Neurology and the gut: Autonomic neuropathy and dysautonomia

The gastrointestinal (GI) tract possesses a complex system of neural circuitry that allows for primary functions of the alimentary system including digestion, nutrient absorption, and elimination of waste. The central nervous system (CNS), enteric nervous system (ENS), and the autonomic nervous system (ANS) communicate through synapses and ganglia to dictate GI physiology, and therefore, understanding the function of these different structures is an important precondition to diagnose and treat motility disorders (Browning and Travagli, 2014[1]). Although the ENS can act independently through neurohormonal regulation, it receives crucial input from both the sympathetic (through thoracolumbar spinal nerves via the sympathetic chain ganglia) and parasympathetic (via the vagus nerve) innervation. Both the sympathetic and parasympathetic branches of the ANS influence and regulate GI blood flow, motility, secretion, and absorption and possibly the microbiome.