General features of pseudoseizures:
(1) do not respond to anticonvulsant medication
(2) no abnormalities on EEG, with intact posterior background activity during a state of apparent unresponsiveness to stimulation
(3) EEG together with closed circuit TV (CCTV) monitoring can demonstrate the lack of correlation activity and epileptiform discharges
Psychogenic seizures:
(1) history of psychiatric comorbidity (somatoform, dissociative, affective, personality disorders) or abuse (physical and/or sexual)
(2) may have a history of recent stress
(3) a typical attack that displays nonphysiologic features that can be induced or stopped with suggestion techniques
(4) may show shaking, jerking or thrashing with retained awareness
Syncopal or vasovagal seizures:
(1) tonic or clonic movements may occur, associated with cerebral anoxia.
(2) presence of presyncopal signs and symptoms (hypotension, bradycardia, anxiety, pallor, perspiration, trembling or cool, clammy skin)
(3) loss of consciousness without convulsions
(4) history negative for birth injury, cranial trauma or brain infections but positive for previous syncopal episodes
Some patients may suffer from both epilepsy and pseudoseizures (mixed). This may be more common in patients with mental retardation.
While an increased serum or plasma prolactin level during an event can be supportive of the diagnosis of epileptic seizure, the absence of change in prolactin levels is not predictive of pseudoseizures.
A patient with epilepsy may have a normal interictal EEG and some patients with epilepsy may show no ictal EEG changes during major motor activity (Krauss).
