Increased creatine kinase and spontaneous activity on electromyography, in amyotrophic lateral sclerosis

Mild to moderate elevation of muscle creatine kinase (CK) is commonly observed in amyotrophic lateral sclerosis (ALS). Although the determinants of increased the CK in ALS remain uncertain, we hypothesize that fasciculations and muscle denervation can be involved by damaging the muscle fibre.

We studied 87 ALS patients in whom CK determination was performed. In 47, a standardized EMG investigation was performed. In 22 patients a second CK determination was performed a mean of 5 months later. CK values were compared between different patients arranged in groups as determined by the number of regions with fasciculation as detected on the clinical examination, and the number of muscles with fasciculation or with fibrillation potentials as observed on EMG.

43% of our population had an increased CK value. Four out of 5 patients with suspected ALS had an increased CK value. The number of patients with increased CK value was not different between sexes, or between bulbar and spinal-onset patients. CK value was not related with disease duration, and did not change at the second measurement. CK value was not different between the groups studied.

The fasciculations,and the signs of denervation on EMG, are not determinants for high CK values in ALS patients, which are still unknown. Increased CK can be useful in the differential diagnosis of patients with lower motor neuron disorders.