Motor neuron disease and its management.

Motor neuron disease (MND) is a progressive neurodegenerative condition, affecting pyramidal neurons of the corticospinal tract (upper motor neurons (UMN)), brainstem motor nerve nuclei and spinal cord anterior horn cells (lower motor neurons (LMN)). Clinical presentation varies, according to the site(s) affected and the relative balance between UMN and LMN signs (see Table 1). The term ‘amyotrophic lateral sclerosis’ (ALS) is widely used interchangeably with ‘motor neuron disease’, though ALS is stric tly the combination of UMN and LMN degeneration. Both terms are used to encompass limb and bulbar onset forms of the disease. Hence, ALS, progressive bulbar palsy and progressive muscular atrophy (the latter most often an LMN variant of the syndrome) all fall under the rubric of ALS/MND. The rate of progression also varies, but median survival for patients with limb onset (75% of total) is 3.5 years and with bulbar onset (25%) 2.5 years1. Although the clinical features of MND are predominantly or entirely motor, the disease is not confined to motor neurons alone. Psychological2, neuroimaging3 and patholog ical studies4 demonstrate the involvement of other central nervous system regions. Furthermore, well recognised ‘MNDplus’ syndromes are seen in which other features develop in parallel with the motor disorder (Table 1). This review focuses on the diagnosis and management of MND. The problems caused by the disease vary, but in all cases there is progressive impairment of limb, bulbar and respiratory function. Unfortunately, much current practice lacks supportive evidence – well designed, adequately powered clinical trials are a recent development in MND. Most studies have focused on attempts to delay disease progression, rather than to evaluate symptom contro l. Some therapies are of proven efficacy in situations (eg spasticity) which are akin, but not identical, to those that arise in MND. Particular areas of uncertainty will be highlighted.