases (literature reviewed in [12]). Blindness is usually reported to be of cortical origin. F r o m the investigations in case 2 we could also show a related functional disturbance in the occipital lobes by means of E E G and S P E C T (Figs. 2, 3). We had previously been able to show that the hyperperfusion in ictal S P E C T and the ictal EIEG focus are usually of identical localization [11]. The exact mechanism of postictal blindness, however, remains debatable. Neuronal exhaustion akin to T o d d ' s paralysis, selective vulnerability of the occipital cortex, especially in children, active inhibition by a hyperpolarization mechansim and brain anoxia with metabolic changes have been proposed [5, 7, 13].

References 1. Ashby H, Stevenson S (1903) Acute amaurosis following infantile convulsions Lancet 1 : 1294-1296

46 2. Ayala G (1929) Sullo "status epilepticus amauroticus.'" Boll Accad Med Roma 55 : 288-290 3. Barry E, Sussman NM, Bosley TM, Harner RN (1985) Ictal blindness and status epilepticus amauroticus. Epilepsia 26 : 577-584 4. Bazzi DT (1946) Le cecita di natura epilettica. Clin Nuova 3 : 49-54 5. Efron R (1961) Post-epileptic paralysis: theoretical critique and report of a case. Brain 84 : 381-394 6. Gowers W R (1881) Epilepsy and other chronic convulsive diseases: their causes, symptoms and treatment. Churchill, Londoll 7. Jasper H (1955) Electrical activity in the depths of the cortex as compared to that on the surface. Trans A m Neurol Assoc 80: 21-22

8. Mumenthaler M (ed) (1984) Synkopen und Sturzanffille. Thieme, Stuttgart 9. Penfield W, Rasmussen T (1950) The cerebral cortex of man. Macmillan, New York 10. Russel WR, Whitty CWM (1955) Studies in traumatic epilepsy. 3. Visual fits. J Neurol Neurosurg Psychiatry 18:79-96 11. Stefan H, Bauer J, Feistel H, Schulemann H, Neubauer U, Wenzel B, Wolf F, Neund/3rfer B, Huk WJ (1990) Regional cerebral blood flow during focal seizures of temporal and fronto-central onset. A n n Neurol 27:162-166 12. Taly AB, Kumar A A , Mohan PK (1986) Blindness - a rare post-ictal phenomenon. J Assoc Physicians India 34:741-743 13. Todd R (1854) Clinical lectures on paralysis, diseases of the brian and other affections of the nervous system. London