Characteristics of muscle cramps as a prodromal symptom of sporadic amyotrophic lateral sclerosis.

BACKGROUND

Prodromal symptoms of sporadic amyotrophic lateral sclerosis (SALS) including muscle cramps were reported; however, their detailed characteristics have not been sufficiently studied.

OBJECTIVES

To clarify the detailed profiles of prodromal symptoms in SALS.

METHODS

Patients with SALS (n = 47) and healthy controls (n = 25) were enrolled. A questionnaire-based survey was conducted to investigate symptoms before and after disease onset, including sensory, autonomic, sleep, cognitive disturbances, and frequent muscle cramps. Frequent muscle cramps were defined as those occurring at least twice per month in the lower limbs, or at least once per month in the upper limbs or trunk. We evaluated the relationship between surveyed symptoms and clinical characteristics.

RESULTS

Prodromal frequent muscle cramps were observed in 29.8% of SALS patients, most frequently in the lower limbs. With disease progression, the sites with cramps increased, and the frequency of cramps during awakening also increased. The SALS patients with prodromal cramps had greater lean mass than those without (p = 0.023). Multivariate analysis showed that the presence of cramps after disease onset was associated with a slower longitudinal decline in the ALSFRS-R score (p = 0.048). Upper limb-onset SALS patients experienced cramps more frequently before onset than bulbar-onset patients did (p = 0.033).

CONCLUSIONS

Frequent muscle cramps often precede muscle weakness during the prodromal phase of limb-onset SALS. The frequency of cramps increased with disease progression. Prodromal cramps were associated with lean mass, whereas cramps after disease onset were associated with a slower rate of disease progression.