EX2 Lecture 8: CNS Flashcards
What are the characteristics of a classic migraine?
Aura (may include any of the following: nausea, vomiting, visual scotomas, or even hemianopsia and speech abnormalities)
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Severe throbbing/pulsing UNILATERAL headache for 1 hour to a 1-2 days.
what does the CNS do
integrates sensory information and generates motor output and other behaviors necessary to interact with the environment
what are neurons
electrically excitable cells that process and transmit information via electrochemical processes
what is neuroglia
nonneuronal support cells that perform a variety of functions in the CNS such as maintaining extracellular ion concentration, providing nutrients to neurons, and insulating/controlling the speed of conduction in neurons
what is the blood brain barrier (BBB)
protective separation of the circulating. blood from the extracellular fluid in the CNS that limits penetration of substances including most medications
What is the difference between a classic and a common migraine?
Common migraines do not have the aura but the headache is similar
What is the common treatment for migraines?
NSAIDs
What is the more pharmacologically advanced treatment for migraines?
Triptans
what are triptans
serotonin neurons involved with numerous functions in the body such as mood, sleep, appetite, temperautre regulation, perception of pain, regulation of blood pressure and vomitting
(5-HT)
What is 5-HT?
Serotonin
What are the two 5-HT receptors we care about in migraines?
5-HT1B, which is the serotonin receptor found in the substantia nigra and globus pallidus (cheese of the pizza)
5-HT1D, general serotonin receptor in the brain.
What is the Mechanism of Action (MoA) for a triptan?
Act on intracranial blood vessels and peripheral sensory nerve endings, resulting in vasoCONSTRICTION and DECREASED release of inflammatory peptides.
What is the clinical indication for sumatriptan?
Migraines (First-line therapy for severe migraine attacks)
What are the contraindications for sumatriptan?
CAD
Angina (via coronary vasospasms)
Stroke (induce coronary vasospasm stroke)
(Note: All are related to the vasoconstriction aspect)
If I need sumatriptan ASAP, what formulation should I take?
Injections or nasal (faster onset than oral)
What is the first-line therapy for severe migraines?
Triptans
What are the other medications used for migraines besides triptans?
Ergot alkaloids, such as ergotamine
What is the MoA for ergotamine?
Vasoconstriction of smooth muscle working mostly at the alpha receptors.
What is the difference between ergotamine and sumatriptan?
Triptan is more effective for acute migraine attacks.
When is ergotamine most effective?
Very early in a migraine attack. Often combined with caffeine.
Why should I be wary using ergotamine and what are some side effects to be concerned about?
Frequent usage can cause rebound headaches.
Side effects can include Cyanosis, Ischemia, and prolonged vasospasms.
what is the dose of ergotamine to stay under to avoid vasospasm risk
no more than 6mg per attack or 10mg weekly
What are some prophylactic treatments for migraines?
None that have achieved notable success. (for acute migraines)
BUT
some common ones used still (shown to be effective in prevention in some pts but NO value in acute migraine):
propranolol (non-selective BB and lipophilic), topiramate (anticonvulsant), and valproic acid (Anticonvulsant)
Uncommon: Amitriptyline (TCA)
verapamil (CCB)
How fast is sumatriptan’s onset?
1.5 hours orally, 0.2 hours SubQ.
This means I can take another one within 1-2 hours if I really need to.
what is neurodegeneration
progressive loss of structure or function of neurons, including death of neurons
list diseases that occur as a result of neurodegenerative processes
ALS, parkinsons, alzheimers, huntingtons
what is a tremor at rest characteristic of
parkinsonism, when it is often associated with rigidity and an impairment of voluntary activity
What is chorea?
Chorea consists of unpredictable, irregular, involuntary muscle jerks that occur in different parts of the body and impair voluntary activity.
Huntington’s disease is also known as Huntington’s Chorea
What is athetosis?
Abnormal movements that are slow and writhing in nature.
What is dystonia?
Abnormal posturing, muscle rigidity
What are tics? Most notable disease?
Sudden, coordinated abnormal movements that occur repetitively. Usually in the head/face area, such as shoulder sniffing or sniffing in children.
Gilles de la Tourette syndrome or Tourette’s (chronic multiple tics)
What are some of the most notable signs of parkinson’s? first symptom and declining ability during disease?
Combination of rigidity, bradykinesia, tremor, and postural instability. Bradykinesia often comes before the diagnosis can be made. (first)
cognitive decline occurs as disease advances
What is the pathology of Parkinson’s?
Loss of dopamine neurons in substantia nigra.
Dopamine normally inhibits GABA, which is an INHIBITORY NT.
Ach will bind to the GABAergic neuron to activate it, but dopamine normally inhibits it.
other non motor symptoms of parkinsons
affective disorders (anxiety, depression)
confusion
cognitive impairment
personality changes
apathy
fatigue
abnormalities of autonomic function (sphincter or sexual dysfunction, dysphagia and choking, sweating ab., sialorrhea, distubrances in BP regulation)
sleep disorders
sensory complaints or pain
What are the two goals of treatment of Parkinson’s based on the pathophysiology?
Increase Dopamine levels.
Inhibit Ach.
( dopamine from substantia nigra usually inhibits the gabaergic output from striatum but dopamine loses ability to do so in parkinsons)
What is the special characteristic of Levodopa vs dopamine?
Levodopa is a prodrug/metabolic precursor that CAN cross the BBB via an L-amine transporter (LAT). It is then decarboxylated to dopamine.
Dopamine cannot actually cross the BBB, therefore injecting or eating dopamine does nothing for Parkinson’s
how much administered levadopa actually gets tot he brain when given by itself? why is that?
1-3%
the remainder is metabolized extra cerebrally, predominantly by decarboxylation to dopamine which does not penetrate the BBB
levadopa must be given in LARGE amounts when given alone
Why do we add carbidopa to levodopa?
Carbidopa is an inhibitor of the decarboxylating enzyme, so more Levodopa can get into the brain. Carbidopa DOES NOT penetrate to the BBB.
so, peripheral metabolism of levadopa is reduced, plasma levels of levadopa are higher, plasma half life is longer, and more available to enter the brain
Concomitant adminstration of carbidopa and levadopa can reduce the daily amount of levodopa required by up to _____. Carbidopa acts as levadopas _____
75%, bodyguard
What are some common side effects of levodopa and carbidopa?
Dizziness, Nausea, dyskinesia, constipation.
how is combination levadopa/carbisopa treatment initiated? with or without food?
small doses eg carbidopa 25mg levadopa 100mg three times daily and gradually increased
take with food for delayed absorption, without food if need more immediate absorption