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Neurology India, Vol. 51, No. 1, Jan-Mar, 2003, pp. 115-116 Short Report Occipital seizures presenting with bilateral visual loss S. Hadjikoutis, I. M. Sawhney Department of Neurology, Morriston Hospital, Morriston, Swansea SA6 6NL, United Kingdom.
Accepted on 02.08.2001. Code Number: ni03036 Transient visual loss may occur with occipital seizures as an ictal or post-ictal phenomenon. Its duration varies from less than one minute to days, or can be permanent. We describe a 61-year-old man presenting with headache, vomiting and bilateral visual loss. EEG revealed persistent spike discharge in the occipital lobes suggesting occipital seizures. His vision improved with carbamazepine. Key Words: Occipital seizures, Epilepsy, Blindness Occipital seizures constitute 8% of total seizures in the epileptic population.1 They originate from an epileptic occipital focus that is triggered spontaneously or by external visual stimuli (photosensitive occipital epilepsy). They are characterized by visual phenomena, e.g. as bright coloured or occasionally dark rings, spots or simple geometric forms that are continuous or flashing. More complex visual hallucinations include complex scenes often related to past experiences. These may be accompanied by macropsia, micropsia, or perception of scenes of people or animals described as static or moving horizontally, approaching or moving away. Visual loss occurs with occipital seizures2 and may be an ictal or post-ictal phenomenon.3 Ictal blindness may appear ab initio or less commonly after other manifestations of occipital seizures. We describe a case of occipital seizures, which manifested with bilateral visual loss. Case report A 61-year-old man presented in January 2000 with respiratory failure secondary to an infective exacerbation of Chronic Obstructive Airway Disease. He had a prolonged hospitalization and he was ventilated in Intensive Care Unit (ICU). During his recovery in ICU, he noticed bilateral visual impairment. CT scan of the brain showed bilateral occipital lobe ischemia consistent with watershed infarction. His visual acuity on discharge was 6/18 bilaterally. In June 2000 he presented with a history of sudden onset of headache, vomiting and bilateral visual loss. On examination he was conscious and fully orientated. Visual acuity was decreased to light perception only. Pupils were equal and reactive to light, ocular movements were intact and fundoscopy was normal. There were no other abnormal neurological signs. General medical examination was normal. Hematological and biochemical investigations as well as an ECG and chest X-ray were normal. The initial suspected diagnosis was recurrent occipital stroke. He had a generalized tonic clonic seizure within three hours of admission. A CT scan of the brain showed no evidence of new ischemic changes. An EEG showed spike discharges in the occipital lobes (Figure 1). The findings were consistent with the diagnosis of occipital seizures. He was commenced on carbamazepine (200 mg twice daily) and his vision improved significantly and returned to baseline (i.e. 6/18 bilaterally). Repeat EEG on the day of discharge showed no evidence of spike discharge in the occipital lobes (Figure 2). The patient did not have any recurrent occipital seizures after three months follow-up, and his visual acuity remained stable. The final diagnosis was occipital seizures secondary to old bilateral occipital ischemia. Discussion Blindness (amaurosis) is a common ictal or post-ictal symptom of idiopathic and symptomatic occipital seizures. Blindness may follow visual hallucinations and progress to other ictal epileptic symptoms but often occurs as the initial or the only ictal seizure manifestation with an abrupt onset. The duration of ictal blindness varies between less than one minute and days (status epilepticus amauroticus) or can be permanent.4 Onset of ictal blindness in adulthood nearly always indicates symptomatic epilepsy5 whereas in children, it is usually a manifestation of benign occipital epilepsy.6 Ictal EEGs during blindness demonstrate seizure activity7 or relative flattening.8 An interesting rare variation of ictal blindness is `white ictal blindness'.9 The patient cannot see because everything is white `like a white sheet in front of their eyes'. Occipital seizures presenting with ictal blindness may imitate conditions which cause transient visual loss (e.g. migraine, retinal artery emboli). In conclusion, ictal blindness may appear ab initio or less commonly after other occipital seizure manifestations. An EEG should be considered in any patient presenting with sudden onset of unexplained visual loss. Ictal blindness often responds very well to antiepileptic drugs. References
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