Movement Disorders and Neurosurgery (Week 4--Pouratian and Bordelon) Flashcards Preview

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Reasons chemical neuromodulation (pharmacology) can fail

1) Disease progression

2) Excessive side effects of medical therapies

3) Lack of efficacy of available therapeutics


Why would we do deep brain stimulation?

For patients with complications or ineffective relief from pharmacotherapy

Effective dose of L-DOPA window narrows over time


How does DBS work?

1) Restores more normal pattern of electrical rhythms in the brain

2) Disrupts or interferes with abnormal electrical patterns induced by neurodegenerative process


Advantages of DBS over lesioning (old method)

1) Reversible (just stop the stimulation)

2) Modulatable (make adjustments by programming)


Which PD patients do we give DBS to?

1) Patients with advanced disease that have developed motor fluctuations

2) Patients who are intolerant of side effects of standard medications


Surgical (DBS) candidates

1) Diagnosis of PD

2) Responsive to carbidopa/levodopa

3) Cognitive "intact" without significant dementia


Where do we stimulate to treat PD?

Stimulate structures that are hyperactive in PD

1) Subthalamic nucleus: may allow for greater medication reduction

2) Globus pallidus internus (GPi): considered if psychiatric or cognitive issues present but nor exclusionary

Studies have shown equivalent motor response though


Does DBS treat all symptoms of PD?

No, only treats motor symptoms

Can adversely affect psychological and cognitive function

GPi is generally more well-tolerated target for therapy than STN


DBS treatment for essential tremor

DBS used when Essential Tremor interferes with patient's life

Stimulation target is Ventral intermediate nucleus (Vim) of thalamus, which receives major inputs from dentato-rubro-thalamic tract

Remember, dentate nucleus is in cerebellum; lateral cerebellar hemispheres have pathology that results in abnormal activity in cerebellar projections to thalamus


DBS to treat dystonia

FDA approved to treat genetic dystonias but is used off-label for cervical dystonia and other focal and segmental dystonias

Stimulation target is GPi, usually bilaterally


What is the best predictor of DBS effectiveness?

Levodopa responsiveness

L-DOPA response approximates DBS efficacy; non-L-DOPA responsive symptoms generally not improved with DBS


Programming after DBS implantation

Need to program the device to give constant stimulation, but must adjust parameters (takes 3-6 months):

Amplitude (0-10 volts)

Pulse width (msec)

Frequency (130-185 Hz)

Electrode configuration (pseudomonopolar, bipolar, guarded cathode)



Essential tremor

Most prevalent movement disorder

Bilateral postural tremor with or without kinetic tremor, involving hands and forearms, that is visible and persistent

>5 years

Etiology not clearly defined but maybe association with LINGO1, cerebellar changes, Lewy bodies in locus coeruleus



Uncontrolled co-contraction of agonist and antagonist muscles resulting in abnormal posture or movement

DYT-1 (Oppenheim Dystonia) is a generalized primary dystonia and kids are given DBS to treat DYT-1

Treat dystonia with BoTox, trihexyphenidyl, baclofen, benzodiazepines


Side effects of DBS


Others too...

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