DISTURBANCES OF CONSCIOUSNESS Flashcards
What are the two parts of the brain that control the normal conscious state?
Cerebral hemispheres
Brainstem reticular activating system
What are the two most common causes of transient loss of consciousness?
Syncope
Seizures
Other than syncope and seizures, what are the other causes of transient loss of consciousness?
Hypoglycaemia Narcolepsy/cataplexy Hyperventilation Vertebrobasilar ischaemia Vertebrobasilar migraine Psychogenic or 'non-epileptic' attacks
What is the definition of syncope?
Transient loss of consciousness and posture that results from a global reduction in blood flow to the brain.
What is vasovagal syncope?
Syncope as a result of a sudden drop in blood pressure resulting from peripheral vasodilation. There is a subsequent paradoxical bradycardia (explained by the Bezold-Jarisch reflex) mediated by the vagus nerve, which leads to further drop in blood pressure and the result is syncope.
What are the common precipitates of vasovagal syncope?
Prolonged standing (especially in a hot or crowded place)
Strong emotion
Intense pain
What would indicate cerebral hypoxia in someone suffering vasovagal syncope?
Their eyes would roll upwards
Brief clonic movements
What is micturition syncope?
Vasodilatation during emptying of bladder, which occurs alongside postural hypotension on standing and bradycardia. Most common in men who get up to go to the loo in the middle of the night. Sudden loss of consciousness followed by rapid recovery.
What are some of the features of vasovagal syncope?
Patient is usually upright Light headedness Gradual dimming of vision Ringing in the ear Salivation Sweating Nausea Vomiting Pallor (which lasts even after recovery of consciousness) Clammy Low volume slow pulse
What is cough syncope?
Sustained coughing elevates the intrathoracic pressure sufficiently to impair venous return to the heart.
What is postural hypotension?
Upright posture is accompanied by an uncompensated fall in blood pressure and therefore also cerebral blood flow..
Who is most likely to suffer from postural hypotension?
Adolescents
People who have been in bed a long time due to illness
Autonomic neuropathy (eg diabetes, Guillain-Barre)
Hypovolaemia (eg blood loss, diuretic therapy, Addison’s disease)
Neurodegenerative diseases (Parkinson’s, multisystem atrophy)
Drug (antihypertensives)
What is syncope due to primary cardiac dysfunction?
Syncope of direct cardiac origin caused by a cardiac arrhythmia, aortic stenosis, HOCM, pulmonary stenosis, pulmonary hypertension, PE, ventricular failure (eg MI, dilated cardiomyopathy). Syncope is usually abrupt without warning. There is marked pallor followed by rapid return of colour. Brief tonic or clonic movements may be present.
What is syncope due to carotid sinus disease?
If a patient with hypersensitive carotid sinus (eg atheromatous disease) turns their head quickly when wearing a tight collar, or if carotid sinuses are massaged, patient can become hypotensive and lose consciousness.
What are some of the key differences between syncope and a seizure that can help you differentiate which was responsible for the loss of consciousness?
Syncope often standing whereas seizure any position.
Onset of seizure is sudden with little warning. Syncope often has prodrome.
Tone is reduced or normal in syncope, whereas seizures often involves prolonged increase in tone.
Urinary incontinence is common in seizure, less common with syncope.
Patient may bite their tongue during generalized seizure, less common with syncope.
Following a seizure, patient is confusedm drowsy with headache and aching muscles - postictal state. Following syncope, patient recovers quickly with slight malaise.
Injury is more common with seizures.
What are the prodromal symptoms (warning signs) of hypoglycaemia?
Feeling tremulous (shaky)
Sweaty
Palpitations
Disorientation
What are the causes of hypoglycaemia?
Overtreatment of diabetes Liver failure Hypopituitarism Addison's disease Insulinomas
Does hypoglycaemia occur in healthy subjects who have not eaten?
No.
What is narcolepsy?
A disorder associated with excessive sleepiness and sleep attacks at inappropriate times. Associated with cataplexy as well as hypnogogic and hypnopompic hallucinations. There is a strong genetic component.
What is cataplexy?
Attacks of sudden reduction in muscle tone, lasting several seconds to minutes, usually precipitated by excitement or emotion.
What does hypnogogic mean?
The transitional state of going to sleep.
What does hypnopompic mean?
The transitional state of waking up.
