Clinical CNS Parkinson's Flashcards
Define PD:
A chronic progressive neurodegenerative condition resulting from the loss of the dopamine containing cells of the substantia- nigra
The resulting dopamine deficiency within the basal ganglia leads to movement disorders
Describe the prevalence of PD:
2nd most common neurodegenerative disease after AD
Around 137,000 pts with PD in UK
Lifetime risk of being diagnosed with PD is 2.7% (1in 37 people)
Increasing prevalence with age (over 80)
More common in men than women
What is early onset PD?
1 in 20 patients diagnosed before 40 years old
What are the different classes of clinical presentation in PD?
Motor symptoms
Non-motor symptoms
Name the motor symptoms of PD:
Bradykinesia
Muscle rigidity
Tremor
What is Parkinsonism?
All of the motor symptoms
PD is a type of Parkinsonism but there are other causes e.g drug induced Parkinsonism, stroke
Name the non-motor symptoms of PD:
Depression/anxiety
Fatigue
Cognitive impairment/ dementia
Sleep disturbance
Constipation
Dysphagia
Weight loss
Hyposmia (decrease sense of smell)
Sialorrhoea (drooling/ excessive salivation)
Excessive sweating
Urinary/bladder problems
Pain
Hypotension
Name and describe the different dopaminergic pathways leading to PD symptoms:
Motor control (nigrostriatial system)
Behavioural effects (mesolimbic and mesocortical pathways)
Endocrine control (tuberohypophyseal system)
Define bradykinesia:
Slowness of voluntary movement
This can be asymmetrical and unpredictable
Describe the symptoms of bradykinesia:
Mask like face/ limited expressions/ limited blinking
Hypophonia (soft voice) and/ or monotonous voice
Micrographia (small handwriting)
Difficulty performing fine motor actions (e.g fastening buttons/ shoelaces)
Walk with a shuffling gait (take smaller steps than normal)
Describe what rigidity is:
Increase in muscle tension
Characteristic of stooping posture
Rigidity affects balance, increased risk of falls (harmful as slow reactions due to bradykinesia)
Associated with muscle pain
What areas does rigidity commonly affect in PD?
Mostly affects flexor muscles of trunk and limbs
Flexor= any muscle that decreases the angle between bones on 2 sides of a joint e.g elbow/ knee
Describe the symptoms of a tremor in PD:
Not all PD patients will have a tremor
Resting tremor, normally in one or both hands, stops with voluntary movement or mental concentration
‘Pill rolling’, fingers roll in a circular movement as in rolling fingers between thumb
What areas does a tremor commonly affect in PD?
Hands
May affect:
-chin, lips, face and legs
May appear unilaterally
Name common drugs that can cause a SE of tremor:
Antipsychotics normally in first 10 weeks of taking and more common in 1st gen e.g haloperidol, chlorpromazine- generally dose related and reversible
B agonists e.g salbutamol/ salmeterol
Antiemetics e.g prochlorperazine, metoclopramide
Co-trimoxazole, SSRIs, lithium, valporic acid, medroxyprogesterone
What are the extrinsic aetiology’s of PD?
Most causes idiopathic
Environmental and physical
What is the environmental aetiology of PD?
Prescription drugs- all of above+ reserpine and tetrabenazine
Recreational drugs
What is the physical aetiology PD?
Cerebral ischaemia
Viral encephalitis
Brain stem injury
Dementia pugilistica
What are the intrinsic aetiology’s of PD?
Genetic- 10% inherited/ DNA damage
Age
What is the genetic aetiology of PD?
a-synuclein point mutations
Lewy body formation
Parkin gene mutation (early onset)
Describe the Parkin mutation in PD:
Mutation in parkin, most common cause of early onset disease
Enzymatic protein, maintaining mitochondrial quality control
Encoded by PARK2 gene
Neuroprotective protein- against a-synuclein
How can reserpine and tetrabenazine cause Parkinsonism like symptoms?
Depletes monoamines from pre-synaptic storage, decreases dopamine release
How can recreational drugs cause Parkinsonism like symptoms?
