Motor neurone disease (MND) is characterised by progressive degeneration of the motor neurones of the brain, brain stem or spinal cord. Depending on the site of the lesions, characteristic signs may include spasticity, muscle stiffness, brisk or diminished reflexes, muscle wasting and fasciculation, and both flaccid and/or spastic weakness.
The classification and terminology used to describe the different MND syndromes are not always clear or consistent. This partly reflects uncertainties surrounding the underlying causes of MND and the mechanism of neuronal damage. There is also debate about the extent to which different syndromes are simply manifestations of the same disease process or whether there are several different disease mechanisms.
The term 'motor neurone disease' is used to describe variants of the disease – namely progressive muscular atrophy (PMA) and amyotrophic lateral sclerosis (ALS), which includes progressive bulbar palsy (PBP). ALS, which is characterised by both upper and lower motor neurone signs, is the most common form of MND, accounting for 65% to 85% of all cases. Adult onset MND usually starts insidiously with symptoms and signs including stumbling, foot drop, weakened grip, slurred speech, cramp, muscle wasting, twitching and tiredness. Other symptoms of MND include muscle stiffness, paralysis, incoordination and impaired speech, swallowing and breathing. Most individuals die from ventilatory failure, resulting from progressive weakness and wasting of limb, respiratory and bulbar muscles within approximately 3 years of the onset of symptoms.
NICE was advised that, despite the terms of the product licence, it has been common clinical practice for riluzole to be used in all of the forms of MND referred to in paragraph 2.3. This may in part be because the mainland European and UK nomenclature for the disease differs. In mainland Europe, the terms MND and ALS are often used interchangeably. This document refers to ALS specifically in accordance with the terminology used in the current product licence for riluzole.
There is no diagnostic test for MND. The diagnosis requires the demonstration of clinical signs affecting both the brain and spinal cord. Diagnosis is often delayed and can take more than 16 months from the onset of initial symptoms, which are commonly non-specific and include general fatigue.
The incidence of ALS ranges from 1.8 to 2.2 per 100,000 population and prevalence ranges from 4.0 to 4.7 per 100,000 population in the UK. Therefore at any one time about 2,000 individuals per year in England and Wales are affected by ALS.
There is a range of pharmacological interventions that provide symptomatic relief for people with MND. Surgical intervention may be necessary. Such interventions include percutaneous gastrostomy to enable feeding as the ability to swallow decreases and tracheostomy with or without ventilatory support to aid breathing as respiratory muscle weakness increases.
Supportive and palliative care is currently available for people with MND. A wide range of multidisciplinary health and social services is required, particularly in the late stages of the disease, and need to be tailored to suit individual needs. NHS, personal social service and voluntary sector services needed include physiotherapy, occupational therapy, speech and language therapy and augmentative communication, mobility aids and district nursing support. In the later stages of the disease, the following interventions may also be required: enteral feeding (for severe dysphagia), domiciliary or hospice care, and ventilatory support, including mechanical ventilation and tracheostomy.