Clinical and Research techniques for investigating the human Nervous system

Question 1

who pioneered the standardized exam?

Answer 1

charcot

Question 2

what are 2 clinical methods of assessment?

Answer 2

1. clinical history of patient (i.e their lifestyle, any recent changes…etc..)
2. clinical examination (measuring BP, heart rate..etc..)

Question 3

What is a neurological exam?

Answer 3

it is a baseline assessment of overall neurological function (brain, spinal cord, and pathways) and if they’re working as they should be (broad examination)

Question 4

What are 6 types of neurological exams?

Answer 4

1. Mental Status –> i.e. whats ur name, whens ur birthday… questions that test general awareness
2. cranial nerves –> assessment to see if cranial nerves are damaged like for oculomotor pathway damage, the test would be to shine a light in the eyes to see if pupils would contract
3. motor examination
4. sensory examination
5. cerebellar function
6. deep tendon reflexes (assesses lower motor neuron function like muscles in afferent pathways in PNS and CNS)

Question 5

What is a commonly used test to check deep tendon reflexes?

Answer 5

the patellar tendon reflex (tapping knee and seeing if it will jerk upwards)

Question 6

What is the common test for cranial nerves?

Answer 6

test on the CN 2-3 (cranial nerves 2 and 3) involves the oculomotor pathway, shining a light on the patients pupil and seeing if it contracts

Question 7

What is impaired upper motor neurons?

Answer 7

upper motor neurons are in the cortex and brain stem while the lower motor neurons are in the spinal cord and cranial nerves. Upper motor neuron impairment is related to some type of impairment in the cortex and brain stem areas instead of the spinal cord and cranial nerve damage areas

Question 8

What 2 tests to assess upper motor neuron impairment?

Answer 8

1. Babinski sign –> stroking bottom of foot to see if it curls inwards (if it flares upwards then its a + Babinski, and it shows damaged o upper motor neurons, usually from people who have MS and strokes)
2. Clonus: when holding foot down normally, it should not be shaking at the bottom, but for people who have clonus, it shakes indicating problem with the pathway between motor neurons and the brainstem area

Question 9

What were the initial clincal methods used?

Answer 9

anatomical examination of the brain after death called post-mortem examination

Question 10

What does the neurological examination and history for progression of symptoms indicate about the disease and lesion?

Answer 10

the neurological examination can indicate where the lesion would be, the history of the progression of symptoms can indicate what the disease could be (but cant confirm)

Question 11

What are some examples of pathological clinical methods?

Answer 11

1. Broca’s area (identified damage in the orbitofrontal cortex of patient after death) and linked the symptoms of difficulty speaking with that pathology in their brain. Looked at lateralization of the linguistic function and how its more left brained than right for right handed individuals
2. phineas gage and his rod through the head –> he used to have a normal personality but then it changed after his incident via damage to the frontal lobe
3. Chronic traumatic encephalopathy –> sings of severe neurodegeneration due to too much head trauma in life due to accumulation of Tau proteins

Question 12

What are some downfalls of pathology based clinical methods? how can we prevent this

Answer 12

pathology requires sample of brain which is really hard to get in most people unless they die, so now neuroimaging techniques are used to preserve tissue

Question 13

What are some advantages and disadvantages to MRI imaging clinical methods?

Answer 13

advantages:

• MRI provides fine details of the anatomy
• multiple sequences used to detect specific problems (sequences are different magnetic strengths and pulses which can generate different outputs and areas of the brain) like inflammation, stroke, infection..etc..

Disadvantages

• takes 1 hr (3 min for CT scan)
• children require sedation and special care
• mri and stuff are rly costly
• availability is limited (used in labs only)

Question 14

What is MRI Pulse sequencing?

Answer 14

programmed set of changing magnetic gradients which allow for the radiologist to look at the same tissue in various ways
- combining various sequences is important to reveal diagnostic information about the tissue under question

Question 15

What is a computerized tomography -CT scan? what are some advantages and disadvantages?

Answer 15

method of obtaining image x-ray slices

advantage: - cheap and fast, mostly used in hospitals, and very good at detecting blood and strokes
disadvantages: - image resolution is poor, and can miss rly small blood clots (hard to pinpoint)

Question 16

What are the 3 main components of an MRI machine?

Answer 16

1. magnet
2. radio frequency coil
3. detector

Question 17

What are 3 ways MRI’s are most commonly used to detect any abnormal signs in the brain?

Answer 17

1. using mri methods to measure movement/diffusion of protons in water along fibre tracts; (water moves within myelin in the stream, in cases like MS where theres myelin degeneration, the map of the diffusion of protons will look different); beneficial for detecting illnesses with as depression, developmental disorders and aging
2. Volume measurement: was on the first applications of MRi. Using it to detect the volume changes of brain areas to see if its associated with the symptoms
3. MRI sequences of diffusion weighted and perfusion weighted images have been tailored to identify exactly where an acute stroke lesion in the brain would be (shows that mri can also be used to look at vasculature of brain and blood flow)

Question 18

What are angiogram imaging techniques and what do they test for?

