Functional studies of the parotid and pancreas glands in amyotrophic lateral sclerosis

Functional studies of the pancreas and parotid glands are reported in 17 patients with amyotrophic lateral sclerosis (ALS). The exocrine function of the pancreas was studied by measuring amylase concentration after stimulation with the endogenous secretin-pancreozymine test (ESP). Under these conditions, the pancreatic amylase concentration in ALS patients was found to be markedly decreased by about 45% when compared with those of healthy control subjects. Different conclusions in the literature about a possible impairment of the exocrine pancreas in ALS patients induced us to study the function of the parotid gland, which has close structural, functional, and physiopathological relationship with the pancreas. Flow rate and bicarbonate concentration of parotid saliva were measured after indirect stimulation (intraoral citric acid) and direct stimulation (pilocarpine). After indirect stimulation, both parotid flow rate and bicarbonate concentration from ALS patients were found to be decreased by about 66% and 70% respectively, when compared with controls. On the other hand, direct stimulation with pilocarpine in ALS patients elicited normal responses in both flow rate and bicarbonate concentration of saliva. It is concluded that the pancreatic and parotid deficiencies observed in ALS patients do not indicate primary disease of these exocrine glands. This interpretation is further emphasized by the results obtained by a sweat test, plasma osmolarity, and sialographic studies. The possibility that the gland impairments observed might be due to modifications of the neuroendocrine mechanisms regulating their secretory activity is suggested.