Neuromuscular disease is a very broad term that encompasses many diseases and ailments that impair the functioning of the muscles, either directly, being pathologies of the muscle, or indirectly, being pathologies of nerves or neuromuscular junctions.mooth muscle has been implicated to play a role in a large number of diseases affecting blood vessels, the respiratory tract (e.g., asthma), the digestive system (e.g. irritable bowel syndrome) and the urinary tract (e.g., urinary incontinence).