DBS Flashcards

1
Q

What is DBS?

A

procedure in which stimulating electrodes are placed stereotactically into certain deep brain structures

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2
Q

What conditions will the NHS fund DBS for?

A
  1. PD
  2. Essential tremor (parts of body, usually head + forearms, shake uncontrollably)
  3. Dystonia (sustained, repetitive muscle contraction)
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3
Q

What other conditions can DBS be used for?

A
  • *require individual funding request
    1. epilepsy
    2. chronic neuropathic pain

Current phase I/II clinical trials:

  • tourette’s syndrome
  • depression, OCD
  • alzheimer’s
  • obesity, anorexia
  • addiction
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4
Q

What is the criteria for DBS use in PD?

A

idiopathic PD with 4 classical symptoms:

  1. rigidity
  2. tremor
  3. bradykinesia
  4. postural instability

do not have sensory issues - numbness, tingling
do not get weakness or hyperreflexia
require an MRI scan
no mental disorder
treated with levodopa + still responsive to it
physically fit for surgery

**DBS can only treat the motor symptoms

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5
Q

Describe the DBS procedure for PD.

A

Use MRI scan to work out the target site
connect a stereotactic frame on the patient’s head
drill a 4cm hole into the skull, then insert microelectrode tip to the target site
once the target site has been located, the microelectrode is removed + stimulating electrode is inserted
cap hole, close wound, MRI scan to check electrode at correct site, general anaesthesia for NT stimulus
return to clinic 1month later to programme DBS + adjust drug dosage

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6
Q

What effects can DBS have on Parkinsonian symptoms?

A
Increase 'on' time
Reduce bradykinesia + rigidity 
reduce medication dose 
Improve dyskinesia
effectively treats tremor
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7
Q

What brain regions might be targeted for PD?

A

1/ zona incerta –> target tremors
2/ subthalamic nucleus –> target tremors
3/ globus pallidus internal –> dystonia + tremor

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8
Q

When would DBS be used on an epileptic patient? What area in the brain would be targeted?

A

When medication is inadequate

Target the anterior nucleus of the thalamus

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9
Q

What sites would be targeted to treat chronic neuropathic pain with DBS?

A
Cingulate DBS
Thalamic DBS
Periventricular DBS
Spinal cord stimulation 
Intrathecal morphine pumps 
Peripheral nerve blocks
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10
Q

What sites would be targeted to treat Tourette’s with DBS?

A

thalamic centromedian/ parafascicular complex

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11
Q

What sites would be targeted to treat treatment-resistant depression with DBS?

A

Subcallosal cingulate

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12
Q

What sites would be targeted to treat addiction with DBS?

A

nucleus accumbens

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13
Q

What sites would be targeted to treat Alzheimer’s with DBS?

A

anterior of the fornix

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14
Q

Describe the 4 main hypotheses of the mechanism of DBS.

A
  1. Inhibition hypothesis: PD is due to overactive basal ganglia neurones int he subthalamic nucleus and/or GPi –> DBS can block this and remove spontaneous discharge from GPi neurones
  2. Excitation hypothesis: DBS can excite afferent axons antidromically resulting in jamming the spontaneous activity
  3. Disruption hypothesis: GPi receives input from direct (GABA), indirect (GABA) + hyperdirect (glutamate) pathways
    - -> DBS can inhibit cortical + spontaneous discharges, disrupting/blocking the information flow through the GPi
  4. Neuronetwork modulation hypothesis: combination of the other 3 hypotheses as well as neuroprotection, release of astrocytic gliotransmitters, electrotaxis, cortical plasticity
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15
Q

What sites would be targeted to treat anorexia with DBS?

A

hypothalamus

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