Intended for healthcare professionals

Clinical Review Lesson of the week

Tonic seizures are a particular risk factor for drowning in people with epilepsy

BMJ 2001; 322 doi: (Published 21 April 2001) Cite this as: BMJ 2001;322:975
  1. Frank M C Besag (, medical director
  1. St Piers Lingfield, Lingfield RH7 6PW
  1. Correspondence to: F Besag, Learning Disability Service, Bedfordshire and Luton Community NHS Trust, Twinwoods Health Resource Centre, Bedford MK41 6AT
  • Accepted 28 November 2000

Tonic seizures pose a high risk of drowning because expulsion of air from the lungs causes rapid submersion

It is accepted that people with epilepsy should be supervised when swimming. However, there is little or no guidance about special precautions that should be taken for particular types of seizures. During a tonic seizure the muscles of the chest wall contract and much of the air from the lungs may be expelled. If such a seizure occurs while a person is swimming, the average body density may become higher than the density of the water, causing rapid submersion. When the muscles of the chest wall relax, the person will still be submerged, with the result that water, not air, will enter the respiratory tract and the person will not rise to the surface. We present a case of fatal drowning in a 14 year old boy with epilepsy who had seizures with a marked tonic phase. This case raises an important question with regard to safety: should special precautions be taken to minimise the risk of drowning in patients with tonic seizures?

Case report

A 14 year old boy who had had epilepsy from 7 years of age drowned in a lake on a school outing. His early development was normal. The seizures were all of a similar form: his head and eyes deviated up and to the right; his trunk could either be flexed or straight; he was blue around the mouth; facial twitching was followed by twitching or jerking of the limbs. His parents commented that because he was so rigid it sometimes needed three people …

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