Loss of Consciousness(LOC)

Nota:

• Syncope : a form of LOC in which hypoperfusion of the brain is the cause -- bld flow that joins the brain together with rest of the body has been cut

1. Reflex( Young)
   1. Activation of a primitive reflex that leads mammals to 'play dead' when faced with danger, HBR drops, BP temp drops, dropped cerebral perfusion, lead to syncope. But some have reduced threshold for activation of this reflex
      1. Eg, standing still for long, seeing something scary like bld/needles, if straining--micturition, defaecation
         1. Eg, vasovagal syncope, carotid sinus hypersensitivity, situational syncope--micturition

            Nota:

            • vasovagal syncope: common LOC in young..25ys and sometimes in middle age like 35yrs  in these young pts: they have a warning/pre-syncopal sensation ( i.e. pale, clammy) 
2. Cardiac( Middle-Older age)
   1. Pathologies causing drop in CO
      1. Eg, arrhythmias, CO obstruction such as HOCM, massive PE

         Nota:

         • common cause of LOC in middle age: vasovagal syncope, arrythmias
         1. Arrythmia usually secondary to IHD, Therefore, you can say that most LOC occurs in elderly as IHD occur as pts age and in those with atherosclerosis

            Nota:

            • Pts describe LOC w/o warning/triggers( i.e. suddenly passing out in front of TV). This is why arrythmias can be the most fatal. 
3. Orthostatic(Old)
   1. Means low BP on sitting/standing
      1. when standing, sudden drop in BP that we compensate by vasoconstriction, esp of the 'capacitance' veins in legs

         Nota:

         • This reduces intravascular space, so we can maintain pressure. Pts with reduced intravascular volume(i.e. dehydration)  and in whom with normal autonomic response( tachy and peripheral vasoC) to standing is blunted( i.e. due to drugs/autonomic neuropathy) : increased risk of blackouts
         1. This vasoC takes a few sec, so to prevent a transient fall in BP, our HBR rises
            1. Eg, dehyration, drugs( antihypertensives, anti-sympathetics)

               Nota:

               • Common cause of LOC in elderly: drugs causing ortho hypo ACEi: reduced bld vol and vasoD B-blockers: inability to increase HBR on standing Alpha-blockers: inability to vasoC the major capacitance veins CCB: inability to vasoC and some are negatively inotropic/chronotropic
               1. Poly-pharmacy makes it harder to maintain adequate BP

                  Nota:

                  • Pts describe losing conscious after standing up as their body is unable to compensate for the sudden drop n BP
4. Cerebrovascular
   1. Aka non-cardiac structural causes of reduced cerebral perfusion
      1. Eg, vertebrobasilar insufficiency, aortic dissection, subclavian steal

1. Intoxication
   1. eg, alcohol, sedatives
2. Head trauma
3. Metabolic
   1. Mainly hypoglycaemia
4. Non-epileptic 'seizure'
   1. psychologically driven
5. Epileptic seizure

1. Any warning?
   1. If no, likely cardiac arrythmia/massive PE or can be general seizure
   2. If yes: aura can mean partial epileptic seizure and dizziness mean vasovagal
2. Any precipitating factors?
   1. postural triggers such as standing up mean ortho hypo
   2. fear/pain
      1. vasovagal
   3. LOC by turning head

      Nota:

      • carotid sinus hypersensitivity
   4. LOC whilst sitting/lying down

      Nota:

      • Arrhythmia
   5. LOC when exercising

      Nota:

      • structural cardiac pathology such as aortic stenosis/cardiomyopathy
3. Any recent head trauma?
   1. Subdural haeM esp in elderly/alcoholics

1. Period of LOC( sec/min)
   1. Short-lived/seconds?

      Nota:

      • Vasovagal/arrhythmia
2. Any biting tongue/moving limbs/incontinence?

   Nota:

   • Tongue biting: epileptic seizure Twitching/incontinence: vasovagal

1. Period of recovery and if confused after recovery?
   1. Rapid recovery on sitting/lying?

      Nota:

      • Vasovagal 
   2. Slow recovery with confusion?

      Nota:

      • Epileptic seizure
   3. Rapid spont. recovery

      Nota:

      • Arrhthymia

1. PMH

   Nota:

   • 1. Previous episodes and ask if increasing freq 2. DM : risk of vascular disease, hypoglycaemia, polyuria and dehydration, autonomic dysfunction that cause ortho hypo 3. Heart disease: Ask about palpitations, chest pain...if present previous heart hx, then likely cardiac syncope 4. PVD: claudication?, associated with coronary heart D which has same pathology( atherosclerosis) 5. Epilepsy? 6. Anaemia: hypoxia 7. Psychiatric illness: panic attacks associated with hyperventilation and LOC
2. Drug Hx

   Nota:

   • 1. Insulin? Oral hypoglycaemics: can cause hypoglycaemia 2. Antihypertensives: diuretics, ACEi, B-blockers, CCB cause hypotension 3. Vasodilators: GTN, isosorbide mononitrate...cause hypotension in elderly 4. Anti-arrthymias: can predispose to arrthymias 5. Antidepressants: TCA can cause hypotension
3. Social Hx

   Nota:

   • Alcohol?  Stimulant recreational drugs: cocaine and amphetamines stimulate heart causing tachyarrthymias and a drop in CO
4. FHx

   Nota:

   • Sudden death? esp if unexplained syncope/exercise-induced syncope

Nota:

• Look at side of tongue for bitten tongue

Nota:

• dry mucous membrane, tachycardia, hypotension Occur dur to hypovolaemia and predispose to cerebral hypoperfusion

Nota:

• try to find out if heard trauma occurred before/after LOC (e.g. did they hit their head as they fell?)

1. focal neurological signs

   Nota:

   • signs of peripheral neuropathy? ( due to DM, chronic alcohol abuse)Parkinsonism that may be due to autonomic dysfunction

1. Pulse/murmurs

   Nota:

   • slow/irregular pulse: heart block/AF JVP: look for cannon waves? These are 'a' waves in the jugular pulse caused by right atrial contraction occurring after ventricular contraction has closed the tricuspid valve . These occur in complete heart block( also cause of syncope)
2. BP

   Nota:

   • Check for ortho Hypo. Take BP lying down and within 2 min of standing .  Def of ortho hypo: Drop of > 20 mmhg in SBP or >10mmhg DBP on standing
3. Bruits

   Nota:

   • carotid artery stenosis: carotid bruit

1. Oxygen sats

   Nota:

   • Hypoxia secondary to massive PE
2. Bloods
   1. Capillary bld glucose

      Nota:

      • Exclude hypoglycaemia? Undiagnosed DM which can lead to polyuria and dehydration Established DM with autonomic dysfunction can lead to hypotension and blackouts
   2. FBC

      Nota:

      • Anaemia?
   3. U&E

      Nota:

      • exclude electrolyte abnormality
3. ECG

   Nota:

   • Arrthymia?: but need to know that they are intermittent and so the abnormality may not show at time of recording...therefore if normal, it does not exclude a cardiac cause. Guidelines say that use ECG only when more probability that LOC is due to arrthymia( eg, young pt with sudden LOC and no warning/reason)..then you can look for BBB/arrythmia with short PR or long QT interval

1. Echo

   Nota:

   • valve lesion?
2. Carotid sinus massage

   Nota:

   • carotid sinus sensitivity
3. EEG

   Nota:

   • Epilepsy
4. Brain scan( CT can/MRI)

   Nota:

   • epilepsy