History.
Mrs. Yu was a 60-year-old non-drinker who presented with a 1-year history of recurrent, brief, stereotypical “whole body freezing” as witnessed by her husband:
- Begins with a blank staring gaze and abrupt cessation of activity at that juncture.
- Followed by repetitive no-no head turning to both the left and right lasting for 2-3 seconds; associated with facial grimacing. .
- Followed by reduced responsiveness for around 1 minute
- Followed by a complete recovery of consciousness.
- No particular triggers; 4-7 times per month, increasing in frequency; occur while sitting or standing; no out-of-sleep events.
Physical examination.
Normal neurological examination.
MOCA 18/30.
Investigations.
1st EEG: left temporal delta slow.
2nd EEG with sleep deprivation:
- Left temporal delta slow.
- Clinical event captured:
- Painful facial muscle spasm (8-14 seconds, tracings contaminated by muscle artefacts).
- Followed by forceful head turning to the right (3-5 seconds).
- Appeared to relax with eyes open; recorded left hemisphere theta slowing with left temporal focal delta slowing for 3 seconds; the background then returned to a generalized beta rhythm.
MRI brain: normal; paired amyloid PET: no significant beta-amyloid deposition; FDG PET: non-specific findings.
Home video:
- Facial grimacing.
- Followed by head turning to the left with intervening sudden right-ward jerks; right arm posturing with oral automatism.
- Verbally unresponsive during the event, lasting for <30 seconds
- Return to normal within 10 seconds.
EEG reviewed with epileptologist:
- Clinically: facial grimacing; heading turning to both sides; followed by disorientation; no definite lateralizing features or evolution.
- Electrographically: follow the onset of the clinical event, left hemisphere rhythmic delta lasting for 6 seconds with evolution (decremental frequency down to 2 Hz, no spatial evolution or suppression.
Video EEG:
- Interictally: left temporal spike waves and slow waves.
- 5 seizures captured
- Electrographically: electrical onset at FT7-FT9 with rhythmic slowing
- Clinically: abrupt freezing while browsing her iPad or peeling an orange occurred BEFORE the electrical onset of left temporal rhythmic slowing.
- Confirmed left mesial temporal lobe epilepsy.
LP: WCC 3, protein / glucose normal, NMDA / autoimmune encephalitis panel negative.
Thought process.
Syndrome:
- Chronic, episodic, brief, stereotypical sequence of facial grimacing / head turning / right arm posturing.
Localization:
- Cerebrum; likely the temporal lobes.
Etiology:
- Seizure
- Amyloid spells / transient focal neurological episodes
- PNES / functional movement disorder
Learning points:
- I had mistakenly concluded that the events were likely amyloid spells or functional in etiology: very brief episodes (against the 10-20 rule), no electrographic correlation during the event (not concluded as “electrographic seizure”).
- Looking forward, 1. do not rely solely on event duration to accept or refute a diagnosis of seizure; the 10-20 rule is a rule of thumb; a seizure can be very brief, c.f. faciobrachial dystonic seizure in LGI1-related autoimmune encephalitis; 2. do not rely solely on EEG to accept or refute a diagnosis of seizure; electrographic seizure foci may not be apparent on scalp surface EEG, especially for focal seizure; 3. if uncertainty arises, video EEG is essential to clarify the nature of the event.