Cardiac sympathetic function in the patients with amyotrophic lateral sclerosis: analysis using cardiac [¹²³I] MIBG scintigraphy

Amyotrophic lateral sclerosis (ALS), which is the most serious form of degenerative motor neuron disease in adults, is characterized by upper and lower motor neuron degeneration, skeletal muscle atrophy, paralysis, and death. Some patients with respiratory-dependent ALS die of sudden cardiac arrest or anoxic encephalopathy following circulatory collapse, which may be associated with sympathetic hyperactivity. Cardiac [¹²³I] MIBG scintigraphy is a diagnostic method of cardiac sympathetic function. However, few reports have addressed cardiac sympathetic function in ALS patients using this technique. We investigated cardiac sympathetic function in 63 ALS patients and 10 healthy volunteers using cardiac [¹²³I] metaiodobenzylguanidine (MIBG) scintigraphy [heart/mediastinum ratio (H/M ratio) in the early phase and washout ratio (WR)] at the time of diagnosis. The WR of cardiac [¹²³I] MIBG scintigraphy, which indicates cardiac sympathetic activity, was significantly increased in ALS patients compared with controls. ALS patients with an increased WR exhibited a significantly higher progression rate compared with those with normal WR. Moreover, the survival of ALS patients with increased WR was significantly decreased compared with those with normal WR. These results suggested that some patients with ALS have sympathetic hyperactivity at the time of diagnosis. ALS patients may suffer from chronic cardiac sympathetic hyperactivity, which is associated with sudden cardiac death and stress induced cardiomyopathy. Increased WR in cardiac [¹²³I] MIBG scintigraphy may be a predictive factor in ALS patients.