Movement Disorder and Neurosurgery Flashcards
What is a movement disorder?
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
How do you subclassify disorders of movement?
▪️ Hyperkinetic movement (e.g., chorea, tremor, tics, myoclonus, dystonia, ataxia, spasticity)
▪️ Hypokinetic movement (e.g., bradykinesia, rigidity, balance problems, parkinsonism)
What does the basal ganglia do?
▪️ Motor control
▪️ Motor learning
▪️ Executive functions and behaviours
▪️ Emotions
How are the basal ganglia organised?
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)
What is the effect of dopamine on the basal ganglia?
Dopamine can enhance the activity of neurons in the basal ganglia, involved in movement, motivation, and reward-processing
Why do so many basal ganglia disorders affect cognition and emotion?
Because the basal ganglia are interconnected with many parts of the brain responsible for cognitive and emotional processing
What is the difference between Parkinson’s disease and Parkinsonism?
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
How may imaging differentiate pre and post-synaptic Parkinsonism?
▪️ 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)
What is an ‘atypical Parkinsonian disorder’ and how might you know?
▪️ 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
Why are there so many non-motor symptoms in Parkinson’s disease?
▪️ Dopamine also plays a role in mood, cognition, and sleep
▪️ Disruption of other brain areas due to spread of pathology (Lewy bodies)
What is DBS?
A reversible means of altering physiological circuits in the brain through electrodes implanted into deep structures
Who is the ideal PD candidate for DBS according to the NICE guidelines?
▪️ Medically refractory disease
▪️ Presence of dystonia
What movement disorders can DBS be used for?
▪️ Parkinson’s disease
▪️ Dystonia (involuntary spasms)
▪️ Essential tremor
What are the advantages of DBS?
▪️ Non-destructive (compared to traditional method of thalamotomies)
▪️ Reversible
▪️ Adjustable - can increase voltage is symptoms get words
What are the disadvantages of DBS?
▪️ Usually surgical risks and complications (e.g., infection, mortality)
▪️ Expensive
▪️ High maintenance
What types of pain can be helped with DBS?
▪️ Neuropathic
▪️ Nociceptive
How are patients selected for DBS surgery?
Through a multidisciplinary team
Where are the electrodes typically placed for DBS in PD?
Motor area of the subthalamic nucleus
What is the role of the neurologist during DBS surgery?
To monitor movement
What are the main components of the DBS system?
▪️ Battery pacemaker generates electricity (external to begin with then placed in chest)
▪️ Two electrodes
▪️ Two cables
What complications are associated with DBS surgery?
▪️ 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
What psychiatric conditions may DBS be experimentally tried in?
▪️ Tourette’s syndrome
▪️ Depression
▪️ OCD
▪️ Epilepsy?
(Newer trials in AD, AN, and addiction not yet clear)
How might DBS be used in TS?
▪️ Electrodes in centromedian nucleus/intralaminar thalamic nucleus
▪️ >60% reduction in tic scores in intractable cases
How might DBS be used in depression?
Target subgenual cingulate which shows overactivity in treatment resistant depression and decreased activity after clinically effective therapy
What target might you consider for DBS in OCD?
Subthalamic nucleus
What is ataxia?
Impairment in muscle control, causing clumsy voluntary movements, usually related to the cerebellum
Can affect coordination, balance, and speech
What is apraxia?
Loss of ability to carry out skilled movements and gestures, despite maintaining physical ability and desire to perform them
What symptoms might occur from basal ganglia dysfunction?
Trouble starting, stopping, or sustaining movement
What is the difference between tics, myoclonus, and chorea?
▪️ 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’
