Surgery in Movement Disorders Flashcards
Traditional Neurosurgery restores abnormal anatomy
- Aims to modify pathological anatomy
- Usually deals with acute disease
- Often lifesaving surgery
Why should we perform functional neurosurgery?
- Surgical intervention - change in function
- patient with chronic neurological disorders
- Rarely life threatening
What is the ultimate aim for functional neurosurgery?
To improve symptoms and quality of life
What are the indications for functional neurosurgery?
- symptoms of movement disorders: PD, dystonia, tremor
- Chronic pain syndromes: phantom pain, cluster headache
- Neuropsychiatric conditions: Tourette, OCD, depression
- Epilepsy
What does functional neurosurgery demand?
Minimal risk of inflicting morbidity and mortality
In 1930, what did the american neurosurgeon suggest?
Basal Ganglia were involved in the control of movement
What is the history of surgery for movement disorders: desperate measures?
Lesions can modulate the brain circuits that control the movement
- Victor Horsley-1890
- Corticospinal tract
- Stereotaxis - Meyers 1930
- Basal Ganglia
- Open procedures
What is the stereotactic technique?
- Accurate navigation within the brain in a minmally invasive fashion
- Horsely and Clarke frame (1905)
- Hindered by lack of imaging - Spiegel & Wycis (1947)
- Ventriculography
- Internal landmarkers
- Need for stereotactic atlases
What did Irving Cooper do?
- He made a small temporal craniotomy – lifted the brain up and he went underneath the brain to cut the cerebropeduncle – he was cutting the corticospinal tract rather than taking all of the cortex out disconnecting the cortex by dividing the corticospinal tract
- He nicked the anterior choroidal artery on his way in – he couldn’t stop the bleeding
- Place a small silver clip across the small blood vessel to occlude it
- Anterior choroidal artery goes to the basal ganglia
- Ligation of the left anterior choroidal artery
What can lesions positively alter?
Neural function
History: lesions can positively alter neural function
- Surgery for Parkinson’s disease, chronic pain, psychiatric disorders
- Tens of thousands of pallidotomy/thalamotomy procedure was performed - there was no other treatment
What happens if you ligate the anterior choroidal artery in 40 patients?
About 2-3 patients will die because the anterior choroidal artery has variability it is very big
Why did surgery fall out of favour?
- The age of drugs
- L-dopa 1967 (Cotzias)
- Chlorpromazine - Indiscriminate use of lobotomy by psychiatrists
Why has surgical neuromodulation made a come back?
- Intolerable side effects
- Lack of efficacy
- Motor fluctuations
Parallel circuits … with significant crosstalk!
- This shows you some of the major connections between different areas of the brain – doesn’t show you all of the connections
- The model is clear that the cortex sends information via the corpus stratium through the Basal Ganglia and back to the cortex via the thalamus
- There are circuits that are running in parallel between motor parts of the cortex, limbic part of the cortex and cognitive/associative part of the cortex – these go through the basal ganglia in parallel but there is a lot of crosstalk between them
- There is a lot off cross talk between these circuits
Parkinson’s disease
you lose a lot of neurons in particular neurons of the substantia Nigra in pars compacta
• Parkinson’s disease has various stages – start losing nigral neurons quite late – start losing gut cells and medullary cells far before we start losing substantia nigra cells – you have to lose 50-70% of your nigra cells before you get symptoms
What is substantia nigra pars compacta?
Susceptible pathophysiology of alpha-synuclein accumulating in parkinsonian nerve cells - they have a very high metabolic requirement
What does alpha-synuclein affect?
Mitochondrial functions
What do each substantia nigra pars compacta cells thought to make?
100,000 synapses with different neurons throughout the brain
What happens when you lose substantia nigra?
You get a mismatch and cardinal symptoms of Parkinson’s diseaseget mismatch of activity in various parts of the basal ganglia
What happens when the thalamus doesn’t excite the cortex?
The cortex gives the bradykinesia
When do we get an improvement?
• If we put a lesion in the subthalamic nucleus in the Globus pallidus interna or stick an electrode and pass an electrical current through the area blocking the information that is going through that pathway
What is the function of the parallel circuits?
- Function of the brain is information processing
- Brainstem is the vegetative part of the brain – breathing and cardiac function, acid-base balance, homeostasis
- Reactive system – saw tooth
- Subconsciously you are making a prediction of what is going to happen – if the prediction is wrong, the movement will be pathological
- Emotion is an internal prediction of what is happening on outside
What will help with movement?
If we lesion STN
