clinical + research techniques for investigating the nervous system Flashcards
for investigating neuroscience, what are the clinical methods?
clinical history + exam
neuropathology
imaging
electrophysiology
chemical studies
what questions are asked when taking the patients history?
age
sex
handedness
when, what and where is the problem
associated conditions
medication, allergies
family history
developmental history
what is observed/taken in a patients physical exam?
mental status (awake or comatose)
language (receptive and expressive)
cranial nerve exam
cerebellar exam
strength
tone (stiff or flexible)
reflexes
gait
cranial nerves are important for what part of the brain’s assessment?
brainstem
cranial nerves are typically tested in what kind of patient?
comatose
what is an example of a cranial nerve test they use that does not require a MRI or CT scan?
pupillary response: optic nerve, constricts (small) pupil
what are some tests to discover cerebellar signs that do not require MRI or CT scans?
nystagmus (eye jerk)
ataxia or unsteady gait (jack sparrow walk)
slurred speech
dyadiadochikynesia (cannot perform rapid alternating muscle movement)
what is the sensory response to pain?
withdraw
what is the pathway of a sensory response to heat?
hot object -> sensory receptors -> spinal cord -> muscle contracts and withdrawn parts being stimulated
what is the name for the type of reflexes that are normal in babies up until a certain age?
primitive
what do primitive reflexes help us identify?
brain lesions if reflex is there when it should be gone or does not exist completely
what are some examples of primitive reflexes in babies?
tonic neck reflex, grasp reflex, step reflex, crawl reflex
what is the deep tendon reflex?
hammer on knee, leg kicks up
the deep tendon reflex can be triggered by?
stretch receptors
reflex responses help doctor to?
localize where the lesion is
if there is an increased reflex, this suggests that there is a lesion..?
above the level tested
if there is a decreased reflex, there is a lesion..?
at the level or below the level tested
what is clonus?
brain or spine injury above lumbar
can clinical methods (neurological exam) show exactly where the lesion is?
no
the methods that were initially used to examine where brain lesions were was?
pathological post-mortem examination (brain after death)
what is brocas area responsible for?
speech
damage of the frontal left cortex associated with?
difficulty speaking
established lateralization of the lingusitixc funcgtion mainly in what hemisphere for right handed individuals?
left hemisphere
pathology can identify?
post-mortem brain changes
pathology can now give the?
subtype of disease
can pathology show the types of cells?
yes
pathology requires a sample, so how have we tried to avoid this?
brain imaging
what is a CT scan?
image with series of x-ray slices/images put together
what are the advantages of a CT scan?
- cheap and fast
- most common scanning method
- good at detecting blood
what are the disadvantages of a CT scan
- limited resolution
- can miss acute stroke lesions
- not as precise
what is an MRI scan?
a magnetic field where a radio signal moves a sequence of cells
what are the advantages of an MRI scan?
- very fine details of anatomy
- multiple sequences can be used to detect specific problem
what are the disadvantages of an MRI scan?
- take an hour
- children require sedation
- cost
- limited availability due to cost
what was one of the first applications of the MRI?
volume measurement
if someone has alzheimers, will they have a larger brain volume or a smaller brain volume?
smaller! experience shrinkage
what are two types of MRI sequences (______ weighted)
diffusion-weighted and perfusion weighted
what is a diffusion weighted MRI
water distribution
- diffusion of protons in water along fibre tracks
what is a perfusion rated MRI?
blood comes in and flow
MRI methods that use diffusion methods are used to examine tracts in patients with what kind of problems?
- brain tumors
- illness (depression)
- developmental disorder (autism)
- aging
what is magnetic resonance spectroscopy (MRS)?
the ratio of chemicals in a certain region
what are the advantages of MRS
- provides quantification of specific metabolites or neurotransmitters in specific regions of interest
what are the disadvantages of MRS?
- cannot from blood or urine
does CT, MRI, or MRS show the vascular aspect (arteries, veins) of the brain?
no!
what is an angiogram?
radio-opaque substance, or dye, to make the blood vessels visible under x-ray
what are the advantages of angiograms?
very precise mapping of the blood vessels (even smaller ones)
what are the disadvantages of angiograms?
requires a catheter to put into the blood vessels and injection of dye which can lead to vessels rupture or allergic reaction
sometimes the problem does not affect the structure of the brain but..?
the function of the brain cells
what is an electroencephalogram (EEG)?
difference in electrical potentials generated by the brain
what are the advantages of an EEG
- high temporal resolution
- useful monitoring state of arousal
- cheap
what are the disadvantages of an EEG?
- poor spatial resolution (no precise localization)
- restricted mainly to cortical activity (cannot if it is small or deep)
what is a common disorder EEG is used to monitor?
seizures
what are grids used for in an EEG
put directly onto the brain for precise mapping
what are depth electrodes used for in an EEG
implanted into the brain for deeper structure recording
what is an electromyogram (EMG)?
patient muscle activity is recorded either at the surface or using a needle inserted within the muscle
what are the advantages of an EMG
- allow to measure precisely activity in the muscle
- detect when the muscle is not getting enough nerve input and is “disconnected”
- can help define the type of muscle disease
what are the disadvantages of an EMG
- painful needle insertion depending on placement
what is nerve-conduction stimulus (NCS)
patient nerve activity is recorded by stimulating the nerve and recording the time for its connected muscle to be activated
what are the advantages of NCS
- measure the precise activity of the nerve (both speed and wave form of the amount of muscle used)
- can narrow down type of disease by injury pattern
what are the disadvantages of NCS
can be painful with the stimulation of the nerve
until the year 2000, what was the most used method for genetic testing?
karyotypes
what do karyotype genetics allow?
visualize different chromosomes using a staining method and microscope
what can copy number variation due (in relation to karyotypes)?
can be either a gain or loss of DNA
what is comparative genomic hybridization (CGH)?
obtain patient DNA, have a reference sample plus patient DNA, compare copy of gene
in CGH, if there is a gain in the patient, what colour is it?
red
in CGH, if there is a deficit in the patient, what colour is it?
green
what is an advantage of CGH
map changes in the copy number for the entire genome so do not need to know which gene could be affected in patient
what is a disadvantage of CGH
will not be able to tell if a patient has a single base pair change
what is next generation sequencing (NGS)?
multiple fragments sequenced at once, has a single base pair resolution
what are the advantages of NGS
multiple sequences at the time allow for faster and cheaper sequencing of entire genome
what are the disadvantages of NGS
- more error-prone than one gene
- need a reference genome for aligning the fragments of colour coded sequences
what are the clinical methods for both central and peripheral called?
brain metabolies
what are the two forms of brain metabolites
lumbar puncture / spinal tap
magnetic resonance spectroscopy (MRS)
what is a lumbar puncture?
looks at the level of red blood cells, white blood cells, glucose, protein in cerebrospinal fluid (CSF)
what are the advantages of lumbar puncture
- allows to get CSF, which can identify chemical, metabolic, or immune differences
- less invasive than getting brain tissue
what are the disadvantages of lumbar puncture
- patient must be collaborative
- risk of pain and infection
