This article is from the Epilepsy FAQ, by Andrew Patrick (firstname.lastname@example.org) with numerous contributions by others.
Psuedoseizures (or psychogenic seizures) are quite common and can occur
in people who have, or do not have, Epilepsy. The attacks are triggered
by a conscious or unconscious desire for more care and attention. The
seizures start with rapid breathing, triggered by mental stress,
anxiety, or pain. As the person breaths rapidly, they build up carbon
dioxide in their body and change their chemistry. This can cause
symptoms very much like Epileptic seizures: prickling in the face,
hands, and feet, stiffening, trembling, etc. The appropriate treatment
for pseudoseizures is to calm the person and start them breathing at a
normal rate. Treatment should also involve investigating the mental and
emotional factors that led to the psuedoseizure.