Syncope and seizure: a raised CK pointed to a seizure.

Clinical bottom line (level 1b)

Patients with a transient loss of consciousness and a CK of 188 or more, were likely to have had a seizure.
A CK < 188 made a seizure less likely but could not exclude it.

Libman et al: Journal of General Internal Medicine 1991; 6: 408-412

Expires October 2004

The study

Setting: emergency department, university teaching hospital, Canada

96 patients (aged mean 53 years, 50% male) transient loss of consciousness

Excluded if

<16 years old

failure to regain consciousness fully before leaving emergency department

no clear loss of consciousness

Independent blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
Reference standard:

chart review at 3 to 4 months (chart information revealed line-by-line by physician blinded to CK result). Tonic-clonic seizure if:
- witnessed
- captured on ECG
- post-ictal with transient loss of consciousness or evidence of incontinence without other clear cause

Diagnostic test: creatinine kinase (CK); positive if > 188 Units/l (typically done 3 to 4 hours after event). Was a routine investigation (when remembered)

The evidence

pre-test probability of seizure: 44%, (95% CI: 34% to 54%)

diagnostic test	seizure	no seizure	LR+ (95% CI)	post-test probability	LR- (95% CI)	post-test probability
CK 188 or more	18	1	23 (3.2 to 170)	95%	0.58 (0.45 to 0.76)	31%
total	42	54

Comments

Needs to be prospectively validated.
Seizure rate seems high in the study - were patients with known epilepsy included?

Citation

Libman MD, Potvin L, Coupal L, et al: seizure vs. syncope: measuring serum creatinine kinase in the emergency department. Journal of General Internal Medicine 1991; 6: 408-412

Contributor: Chris Ball and Clare Wotton, October 2000
Reviewer:

_{Clinical Question.}

_Patient	_{transient loss of consciousness}
_{Intervention or Exposure}	_{CK 188 or more}
_Outcome	_seizure