201 cns Flashcards
What is epilepsy?
-sudden excessive high frequency neuronal discharge
-highly synchronous discharges (not random)
-may be loss of consciousness
-behavioral changes related to sire of discharge.
risk factors of sezuires
-disturbed water/electrolyte levels
-disturbed glucose levels
-raised body temperature
-sleep disturbance
-toxicity
-heredity
-tumors
diagnosis of epilepsy
-seizures must be recurrent and spontaneous
-EEG records abnormal electrical charges
types of generalized seizures
- tonic-clonic seizures ( patient falls, stiffens, convulses, hyper-salivation, laboured breathing)
- tonic (stiffening of body)
- clonic (impairment of consciousness)
-absence ( eyelids flutter, head drops)
-myoclonic ( involuntary,s shock-like jerks)
-atonic (sudden loss of muscle tone)
types of focal seizures
-simple focal ( retains awareness)
-complex focal ( altered awareness, confusion)
-secondarily generalized seizures ( focal seizure that lead to tonic-clonic seizure)
what is status epilepticus ?
tonic-clonic seizure lasts more than 5 minutes, person doesn’t regain consciousness in between
how do seizures arise?
dynamic between excitation and inhibition is disturbed ( loss of inhibition)
how do seizures stop without intervention?
- K channel activation
-Na channel deactivation - glutamate receptor desensitization
- glutamate depletion
how do antiepileptics work?
- decrease excitatory mechanism
- inhibit glutamate neurotransmission
- inhibition of calcium channel
-enhancement of GABA function - inhibition sodium channels ( preferentially block cell that are firing repetitively, not all of them)- prefer the inactivated state of sodium channels, preventing them from becoming activated)
Drugs that reduce glutamate release
-lamotrigine, phenytoin, carbamazepine, sodium valproate ( Na- channel block)
-gabapentin, pregabalin ( Ca- channel block)
-levetiracetam (reducing vesicle fusion)
Drugs acting at GABA synapses
- vigabatrin, sodium valproate (increase GABA levels)
-tiagabine ( decrease GABA inactivation)
-benzodiazepines ( prolong channels open time)
Non- pharmacological treatment of epilepsy
- surgery
-vagus nerve stimulation (stimulation with a pacemaker type device)
-deep brain stimulation
-ketogenic diet ( brain is forces to use ketones rather than glucose)
sodium valproate (indication, monitoring, precautions)
-can be used for all forms of epilepsy
-monitor liver function before therapy and during first months
-measure full blood count and ensure no undue potential bleeding before starting
-highly teratogenic ( contraception needed)
-vitamin D supplementation
carbamazepine (indication, monitoring, precautions)
-focal and secondary generalized tonic-clonic
-primary generalized tonic-clonic
-monitor plasma concentration for optimum response 4-12 mg/L measured after 1-2 weeks
-blood counts and hepatic and renal function test
-increased risk of stevens-jonson syndrome
-vitamin D supplementation
lamotrigine (indications, monitoring, precautions)
- used for monotherapy of focal, primary and secondary generalized tonic-clonic or seizures associated with Lennox-Gastaut syndrome
- plasma drug concentration should be monitored before, during and after pregnancy
-can cause hypersensitivity (skin rash)
-can cause bone marrow failure
levetiracetam (indications, monitoring, precautions )
-used for monotherapy of focal seizures
-monitor plasma concentrations during pregnancy
-can cause depressions and suicidal ideation emerge
-increased risk of somnolence or other CNS side effects
what are the symptoms of Parkinson’s disease?
Cardinal: -tremor
-bradykinesia
-rigidity
-postural instability
Other symptoms: mental changes,
constipation, sexual dysfunction, urinary problems, sleep disturbances, pain, impulsive behavior
what is the pathology of Parkinson’s disease?
- lewy bodies (contain alpha-synuclein)
- aggregated of alpha- synuclein
-leading pathogenic hallmarks in brain biopsies
-loss of DA producing neurons in substantia nigra- imbalance in direct and indirect pathways
-loss of cotrico-spinal output
-decreased movement, rigidity
what are treatment options for parkinson
-L- dopa: replace dopamine
-AADC inhibitors: increase availability
- MAO-B inhibitors: decrease breakdown eg. entacapone, rasagiline, selegiline
- D2 agonists: rotigotine (patch), apomorphine (in advanced PD)
-glutamate antagonists (amantadine) reduce dyskinesia cause by levodopa
Levadopa therapy
- levadopa is given with cabidopa (inhibit dopa decarboxylase) to enable it to cross BBB and prevent breakdown in the gut
-long term use can cause dyskinesia and motor fluctuations
-Late and missed doses can lead to complications such as pneumonia and falls
what are the risk factors of PD?
- increasing age
-male - head trauma
-genetic mutation
treatment for Alzheimer’s disease
-acetylcholinesterase inhibitors (increases acetylcholine)
(donepezil, galantamine, rivastigmine)
-NMDA receptor antagonists (memantine)
(reduces glutamate because it creates oxidative stress which breaks down proteins and nucleic acid so it contributes to cell death)
-new drug: lecanemab (reduce αβ)
what are the symptoms of dementia
cognitive: memory loss, lack of concetration, disorientated, speech difficulties
non-cognitive: agitation, aggression, distress, psychosis
diagnosis for dementia
-Alzheimer’s: >60, memory loss
-vascular: screened for depression, psychomotor retardation
-lewy body: visual hallucinations and parkinson symptoms
-frontotemporal: <65, semantic, non-fluent
what are the symptoms of schizophrenia and what are the pathways associated with them
-positive: hallucinations, delusions (mesolimbic pathway)
-negative: emotional apathy, social withdrawal (mesocortical pathway)
-cognitive: disturbance of normal thought processes
first vs second generation antipsychotic drugs
-first: block D2 receptors, more likely to cause side effects eg. phenothiazine derivatives, haloperidol
-second: act on a range of receptors, lower risk of extrapyramidal symptoms and dyskinesia but associated with weight gain and glucose intolerance eg. aripiprazole, clozapine, olanzapine
what are common side effects of antipsychotics
-hyperprolactinaemia (risperidone, amisulpride, sulpiride and 1st gen.)
-sexual dysfunction (risperidone, haloperidol, olandapine)
-CVS (primozide)
-hypotension (clozapine, quetiapine)
-weight gain (clozapine, olazapine)
-hyperglycemia and diabetes
-NMS (all of them)- requires weekly monitoring first 6 weeks then 12 weeks then 1 year.(weight, glucose, lipid, ECG, blood pressure, blood test, liver function)
what are the requirements for high dose antipsychotics
- initial prescription should be written as single dose until effects have been reviewed
-oral and intramuscular dugs should be proscribed separately
-patient should be monitored every 15 minutes
structural deficit of schizophrenia
-disruption of neuronal migration
-enlarged ventricles
-reduced regional cerebral volumes
-loss of neurons
-biomarkers in EEG: changes in response to external stimuli
mechanism of typical (first gen.) psychotics
high affinity D2 receptor antagonists (phenothiazines, haloperidol)
effective only against positive symptoms
serious side effect: DA-related: pseudoparkinsonism, tardive dyskinesia, akathisia, sexual dysfunction
non-DA: sedation, hypotension, peripheral autonomic
mechanism of atypical (second gen.) psychotics
low affinity for D2 receptors
benzamides
less side effects
can cause weight gain and diabetes
what is drug tolerance
-desensitization of receptors, higher doses are required to achieve the effect
-β-arrestin prevent G proteins subunits coupling and block the receptor. this limits the receptor availability for agonist binding