Aim
- To control motor symptoms
- To reduce bradykinesia, tremor, rigidity, on–off fluctuations and dyskinesias
Indicated for PD patients with
- Advanced disease
- PD symptoms refractory to best medical treatment
- Motor fluctuations
- Severe on-off fluctuations
- Dyskinesias secondary to chronic levodopa
- Rigidity or bradykinesia dominant
- Tremor dominant
- Levodopa responsiveness predictive of good outcome with DBS
Preop
- Levodopa test
- UPRDS part 3 score during off and on state
- Gait assessment by physiotherapist
- QTUG walking test
- MimiBEST balance score
- 25 walk test
- Number of steps stride length
- Neuropsychology test
- Psychosis due to dopamine agonist
- Depression itself does not preclude DBS
- 3T-7T MRI
- Proton density volume
- T2 FLAIR
- T1 FGATIR: Fast Gray Matter Acquisition T1 Inversion Recovery
- T1 FGATIR, T2 Flair, CT post STN implantation
- Prescribing
- 24 hours before DBS surgery, any long acting PD medications omitted
- Night before surgery, standard release PD medications omitted from midnight
- If on apomorphine infusion this is tapered over 1-3 weeks prior to surgery
Post op
- Continue PD med
- Clexane 24 hrs post op
- AP and Lateral skull XR before discharge
Target
- STN
- "Double shot expresso"
- Superior for
- Rigidity
- Bradykinesia
- Medication reduction
- Less frequent battery changes
- The major advantage of bilateral STN DBS is levodopa dose reduction which lead to a significant decrease in on-period dyskinesias.
- Is more popular for tremor due to proximity to zona incerta.
- Greater adverse cognitive and mood effects
- May risk behaviour and impulse control disorders, but medication reduction reduces these.
- Subthalamic stimulation is usually performed bilaterally because
- Bilateral STN stimulation can reduce levodopa doses
- Therefore reduce medication induced peak dose dyskinesias
- Since unilateral implantation will still require high doses of levodopa to prevent Parkinsonian symptoms on the non-implanted side
- Bilateral STN stimulation can reduce STN activity → Reduces STN-mediated excitotoxic damage to dopaminergic neurons in the substantia nigra
- Subthalamic nucleus DBS Cons.
- Surgery is more complex
- Patients need frequent stimulator adjustments afterward.
- Risks associated with implanted hardware such as
- Migration
- Malfunction
- Breakage
- Infection
- Necessity of changing batteries every few years.
- GPi
- "Latte"
- Superior for
- Dyskinesia
- Dystonia (including levodopa-unresponsive;
- STN only works for levodopa-responsive),
- Cognition
- Mood
- Apathy
- Axial motor symptoms
- Does not adversely affect speech/swallowing, can be implanted unilaterally, and requires less frequent programming (initially).
- GPi stimulation is relatively comparable with pallidotomy and may be used bilaterally with less side effects than bilateral pallidotomy.
- Choice of target
ㅤ | STN | GPi | VIM | ZI | PPN |
Tremor | ++ | ++ | +++ | +++ | - |
Rigidity | +++ | +++ | - | +++ | - |
Bradykinesia | +++ | +++ | - | +++ | - |
Dyskinesia | +++ | ++++ | - | +++ | - |
Adverse cognitive effects | + | - | - | + | - |
Medication reduction | +++ | +? | +? | ++ | - |
Gait freezing | + | + | - | + | ++? |
Do not work for - Pts eventually succumb to it
- Lower limb and gait symptoms (freezing and postural instability)
- DBS targeting pedunculopontine nucleus area being investigated
- Cognitive defects
Trials
- PD surg trial
- Surgery + BMT > BMT in functional outcome at 1 year
- EARLYSTIM n251 RCT
- STN DBS (improvement of 7.8 score) for PD with early motor complications is better than best medical therapy (deterioration of 0.2 score) even up to 2 years post-surgery
- STN DBS for Parkinson disease
- Incidence:
- 2015 6.2mil PD patients
- >1% der >60 years
- Male: female = 3:2
- Pathophysiologie:
- Cause unknown
- Genetic and environment
- Lack of dopaminergic
- Cells in the Substantia nigra
- Cardia symptoms (can be improved with DBS):
- Rigidity
- Bradykinesia
- Tremor
- Treatment (only works if the meds work):
- Medication (dopamine)
- Surgery
- Other PD symptoms (cannot be improved with DBS):
- Dysarthria
- Dysphagia
- Balance issues
- Myoclonia
- Apraxia
- Dementia
- Hallucinations
- Depression
- Anxiety
- Success:
- 80% improvement
- Parkinson’s emergencies related to DBS
- Failure of swallow or sudden failure of DBS
- Risk of parkinsonism hyperpyrexia syndrome / rhabdomyolysis morbidity +++
- If NBM: Immediately revert to local NBM guidelines – either place NG tube or give Rotigotine patch (conversions from usual available)
- If sudden DBS failure – needs an increase of levodopa, often reverting to what they were on prior to DBS
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