Nervous System Pathophysiology Flashcards
What is the cause of transient loss of consciousness?
Inadequate cerebral perfusion (flow of blood supplied to the brain)
What are three types of loss of consciousness resulting to inadequate cerebral perfusion?
Vasovagal syncope
Exercise related syncope
Epilepsy
What causes epilepsy?
Transient uncontrolled paroxysmal discharges of nerve tissue within the brain (high frequency discharge of action potentials in the brain)
A disturbance of electrical activity
Attacks needs to be recurrent to diagnose epilepsy
What percentage of seizures stop after ten minutes?
80%
What is the idiopathic cause of epilepsy?
Genetics
What does idiopathic mean?
Disease or condition arises spontaneously or the cause is unknown
What are the symptomatic causes of epilepsy?
Head injury Infections like meningitis Brain underdevelopment Stroke Scaring Tumors
What are some causes of epilepsy?
Genetics
Brain infection such as meningitis
Drug abuse such as angel dust (PCP), cocaine, amphetamines
Electric shock
Fever
Head injury
Heat related illness
Poisoning
Pregnancy related - eclampsia (seizure after giving birth)
Stroke
Toxin buildup in the body due to liver or kidney failure
Withdrawal from alcohol or certain medicines after using for a long time
What are the three types of epilepsy?
Focal
Generalised
Status epilepticus
What are the three types of focal (partial) epilepsy?
Simple focal
Complex partial
Secondary generalised
What are the types of generalised epileptic seizures?
Absences Tonic Atonic Myoclonic Tonic clinic Clonic
What’s the difference between focal seizures and generalised seizures?
Focal is where only a small part of the brain is affected whereas generalised involves the whole brain
How does simple focal seizures cause symptoms associated with the temporal lobe?
Deja vu getting an unusual smell or taste
Sudden intense feeling of joy or fear
How does simple focal seizures affect frontal lobe?
Stiffness or twitching in part of the body (such as an arm or hand)
How does simple focal seizures affect the parietal lobe?
Feeling of numbness or tingling
How does simple focal seizures affect the occipital lobe?
Visual disturbances
Hallucinations
How long does complex focal seizures typically last?
15-30 seconds
What lobe does complex focal seizures usually affect?
Temporal lobe
What symptoms are associated with complex focal seizures?
Repetitive movements such as fiddling with clothing
Chewing or lip-smacking movements
Muttering or repeating words that don’t make sense
Wondering around in a confused way
LOC may be affected and the patient may seem confused
What is a secondary generalised seizure?
Begins as focal seizure but spreads into the other hemisphere and becomes generalised
What are absent seizures also known as?
Petit mal
How are tonic seizures characterised?
Person becomes rigid and usually falls over
Injuries are common
Usually brief and occur without warning
How are tonic seizures characterised?
Complete and sudden loss of muscle tone
Often called a ‘drop attack’
May result in injuries
Last a few seconds
Recovery usually quick
How are myoclonic seizures characterised?
Muscle jerking
Patient remains conscious
Usually has other generalised forms of epilepsy
Often occurs in clusters but are relatively short lived
How are tonic clonic seizures characterised?
Person becomes unconscious
Body goes stiff and usually falls backwards
They may cry out
They may bite their tongue or cheek
They jerk and shake (convulse) as their muscles relax and tighten rhythmically
Breathing may be affected and become difficult or sound noisy
Pallor or cyanosed
Incontinence (lack of control over urination and voluntary control)
After seizure, breathing and colour return to normal and may feel tired, confused, headache and want to sleep (post ictal)
How are clonic seizures different to tonic clonic seizures?
Similar but patient does not go rigid at the start
Limbs tend to jerk
How are status epilepticcus seizures characterised?
Convulsions lasting longer than 30 minutes
Repeated seizures for over 30 minutes with no recovery in between
Potentially life threatening
What are some causes of nonepileptiform seizures?
Hypoxia Trauma Stroke Hypoglycaemia Metabolic disturbances Eclampsia Fever (febrile) Meningitis Intracranial tumour Drug intoxication Septicaemia Uraemia (High conc of urea in blood) Hypertension
What is the treatment for seizures?
ABCD
Access: blood glucose Heart rate and rhythm Temperature Blood pressure Alcohol or drug usage Signs of injury
Airway: NP
O2 - 100% until reliable measurements can be gained
Position of comfort and try to minimise noise
Refer to treatment plan where possible
Buccal midazolam or diazemuls
How is midazolam presented?
Ampule containinh 5mg in 5ml or buccal pre-filled syringes of 2.5mg, 5mg, 7.5mg and 10mg
What are the three actions of midazolam?
Benzodiazepine derivative (imitates BZ)
Onset of action 2 mins and peak effect 5-10 mins
Short acting sedative decreasing from 15 mins onwards
What are the side effects of midazolam?
Respiratory depression Hypotension Reduced LOC Confusion and increased agitation Amnesia in some patients
How old to patient have to be to administer midazolam IV or IO?
Over 17 years old
Through IV or IO how many grams of midazolam is administered? What is the time interval for doses? What is the max dose?
2mg
Repeat after 2 mins if needed
Max dose 10mg
What is the mg dose of buccal midazolam for adults?
What is the time interval for dosage?
What is the max dose?
10mg
Repeat after 10 mins
Max dose 20mg
What is the presentation of diazepam?
Ampoules containing 10mg in 2ml (IV preferred route)
What is the actions of diazepam?
CNS depressant, anticonvulsant and sedative
What are the indications for the use of diazepam?
Fits longer than 5 mins and still fitting
Repeated fits (not secondary to uncorrected hypoxia or hypoglycaemia)
Status epilepticus
Eclampsia fit (>2-3mins or recurrent)
What cautions should be taken with diazepam?
Respiratory depression Alcohol or CNS depressants Recent dose Hypotension Drowsiness Lightheadedness Confusion Unsteadiness Amnesia
What is the recommended dose IV or IO of diazepam for adults?
What is the time interval for dosage?
What is the max dose?
10mg
Repeat after 5 mins
Max dose 20mg
What is a stroke also known as?
Cerebrovascular Accident (CVA)
What is a stroke?
A loss of cerebral function works symptoms lasting more than 24 hours
What is a transient ischaemic attack (TIA)?
An acute loss of cerebral or monocular function with symptoms lasting less than 24 hours
What percentage of strokes are ischaemic?
85%
What percentage of strokes are haemorrhagic?
15%
What does ischaemic mean?
Clot blocks blood flow to an area of the brain
What does haemorrhagic mean?
Bleeding occurs inside or around the brain tissue
What five different categories are ischaemic strokes classified as?
Large-artery atherosclerosis = a clot from the arteries
Cardioembolism = a clot from the heart
Small-vessel occlusion = a narrowing it weakening of blood vessels
Stroke of other determined etiologies
Stroke of undetermined etiology
What are the two types of haemorrhagic stroke?
Intracerebral haemorrhage (ICH) = bleeding within the brain
Subarachnoid haemorrhage (SAH) = bleeding on surface of brain
What are the causes of ischaemic strokes?
Atherosclerotic (Thickened, hardened arteries narrowed by fatty deposits)
Thrombotic (blood clot)
Embolic (any foreign substances e.g. air)
