w11 Flashcards
(23 cards)
What are the benefits of DBS
Reduction In “Off” Severity
Increase In “On” Time
Reduction In Dyskinesia (e.g. tics)
Suppression Of Medication-refractory Tremor
Can treat different areas of the brain with different stimulation
What types of patients are unlikely to respond well to DBS
patients who ‘Freeze’
patients with postural instability
patients with gait hesitancy
patients with dysarthria (speech difficulty)
what was DBS initially designed for
to treat parkinsons disease, because movement disorder surgeries and drugs were not very effective
What diseases are allowed to be treated with DBS
Parkinson’s Disease Essential Tremor Dystonia Obsessive Compulsive Disorder Epilepsy Tourettes
what diseases could DBS potentially help with
Depression
Pain
Anorexia
Obesity
What type of patient is suited to be treated with DBS
optimised pharmacotherapy is not effective or causes complications. medication-related adverse effects compromise quality of life.
diagnoses of idiopathic Parkinson’s disease.
Responsive to Levodopa (at least 30-50% improvement)
No dementia or untreated depression or other psychiatric disease.
what was the purpose of the study by Schupbach et al
To assess the effect of subthalamic nucleus (STN) stimulation on the quality of life in patients with at an
earlier stage of Parkinson’s disease (PD) (60 years and below).
What were the outcomes of the study by Schupbach et al
Improvement in quality of life (QOL), measured by the
PDQ-39 summary index.
Improvement in motor scores, activities of daily living, levodopa-induced complications, and hours of good mobility, PsychoSocial scores.
what is DBS
DBS is a surgical procedure that delivers high-frequency electrical stimulation to precise areas of the
brain that carries the abnormal signals producing the symptoms.
The exact mechanism of deep brain stimulation is unknown
what effect does high-frequency electrical stimulation have on the brain
an inhibitory effect, altering the abnormal signals
thereby leading to symptom improvement by restoring the balance of communication within the basal ganglia by delivering electrical pulses to a target nucleus
The location of electrode placement varies based on the illness being treated.
What does stimulating the subthalamic nucleus (STN) or globus pallidus internus (GPi) do
helps to restore the normal circuitry of the basal ganglia
targeted for parkinsons disease
what is the basal ganglia
a collection of nuclei deep in the white matter of cerebral cortex.
The basal ganglia includes: striatum (caudate, putamen and Globus Pallidus), substantia nigra and subthalamic nucleus.
what is the function of the basal ganglia and cerebellum
act to fine tune or modify movement on a minute-to-minute basis.
The balance between these two systems allows for smooth, coordinated movement, and a disturbance in either system will show up as movement disorders.
describe the treatment planning steps for DBS
MRI scans of patient. Usually a day or two prior to case. Usually on drug so no movement.
Mounting of headframe. Usually off medication. Morning of case.
CT scan. Defines 3D space.
Image fusion and trajectory planning. Determine Anterior-Posterior (forewords and backwards coordinates), Medial (left and right coordinates) and Vertical (how deep) position, with Ring and Arc (point/angle of entry)
describe the pre-testing operating procedure for DBS
patient is on operating table with head frame and Mayfield adaptor
draping is placed around patient to keep sterile
skin flap and burr hole (with cover? to lock and hold DBS lead) is created
Micro Electrode Recording (MER) and trial stimulation
what is Intra-Op testing
initial testing of DBS implant
occurs during surgery; patient is awake
performed to observe therapeutic effect of DBS stimulation
describe the post-testing operating procedure for DBS
Once testing complete, location is confirmed. Implantation of DBS lead – 1st stage. The patient is taken out of the frame and put under a GA for stage 2.
Stage 2 involves the tunnelling of extensions down the side of the neck and making a pocket below the clavicle. Connecting the brain leads to extensions and the extensions to the IPG (pulse generator). Then placing the IPG in the pocket and closing up.
post-DBS lead localisation will confirm placement post-op
what are the different components DBS hardware
IPG/neurostimulator
lead and electrodes
extension cable
patient programmer
what types of batteries are offered for DBS neurostimulators
primary cells
rechargable
what are the typical program settings for DBS patients
monopolar stimulation (one contact)
2.3 volts
60-90 us pulse width
130 (?) Hz
what are the different parameters you can adjust for DBS stimulation
Electrode(s) On The DBS Leads Selected to Deliver Stimulation (four electrodes total)
Polarity Assignments Of Active Electrodes
Amplitude
Pulse Width
Rate /Frequency
what are the different polarity assignments available for DBS electrodes
Monopolar 0-
Bipolar adjacent
Bipolar 1 apart
Bipolar 2 apart
what research is being performed for DBS
closed loop control / automation - need to sense sufficiently robust biomarker
automated titration (different simulations at different areas)
Phase or amplitude triggered therapy
segmented leads - contact shapes that are not fully wrapped around the lead
