Transient Loss of Conciousness
In this episode we are going to be covering the assessment of Transient Loss of Conciousness (T-LOC) and discussing some of the differentials that could be responsible, from the easily discharged to the potentially life threatening.
What we aren’t covering is the potential complicating factors such as concomitant injuries so as always we need to ensure we are performing thorough assessments and applying sound clinical judgment. [1]
The History:
Take a really detailed history, I always like to work chronologically from the events leading up to the collapse. I make a point of telling patients to be very descriptive as we not only need to know what happened and develop a time line of events but also to understand what they felt, what the saw, what they remember and also what any external observers saw. Be sure to ask
Was it a T-LOC?:
The first and most obvious step is to ascertain was this actually a loss of consciousness. Patients and Lay persons tend to use the word “collapse” interchangeably to describe conditions such as “faint”, “fall”, “fit” and “dead” and so it is really important to ascertain if there was a loss of consciousness or if they came to end up on the floor from other means.
If you are struggling to work this out as maybe the patient can’t remember or they are particularly cryptic in their description of events no matter how hard you try to decipher them, it is safest to assume there was a Loss of consciousness and go from there.
Patients may present to you with "pre-syncope" or a near loss of conciousness, without a fully blacking out. Whilst it is important to make a distinction between these in your work up, we should not be reasured by the fact the patient didn't fully lose conciousness. A 2019 multicentre study showed that there are statistically similar 30 day mortality rates between these two presentations. [12]
The circumstances of the event:
what were they doing before the event? Had they just worked out? Had they eaten a big meal? Got out of the shower? Been urinating or coughing or even adjusting their tie… these all give varying clues as to possible differentials discussed below.
Collapse during exercise = redflag , collapse after exercise potentially vasovagal
The person's posture immediately before loss of consciousness:
It is unusual for less concerning causes of collapse to happen when a person is sat comfortably because of the increased functional reserve we have at rest. Cases of people who have collapsed whilst seated, without an obvious provoking factor (e.g. tooth extraction at the dentists) should be investigated very carefully for more sinister causes of collapse. However vasovagal syncope’s are common in people who have been standing for a long time and orthostatic syncope’s or postprandial syncope’s often occur when transitioning between sitting and standing.
Were there prodromal symptoms (such as sweating or feeling warm/hot) ?
Absence of these may suggest a more sinister cause such as fitting or cardiac syncope. Presence of prodrome with obvious provoking factors reassure us of a less sinister cause such as situational or vasovagal syncope.
The patients appearance (for example, whether eyes were open or shut) and colour of the person during the event
Eyes are often open during events such as syncope or seizures, and is often remembered by witnesses as they find it quite disconcerting. Psychogenic seizures or non epileptic seizures often have eyes closed, though this single feature is obviously not diagnostic [14] . Commenting on patients head position during the even is useful. Head turning to the side can be indicative of seizure activity.
The presence or absence of movement during the event (for example, limb-jerking and its duration)
So a lot of people will recognise this question as being able to distinguish between a probable syncope and a fit,. However, it is important to remember the early stages of a syncope can have “fit like” motion and noisy breathing. People who faint that are held up can have reflex seizure activity and may have myoclonic jerking until they are on the ground, so it is important to put this question into perspective with the rest of the picture. [3] [4]
Any tongue-biting (record whether the side or the tip of the tongue was bitten) ?
Tongue biting is not necessarily diagnostic of a seizure, although it should certainly increase our suspicions. The literature is sparse, of poor quality and varies slightly in what it seems to report. But general themes that it seems to agree on are that tongue biting is not present in all seizures, but occurs more often than in syncope. Fitting generally tends to result in bilateral or lateral tongue injury, where as syncope is generally central and this is from the fall rather than anything else. [5] [6]
Duration of the event (onset to regaining consciousness)
To diagnose a T-LOC it must have a rapid onset and a relatively rapid recovery. Putting exact times on these are difficult, as we would perhaps have slightly different tolerances for what we would expect dependent on the cause and the situation.
Just because the event was very rapid, does not mean it is any less concerning, as cardiac syncope can take place over seconds.
