This article includes a summary and comparison of the most common neurodegenerative diseases; Parkinson’s disease, Motor Neuron Disease and Multiple Sclerosis.
Disease | Epidemiology and Aetiology | Pathology | Onset and Progression | Clinical Features | Investigations | Treatment |
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:
| 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:
| 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 Progressive 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.
| 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. |
