Hystero-epilepsy - Diagnosis

Diagnosis

The differential diagnosis of PNES firstly involves ruling out epilepsy as the cause of the seizure episodes, along with other organic causes of non-epileptic seizures, such as syncope, migraine, vertigo, and stroke, for example. However, it is important to note that between 10-30% of patients with PNES also have epilepsy. Frontal lobe seizures can be mistaken for PNES, though these tend to have shorter duration, stereotyped patterns of movements and occurrence during sleep. Next, factitious disorder (simulating seizures intentionally for psychological reasons) and malingering (simulating seizures intentionally for secondary gain such as compensation or avoidance of criminal punishment) are excluded. Finally other psychiatric conditions that may superficially resemble seizures are eliminated, including panic disorder, schizophrenia, and depersonalisation disorder.

The most conclusive test to distinguish epilepsy from PNES is long term video-EEG monitoring, with the aim of capturing one or two episodes on both videotape and EEG simultaneously (some clinicians may use suggestion to attempt to trigger an episode). Conventional EEG may not be particularly helpful because of a high false-positive rate for abnormal findings in the general population, but also of abnormal findings in patients with some of the psychiatric disorders that can mimic PNES. Additional diagnostic criteria are usually considered when diagnosing PNES from long term video-EEG monitoring because frontal lobe epilepsy may be undetectable with surface EEGs.

According to a study in 23 patients, there is an elevated frequency of childhood abuse, especially in those with motor involvement. A studies has indicated that the metaphors patients use is associated with repressed memories.

Following most tonic-clonic or complex partial epileptic seizures, blood levels of serum prolactin rise, which can be detected by laboratory testing if a sample is taken in the right time window. However, due to false positives and variability in results this test is relied upon less frequently.