Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BB2 > Deep Brain Stimulation > Flashcards

Deep Brain Stimulation Flashcards

1
Q

What is deep brain stimulation?

A

Procedure in which stimulating electrodes are placed stereotactically into certain deep brain structures
100Hz frequency parameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the mechanism of DBS?

A

Electrodes connected to implanted pulse generator

  • electrodes secured to skull
  • cable tunnelled around ear down neck to generator which is in front of chest
  • battery replacements for generator required every 3-4 years
  • rechargeable systems developed with lifespan of 10 years
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is DBS used for?

A

NHS funded

  • Parkinson’s (hypokinetic)
  • essential tumour (hyperkinetic)
  • dystonia (hyperkinetic)

Individual funding requests

  • epilepsy
  • chronic neuropathic pain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is being experimented with DBS?

A
  • treatment of psychiatric disorders
  • dementia
  • eating disorders
  • disorders
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is dystonia?

A

brain disorder with sustained or repetitive muscle contractions resulting in twisting and repetitive movements/abnormal fixed postures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the criteria in DBS for Parkinson’s disease?

A
  • idiopathic PD
  • 4 classical symptoms (rigidity, tremor, bradykinesia, postural instability)
  • do not have sensory issues (as would therefore be related to nerves and would not be Parkinsons)
  • do not get weakness/hyper-reflexia (would be affecting pyramidal tract so not idiopathic Parkinsons)
  • require MRI scan to check for abnormalities
  • no mental disorders
  • treated with levodopa (as response to levodopa is good confirmation of Parkinsons)
  • still respond to levodopa (DBS will not work if no dopamine neurons available)
  • physically fit for surgery
  • realistic expectation of surgery (not a cure but will help with motor symptoms)
  • age (younger the better?)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What symptoms of Parkinsons does DBS treat?

A

Only the motor symptoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How is DBS carried out for Parkinson’s?

A
  • ensure patient has washed hair with anti-bacterial shampoo, emptied bowels, had good sleep
  • patients not on medication so will arrive at hospital slow and stiff
  • use MRI scan to work out target site
  • connect stereotaxic frame on patient’s head/do 3D printing of skull to create something that fits on after some anaesthetic as frame can be painful
  • shave hair off
  • drill 4cm hole into skull, insert microelectrode tip to target site
  • each brain structure has distinct neurophysiological spiking
  • remove microelectrode and insert stimulating electrode
  • cap hole, close would, MRI scan to confirm correct electrode site and general anaesthesia for neurostimulator implant
  • return home next day, 1 month later return to clinical programme DBS and adjust drug dosage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the effects of DBS on Parkinsons?

A
  • increases ‘on’ time (time where drug is working - still have to take levodopa but less of it)
  • decrease bradykinesia and rigidity
  • reduce medication dose
  • improves dyskinesia as less drug required
  • effectively treats tremor (levodopa not good with tremor)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which brain regions does DBS work on?

A
  • zona incerta (tremor)
  • subthalamic nucleus (tremor)
  • global pallidus internal (dystonia and tremor)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When and how does DBS treat epilepsy?

A
  • when medications are inadequate
  • epilepsy surgery not always possible as cannot identify focal brain region (remove seizure origin)
  • electrode implanted into anterior nucleus of thalamus as part of brain which spreads seizure
  • only reduces do not eliminate seizure frequency
  • benefits 50-60% epileptic patients so NICE do not fund, have to make individual funding requests
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does DBS treat chronic neuropathic pain?

A
  • treat pain when medications are inadequate
  • surgery via lesion to brain regions related to pain pathway is more invasive than DBS
  • only reduce NOT eliminate pain experience
  • benefits 15-50% of pain in patients
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is pallidotomy?

A

Make a lesion to the globus pallidus use an electrical probe of 80 degrees Celsius for 1 minute

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is thalamotomy?

A

make a lesion to the thalamus using an electrical probe of 80 degrees Celsius for 1 minute

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the 3 types of tremors?

A
  • resting tremor
  • Postural tremor (shaking whilst putting hand up)
  • Intentional tremor (shaking whilst trying to do something e.g. writing)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is essential tremor?

A

A brain disorder causing part of body (head and forearms) to tremor uncontrollably
Often genetic

17
Q

What types of causes can induce Parkinsons?

A

Idiopathic
Vascular Parkinsonism
Drug Induced Parkinsonism - e.g. drugs to be used for schizophrenia

18
Q

What is the function of the thalamus?

A

Central control as everything leaving the brain and coming up from spinal cord passes through thalamus

19
Q

What happens to levodopa dose overtime?

A

Dosage increases - have to take it more frequently as effects are worn off quicker
Also dyskinesia worsens as you take more

20
Q

What are some other regions/uses for DBS?

A

Resistant Depression - Brodmann area 25
Anorexia - hypothalamus
Addiction - nucleus accumbens
Alzheimer’s disease - anterior of fornix

21
Q

What are the pros of DBS?

A
  • proven safe, no deaths
  • effective in treating movement disorders
  • improves tremor which are levodopa resistant
  • effects are reversible and area can be tailored to patient’s clinical status
  • patients who have undergone DBS are still candidates for other treatment options - stem cell/gene therapy
  • allows decrease in medication/makes medication more tolerable
22
Q

What are the cons of DBS?

A
  • 2-3% risk of brain haemorrhage causing paralysis/stroke/speech impairment (so tell patients week before to stop taking aspirin/heparin)
  • small risk of CSF leakage = headaches and meningitis
  • 15% risk of temporary problems with transplantation = infection/allergy to implant so have to take it out and redo
  • temporary tingling in face/limbs, loss of balance, dizziness, concentration issues
  • migration of electrodes from original implantation site
  • temporary rebound in worsening of tremor when stimulation stopped
  • no absolute guarantee DBS will benefit patients
23
Q

What are the 4 hypothesis for DBS mechanism of action?

A

1 - inhibition hypothesis
2 - excitation hypothesis
3 - disruption hypothesis
4 - neuro-network modulation hypothesis

24
Q

What is inhibition hypothesis?

A
  • PD due to overactive basal ganglia in STN and op GPi
  • DBS can block this removing spontaneous discharge from GPi neurons
  • if give GABA agonists/lesion GPi alleviate problem
25
Q

What is excitation hypothesis?

A

Neurones in the thalamus have an a.p and go from cell body to synapse = orthodromic

  • too much activation of the cortex
  • DBS excites afferent axons so creates excitation in the opposite direction towards cell body (antidromic) = ‘jamming’ of spontaneous activity= reduction of excitation of cortex
26
Q

What is the disruption hypothesis?

A
  • have direct, indirect and hyperdirect pathways (doesn’t go through striatum) which all terminate in GPi
  • by stimulating the GPi you disrupt/block flow before it goes to thalamus stopping GPi functioning
27
Q

What is the neuro-network modulation hypothesis?

A
  • explains delayed effect of DBS
  • involves neuroprotection, release of astrocytic gliotransmitters, electrotaxis, cortical plasticity which all result in DBS working

BB2 (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions