OpenHealth Q&A

Differentiating Seizures from PNES: A Clinical Inquiry

A 26-year-old woman visited a neurology clinic following a tonic-clonic seizure, which was directly observed by a physician. During the seizure, she displayed right lateral eye deviation along with rigidity, leading to full-body rhythmic twitching; her eyes remained open and shifted to the left. This episode lasted approximately two minutes before it ceased, after which the patient exhibited a pronounced postictal state and attempted to decline medical assistance. Laboratory tests indicated a heightened serum lactate level within 20 minutes of the incident, although no electrolyte imbalances were detected. Notably, two hours later, the eye examination revealed nystagmus and a significant bite on the lateral aspect of her tongue. Following the seizure, she reported extreme fatigue but returned to her baseline condition within roughly an hour. It is suspected that her episode was triggered by a high dosage of prednisone and inadequate sleep. Before the event, she experienced auditory symptoms such as loud ringing in her left ear and a feeling of impending doom, paired with an inability to verbalize her distress. Previously, the patient underwent a neurological assessment a year earlier, where one clinician suggested the possibility of a functional neurological disorder (FND), based on symptoms like unexplained weakness, extreme fatigue, and mental fogginess. However, her neurologist subsequently dismissed this diagnosis, citing a lack of objective findings during the examination, such as a normal Hoover sign, in addition to tests that revealed known respiratory conditions leading to myoclonus and convulsive syncope due to hypoxia. The patient was also diagnosed with chronic fatigue syndrome (CFS) and post-exertional malaise (PEM). Upon further exploration of her history, the patient recalled a prior episode of loss of consciousness several years earlier, during which she was found unresponsive and lethargic in her dorm room, surrounded by saliva and vomit. This incident necessitated a visit to the emergency department, facilitated by her friends. Following her recent consult, the patient was initiated on antiseizure medications (ASMs) and received nasal midazolam for emergency use; she was also advised not to drive for six months and scheduled for a 48-hour ambulatory EEG. Her medical history includes a cerebrovascular accident related to left ventricular assist device (LVAD) placement, respiratory complications, past episodes of hypoxia, convulsive syncope, CFS, PEM, and a diminished blood pressure response to physical exertion, along with asthma. The key inquiry is whether this clinical presentation and medical history align more closely with a functional disorder (PNES) or an authentic seizure episode. It’s acknowledged that the initial EEG performed 24 hours post-seizure returned normal results. As a medical assistant, I have several questions regarding the rationale behind the initiation of ASMs for this patient. What considerations led the physicians to decide on this treatment? How do clinicians differentiate between PNES/FND and genuine seizures, particularly before receiving the results of the ambulatory EEG? Furthermore, if a functional disorder is suspected, do medical professionals still prescribe medication, or is it deemed unnecessary in that context? How can one ascertain the seriousness with which non-neurologists treat patients with FND?

Answers (1)

8/15/2025, 1:50:55 AM

OpenHealth AI

Main Points Overview: The clinical scenario suggests a complex case where differentiating between seizures and psychogenic non-epileptic seizures (PNES) is critical. The initiation of antiseizure medications (ASMs) may be due to the observed seizure characteristics, past history, and the need for immediate symptom management. Understanding this differentiation involves considering the nature of the episodes reported, their triggers, and the patient’s medical history.

Explanation: In distinguishing between PNES and true seizures, neurologists examine several factors: the event characteristics, patient history, and response to treatment. Your patient’s observed tonic-clonic seizure—with vocalization and a postictal state—suggests a genuine seizure. However, the history of unexplained symptoms raises the question of a functional neurological disorder (FND).

1. Seizure vs. PNES:

   • Characteristics of Seizures: Genuine seizures often involve distinct physical manifestations (like limb jerking and postictal confusion), while PNES may show different patterns.
   • Historical Context: Previous episodes, like loss of consciousness and conditions such as chronic fatigue syndrome, may overlap with both seizure types, complicating diagnosis.

2. Rationale for Using ASMs:

   • Initiating ASMs may stem from the need to manage acute episodes—especially when observing a seizure and acknowledging a potential risk for further episodes.
   • Given the complexity and potential seriousness of her history (including the cerebrovascular accident and respiratory issues), clinicians may prioritize seizure control to prevent injury or complications from recurrent seizures.

3. Differentiating Before EEG Results:

   • Clinicians often rely on clinical history, witnessed events, and neurological examinations. If a seizure-like episode is observed directly, it may warrant immediate ASM treatment even before definitive EEG results to ensure patient safety.

4. Managing Possible FND:

   • If a functional disorder (PNES) is suspected, some clinicians might still prescribe medications to manage coexisting conditions (like anxiety) or to support the patient during diagnosis.
   • The approach to prescribing in the context of FND varies widely among healthcare providers. Some may see it as necessary to ensure safety, while others might focus on psychotherapy and non-pharmacological interventions.

Next Steps:

1. Monitor Symptoms: Keep a detailed record of seizures, triggers, fatigue levels, and any new symptoms.
2. Follow-Up with Neurology: Discuss concerns about the differentiation between FND and genuine seizures with a neurologist, who may consider reevaluating the diagnosis as more information (like the ambulatory EEG) becomes available.
3. Lifestyle Modifications: Encourage maintaining good sleep hygiene, managing stress, and avoiding known triggers, which may help in both seizure control and overall well-being.
4. Educate on Management: If PNES is confirmed, understand that treatment may shift toward psychological therapies rather than ASMs alone.

Should you have more specific queries or need further clarifications, feel free to ask.