Following
vagotomy it is a common finding to observe a
neuroma at the upper extremity of the nerve. Furthermore, Tinel, quoting Ranson, believes that the sensory fibers of the sectioned pneumogastric may be affected by ascending degeneration. In fact, during thoracic
vagotomy after an unsuccessful abdominal
vagotomy, histological examination of the resected right thoracic nerve demonstrated disorganization with the appearance of partial ascending degeneration. It appeared possible, therefore, to assess the quality of a
vagotomy, by studying the histological appearance of the resected vagus when a further operation using the thoracic approach is necessary. An experimental study was conducted in dogs and the results confirmed the presence, at the upper extremity, of both an
amputation neuroma and neuronal changes, though these latter lesions were limited to a region 3 cm above the section level. It is reasonable to assume, therefore, that the lower segment of a vagus resected by the thoracic approach, after an unsuccessful abdominal
vagotomy, should show degenerative lesions if the
vagotomy had been effective, but these lesions are limited in extent.