Recurring episodes that are in a short time frame (multiple episodes today), or occur regularly without any ongoing diagnosis or current investigation would concern me and definitely prick up my ears as a potential redflag. Perhaps the only exception to this rule would be is a clear situational / vasovagal syncope history and evidence that the patient was not allowed to recover fully between episodes. I.E. the army cadet who has fainted on the very hot parade square and has promptly been walked off it by their colleagues, there is a chance they may have another syncope as their blood pressure hasn't had time to stabilise.
Presence or absence of confusion during the recovery period
Whether there is a post ictal period is a good indicator of if a patient has had a seizure or not. That is not to say we should expect patients who have fainted to get straight back up and act like their normal selves. Tiredness, mild dizziness, nausea and feeling generally grotty is to be expected after a faint, however we would expect them to be able to hold a conversation relatively soon after regaining consciousness. [7]
Weakness down one side during the recovery period.
Or any positive signs really, can be indicative that there is something more sinister going on. Although it is unusual for a CVA to present with a loss of consciousness[8] , they can obviously present with seizure activity. If we think the patient may have had a seizure and is now presenting with a sustained hemiparesis or other neurological signs, we should had CVE high on our list of causes. There is of course a chance the patient could have had a seizure from some other cause i.e. EP, and is now presenting with a Todds paresis [9]. Telling these apart in this situation can be a night mare, and so if the patient isn’t known to have Todd paresis and the symptoms are sustained, it is probably a good idea to treat for the worst case scenario and get the patient to a scanner.
Past medical History:
As with every case we need to take a detailed past and family medical history.
Diabetes can predispose to cardio vascular disease. Polyurea can lead to dehydration +/- hypoglycemia and so may increase risk of Orthostatic hypotension. [10] [11]
Patients on dieuretics, ACE inhibitors, Beta Blockers, Calcium Channel blockers, vasodilators, antidepressants can cause hypotension and predispose to orthostatic drops. Antiarythmics can paradoxically cause arythmias. [10]
Patients with cardiac abnormalities electrical or obstructive are redflags in the context of T-LOC. Patients who have any sudden unexplained or cardiac death of young people (Under 40) in their family history should be reffered for a 24 hour cardiology follow up. [1]
Assessment:
Assess for injury:
As above, we are assuming these patients have been uninjured from the fall, however a routine injury scan should form part of your assessment. Pay particular attention to the head and for subtle injuries to the tongue and cheek as above.
Cardiovascular Assessment:
Patients should have a thorough assessment including ECG, auscultating heart sounds and listening for carotid bruitis.
ECG: All T-LOC patients must have a 12 - lead ECG and any abnormality should be refered on for assessment. You should be confident in identifying and excluding the following according to NICE Guidance. [1]
- Conduction abnormality (any degree of heart block).
- Inappropriate persistent bradycardia.
- Any ventricular arrhythmia (including ventricular ectopic beats).
- Long QT (> 450 ms) and short QT (< 350 ms) intervals.
- Brugada syndrome.
- Ventricular pre-excitation (part of Wolff-Parkinson-White syndrome).
- Left or right ventricular hypertrophy.
- Abnormal T wave inversion.
- Pathological Q waves.
- Atrial arrhythmia (sustained).
- Paced rhythm
Heart Sounds: NICE Guidance states that you must be competent at finding new added heart sounds or murmers. There are lots of resources available to assist with improving your knowledge around heart sounds. As a bare minimum you should be able to recognise normal and abnormal heartsounds as this could be a sign of an obstructive cardiac problem which caused the T-LOC. These patients would require urgent cardiology reivew.
Neurological Assessment :
Dependent on the presentation of the patient it would be prudent to do a neurological exam. Assessing mental state, cranial nerves, gait and reflexes might be appropriate dependent on your earlier finding and history.
Abdominal Assessment:
A cursory abdominal exam can be beneficial and documenting a normal exam is important for our paperwork. AAA can present with syncope but will likely have abdominal pain or a pulsatile mass.
Ectopic pregnancies can also present with syncope as a presenting symptom. Up to 20% of women with ectopic pregnancies can present haemodynamically unstable on initial assessment, so we should be sure to ask about pregancy in our history and examine the abdomen for tenderness. [13]
Hopefully thats has been a useful summary of T-LOC. But don't just take our word for it be sure to read around the subject and look at the references provided.
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