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ARTICLES: Roberto D’Alessandro, Maria Guarino, Gabriele Greco, and Leona Bassein Risk of seizures while awake in pure sleep epilepsies: A prospective study Neurology 2004; 62: 254-257 [Abstract] [Full text] [PDF]

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Risk of seizures while awake in pure sleep epilepsies: A prospective study

Dougall.J.P McCorry, Tony Marson   (23 March 2004)

Reply to McCorry et al

Roberto D'Alessandro, Maria Guarino, Gabriele Greco, and Leona Bassein   (23 March 2004)

Risk of seizures while awake in pure sleep epilepsies: A prospective study 23 March 2004
Dougall.J.P McCorry, Neurosciences, The Walton Centre The Walton Centre, Lower Lane, Fazakerly, Liverpool,, Tony Marson Send Correspondence to journal: Re: Risk of seizures while awake in pure sleep epilepsies: A prospective study dougallmccorry{at}yahoo.com Dougall.J.P McCorry, et al.	D’Alessandro et al have shown that patients presenting with infrequent seizures confined to sleep have an excellent prognosis. After 2 years follow-up, only 22% had a seizure recurrence, and after 6 years follow up the estimated risk of a seizure recurrence while awake was 13%. [1] We would like to raise two questions not addressed in the discussion. The selected cohort had factors that have been identified to predict a good prognosis: cryptogenic origin (over 80% had normal imaging) with no associated neurological deficit[2]; infrequent pre-treatment seizures; and delay in patient recruitment from the reference seizure. [3] A previous history of seizures occuring exclusively during sleep may not be of independent prognostic significance. Secondly, while most of the patients had a good prognosis, patients with a baseline seizure frequency of greater than six per year had around six times the risk of experiencing a seizure while awake. In addition, they calculate a 25% chance of experiencing a daytime seizure over 6 years although confidence intervals (which were not given) are presumably wide. In the UK, the DVLA allows patients with epilepsy to drive if they have had exclusively nocturnal seizures for three or more years regardless of seizure frequency. The relatively high risk of awake seizures in this sub-group and the lack of association to length of time of seizures might suggest more appropriate regulations for this group. References 1. D'Alessandro R, Guarino M, Greco G, Bassein L. Risk of seizures while awake in pure sleep epilepsies. Neurology 2004;62:254-257. 2. Hart YM,Sander JW, Johnson AL, Shorvon SD. National General Practice Study of Epilepsy: recurrence after a first seizure. Lancet 1990;336:1271-1274. 3. Sander, J. W. Some aspects of prognosis in the epilepsies: a review. Epilepsia 1993;34:1007-1016.
Reply to McCorry et al 23 March 2004
Roberto D'Alessandro, Unità di Neuroepidemiologia, Dipartimento di Scienze Neurologiche dell’Università di Bologna Via Ugo Foscolo 7, 40123 Bologna, Italy, Maria Guarino, Gabriele Greco, and Leona Bassein Send Correspondence to journal: Re: Reply to McCorry et al dalessan{at}neuro.unibo.it Roberto D'Alessandro, et al.	McCorry et al raise reasonable questions. Firstly, we stress that patients were recruited through primary neurology practice (as outpatients) and therefore were not selected for severity as may occur in an epilepsy center. We cannot exclude that some selection bias may have occurred. However, this is the picture of pure sleep epilepsy in our region, that shows an overall good prognosis. Secondly, our findings do not support the contention that length of sleep epilepsy duration protects against the occurrence of a seizure while awake(as expected on the basis of previous retrospective studies). This may be due to an insufficient statistical power of our sample. However, we stress that compliance with therapy is probably a major protective factor.