DBS Flashcards
What is DBS?
procedure in which stimulating electrodes are placed stereotactically into certain deep brain structures
What conditions will the NHS fund DBS for?
- PD
- Essential tremor (parts of body, usually head + forearms, shake uncontrollably)
- Dystonia (sustained, repetitive muscle contraction)
What other conditions can DBS be used for?
- *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
What is the criteria for DBS use in PD?
idiopathic PD with 4 classical symptoms:
- rigidity
- tremor
- bradykinesia
- 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
Describe the DBS procedure for PD.
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
What effects can DBS have on Parkinsonian symptoms?
Increase 'on' time Reduce bradykinesia + rigidity reduce medication dose Improve dyskinesia effectively treats tremor
What brain regions might be targeted for PD?
1/ zona incerta –> target tremors
2/ subthalamic nucleus –> target tremors
3/ globus pallidus internal –> dystonia + tremor
When would DBS be used on an epileptic patient? What area in the brain would be targeted?
When medication is inadequate
Target the anterior nucleus of the thalamus
What sites would be targeted to treat chronic neuropathic pain with DBS?
Cingulate DBS Thalamic DBS Periventricular DBS Spinal cord stimulation Intrathecal morphine pumps Peripheral nerve blocks
What sites would be targeted to treat Tourette’s with DBS?
thalamic centromedian/ parafascicular complex
What sites would be targeted to treat treatment-resistant depression with DBS?
Subcallosal cingulate
What sites would be targeted to treat addiction with DBS?
nucleus accumbens
What sites would be targeted to treat Alzheimer’s with DBS?
anterior of the fornix
Describe the 4 main hypotheses of the mechanism of DBS.
- 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
- Excitation hypothesis: DBS can excite afferent axons antidromically resulting in jamming the spontaneous activity
- 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 - Neuronetwork modulation hypothesis: combination of the other 3 hypotheses as well as neuroprotection, release of astrocytic gliotransmitters, electrotaxis, cortical plasticity
What sites would be targeted to treat anorexia with DBS?
hypothalamus