Potential Therapeutic Benefits of Riluzole in Pre-Symptomatic Familial Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease which attacks the motor system. Current treatment for sporadic ALS or Cu, Zn superoxide dimutase 1 (SOD 1 mutation) familial ALS, produces only a modest increase in survival. Riluzole, has been available since 1995 and remains the only disease modifying therapy available for ALS. Using the statistical motor unit number estimation (MUNE) technique, we performed a longitudinal study of 2 asymptomatic SOD 1 gene mutation carriers and 1 non SOD 1 subject with a strong family history of ALS, to determine whether early institution of Riluzole can reduce that rate of motor unit loss in familial amyotrophic lateral sclerosis (fALS). During the study period, we were able to detect loss of motor units in the pre-symptomatic phase of the disease. At the time of symptom onset, subjects were treated with Riluzole and in all the cases, there was “symptomatic” improvement as well as an improvement in motor unit number estimation (MUNE). Riluzole is not a disease altering agent but possibly if given early in the pre-symptomatic phase of the disease, before significant motor neurone loss has occurred, it may have some therapeutic benefit. This effect may have implications for the management of asymptomatic carriers of the SOD 1 gene, as these subjects are at risk of developing ALS.