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 spectrum 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.
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." Epileptic 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.
Medically, when used on its own, the term seizure implies an epileptic seizure. 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 pathophysiological causes include:
- Benign paroxysmal positional vertigo
- Breath-holding spells of childhood
- Hyperekplexia, also called startle syndrome
- Hypoglycemia and associated neuroglycopenia
- Non-epileptic myoclonus
- Parasomnias, including night terrors
- Paroxysmal kinesiogenic dyskinesia
- Reflex anoxic seizures
- Primary central nervous system lymphoma
- Repetitive or ritualistic behaviours
- Syncope (fainting)
- Trauma-induced seizure (head injury)
- Joseph H. Ricker (ed), ed. (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).