Confusion and syncope

Confusion is a symptom, not a diagnosis. Confusion is a recent alteration in higher cerebral functions such as memory, attention and awareness (not alertness or consciousness). There is a broad range of severity of confusion; it can be as minor as a disturbance to short-term memory, to an inability to relate at all to the surrounding environment, and process sensory input (delirium).

There are four groups of disorders that account for most cases of diffuse cortical dysfunction:

  • Exogenous toxin
  • Drug withdrawal
  • Primary intracranial disease
  • Systemic diseases secondarily involving the CNS

There are two groups of patients with confusion that require urgent attention:

  • Hypoglycaemics
  • Hypoxaemics

Therefore, in any patient with confusion it is important to conduct pulse oximetry and bedside BSL testing. Vital signs are important; if patient hyperthermic, consider infection and find possible source. Similarly, lungs auscultation may reveal ischaemia.

Differential diagnoses:

  • Cerebral hypoxia
    • AMI
    • Respiratory failure
    • CHF
  • CNS infection
  • Elevated ICP
  • Systemic
    • Hypoglycaemia
    • Sepsis
    • Hepatic encephalopathy
  • Intoxication and withdrawal (not just from illicit substances but from prescribed medication)
  • Medication side-effect
  • Trauma
  • Subarachnoid haemorrhage

Basic investigations:

  • BSL
  • Pulse oximetry
  • Urinalysis (?infection)
  • CXR (?infection)
  • UE&C’s and blood cultures
  • LFTs
  • · ECG

Syncope questions

The final common pathway for all causes of syncope is dysfunction of both cerebellar hemispheres or brainstem. It is a transient LOC. The life-threatening causes of syncope are primarily cardiovascular in origin.

The causes of syncope can be categorised into:

  • Syncope due to hypoperfusion
    • Focal hypoperfusion of CNS
      • Cerebrovascular disease
      • Subarachnoid haemorrhage
    • Systemic hypoperfusion
      • Aortic stenosis
      • AMI
      • Tachycardia
      • VF
      • 2nd or 3rd degree heart block
      • Aortic dissection
      • Neurocardiogenic (vasovagal)
      • Miscellaneous reflex
  • Syncope not due to hypoperfusion
    • Hypoglycaemia
    • Hypoxia
    • Seizure
    • Drug-induced
    • CO poisoning

Life-threatening causes of syncope:

  • Hypovolaemia/haemorrhage
  • AMI
  • Arrhythmias
  • Aortic stenosis (severe)
  • Hypoglycaemia
  • PE
  • Subarachnoid haemorrhage
  • Stroke

Questions to ask:

(a) What actually happened in the syncopal event (character of event)? Key elements include (i) setting (e.g. postprandial), (ii) rate of onset, (iii) standing, sitting or supine at time of onset, (iv) duration and (v) rate of recovery. Sudden onset while sitting/supine and more than a few seconds duration à think serious (cardiac) cause.

(b) What happened before the event? –> preceded by exertion (outflow obstruction), emotional stress, urination, defecation (reflex syncope), aura (seizure)

(c) Associated symptoms? –> chest pain or breathlessness (AMI/PE), gray/black vision (neurocardiogenic), incontinence of urine/stool (seizure)

(d) Past medical history?

· Cardiovascular disease? Arrhythmias? Valve problems?

· Diabetic? (at risk of hypoglycaemia)

· Recent surgery?

· Recent bleeding? Vomiting? Diarrhoea?

(e) Medications? –> beta-blockers, CCBs, ACE-Is, insulin and oral hypoglycaemics, diuretics, Digoxin

(f) Recreational drug use?

(g) Occupation? (CO poisoning)

Questions to ask all the time:

· Smoker?

· Appetite?

· Weight loss?

· Any recent changes to medications?

· Allergies?

· Diabetic?

Some causes and their clinical features:

  • Arrhythmia –> abrupt onset and rapid recovery
  • Outflow obstruction –> related to exertion; rapid recovery
  • AMI –> recovery often incomplete
  • PE –> dyspnoea and recovery often incomplete
  • Aortic dissection –> recovery often incomplete
  • Subarachnoid haemorrhage –> focal neurologic findings

Most important investigations = ECG, postural BP, then Ix according to D.Dx.