Amyotrophic Lateral Sclerosis – Clinical Features, Pathophysiology and Management

Abstract

Amyotrophic lateral sclerosis (ALS), first described by Jean-Martin Charcot 145 years ago, is an age-related neurodegenerative disorder that leads to destruction of motor neurons. The disease begins focally in the central nervous system then spreads inexorably. The clinical diagnosis, defined by progressive upper and lower motor neuron findings, is confirmed by electromyogram. Additional testing excludes other conditions. The disease is heterogeneous, but most patients die of progressive weakness and respiratory failure less than 3 years from symptom onset. Like other neurodegenerative diseases, ALS is thought to have genetic and environmental causes. Five to 10 % of cases are inherited. Genetic factors, age, tobacco use and athleticism may contribute to sporadic ALS, but major causes are unidentified for most patients. Complex pathophysiological processes, including mitochondrial dysfunction, aggregation of misfolded protein, oxidative stress, excitotoxicity, inflammation and apoptosis, involve both motor neurons and surrounding glial cells. There is clinical and pathological overlap with other neurodegenerative diseases, particularly frontotemporal dementia. One medication, riluzole, which was approved in 1996, prolongs survival by several months. Numerous ensuing clinical trials have been negative. Researchers currently aim to slow disease progression by targeting known pathophysiological pathways. Approaches under examination are directed at muscle protein, energetic balance, cell replacement and protein aggregation. Until the causes and more robust neuroprotective agents are identified, symptomatic therapies can help improve expectancy and quality of life. Palliative care ensures dignity in advanced stages.