Neuro Lecture 1 Flashcards
EEG measure the spontaneous electrical activity of the what?
Superficial cortex
How many electrodes are placed on a person for an EEG?
20+
Who reads EEGs?
Neurologist who has fellowship training in neurophysiology
How many people will have an abnormal EEG?
8% of people. Must be clinically correlated for diagnosis
How many % of patients with epilepsy have a normal EEG?
20% (not sensitive, not specific)
Can an EEG measure activity deeper in the brain?
No
How long is a routine EEG for?
20-120 minutes
What can cause significant artifact on the EEG?
movement of muscles
ex- blinking eyes, moving arm, etc
Someone with a primary _________ epilepsy is unlikely to have a normal EEG.
generalized
What is an EEG where leads are kept on for 6+ hours (usually 8).
extended EEG
What is where the patient is discharged to go home with EEG recording, somewhat like a Holter monitor.
Ambulatory EEG
Leads are left on for 24-72+ hour, inpatient.
Video EEG (usually take off of all meds, usually for pre-op)
Are all EEGs done with video?
Yes
Subdural or stereotactic depth electrodes. Leads are used for stimulation and recording.
Implanted EEG
Done right before surgery (make sure you aren’t taking out the right area)
Benefits of implanted EEG
Incredible detail
can transmit information
What 2 things is a CT of the head excellent for showing?
Bone and blood
CT shows the ventricles reasonably well in adults and children > ___ years old. Grey-white matter contract is visible.
2 years old
Test where an area of the brain is turned off, then wake patient up and put then through a battery of tests.
Wada test
what type contrast is used for CT?
Iodine
why can’t you see the different in white and grey matter in infant CTs?
Don’t get myelin until about 18 months old
What type stroke will show up on CT?
hemorrhagic
What is the natural exposure from air, food, etc. in the USA?
3.1 mSv/year (about 4 in ABQ)
how much radiation is a CT of the head?
2.0 mSv
for the heart stress test, which has higher radiation exposure?
Thallium
How much radiation from a PET scan?
14.1 mSv
What 3 conditions is a head CT good for?
Traumatic injury to the head
Stroke (hemorrhagic)
suspected increased ICP
What is a MRI good at showing?
brain tissue
Can a head MRI be done with many implanted metal devices in the patient?
Yes, it is a different machine used with a “send-receive coil”
What type contrast is used with MRI?
Gadolinium
Does a MRI cause radiation?
Nope
2 reasons for brain MRI with contrast.
Infection or neoplasm
Do 3 tesla and 1.5 tesla cost the same?
Yes (3 tesla MRI has better imaging)
Why doesn’t MRI show bone well?
Bone doesn’t have much water
How long does a MRI usually take?
30-45 minutes but can do fast MRI with thicker sections (only about 5 minutes)
What detects pairs of gamma rays emitted indirectly by a tracer (usually fludeoxyglucose)?
PET scan
What is a PET scan good at showing?
Areas of increased metabolic activity (glucose uptake)
What 2 things in the brain are more metabolically active?
Tumor
Epileptogenic
What are some limitations of PET scans?
Images aren’t sharp
Must be compared w/ normal brain images
High radiation exposure (14 mSv)
Scan done within 2 hours of giving fludeoxyglucose
What is similar to PET but directly measure emitted gamma radiation?
Single Photon Emission CT (SPECT)
How is a SPECT different than a PET?
Directly measure emitted gamma radiation
Not as sensitive as PET, longer 1/2 life of tracers
Bigger window to do scan
When may you get a medication level way more than prescribed?
After a patient has had a seizure then are given lots of their seizure meds.
What is a PET scan good at showing?
Areas of increased metabolic activity (glucose uptake)
What drugs can cause seizures?
Cocaine
Ecstasy
Meth
any stimulant drugs
Level to see how much medication is in a patient’s blood. Don’t know when they last took their medicine, if they took their medicine, etc.
random medication level
What are 2 rules of thumb for drug levels.
- If they are still having seizures- drug is too low
2. If they are having side effects- drugs is too high
Why do you get a random drug level.
To see if a patient has really been taking their meds.
What is the biggest reason for a breakthrough seizure in someone with epilepsy?
Skipping their medication
What is a medication level taken right before their morning dose?
Trough level
What is the peak level a measure of?
Absorption of the medication
If you want to see if a person is given enough of their drug, what level do you want to get?
Trough level
Are there separate orders for random or troughs?
No, only you will known
What should you order when a person presents with a seizure?
Toxin screen (a lot of street drugs cause seizures)
When do you order LFTs and ammonia levels?
When someone is on an anti-epileptic med that affects P450
What 2 drugs most commonly cause liver problems?
Valproic acid, carbamazepine
Why do you want to order a CBC with differential and a Chem 7?
Some meds can cause anemia, changes in sodium, etc.
Do you worry more about levels in the system or CBC with differential?
CBC with differential (and history)