MPTP (contaminant found in MPPP ‘synthetic heroin’)- metabolite kills dopamingeric neurons in the substantia nigra, sudden irreversible Parkinsonism
What physical symptoms can cause Parkinsonism?
Dementia Pagilistica- late onset syndrome of dementia and Parkinsonism
Occurrence associated with multiple concussions/ head injuries e.g professional fighters
Other head trauma affecting the aopaergic system- head injury/ stroke
Describe how viral illnesses can cause Parkinsonism:
Encephalitis lethargica epidemic- aka sleeping sickness
Killed 500,000 people worldwide
Symptoms were severe Parkinsonism
Increase drowsiness and rigidity
Sufferers gradually ‘seized up’
Eventually catatonic- state of permanent rigidity
Short term relief from L-dopa
Describe the diagnosis for PD:
Normally present in primary care
Refer urgently and untreated to a specialist (neurologist/ geriatrician)
No conclusive diagnostic test
Diagnosis will be decided on symptoms, medical history and a detailed neurological examination
Name and describe the neurological examinations that occur for a PD diagnosis:
Brain scans e.g MRI- exclude differential diagnosis
Dopamine Transporter scan (DaTSCAN)- measures density of nigrostriatial dopamine transporter sites:
-but abnormal DaTSCAN can’t solely confirm diagnosis as similar loss can occur in other neurological conditions
-not routinely performed a not recommended by NICE
An improvement in symptoms upon starting parkinsons med will support a diagnosis of PD
What are the steps in diagnosing PD?
Step 1: Diagnosis of parkinsonian syndrome- motor symptoms
Step 2: Exclusion criteria
Step 3: Supportive criteria
What is the first line treatment in PD with motor symptoms?
Offer Levodopa to patients with early PD whose motor symptoms affect their QoL
Consider a choice of dopamine agonists, L dopa, or MAO-B inhibitors with early PD whose motor symotms don’t affect QoL
What is the adjuvant therapy in PD with motor symptoms?
Offer a choice of dopamine agonists, MAO-Bi or COMTi as an adjunct to L dopa
If dyskinesia is not adequately managed by modifying existing therapy, consider amantadine
Describe the use of L-dopa in PD:
Dramatically improves motor function (around 80%), 20% restored to normal motor function
Palliative treatment- no effect on disease progression
Effectiveness decreases with time, must escalate dose:
-receptor down regulation
-disease progression
When should you start L-dopa?
Different for every patient
e.g older patient may want to start asap but younger may want to start it later
What are the unwanted SEs of L-dopa?
Dyskinesia (involuntary movements)
Fluctuations in clincal state
Acute SEs
Describe the dyskinesia SE for L-dopa:
From 2 years of starting (50% of patients by year 5)
Affects face, arm and trunk (limbs)
Describe the fluctuations in clinical state SE for L-dopa:
‘On-off’ phenomena (bradykinesia/ rigidity suddenly worsen then better)
Wearing off effect (end of dose deterioration)
Freezing
What are possible solutions for PD patients when they get symptoms due to wearing off their medication?
Mainly long term
Night and first thing in the morning as its the longest time without medication
Using SR or COMTi (entacapone) can help stop this
Describe the acute SEs for L-dopa:
Nausea and anorexia
Hypotension
Sleep disturbances including sudden onset of sleep implications for driving
Psychological effects- anxiety/ depression, schizophrenia symptoms
Name inhibitors that is given with L-dopa to inhibit the metabolism and why?
Dopadecarboxylase inhibitors:
-carbidopa
-benserazide
L-dopa is always given in combo with one
These decrease peripheral metabolism of L-dopa and improve absorption of L-dopa which decreases peripheral SEs
They don’t cross the BBB
Name the brands of the dopadecarboxylase inhibitors:
Carbidopa+ L-dopa= Co-careldopa (Sinemet®)
Benserazide+ L-dopa= Co-beneldopa (Madopar®)
Name 2 COMTi:
Entacapone
Tolcapone- rarely used due to risk of liver toxicity