Helpful Tools in the Diagnosis and Study of Psychogenic Nonepileptic Seizures

While it would be ideal to have a single test that can tell the difference between psychogenic nonepileptic seizures (PNES) and epilepsy seizures, unfortunately, one is not yet available. The diagnosis of PNES requires capturing the typical events on video EEG monitoring with expert EEG interpretation. 

Psychogenic nonepileptic seizures (PNES) are commonly misdiagnosed as epilepsy, leading to treatment that does not treat the events and may have many side effects. A recent review in the journal Seizure by T. Sundararajan and colleagues looked at a variety of biomarkers used in the diagnosis of PNES versus epilepsy seizures.

Here is a summary of the effect of different markers to diagnose PNES.

• Neuroimaging - tests such as CT, MRI, or PET scans can show changes in the structure of the brain that may be associated with epilepsy.
  • Structural changes in the brain are not able to tell the difference between PNES and epilepsy.
• Autonomic nervous system - for example changes in heart rate, blood pressure, or sweating.
  • A very high heart rate during a complex partial seizure or greater variability in heart rate during an event is more likely with an epilepsy seizure than with a PNES event.
• Prolactin levels - Prolactin, a hormone released from the pituitary gland in the brain, is sometimes stimulated by seizures.
  • The blood level of prolactin after an event is not enough to diagnose PNES from epilepsy seizures.
• Cortisol levels - Cortisol is a hormone that regulates how the body processes and responds to stress.
  • Studies on cortisol levels in PNES do not show consistent results.
• Creatinine kinase - This is an enzyme that is released from muscles with increased energy use.
  • There are many causes of increased creatinine kinase, so this is not specific enough to diagnose PNES or seizures.
• Neuron-specific emolase - This is an enzyme that is released when damage to neurons occurs.
  • Two studies have shown increases in this substance with epilepsy seizures and not after PNES. However, there can be other causes of these changes too, including any type of blood disease.
• Neuropeptides (Ghreiln and nesfatin-1) - These are small substances that monitor many functions in the nervous system and can be measured in the blood and saliva.
  • These are not reliable to diagnose PNES or epilepsy seizures.
• Brain derived neurotrophic factor - This is a protein that helps in growing nerve cells.
  • This is not reliable to diagnose PNES or epilepsy seizures.
• Leukocytosis - This refers to an increase in white blood cells in the blood.
  • Increased white blood cells have been seen after epilepsy seizures, but there can be many causes of this. Changes in these cells are not enough to diagnose epilepsy seizures from PNES.
• Platelet membrane serotonin transporter - This is a protein found on the surface of platelets in the blood. They are important for blood clotting.
  • One study showed lower density in this protein after epilepsy seizures and not in PNES, but the cause of this difference is not known.