Movement Disorder and Neurosurgery

Question 1

What is a movement disorder?

Answer 1

A category of neurological conditions that cause problems with movement. This could be:
▪️ Increased
▪️ Decreased
▪️ Voluntary
▪️ Involuntary

Including PD, HD (chorea), dystonia, parkinsonism, TS etc

Question 2

How do you subclassify disorders of movement?

Answer 2

▪️ Hyperkinetic movement (e.g., chorea, tremor, tics, myoclonus, dystonia, ataxia, spasticity)
▪️ Hypokinetic movement (e.g., bradykinesia, rigidity, balance problems, parkinsonism)

Question 3

What does the basal ganglia do?

Answer 3

▪️ Motor control
▪️ Motor learning
▪️ Executive functions and behaviours
▪️ Emotions

Question 4

How are the basal ganglia organised?

Answer 4

Group of subcortical nuclei:
1. Input nuclei (e.g., caudate nucleus, putamen, nucleus accumbens)
2. Output nuclei (e.g., GPi and substantia nigra pars reticulata)
3. Intrinsic nuclei (e.g., GPe, subthalamic nucleus, substantia nigra pars compacta)

Question 5

What is the effect of dopamine on the basal ganglia?

Answer 5

Dopamine can enhance the activity of neurons in the basal ganglia, involved in movement, motivation, and reward-processing

Question 6

Why do so many basal ganglia disorders affect cognition and emotion?

Answer 6

Because the basal ganglia are interconnected with many parts of the brain responsible for cognitive and emotional processing

Question 7

What is the difference between Parkinson’s disease and Parkinsonism?

Answer 7

Parkinsonism = umbrella term describing symptoms of tremors, muscle rigidity, and slowness of movement

Parkinson’s disease = most common type of parkinsonism caused by degeneration of dopaminergic neurons

Question 8

How may imaging differentiate pre and post-synaptic Parkinsonism?

Answer 8

▪️ PET/SPECT to measure level of dopamine transporter in the brain, responsible for reuptake of dopamine
▪️ In presynaptic parkinsonism, there is a loss of dopamine transporters (e.g., PD)
▪️ In postsynaptic parkinsonism, there is a loss of dopamine receptors (e.g., atypical parkinsonian disorder)

Question 9

What is an ‘atypical Parkinsonian disorder’ and how might you know?

Answer 9

▪️ Progressive disease with similar symptom presentation to PD as well as changes in BP, breathing, and eye movements
▪️ BUT loss of dopamine receptors so don’t respond as well to levodopa

E.g., MSA, PSP, CBD

Question 10

Why are there so many non-motor symptoms in Parkinson’s disease?

Answer 10

▪️ Dopamine also plays a role in mood, cognition, and sleep
▪️ Disruption of other brain areas due to spread of pathology (Lewy bodies)

Question 11

What is DBS?

Answer 11

A reversible means of altering physiological circuits in the brain through electrodes implanted into deep structures

Question 12

Who is the ideal PD candidate for DBS according to the NICE guidelines?

Answer 12

▪️ Medically refractory disease
▪️ Presence of dystonia

Question 13

What movement disorders can DBS be used for?

Answer 13

▪️ Parkinson’s disease
▪️ Dystonia (involuntary spasms)
▪️ Essential tremor

Question 14

What are the advantages of DBS?

Answer 14

▪️ Non-destructive (compared to traditional method of thalamotomies)
▪️ Reversible
▪️ Adjustable - can increase voltage is symptoms get words

Question 15

What are the disadvantages of DBS?

Answer 15

▪️ Usually surgical risks and complications (e.g., infection, mortality)
▪️ Expensive
▪️ High maintenance

Question 16

What types of pain can be helped with DBS?

Answer 16

▪️ Neuropathic
▪️ Nociceptive

Question 17

How are patients selected for DBS surgery?

Answer 17

Through a multidisciplinary team

Question 18

Where are the electrodes typically placed for DBS in PD?

Answer 18

Motor area of the subthalamic nucleus

Question 19

What is the role of the neurologist during DBS surgery?

Answer 19

To monitor movement

Question 20

What are the main components of the DBS system?

Answer 20

▪️ Battery pacemaker generates electricity (external to begin with then placed in chest)
▪️ Two electrodes
▪️ Two cables

Question 21

What complications are associated with DBS surgery?

Answer 21

▪️ 1% risk of mortality/severe morbidity
▪️ 2-10% risk of infection
▪️ 10% risk of lead breakage or hardware failure
▪️ Target specific complications (usually reversible)
▪️ Cognitive and mood disturbance

Question 22

What psychiatric conditions may DBS be experimentally tried in?

Answer 22

▪️ Tourette’s syndrome
▪️ Depression
▪️ OCD
▪️ Epilepsy?

(Newer trials in AD, AN, and addiction not yet clear)

Question 23

How might DBS be used in TS?

Answer 23

▪️ Electrodes in centromedian nucleus/intralaminar thalamic nucleus
▪️ >60% reduction in tic scores in intractable cases

Question 24

How might DBS be used in depression?

Answer 24

Target subgenual cingulate which shows overactivity in treatment resistant depression and decreased activity after clinically effective therapy

Question 25

What target might you consider for DBS in OCD?

Answer 25

Subthalamic nucleus

Question 26

What is ataxia?

Answer 26

Impairment in muscle control, causing clumsy voluntary movements, usually related to the cerebellum

Can affect coordination, balance, and speech

Question 27

What is apraxia?

Answer 27

Loss of ability to carry out skilled movements and gestures, despite maintaining physical ability and desire to perform them

Question 28

What symptoms might occur from basal ganglia dysfunction?

Answer 28

Trouble starting, stopping, or sustaining movement

Question 29

What is the difference between tics, myoclonus, and chorea?

Answer 29

▪️ Tics = sudden, brief repetitive movements usually preceded by an urge
▪️ Myoclonus = sudden, brief involuntary muscle twitch/jerk, either spontaneous or in response to stimulus
▪️ Chorea = irregular, rapid, jerky, involuntary movements that are not repetitive, ‘dancing’