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

Date First Published:

July 9, 2011

Last Updated:

July 21, 2011

Report by:

Markus Arnold, Medical Student (Manchester Royal Infirmary)

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 NMS]?

Search Strategy:

Medline (1948 to June Week 4 2011) and Embase (1980 to week 26 2011) using the Ovid interface.

Search Details:

{[(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 (History/) OR (exp Medical History Taking/)] AND [(neurally mediated syncope.mp.) OR (reflex syncope.mp.) OR (vasovagal.mp.) OR (simple faint.mp.) OR (faint.mp.) OR (exp Syncope, Vasovagal/)]} LIMIT to humans AND english language.

Outcome:

In Medline 341 papers were found of which 3 were relevant. In Embase 2442 papers were found, of which 2 were relevant, 3 were duplicates and two were deemed to be of insufficient quality to be included.

Relevant Paper(s):

Study Title	Patient Group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Clinical Findings as Predictors of Positivity of Head-Up Tilt Table Test in Neurocardiogenic Syncope. Asensio, E., Oseguera, J., Loria, A., et al. 2003 Mexico	117 consecutive patients referred for investigation of syncope over a 3 year period. 20 other patients had been excluded after cardiologist interview due to syncope of non-vasovagal cause. The most frequent variables of the histories were compared to the HUTT result.	Prospective cohort study	Dizziness, nausea and sweating predicting risk of positive HUTT for vasovagal syncope	24.78 times greater risk of positive HUTT	Excluding 20 patients may introduce a bias into the results. No attempt to validate results No reference to ethical approval. No reference to statistical power.
Diagnostic criteria for vasovagal syncope based on a quantitative history. Sheldon, R., Rose, S., Connolly, S., et al. 2006 Canada	418 patients were recruited over a 78 month period from 3 centres. Patients were included if they had a confirmed or working diagnosis of syncope, and excluded if there was history of heart disease or epilepsy. These patients were however used as part of a larger study on T-LOC. 118 variables were recorded from each patient and used to derive the Calgary Syncope Symptom Score.	Prospective cohort study	Calgary Syncope Symptom Score: Sensitivity for vasovagal syncope, ≥-2 points	89.30%	No reference to statistical power. No validation group. Relative lack of demographic data.
		Prospective cohort study	Calgary Syncope Symptom Score: Specificity for vasovagal syncope, ≥-2 points	90.80%
Diagnosing vasovagal syncope based on quantitative history-taking: validation of the Calgary Syncope Symptom Score. Romme, J., van Dijk, N., Boer, K., et al. 2009 The Netherlands	380 patients from a single hospital over a 26 month period were used in the study. Patients presenting with T-LOC aged ≥18 were eligible, and excluded for a history of heart disease or epilepsy. The outcome of each patient was compared to that predicted by the Calgary Syncope Symptom Score.	Prospective cohort study	Calgary Syncope Symptom Score: Sensitivity for vasovagal syncope, ≥-2 points	87%	No reference to statistical power.
		Prospective cohort study	Calgary Syncope Symptom Score: Specificity for vasovagal syncope, ≥-2 points	32%	No reference to statistical power.
Diagnostic Value of History in Patients With Syncope With or Without Heart Disease. Alboni, P., Brignole, M., Menozzi, C., et al. 2001 Italy	341 patients were analysed over a six month period from the syncope unit of three hospitals. 191 patients had suspected or certain heart disease, and 146 did not. 46 variables were collected from each patient and compared to the results of the HUTT.	Prospective cohort study	Patients with heart disease	8%	Aim of study not entirely in line with the clinical question, as such it is hard to analyse the results of the entire group. Relative lack of patient demographics. No reference to statistical power. No reference to ethical approval.
			Abdominal prodrome: Sensitivity for NMS	99%
			Abdominal prodrome: Specificity for NMS	40%
			>4 years between first and last episode: Sensitivity for NMS	87%
			>4 years between first and last episode: Specificity for NMS	14%
			Nausea on recovery: Sensitivity for NMS	96%
			Nausea on recovery: Specificity for NMS	39%
			Patients without heart disease	70%
			>10 second prodrome: Sensitivity for NMS	68%
			>10 second prodrome: Specificity for NMS	50%
			≥3 episodes: Sensitivity for NMS
			≥3 episodes: Specificity for NMS
Tilt Testing: Is It Necessary in All Patients with Suspected Vaso-Vagal Syncope? Kulakowski, P., Piotrowska, D., Konofolska, A. 2005 Poland	202 patients who were admitted to the syncope unit to be investigated for NMS. All had symptoms that had let referring doctors to suspect NMS. A 34 question questionnaire was used to collect historical information and this was compared to the HUTT result.	Prospective cohort study	≥-2 points in whole group: Sensitivity for positive HUTT	78%	Results obtained from reading graph, poor presentation of results. No reference to statistical power. No reference to ethical approval. No external validation.
			≥-2 points in whole group: Specificity for positive HUTT	52%
			≥-1 points in subgroup with >4 episodes: Sensitivity for positive HUTT	95%
			≥-1 points in subgroup with >4 episodes: Specificity for positive HUTT	60%
			≥-1 points in subgroup with >2 episodes in the last month: Sensitivity for positive HUTT	88%
			≥-1 points in subgroup with >2 episodes in the last month: Specificity for positive HUTT	92%

Author Commentary:

The available pieces of evidence for the most relevant historical features of NMS and any possible decision rule are hard to compare against each other. The five studies examined have slightly different aims and outcomes, plus are not based in an ED setting, so the focus is more towards a diagnosis rather than risk stratification. In the context of a wider ED guideline it should be noted that high risk patients should have already been identified in a screen for cardiac disease, so perhaps the low specificity of some of these results is less of a concern.

The recent guideline on T-LOC published by NICE commented on similar difficulty and took the route of a more general recommendation involving clinical judgement, and a system used by the DVLA for its ease of remembrance.

A reasonable compromise considering the would seem to be to take a middle ground of the Calgary Syncope Symptom Score and the NICE guideline's approach of 3 P's (posture, provoked, prodrome) with no features suggesting an alternative diagnosis.

Bottom Line:

Discharge a patient in the presence of one of a) posture (symptoms brought about by prolonged standing), provoking factor (symptoms brought about by a reasonable factor i.e. needlesticks) or prodrome (i.e. sweating or warmth beforehand) and all of b) no history of heart disease, no features suggesting an alternate diagnosis and their first episode being before 35 years of age.

References:

Asensio, E., Oseguera, J., Loria, A., et al.. Clinical Findings as Predictors of Positivity of Head-Up Tilt Table Test in Neurocardiogenic Syncope.
Sheldon, R., Rose, S., Connolly, S., et al.. Diagnostic criteria for vasovagal syncope based on a quantitative history.
Romme, J., van Dijk, N., Boer, K., et al.. Diagnosing vasovagal syncope based on quantitative history-taking: validation of the Calgary Syncope Symptom Score.
Alboni, P., Brignole, M., Menozzi, C., et al.. Diagnostic Value of History in Patients With Syncope With or Without Heart Disease.
Kulakowski, P., Piotrowska, D., Konofolska, A.. Tilt Testing: Is It Necessary in All Patients with Suspected Vaso-Vagal Syncope?