Neurodegenerative Disease – Comparison
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This article includes a summary and comparison of the most common neurodegenerative diseases; Parkinson’s disease, Motor Neuron Disease and Multiple Sclerosis.

Epidemiology and Aetiology
Onset and Progression
Clinical Features
Parkinson’s Disease
Present in 0.5-1% of the over 60’s
Cause essentially unknown. Some cases due to rare genetic defects, other cases the result of drugs.
Other disease (e.g. Wilson’s disease) can cause Parkinsonian symtpoms
Loss of dopaminergic neurons in the basal ganglia (particularly substantia nigra) and subsequent reduction of dopamine release. Symptoms seen when dopamine levels reach 20-40% of normal
Age 45-60
Slowly Progressive
No Remission
Classic triad of rigidity, tremor and bradykinesia. Other symptoms include:
  • Gait
    • Reduced arm swing
    • Short shuffling steps
  • Hallucinations (also related to treatment)
  • Speech – monotonous, may become slurred
  • Plain face (‘mask’)
  • Depression
  • Dementia
Diagnosis is clinical. MRI is often normal, and other tests do not yield satisfactory results.
L-DOPA is main drug used. Once crosses BBB it is converted to dopamine, and increases dopamine levels in the brain. Efficacy decreases with prolonged use. Newer selective D3 agonists (pramipexole and roprinarole) are becoming popular. Have fewer side effects, and dosage is easier.
Other drugs used as adjuncts help decrease the dose and prolong the efficacy of L-DOPA.
M:F – 2:1
Genetic factors
Distance from the equator
Autoimmune reactions against myelin and oligodendrocites, resulting in demyelination and axonal loss. Only occurs in CNS.Nerve conduction slowed.
Age 20-45
Very variable, although most commonly relapsing and remitting
Can include almost any neurological sign, but most commonly:
  • UMN signs
  • INO
  • Visual Disturbance
  • RAPD
  • Numbness and parasthesia
  • Sphincter Function affected
  • Ataxia
  • Fatigue
MRI – shows active lesions (plaques). Can be diagnostic if multiple plaques present on multiple occasions. Visual evoked potentials – can show delayed nerve tranmsission in optic nerve
Acute – steroids (e.g. prednisolone) can help induce remission.
Long-term – immunomodulators (β- interferon)help reduce the incidence of remission, but do not alter long term outcome. Baclofen used to reduce symptoms (GABA antagonist). Other experimental agents may reduce remissions
Slight male predominance
Aetiology is basically unknown.
Sometimes caused by hypocalcaemia.
Degeneration of upper and lower motor neurons in the CNS. Peripheral nerves are not affected
Middle Age
Most patients will not survive more than 3 years.
No remission
Essentially causes a mix of UMN and LMN signs. Usually sigs begin at extremities, and work upwards.
  • Wasting
  • Fascicluation
  • Weakness (often pyramidal pattern)
  • Absent / hyperreflexic reflexes
  • Bulbar and pseudobulbar features
  • ALSloss of tone, and paraparesis
  • Dementia
  • No sensory Signs!
Diagnosis is usually clinical, but may be confirmed by EMG and nerve conduction studies. Nerve conduction is usually normal. EMG shows denervation and fibrillation.
MRI will be normal, and exclude foramen magnum or spinal cord compression.  
Treatments are generally very ineffective.
Riluzole – sodium channel blocker – may slow disease progression very slightly
Baclofen – GABA agonist
This helps to reduce spasticity
Drooling may be improved with amitriptyline or propantheline.


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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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