Photosensitivity and Epilepsy

Alberto Verrotti MD, PhD; Daniela Trotta, MD; Carmela Salladini, MD; Giovanna di Corcia, MD

Disclosures

J Child Neurol. 2004;19(8):571-578. 

In This Article

Prognosis and Therapy

The prognosis for control of seizures induced by visual stimulation is generally very good,[67,93,94,95,96,97]especially in pure photosensitive epilepsy and juvenile myoclonic epilepsy in which valproate is the drug of choice,[21] although recovery is unlikely before the age of 20 years.[95] It was noted that photosensitivity disappeared earlier in photosensitive patients treated with valproate than in untreated patients; without a change in medication, photosensitivity disappeared as the patients became older; therefore, it was proposed that photosensitivity disappeared spontaneously around 24 years of age.[94] The study of Harding et al. demonstrated that there is a 14 to 37% probability that photosensitivity will disappear spontaneously, but there is no way of identifying which individuals will have such a remission.[97]

Reilly and Peters emphasized the predictive value of an epileptiform response that continues after the train of flashes stops, but its predictive value, as distinct from that of an otherwise identical response that ends with the train of flashes, remains controversial.[98]

Moreover, a recent study demonstrated that in patients with a history of photosensitive seizures, abnormalities to patterned intermittent photic stimulation are more common than those to diffuse intermittent photic stimulation and, although consistent with the clinical history of photosensitivity, are not a reliable predictor of the patient being poorly controlled.[1] Abnormalities to diffuse intermittent photic stimulation are, however, significantly associated with current seizures.

However, it is important to remember that photosensitivity was not necessarily concordant with the evolution of the epilepsies. The photosensitivity sometimes began several years after epilepsy onset and sometimes disappeared before the seizures stopped. Probably, the pathophysiologic mechanisms of photoparoxysmal response in some photosensitive patients might undergo an evolutionary process.[51]

The large majority of patients do not need anticonvulsant therapy, but, when needed, the drug of choice is valproate in monotherapy.[67,93,94,95,96,97] Experience suggests that clobazam could be a helpful adjunct. Lamotrigine, topiramate, and levetiracetam have also been recommended as possible second choices, but there are no conclusive studies of prolonged use of these drugs in human photosensitivity.[21]

Our experience confirms that this type of epileptic patient has a good prognosis for control of seizures; in fact, over 80% of our subjects showed an excellent response to valproate monotherapy or in association with other antiepileptic drugs,[99] as reported in other studies.[67,93,94,95,96,97] Probably, the good response to the therapy of our children can be explained because all had idiopathic photosensitive epilepsy and none had epilepsy secondary to cerebral lesions or metabolic diseases; all of our patients treated responded to pharmacologic therapy independently of the persistence or disappearance of photosensitivity.

The most effective treatment is avoidance of the provoking stimulus. This can be difficult if the real trigger is not known. The parents of children with television-induced seizure should ensure that they are not closer than 2 meters from the set and do not approach it to switch or adjust the controls because it has been suggested that the nearness of the child to the set is an important factor.[67] Takahashi and Tukahara pointed out that children should not concentrate too much on watching television or be too close to the television screen in a dark room.[100,101]

Patients who suffer from seizures with sunlight can be helped by wearing polarized eyeglasses during the summer.

Stimulus avoidance and stimulus modification can be an effective treatment in some patients and can sometimes be combined with antiepileptic drug treatment. The effectiveness of these maneuvers will depend on the individual's degree of photosensitivity, awareness of subtle signs and symptoms when exposed to potentially provocative stimuli, and patient compliance.


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