Hypothesis: The pathophysiology of snoring and obstructive sleep apnoea is still unclear. Two theories are proposed. The first is the obstructive theory, which postulates palatopharyngeal muscle hypertrophy leading to airway narrowing; there is no neural role. The second is the neurogenic theory, which postulates neural degeneration due to vibratory stretch trauma, leading to muscle atrophy and collapse. As identification of nerve fibres in the uvula and palate is difficult and time-consuming, all previous studies aiming to differentiate between these two theories have been based on indirect observation of the muscles, rather than direct study of the nerves.
Methods: We conducted a prospective study to directly observe and study nerve fibres in uvular specimens from 10 cases of obstructive sleep apnoea, compared with specimens from 10 cases of simple snoring, using transmission electron microscopy. Five autopsy cases served as controls.
Results: Obstructive sleep apnoea was associated with definite degenerative changes in myelinated and unmyelinated nerve endings. These degenerative changes were present to a lesser degree and in a smaller proportion of cases of simple snoring.
Conclusion: The events postulated by the neurogenic theory of obstructive sleep apnoea appear to play an important role in the pathophysiology of snoring and obstructive sleep apnoea.