W6 - Parkinson's and MND Flashcards
Discuss the aetiology of Parkinsonism.
Idiopathic Parkinsonism – aka Parkinson’s Disease
Secondary Parkinsonism – aka Parkinson’s Syndrome
- Postencephalitic parkinsonism
- Atherosclerotic ischaemic damage to BG
- Drug-induced (eg phenothiazines, reserpine)
- Exposure to toxins
- Shy-Drager syndrome
- Wilson’s Disease
Briefly define the term Parkinson’s disease (PD). Is it a common condition?
PD is a condition ‘associated with progressive loss of dopaminergic neurons in the substantia nigra, as well as with more-widespread neuronal changes that cause complex and variable motor and non-motor symptoms’.
- One of the most common neurologic disorders
- Affects ~1% of individuals >60 years old
- Incidence: ~4.5-21 cases/100,000 per year
- Prevalence: ~120 cases/100,000
In Australia: - Prevalence: 1/350 Australians have PD
- Incidence: 30 people diagnosed daily (1:1000 for people >65, 1:100 over 75)
Discuss the typical histological changes seen in the CNS of PD patients. Where in the CNS do these changes occur? What is the key biochemical anomaly encountered in PD?
Histological changes:
- Depigmentation of the SN and decreased pigmented dopamine neurons.
- Gliosis in the SN and other basal ganglia
- Lewy bodies – a deposit of aggregated a-synuclein oligomers typically found in neuronal cell bodies of Parkinson’s sufferers.
- Lewy neurite – same deposit found in swollen neuronal processes of PD sufferers.
These changes occur in pigmented nuclei of the CNS - Mainly the Substantia Nigra (SN), but also loecus ceruleus etc.
Key biochemical anomaly:
- Lack of dopamine released by SN causes dysfucntion of the extrapyramidal system
List and briefly define the clinical features of Parkinson’s disease (ie. symptoms and signs)
- Akinesia – Difficulty initiating movement
- Bradykinesia – Difficulty maintaining movement, slow movement
- Rigidity - Normally leadpipe (sustained resistance throughout full PROM) but may be cogwheel (jerky resistance to passive movement) if superimposed with resting tremor
- Resting tremor - Tremor that appears when limbs relaxed and disappears with active movements
- Impaired automatic postural responses to position and movement
- Decreased muscle power – Due to lack of coordination
- Muscles easily fatigue
- Myerson’s sign – Patient is unable to resist blink reflex during repeated percussion of the glabella (brow).
Later stages:
- Festinating gait - Patient stoops forward and takes short, shuffling steps that are difficult to initiate and terminate.
- Monotonous voice
- Micrographia - Very small hand writing
- Parkinsonian posture - Flexed posture of neck, trunk and limbs
- Depression
- Dementia (10-20% of cases)
Describe the Parkinsonian gait and posture
Parksinsonian gait: ‘Festinating’ gait, where the sufferer stoops forward with short, shuffling steps. Walking is hard to initiate and hard to terminate.
Parkinsonian posture: Stooped forward, bent at the knees, hip and neck. Arms held close to sides and flexed at elbows and wrists. Hands are outstretched and extended at thumbs, flexed at MCP joints.
Which of the clinical manifestations of Parkinson’s disease are primary i.e. due to the histopathological changes, and which are secondary i.e. due to a combination of primary clinical manifestations?
Primary:
- Bradykinesia
- Akinesia
- Decreased muscular power
- Resting tremor
Secondary:
- Parksinsonian (festinating) gait
- Parkinsonian (flexed) posture
- Myerson’s sign
- Micrographia
- Depression
Discuss the clinical course of Parkinson’s Disease.
Usual onset >50 years old Slow progression - Honeymoon period (0-3 years) - Motor complication period (3-8 years) - Resistant symptoms (8-15 years) - Cognitive decline period (15-20 years)
2/3 of patients disabled within 5 years
80% of patients are disabled after 10 years
How is Parkinson’s Disease treated?
- Mild-moderate Parkinson’s - Vigorous walks on 3 days per week
- Drug therapy - Levodopa (precursor to the catecholamines - dopamine, epinephrine and norepinephrine)
- Gene therapy currently being trialled (some improvements in motor symptoms reported)
- Surgery, emotional support and exercise also indicated
Discuss the pathological changes encountered in the CNS in patients with MND.
UMN loss, characterised by:
- Atrophy and pallor of corticospinal tracts
- Precentral gyrus atrophy (motor cortex)
LMN loss, characterised by:
- Muscle atrophy
- Anterior/ventral (motor) spinal cord root: discolouration and atrophy of grey matter
List the symptoms and signs which are indicative of upper motor neuron (UMN) disease.
- Weakness of muscle groups - distal movements, hip flexion, shoulder abduction
- Spasticity
- Hyperreflexia (DTRs)
- Loss of superficial reflexes
- Extensor plantar response (Babinski’s)
List the symptoms and signs which are indicative of lower motor neuron (LMN) disease.
- Weakness of individual muscles
- Hyporeflexia (DTRs)
- Muscle wasting
- Fasciculations
- Hypotonia
LMNs are the final common pathway for all movement, including “higher order” motor functions, and thus the following may also be affected:
- Posture and gait
- Voluntary movement initiation
- Coordination
Briefly define the term “Amyotrophic Lateral Sclerosis (ALS)”.
Most common form of MND (a condition causing death of motor neurons) that is characterised by progressive bilateral loss of motor function muscle stiffness and twitching to dysarthria and dysphagia. LMNs are usually (but not always) affected first and UMN Ssx appear ~12mths later.
List and write notes on early clinical manifestations of ALS.
Mainly observe LMN Ssx:
- Muscle weakness - Affecting distal muscles supplied by long nerves first and progressing proximally
- Muscle atrophy - Occurs early and is prominent. Affects upper limbs earlier and lower limbs later. The extraocular muscles are usually spared.
- Fasciculations - Occur in atrophying muscles.
- DTRs - Preserved during early phase (especially in upper limbs)
- +/- Muscle cramps
List and write notes on the late manifestations of ALS.
Observe the addition of UMN Ssx, mainly in the lower limb:
- Spasticity & hyperreflexia
- Clonus
- Extensor Plantar Response (Babinski’s)
- Superfivcial reflexes, cremasteric reflex, bowel and bladder function are all preserved.
Describe the classic triad of clinical manifestations in ALS.
- Atrophic weakness - Forearms and hands
- Slight spasticity of legs
- Generalised hyperreflexia (in spote of amyotrophy)
