Is functional neurological disorder (FND) a seizure disorder?

Is Functional Neurological Disorder a Seizure Disorder?

No, functional neurological disorder (FND) is not a seizure disorder—it is a distinct neurological condition that can manifest with seizure-like episodes (called functional seizures or dissociative seizures) as one of several possible symptom presentations, but these episodes are fundamentally different from epileptic seizures. 1, 2

Understanding the Distinction

FND is characterized by altered neurological symptoms (motor, sensory, or cognitive) that are incompatible with recognized neurological or medical diseases but cause real disability. 1 The disorder encompasses diverse symptoms including:

• Weakness and motor dysfunction 1
• Movement disorders (tremor, jerks, dystonia) 1
• Seizure-like events (functional/dissociative seizures) 1
• Sensory symptoms 1
• Cognitive deficits 1

The critical distinction is that FND arises from a potentially reversible miscommunication between the brain and body rather than from structural damage or degenerative disease to the nervous system. 1 This is fundamentally different from epilepsy, where seizures result from abnormal electrical discharges in the brain.

Functional Seizures vs. Epileptic Seizures

Functional seizures can look and feel similar to epileptic seizures but are a common and highly disabling form of functional neurologic disorder, not caused by epileptic discharges. 3 Key differentiating features include:

• Electroencephalography (EEG) findings: Functional seizures show no epileptic discharges during episodes, whereas epileptic seizures demonstrate characteristic abnormal electrical activity 3
• Clinical features: Functional seizures demonstrate internal inconsistency and variability with attention that differs from epileptic patterns 2
• Underlying mechanism: Functional seizures are caused by biological, psychological, and social factors unrelated to epileptic discharges 3

Diagnostic Framework

FND is a positive diagnosis based on recognizable clinical signs demonstrating internal inconsistency, not a diagnosis of exclusion. 1 The American Academy of Neurology recommends diagnosing FND based on positive clinical signs showing internal inconsistency of symptoms, with symptoms being real, disabling, and involuntary—not deliberately produced. 1

Key diagnostic features include:

• Internal inconsistency: Symptoms vary in ways that don't follow recognized neurological patterns 2
• Disproportionate severity: Symptom severity exceeds what would be expected from examination findings or imaging 2
• Variability with attention: Symptoms demonstrate characteristic fluctuation and improvement with attention redirection 1

Treatment Implications

The treatment approach for FND differs fundamentally from seizure disorder management:

• First-line treatment: Multidisciplinary rehabilitation centered on occupational therapy and physical therapy, grounded in a biopsychosocial framework with patient education and self-management strategies 1
• For functional seizures specifically: Psychotherapy is an emerging evidence-based treatment, with sensory grounding techniques and anxiety management as core interventions 4, 3
• Avoid antiepileptic drugs: Unlike epileptic seizures, functional seizures do not respond to antiepileptic medications, and relying primarily on pharmacological approaches is a critical error in FND management 1

Common Pitfall to Avoid

Do not treat FND like epilepsy or other structural neurological conditions. 1 Critical errors include:

• Focusing on impairment-based rather than functional goals 1
• Relying primarily on pharmacological approaches designed for epilepsy 1
• Pursuing acute hospital admission for functional seizures, which are usually unnecessary and highly distressing 4

Prognosis

Unlike progressive neurological conditions or refractory epilepsy, FND symptoms are potentially reversible. 1 Multidisciplinary studies report that 60-96% of patients report improvement after intervention, with improvements in physical function and quality of life at 12-25 month follow-up. 1 Recovery often follows a pattern of symptom remission and exacerbation rather than linear improvement. 1