Non-epileptic seizures are paroxysmal events that mimic an epileptic seizure but do not involve abnormal, rhythmic discharges of cortical neurons. They are caused by either physiological or psychological conditions. The latter is discussed more fully in psychogenic non-epileptic seizures.
A wide array of phenomena may resemble epileptic seizures, which may lead to people who do not have epilepsy being misdiagnosed. Indeed, a significant percentage of people initially diagnosed with epilepsy will later have this revised. In one study, the majority of children referred to a secondary clinic with "fits, faints and funny turns" did not have epilepsy, with syncope (fainting) as the most common alternative. In another study, 39% of children referred to a tertiary epilepsy centre did not have epilepsy, with staring episodes in mentally challenged children as the most common alternative. In adults, the figures are similar, with one study reporting a 26% rate of misdiagnosis.
Differentiation of a non-epileptic attack from an epileptic seizure includes the patient keeping their eyes closed and rarely causing themselves harm (both more common in non-epileptic attacks)
The International League Against Epilepsy (ILAE) define an epileptic seizure as "a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain." Convulsive or non-convulsive seizures can occur in someone who does not have epilepsy – as a consequence of head injury, drug overdose, toxins, eclampsia or febrile convulsions, for example. In these cases, according to neurology and the medical profession, a provoked (or an un-provoked, or an idiopathic) seizure must occur twice before the person can be diagnosed with epilepsy.
Medically, when used on its own, the term seizure usually refers to an epileptic seizure, unless, as stated above, the patient has only suffered one or two provoked or non-provoked seizures, and so has not yet been considered an epileptic. The lay use of this word can also include sudden attacks of illness, loss of control, spasm or stroke. Where the physician is uncertain as to the diagnosis, the medical term paroxysmal event and the lay terms spells, funny turns or attacks may be used.
Possible causes include:
- Syncope (fainting)
- Breath-holding spells of childhood
- Hyperekplexia, also called startle syndrome
- Non-epileptic myoclonus
- Parasomnias, including night terrors
- Paroxysmal kinesigenic dyskinesia
- Repetitive or ritualistic behaviours
- Joseph H. Ricker; Reilly R. Martinez, eds. (October 2003). Differential Diagnosis in Adult Neuropsychological Assessment. Springer Publishing Company. p. 109. ISBN 0-8261-1665-5.
- Hindley D, Ali A, Robson C (2006). "Diagnoses made in a secondary care "fits, faints, and funny turns" clinic". Arch Dis Child. 91 (3): 214–8. doi:10.1136/adc.2004.062455. PMC 2065949. PMID 16492885. (Free full text online)
- Uldall P, Alving J, Hansen LK, Kibaek M, Buchholt J (2006). "The misdiagnosis of epilepsy in children admitted to a tertiary epilepsy centre with paroxysmal events". Arch Dis Child. 91 (3): 219–21. doi:10.1136/adc.2004.064477. PMC 2065931. PMID 16492886. (Free full text online)
- Smith D, Defalla BA, Chadwick DW (1999). "The misdiagnosis of epilepsy and the management of refractory epilepsy in a specialist clinic". QJM. 92 (1): 15–23. doi:10.1093/qjmed/92.1.15. PMID 10209668. (Free full text online)
- Fisher R, van Emde Boas W, Blume W, Elger C, Genton P, Lee P, Engel J (2005). "Epileptic seizures and epilepsy: definitions proposed by the International League Against Epilepsy (ILAE) and the International Bureau for Epilepsy (IBE)". Epilepsia. 46 (4): 470–2. doi:10.1111/j.0013-9580.2005.66104.x. PMID 15816939. (Free full text online).
- What are Non-Epileptic Seizures? from Cleveland Clinic