What is PNES and Its Underlying Pathophysiology
Psychogenic Non-Epileptic Seizures (PNES) are paroxysmal behavioral events that resemble epileptic seizures but originate from psychological mechanisms rather than abnormal electrical brain activity, representing a manifestation of dissociative or conversion disorders. 1, 2
Definition and Core Characteristics
PNES are episodes involving motor, sensory, mental, or autonomic manifestations that mimic epileptic seizures but lack epileptogenic activity. 2 The term "psychogenic non-epileptic seizures" specifically indicates that while these events appear as seizures, they are not epileptic in nature. 3 These episodes represent a serious mental health problem affecting 20-30% of patients attending epilepsy centers and over 10% of seizure emergencies. 2, 4
Underlying Pathophysiology
Psychological Mechanisms
The pathophysiology centers on dissociation operating as a defensive psychological mechanism that the mind uses to cope with trauma and stress. 2 PNES are categorized as manifestations of dissociative or somatoform (conversion) disorders, where the mechanism of dissociation is pivotal. 5 During PNES episodes, there is no cerebral hypoperfusion or abnormal electrical brain activity—patients exhibit signs of unconsciousness even when somatic brain function remains normal. 3
Risk Factors and Predisposing Elements
The "integrative cognitive model" accommodates current understanding of experiential, psychological, and biological risk factors, though considerable heterogeneity exists in presentations. 4 Key predisposing factors include:
- Trauma and acute stress as common precipitants 4
- Post-traumatic stress disorder with high comorbidity rates 2, 4
- Depression and anxiety disorders frequently co-occurring 2, 4
- Personality pathology as an underlying factor 6
- Other dissociative and functional disorders 4
Perpetuating Factors
PNES represent a symptom rather than the underlying disease itself, with predisposing, precipitating, and perpetuating factors requiring case-by-case assessment. 5 The condition is often underdiagnosed, undertreated, and mistaken for epilepsy, leading to inappropriate antiepileptic drug therapy that perpetuates the problem. 2
Clinical Distinction from Epileptic Seizures
Key Differentiating Features
PNES demonstrate asynchronous, side-to-side thrashing movements, while epileptic seizures show symmetrical, synchronous bilateral movements. 1
- Eye position: Eyes are typically closed during PNES, whereas they remain open during generalized epileptic seizures 1
- Duration: PNES typically last less than 30 seconds, compared to 74-90 seconds for epileptic seizures 1
- Tongue biting: Lateral tongue biting is highly specific for epileptic seizures and uncommon in PNES 1
- Oral automatisms: Chewing, smacking, and blinking suggest epileptic rather than psychogenic events 1
Diagnostic Approach
Video-EEG recording of a typical episode is the gold standard for diagnosis, as it can document the absence of epileptogenic activity during events. 2, 5 PNES are diagnosed after medical causes including epilepsy, syncope, and stroke have been ruled out, and psychological mechanisms are identified in their genesis. 2
Important Clinical Pitfalls
A critical caveat is that 20-30% of PNES patients also have comorbid epilepsy (PNES/ES), making diagnosis more complex. 4, 7 These patients with both conditions show younger age at presentation, higher rates of spontaneously activated events, shorter disease duration before PNES onset, but paradoxically longer time to PNES diagnosis. 7
Neuron-specific enolase, prolactin, and creatine kinase are not reliable for validating the diagnosis and should not be relied upon for differentiation. 1
The pathological mechanisms remain incompletely understood despite two decades of research, necessitating further investigation into appropriate psychotherapies and development of clear treatment guidelines. 6