Parkinson’s disease Flashcards
What is it?
Progressive disorder of central nervous system, which is due to dopamine depletion
Risk factors
Male gender
Genetic component
Environmental exposure to insecticides, pesticides and herbicides
Pathophysiology
Decrease in dopamine producing cells in pars compacta region of the substantia nigra
Dopamine produced is secreted to the Putamen and Caudate nucleus
Increase in lewy bodies in substantia nigra
Where is substantia nigra
Midbrain
Signs and symptoms
Facial TRAPS Face - expressionless Tremor (Resting tremor) Rigidity Akinesia Postural instability Shuffling gait
Investigations
No specific test - clinical diagnosis:
CT scan and MRI scan may be arranged but these are usually normal
PET, SPECT and Ioflupane (DaTSCAN) may measure basal ganglia dopaminergic function
Conservative treatment
Patient education
Rehabilitation to improve gait and mobility
Regular assessment of activities of daily living
Medical treatment
Levodopa
Carbidopa
Selegiline
Amantadine
Surgical treatment
This option is unlikely, due to improvements in medical treatment
Complications
Dysphagia
Dementia
Increased risk of falls
Erectile dysfunction
Physiology of levodopa
Crosses the blood-brain barrier (BBB) where it is converted to dopamine
Physiology of carbidopa
Always given with levodopa
It is a dopa decarboxylase inhibitor
Prevents levodopa being metabolised to dopamine in other regions of the body
Thus acts to decrease peripheral side effects
Physiology of selegiline
inhibits monoamine oxidase B (MAO-B)
this enzyme breaks down dopamine
Physiology of amantadine
dopamine agonist
decreases symptoms of Parkinsons
What is it
Degenerative movement disorder caused by a REDUCTION IN DOPAMINE in the SUBSTANTIA NIGRA
*What structures make up the basal ganglia
- Striatum (composed of the putamen & caudate nucleus)
- Globus pallidus (external & internal)
- Substantia nigra
- Subthalamic nucleus
Which structure in the basal ganglia produces dopamine
Substantia nigra
Risk factors
Increasing age
Male
Family history
Being a non-smoker?
What is result of low dopamine
Thalamus will be inhibited
Decrease in movement
What are the names of neuronal inclusions in Parkinsons that gradually become more widespread
Lewy-bodies
Clinical presentation - onset
Onset of symptoms is gradual and commonly presents with impaired dexterity or unilateral foot drop
Onset is ASYMMETRICAL - one side always worse than the other
Describe the tremor in Parkinsons
Resting Tremor
Worse at rest and often ASYMMETRICAL
Pill-rolling of the thumb and fingers
Repetitive hand movements with worsening in rhythm the longer attempted
Describe the rigidity in Parkinsons
Parkinsons is an Extrapyramidal lesion
- Increased tone in the limbs and trunk
- Limbs resists passive extension throughout movement (lead pipe rigidity or cogwheel when combined with tremor) - this is RIGIDITY
- As opposed to the hypertonia of a UMN lesion, which is SPASTICITY where resistance falls away as the movement continues (clasp-knife)
- Increased tone and thus rigidity over entire radius of joint movement
- Can cause pain and problems with turning in bed
State 2 main histopathological findings in the brain in this condition
Loss of dopaminergic neurones (in substantia nigra)
Lewy bodies
What would you expect to see on a CT scan of this patients brain?
No pathology
Patient with Parkinsons is treated with medication. State one class of drug used to provide symptomatic relief in Parkinson’s disease and give one named example of a drug from this class.
Class - Dopamine agonists Named example - Cabergoline OR Class - Monoamine oxidase B inhibitor Named example - Selegiline
State 4 clinical features the neurologist may expect to find on physical examination of Parkinsons patient
Resting tremor
Rigidity
Bradykinesia
‘Freezing’ when starting to walk/turn/cross threshold e.g. reduced arm swing
Describe bradykinesia
Problems with daily activities e.g. doing up buttons, micrographia, expressionless face, dysdiadochokinesia
Describe tremor in Parkinsons
Resting, commonly unilateral, Starts in the hands “pill rolling”
Describe Rigidity in Parkinsons
Cogwheel like, stooped posture
Describe gait in parkinsons
Shuffling, reduced arm swing, slow to start
Describe postural instability in parkinsons
impaired balance, especially when trying to turn
