Parkinson's & Epilepsy recap

Question 1

DTs

Answer 1

hyperadrenergic state - highly excitable
hallucinations, confusion, delusions, severe agitation, generalised tonic clonic seizures

Tx is based on a symptom score, depending on the symptoms, and if the patient scores high enough they are treated with benzodiazepines as required

management: ABC assessment
treat any hypoglycaemia
sedations with benzodiazepines
barbiturates?ICU may be required
screen for Wernicke's encephelopathy
treat with oral thiamine (vit B1) eg pabrinex

Question 2

wernickes encephalopathy

Answer 2

signs and symptoms

Question 3

korsakoffs

Answer 3

signs and symptoms

Question 4

benzodiazepines

Answer 4

resp depression
can precipitate hepatic encephalopathy
in patients with ALD use lower dose

Question 5

phenytoin

Answer 5

10-20mg/l
measured using both free and protein bound phenytoin
in patients with low albumin, the free phenytoin may be normal even if the total level is low due to the low amount protein bound

important info:
inhibitor of p450 enzymes
inducder of p450
narrow therapeutic index
first order kinetics within therapeutic range
highly protein bound
causes hypotension and arrhythmias when given IVI

Question 6

phenytoin kinetics

Answer 6

metabolism is dose dependent
first order kinetics at low concentrations - constantly increasing as dose increases
zero order kinetics at high concentrations - plateaus and metabolised at the same rate even in higher doses

Question 7

sodium valproate

Answer 7

inhibitor of p450 enzymes
teratogenic
monitor levels
pancreatitis is a side effect

Question 8

status epilepticus

Answer 8

> 5mins: IV lorazepam, PR diazepam, buccal midazolam
20mins: alert anaesthetist for further sedation

if benzodiazepines don’t work –> slow IV phenytoin (caution arrhythmias and hypotension)

Question 9

carbamazepine and warfarin

Answer 9

carbamazepine is an enzyme inducer and will therefore induce the metabolism of warfarin, so the dose of warfarin must be increased accordingly, and INR monitored
it would be acceptable to continue using both, with more INR monitoring or to stop carbamazepine in favour of an alternative eg lamotrigine. patient discussion and choice

Question 10

carbamazepine

Answer 10

p450 enzyme inducer
raised GGT due to enzyme induction
hyponatraemia due to carbamazepine causing (rarely) SIADH
can induce its own metabolism

toxicity (as with most anti-epileptics):
cerebellar signs
reduce the dose and monitor until symptoms are under control

Question 11

drug induced parkinsonism

Answer 11

subacute, bilateral onset is unusual in normal parkinson’s, usually tremor starts in one hand

high risk drugs are dopamine antagonists, like haloperidol, stemetil (for vertigo)