Motor neuron disease (MND)

• What is Motor Neurone Disease
• Statistics on Motor Neurone Disease
• Risk Factors for Motor Neurone Disease
• Progression of Motor Neurone Disease
• Symptoms of Motor Neurone Disease
• Clinical Examination of Motor Neurone Disease
• How is Motor Neurone Disease Diagnosed?
• Prognosis of Motor Neurone Disease
• How is Motor Neurone Disease Treated?
• Motor Neurone Disease References

What is Motor Neurone Disease

In motor neuron disease (MND) there is relentless and unexplained destruction of lower and upper motor nerve fibres in the brain and spinal cord, leading to progressive weakness of muscles.

Statistics on Motor Neurone Disease

MND affects 4-6 people out of every 100 000. MND usually presents in middle age and is slightly more common in men.

Risk Factors for Motor Neurone Disease

The cause of MND is unknown. In 5-10% of cases there is a family history, but this is often not the case.

Progression of Motor Neurone Disease

MND has a gradual onset. 70% of patients present with progressive and symmetric limb weakness. This often begins as a foot drop, although deficits in fine hand movements may be noticed first. Localised pain may precede the onset of muscle weakness and wasting by several weeks; this may be severe in late stages of the disease.

The natural history of MND is progressive muscle weakness culminating in death usually from respiratory failure. Patients who are artificially ventilated, fed via gastrostomy and receiving full nursing care may have their life prolonged for a several months albeit in a totally dependent condition.

How is Motor Neurone Disease Diagnosed?

Diagnosis is usually clinical – there is no specific test for diagnosing MND. Investigations which may be helpful include:

• Electromyographic and nerve conduction studies may help with the exclusion of other possible causes.
• MRI scan
• A Muscle biopsy is occasionally performed
• Blood investigations
• Lumbar puncture

Prognosis of Motor Neurone Disease

MND will progress gradually and will invariably cause death usually from respiratory failure or bronchopneumonia. Survival for more than 3 years after onset is unusual although some patients may survive for over a decade.

How is Motor Neurone Disease Treated?

There is no cure for MND, and treatment is aimed at enabling the patient to remain independent as long as possible and controlling symptoms to ensure a reasonable quality of life. A multidisciplinary approach, with input from with input from various sources including GP, neurologist, occupational therapist, physiotherapist, social worker and psychologist is essential.

No treatments have been shown to influence the outcome of the disease however Riluzole (a sodium channel blocker that decreases glutamate release from astrocytes and neurons) has been shown to slow progression of the disease slightly.

Treatment of patients with MND may also involve gait assistive devices (orthotics, walkers), electric wheelchairs, speech assistive devices and suitable food preparations (eg. pureeing food). Gastrostomy may be performed in those with more severe swallowing difficulties.

(Kindly reviewed by Dr. Matthew Kiernan PhD FRACP Associate Professor in Neurology, Prince of Wales Medical Research Institute & Prince of Wales Clinical School, University of New South Wales. Consultant Neurologist, Institute of Neurological Sciences, Prince of Wales Hospital Sydney.)

Motor Neurone Disease References

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