Answer 18

angiograms use a radio-opaque substance or dye to make blood vessels clear under x-rays

• it can be used to show blood clots in the brain even tiny acute ones (also can show how tPA a clot buster can clear up a clot in the brain to renew normal blood flow in vessels)
• essential for picking up things an MRI cant pick up like vascultis (inflammation of blood vessels, aneurysm and vascular malformations

Question 19

What are EEG’s and when are they used to measure?

Answer 19

EEG’s record difference in electrical potentials generated by the brain

• used to see how the problem affects the function of the brain cells
• EEG measures brain rhythms as well (alpha, beta, gamma..etc..)

Question 20

How can EEG be used to detect seizures?

Answer 20

it localizes what goes on in different areas of the brain to see where the seizure started and what areas of the brain it effects via array of electrodes on scalp and reading of gross electrical activity in the brain

Question 21

What 2 things can be used to detect finer location of epileptic activity via eeg?

Answer 21

1. grids (grids of electrodes placed on surface of the brain for months to record activity)
2. depth electrodes to look at deeper neurons

Question 22

What are the advantages and disadvantages of EEG?

Answer 22

advantages: has high temporal resolution, and is useful for monitoring state of arousal; cheap and available
disadvantage: poor spatial resolution and restricted only for cortical activity and not brainstem or periphery

Question 23

WHat is lower motor neuron impairment? (peripheral)

Answer 23

its impairement in the spinal cord and reflexes in the motor neurons to the skeletal muscle areas

Question 24

what is microneurography?

Answer 24

it is a method of determining properties of sensory receptors in the skin of humans (for ALS detection)

• done by stimulating skin receptors and then recording the response
• it is a peripheral nervous system method of analysis

Question 25

What are nerve conduction studies? NCS

Answer 25

they record how fast impulses travel in a nerve; recording action potentials in nerves and fibre types
- certain nerves fire at specific rates therefore if those rates are abnormal in someone it can represent a deficit or a problem

Question 26

what are EMG’s?

Answer 26

• its recording electrodes in the muscle and stimulating (contracting) muscle while recording measurement (measures motor unit), one muscle fiber with all the motor nerves that innervate it
• important way of diagnosing ALS or specific degeneration of motor units and good for detecting any loss or deficits in motor neuron action potentials

Question 27

what are some genetic neurological examinations used?

Answer 27

1. karyotypes: most common way. Allows you to visualize different chromosomes using a staining methods. This is a gross screening process of chromosomes to see any large abnormalities like shrinking or downs syndrome. Defects in genes are not shown in karyotypes because its too specific and certain switching of a.a. will not be detected
2. genome wide approach –> little gene chip that has programmed sequence used to detect specific gene deficits like a.a. mutation.
3. comparative genomic hybridization: hybridization of patient’s dna and comparing it to normal dna and seeing if they are missing or have extra of a certain genes (looks for deletions and duplications)
4. Genome sequencing –> brings genes down t osingle base pair resolution and allows to identify single base pair changes in the DNA sequence which is useful for mutations

Question 28

What is the lumbar puncture method of clinical methods?

Answer 28

involves looking at levels of red blood cells, white blood cells, glucose and specific proteins in the CSF

• very useful to assess blood and infection in csf like meningitis and aneurysm bleeding
• uses spinal tap to obtain CSF from lumbar regions L3, L4 and L5

Question 29

What are a few research methods of neurological assessment that are not used in the hospitals due to the expense and size?

Answer 29

1. PET
2. functional MRI (fMRI)
3. Magneto-encephalogram

Question 30

What is PET? how does it work

Answer 30

positron emission tomography: is invasively injecting radioactived tracers that works on the premise of metabolic activity and generation of photons that show a map of blood flow to measure brain activity in certain areas
- emitts positrons (anti-electrons) that collide with electrons in the brain and create photons (gamma rays) that can be measured and detected

• an example: using PET to show that the uptake in putamen is reduced in patients with parkingsons disease

Question 31

What is fMRI (functional MRI)?

Answer 31

• watches brain in action and good for functional analysis of the brain
• measures blood flow to active parts of the brain using blood-oxygen levels (oxygen increases the strength of magnetic dipoles of photons which is measured by MRI) the functional part is the BOLD signal
  a disadvantage to this is the temporal resolution

Question 32

What is the magneto-encephalogram? whats the advantages and disadvantages?

Answer 32

it detects down to a single axon firing in a millisecond range and its advantages are fast temporal resolution and the disadvantages are the expense and the spatial resolution

Question 33

What are the two methods that can be both used in clinical and research methods?

Answer 33

1. Transcranial Magnetic Stimulation (TMS)

2. Deep brain stimulation

Question 34

What is TMS?

Answer 34

• transcranial magnetic stimulation can either temporarly activate or inhibit certain areas of the brain depending on the strength of the magnetic field
• it can be a single pulse TMS: maps changes in cortical excitability during behavior, or maps changes in cortical motor maps after stroke and during rehab
  or
  repetitive TMS:
• inhibits activity of specific cortical regions
• enhances functional recovery following a stroke
• reduction of chronic pain
• treatment of depression, schizo and addiction and anxiety
• treatment of movement disorders

Question 35

What is Deep brain stimulation? what is it currently being used to treat?

Answer 35

• DBS consists of permanently inserting depth electrodes into a specific area that is stimulated by the stimulator or by the patient whenever possible
• used in parkingson’s, dystonia, severe depression and epilepsy