How can a physical exam, including an act of dropping arms during a spell, differentiate between epilepsy and Psychogenic Non-Epileptic Seizures (PNES)?

From the Guidelines

The arm drop test, where the examiner lifts the patient's arms above their face during a seizure and then releases them, can help differentiate between epilepsy and Psychogenic Non-Epileptic Seizures (PNES), as patients with PNES often unconsciously avoid self-harm, with arms falling to the side or showing controlled descent, in contrast to the uncontrolled fall seen in true epileptic seizures. During a physical exam, this test can be used in conjunction with other clinical features to aid in diagnosis. According to the 2018 ESC guidelines for the diagnosis and management of syncope 1, the presence of certain movements during a spell can provide clues to the diagnosis, such as the mere presence of movements having limited utility for differentiating syncope from epilepsy, but details like the beginning of movements before or after the fall, and their symmetry and synchrony, can be helpful.

Some key distinguishing features between epilepsy and PNES include:

• The duration of loss of consciousness (LOC), with syncope typically lasting less than 30 seconds, epileptic seizures lasting around 1-2 minutes, and PNES often lasting more than 1 minute 1
• The presence of pelvic thrusting, which is more commonly seen in PNES 1
• The nature of the movements, with many movements or restricted movements to one limb or side being more characteristic of epilepsy, and repeated waxing and waning in intensity and changes in nature of movement being more characteristic of PNES 1
• The presence of post-ictal confusion, which is typically seen in epileptic seizures but not in PNES.

It is essential to consider these physical examination findings alongside other clinical features, as no single test is definitive, and video EEG monitoring remains the gold standard for diagnosis. The arm drop test, in particular, works because epileptic seizures involve genuine neurological disruption of motor control, while PNES, though not consciously produced, maintain protective reflexes 1.

From the Research

Differentiating Epilepsy from PNES through Physical Exam

To differentiate epilepsy from Psychogenic Non-Epileptic Seizures (PNES) through a physical exam, including an act of dropping arms during a spell, several clinical features and techniques can be considered:

• Clinical Presentation: PNES often presents with a longer duration of seizures, apparent loss of consciousness, bilateral convulsions, and significant clinical variability without typical epileptic elements such as tongue bite and ictal injury 2.
• Provocative Testing: Techniques like placebo-induced seizures can be highly sensitive in diagnosing PNES, although ethical considerations must be taken into account 2.
• Video-EEG Monitoring: This is the diagnostic gold standard for PNES, allowing for the confirmation of the diagnosis with high accuracy when typical seizures can be recorded 3.
• Psychological and Psychiatric Evaluation: Patients with PNES often have a history of psychological stress, anxiety, somatization, or factitious disorders, which can be crucial in differentiating PNES from epilepsy 2, 4, 5.
• Dropping Arms Test: While not explicitly mentioned in the provided studies, the act of dropping arms during a spell could potentially be used as part of a physical exam to assess for voluntary movement or responsiveness, which might be preserved in PNES but not in epileptic seizures. However, this would need to be interpreted with caution and as part of a comprehensive evaluation.

Key Considerations

• Combination of Diagnostic Techniques: Given the complexity of diagnosing PNES, a combination of diagnostic techniques, including clinical evaluation, psychological assessment, and video-EEG monitoring, may provide the most accurate diagnosis 6.
• High Index of Suspicion: Clinicians should have a high index of suspicion for PNES, especially in patients with atypical seizure presentations or those who have been misdiagnosed with epilepsy 3, 2.
• Multidisciplinary Approach: A multidisciplinary approach, involving neurologists, psychiatrists, and psychologists, is essential for the accurate diagnosis and effective management of PNES 4, 5.