Defects of innervation

ACHALASIA

Achalasia is characterised by an absence of peristalsis in the oesophageal body accompanied by a failure of relaxation of the lower oesophageal sphincter.1 Although the condition can be secondary to other disease processes—for example, Chagas’ disease—in Europeans it is usually a primary disorder. Differing opinions have been expressed as to whether the problem of innervation rests in the dorsal motor vagal nucleus, the vagus itself, or in the intrinsic innervation of the oesophagus, with most evidence favouring the last explanation. By the time of oesophageal biopsy or resection, there is almost total loss of ganglion cells with substantial destruction of myenteric nerves. The changes are accompanied by an inflammatory reaction both within and around the nerves. Neurochemical analysis has shown a reduction in the number of neurons in the myenteric plexus containing immunoreactive vasoactive intestinal polypeptide.2 The way in which the disease evolves remains unclear.

HIRSCHSPRUNG’S DISEASE

Hirschprung’s disease presents at, or soon after, birth. Constipation is accompanied by gaseous abdominal distension. Typically a narrowed distal segment of bowel is demonstrable in which there is loss of parasympathetic ganglion cells from the intramural plexus.3 The aganglionosis is the result of incomplete migration of neurenteric ganglion cells from the neural crest to the most distal part of the gut. Increased acetylcholinesterase activity has been detected in the submucosal and myenteric plexus of the affected bowel segment. Besides using histological criteria for diagnosis—namely, the presence or absence of ganglion cells in …