Dissociative Seizures Flashcards
What are the main differential diagnoses of “funny turns”?
- Normal behaviour (e.g., tantrums in children)
- Medical (e.g., syncope, paroxysmal neurological disorders, metabolic)
- Psychogenic (e.g., dissociative seizures, factitious, other psychiatric presentations
- Malingering
What evidence is there for the unconscious nature of dissociative seizures?
▪️ Experienced clinicians judgement
▪️ Compliance with AEDs
▪️ Telemetry
▪️ Poor imitation of epilepsy
What is the main demographic for DS?
▪️ Female
▪️ Onset in teens/early 20s
▪️ Diagnosis often missed for years
What are the main issues associated with misdiagnosis of DS?
▪️ Missed opportunity for treatment - much better prognosis!
▪️ Multiple trials of anticonvulsants
▪️ Anticonvulsant toxicity (e.g., teratogenic
▪️ Dangerous if treated like “status epilepticus” (e.g., put in ICU)
What can we use to differentiate DS from epilepsy?
- Clinical judgement (most important!)
- Inter-ictal EEG
- Telemetry/EEG with provocation
What signs are common in dissociative seizures but rare in epileptic seizures?
▪️ Duration over 2 minutes
▪️ Eyes closed
▪️ Fluctuating course
▪️ Asynchronous movements
▪️ Aware but unresponsive
▪️ Pelvic thrusting and head side to side
What features are common to epilepsy but rarely seen in DS?
▪️ Post-ictal stertorous breathing (noisy)
▪️ Post-ictal confusion
▪️ Automatisms
Why are major injuries seen more rarely with DS compared to epilepsy?
Some level of protective subconscious control
(BUT minor injuries more common in DS?)
Can dissociative seizures arise from sleep?
Not really, although may seem that way if they arise from slight states of wakefulness in the night
Why might hyperventilation be more common in DS than epilepsy?
Association with anxiety
What can you look for on examination to differentiate DS from epilepsy?
▪️ Non-clonic movements
▪️ Eyes closed
▪️ Avoidance/resistance (particularly to eye opening)
What psychiatric phenomenology are commonly described with DS?
“Panic attacks without panic”:
▪️ Derealisation/detachment
▪️ Somatic symptoms of arousal (e.g., sweating, hyperventilation, palpitations)
▪️ Lack of ictal fear
▪️ Posy-ictal motional “relief”
▪️ Agoraphobia
What clinical features may be supportive of a diagnosis of DS but cannot be used alone?
▪️ Failed response to multiple AEDs
▪️ Absence of risk factors for epilepsy
▪️ Risk factors for DS
What are thought to be the main risk factors for DS?
▪️ Previous MUS
▪️ Childhood trauma
▪️ Past psychiatric history
▪️ Possibly family history of epilepsy or personal history of BI?
How does accuracy of diagnosing epilepsy correct compare to diagnosing DS?
Very similar and reasonably accurate (70-80%)
BUT significantly less accurate correct diagnosis of DS by referring doctors
How useful is routine (inter-ictal) EEG for diagnosing DS?
Not very
How would EEG be used ideally to differentiate DS and epilepsy?
▪️ Video-EEG
▪️ With provocation so aim is to capture a seizure
▪️ Can also do sleep EEG
What sign on video-EEG telemetry is diagnostic of DS?
Preserved alpha rhythm during apparent impaired consciousness
(Alert although appearing not to be)
What signs on video-EEG telemetry would be diagnostic of epilepsy?
▪️ Ictal epileptiform discharges (spike and wave)
▪️ Post-ictal slowing
What are the main problems with using video-EEG telemetry to diagnose DS?
▪️ Can be difficult to capture a seizure, either if they are infrequent or someone has multiple types
▪️ False positives from movement (can look like epileptiform spikes)
▪️ False negatives from simple partial seizures or frontal lobe seizures (could be alert so looks like DS)
What can you do if you want to record a seizure of someone who has them infrequently?
Seizure “provocation” with several methods (e.g., hypnosis, tuning fork, IV saline, suggestion)
Need eyewitness to verify seizure is habitual!
How might serum prolactin be used to differentiate seizure types?
Idea is that lactate in blood increases with increased movement with seizure.
More likely to get a greater increase in epilepsy than DS
BUT rarely done in practice
What should you consider in the psychiatric assessment of someone with possible DS?
- Is there a primary psychiatric disorder mistaken for epilepsy?
- Is there an associated psychiatric disorder?
- Evidence of deliberate simulation?
- Possible predisposing, precipitating, and maintaining factors?
How does ictal anxiety in partial seizures differ from panic attacks?
▪️ Often shorter
▪️ More circumscribed
▪️ Tends to come out of nowhere
▪️ Described as tangibly different from anxiety but can’t describe how
