• 
• 

Three Part Question

In [adult patients with transient loss of consciousness presenting to an ED], [what features of the history] point to a [diagnosis of a seizure]?

Search Strategy

Medline (1948 to June Week 4 2011) and Embase (1980 to week 26 2011) using the Ovid interface.
{[(transient loss of consciousness.mp.) OR (TLOC.mp.) OR (T-LOC.mp.) OR (exp Unconsciousness/) OR (exp Syncope/)] AND [(history.mp.) OR (features.mp.) OR (exp History/) OR (exp Medical History Taking/)] AND [(seizure.mp.) OR (fit.mp.) OR (epilep$.mp.) OR (exp Seizures/)]} LIMIT to humans AND english language.

Search Outcome

In Medline 275 papers were found of which two were relevant. In Embase 932 papers were found, of which two were duplicates.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Sheldon, R., et al 2002 Canada, Wales	671 patients were recruited from neurology, cardiology, pacemaker, arrhythmia and syncope clinics and cardiology wards of three hospitals. Patients recruited had at least one episode of T-LOC and an established diagnosis behind them, and excluded if there was any doubt. 102 patients had a diagnosis of seizure and 569 had a diagnosis of syncope of various cause. 118 variables were recorded from all the patients, which were then analysed to discover which differentiated syncope from seizure and a point score was formed. The derivation group was made up of 270 patients, and validated by groups of 268 patients with firm diagnosis, and 132 patients with syncope of unknown cause.	Prospective cohort study	Sensitivity for seizure diagnosis, ≥1 point	94%	Only seizure patients who have had a diagnostic EEG were included. No table of patient demographics. No reference to statistical power. No external validation.
			Specificity for seizure diagnosis, ≥1 point	94%
Hoefnagels, J., et al 1991 Netherlands	119 consecutive patients of age ≥15 referred to the neurological department over a 12 month period. Patients were referred by the GP, ED or other physicians. 25 were excluded due to lack of eyewitness account, leaving 94 in the study. A ten question questionnaire was provided to the patient and eyewitness, and the diagnostic value of various historical features was calculated.	Prospective cohort study	Prodromal Symptoms		No reference to statistical power. Unclear conclusion on the most effective combinations of symptoms.
			Sens/Spec for seizure: No sweating	98/36%
			Sens/Spec for seizure: No nausia	98/28%
			Sens/Spec for seizure: No spinning sensation	90/28%
			Sens/Spec for seizure: No dimming of vision	88/32%
			Postevent Symptoms
			Sens/Spec for seizure: Disorientation	51/91%
			Sens/Spec for seizure: Sleepy	73/64%
			Sens/Spec for seizure: Tongue bitten	41/94%
			Sens/Spec for seizure: Aching Muscles	39/85%
			Eyewitness Symptoms
			Sens/Spec for seizure: Disorientation	85/83%
			Sens/Spec for seizure: Frothing	44/91%
			Sens/Spec for seizure: Blue face	32/98%
			Sens/Spec for seizure: Pale face	38/17%
			Sens/Spec for seizure: Estimated duration >5 minutes	30/85%

Comment(s)

Although there were only two relevant studies, they both are of a high quality. The decision rule devised by Sheldon et al used a reassuringly large sample size of patients, and the study appears to have been conducted in a solid fashion. It could be said that the results for the rule are surprisingly high, and it is unfortunate it has not been externally validated yet. If that were to happen it put in a lot of trust for the rule. The other study is also strong, but the varied combinations of the different risk factors are hard to put into use for an ED. The results for the single factors are useful, in that the ones matching the decision rule do roughly correlate, lending credence. As much as external validation is needed, in the absence of conflicting evidence the point score proposed by Sheldon appears to be an appropriate choice for an ED.

Clinical Bottom Line

The point score proposed by Sheldon et al can be used to differentiate seizures from other forms of T-LOC. Tongue bitten, 2 points; Déjà vu style aura, 1 point; Emotional stress precipitant, 1 point; Head turning during event according to witness, 1 point; Unresponsive, unusual posturing or jerking during event according to witness, or no memory of the event, 1 point; Confused after event according to witness, 1 point; Presyncope symptoms, -2 points; Sweating prodrome, -2 points; Prolonged standing or sitting precipitant, -2 points Diagnose seizure with ≥1 point.

References

1. Sheldon, R., Rose, S., Ritchie, D., et al. Historical Criteria That Distinguish Syncope From Seizures. J Am Coll Cardiol 2002; 142-148
2. Hoefnagels, J., Padberg, G., Overweg, J., et al. Transient loss of consciousness: the value of the history for distinguishing seizure from syncope. J Neurol 1991; 39-43