Neuro 2 Flashcards
give 2 mechanisms by which you can develop neuropathy
demyelination - Schwann cell damage.
Axonal degeneration - axon damage, conduction remain intact.
Wallerian degeneration - follows nerve section.
Compression - disruption of myelin sheath.
Infarction - microinfarction of vasa nervorum.
Infiltration - by inflammatory cells, granulomas and neoplastic cells.
what changes in the spine could there be in cervical/lumbar degeneration?
osteophytes, thickening of spinal ligaments, narrowing of spinal canal, disc degeneration and protrusion, vertebral collapse, ischaemic changes
if someone is referred to you with suspected Horner’s syndrome, what do you expect to find on examination?
unilateral pupillary constriction with slight ptosis and enophthalmos, loss of sweating on same side
a patient comes to see you complaining of visual loss at the ‘sides of his eyes’ on both sides and has some vague endocrine symptoms, what are you thinking is the cause, what kind of visual loss does he have and where is the lesion?
pituitary neoplasm pressing on the optic chiasm causing bitemporal hemianopia.
you are performing a cranial nerve examination on a patient who has an oculomotor nerve lesion (CN3), what would you see?
ptosis, large pupil, eye down and out.
what is the corneal reflex and what nerve controls it?
trigeminal nerve.
involuntary blinking of eye when the cornea is stimulated by something such as cotton wool.
a small child presents to you with a vesicular rash on the side of their face, their mother says they’ve been struggling to eat recently as well - what do you suspect is the cause and how would you treat it?
Ramsay Hunt syndrome caused by herpes zoster/shingles, treat with fanciclovir
name a drug that can cause sensorineural deafness?
gentamicin, furosemide
what is mononeuritis multiplex? give 3 examples of causes
2+ peripheral nerves affected, causes tend to be systemic - WARDS PLC: Wegener's AIDs/Amyloid Rheumatoid Diabetes mellitus Sarcoidosis PAN Leprosy Carcinomatosis
give the 2 subtypes of gliomas
astrocytoma and oligodendroglioma
name 3 types of primary malignant brain tumour
glioma, embryonal tumours, lymphoma
name 2 types of benign brain tumour
meningioma, neurofibroma (e.g. from Schann cells)
what is the most common cause of brain tumours?
metastases:
bronchus, breast, stomach, prostate, thyroid, kidney.
what are the common sites of meningiomas?
parasagittal region, sphenoidal region, subfrontal region, pituitary fossa and skull base
what are the 4 main classes of symptoms you can get from a brain tumours?
raised ICP, seizures, focal neurology, personality change
what investigation would you use to stage a brain tumour?
CT/MRI + CXR etc to look for primary
how would you manage a brain tumour?
surgical removal if possible.
IV/PO dexamethasone to reduce cerebral oedema.
phenytoin to treat epileptic seizures.
radiotherapy.
what is the primary infection in shingles?
chicken pox - reactivation of herpes zoster/varicella zoster virus
what are the clinical features of shingles?
dermatome distribution of rash (papules and vesicles), pain and tingling.
most common in lower thoracic dermatomes and ophthlamic division of trigeminal nerve.
how would you treat shingles?
oral acyclovir or valaciclovir as early as possible
what is the main complication of shingles and how would you treat it? how is it prevented?
post-herpetic neuraligia - pain in distribution of affected nerves.
treat with carbamazepine or phenytoin.
prevented by prompt antiviral treatment.
how do anti-epileptic drugs work?
they work on sodium channels to inhibit action potentials to stop continuous firing of neurones
pyridostigmine is used in a neurotransmitter disease, which one and how does it relieve symptoms?
myasthenia gravis - acetylcholinesterase inhibitor, which means ACh is around longer to attach to the post-synaptic membranes
baclofen is used for muscle spasticity in what disease, and how does it work?
Huntington’s chorea - GABA agonist.
what type of drug do you prescribe in trigeminal neuralgia?
anti-epileptic, carbamazepine
ceftriaxone is prescribed in bacterial meningitis, what class of antibiotic is it?
3rd generation cephalosporin
give 2 examples of benzodiazepines. what are they used for?
diazepam, lorazepam, chlordiazepam - first line management of seziures and status epilepticus, management of alcohol withdrawal rections.
how do benzodiazepines work?
target the gamma-aminobutyric acid type A (GABA-a) receptor, which is a chloride channel that opens in response to binding by GABA (main inhibitory neurotransmitter) - opening the channel makes the cell more resistant to depolarization.
benzodiazepines facilitate and enhance binding of GABA to GABA-a receptors and have a widespread depressant effect on synaptic transmission - cause reduced anxiety, sleepiness, sedation, anti-convulsion.
what is carbamazepine used to treat?
epilepsy - focal seizures ± secondary generalisation and for primary generalised.
trigeminal neuralgia.
how does carbamazepine work?
inhibits neuronal sodium channels, stabilising resting membrane potentials and reducing neuronal excitability.
this may inhibit spread of seizure activity, and control spread of neuralgic pain by blocking synaptic transmission.
what are valproates used for? name one.
epilepsy - 1st choice for generalised/absence seizures and focal seizure treatment.
sodium valproate, valproic acid.
what are gabapentin/pregabalin used to treat?
focal epilepsies as an addition to carbamazepine.
also for neuropathic pain and migraine prophylaxis.
how does gabapentin work?
closely related to GABA - binds to voltage sensitive calcium channels, preventing inflow of calcium and thus inhibiting neurotransmitter release, interfering with synaptic transmission and reducing neuronal excitability.
give some examples of dopaminergic drugs
levodopa (as co-careldopa, co-beneldopa), ropinirole, pramipexol
how do dopaminergic drugs work to treat Parkinson’s?
there’s a dopamine deficiency in Parkinson’s - treatment increases dopaminergic stimulation to the basal ganglia.
levodopa = dopamine precursor that is able to cross the BBB.
ropinirole and pramexipol = selective agonists for the D2 receptor, which predominates in the basal ganglia - used to delay starting levodopa.
what is levodopa always given with? why?
a peripheral dopa-decarboxylase inhibitor e.g. carbidopa - combined preparations (co-careldopa, co-beneldopa).
this is to reduce conversion to dopamine outside the brain, reducing SE of nausea, and lowering the dose.
what class of drug do rivastigmine and neostigmine belong to? what are they used to treat?
acetylcholinesterase inhibitors.
Alzheimer’s disease, Lewy body dementia and Parkinson’s disease. also myasthenia gravis.
how do acetylcholinesterase inhibitors work as neurological drugs?
inhibit ACh break down. in neurodegenerative disorders they are used to treat memory and learning deficit symptoms - improve due to role of ACh in cognition.
in myasthenia gravis there are too few ACh receptors, so with greater ACh availability, symptoms improve.
