THE CAUSE OF SELDOM INCIDENCE OF GLOSSOPHARINGEAL NERVE NEURALGIA

Abstract

Trigeminal neuralgia (TN) and glossopharyngeal neuralgia (GN) are caused by compression of the roots of these nerves by adjacent vessels – neurovascular conflict. The purpose of the research was to study the topographic and anatomical relationship of the trigeminal nerve root (TNR) with the superior cerebellar artery and the glossopharyngeal nerve root (GNR) with the posterior inferior cerebellar artery, and to assess the impact of anatomical pattern on frequency of glossopharyngeal and trigeminal neuralgia occurring. Topographic and anatomical relationship of glossopharyngeal and trigeminal nerves with adjacent arteries was studied in 50 anatomic specimens (in sito) of persons who did not suffer from trigeminal or glossopharyngeal neuralgia. The specifics of neurovascular conflict in 4 patients with glossopharyngeal neuralgia were also analyzed during microvascular decompression surgery. The superior cerebellar artery loop crossed the surface of the trigeminal nerve root in 44 % of anatomical specimens of subjects without neuralgia during life-time. In a case of age vessel dolichoectasia the peak of the arterial loop would be located below the upper edge of the trigeminal nerve root resulting in the neurovascular conflict. In most anatomical specimens the posterior inferior cerebral artery loop was located collateral to the glossopharyngeal nerve root, preventing development of neurovascular conflict. Only in one of the 50 specimens the artery loop was placed at an angle with the glossopharyngeal nerve. In patients with glossopharyngeal neuralgia microvascular decompression surgery revealed that the distal arm of the posterior inferior cerebellar artery loop was located at an angle with the glossopharyngeal nerve root. Thus, the special topographic and anatomical relationship between the glossopharyngeal nerve and the posterior cerebellar artery cause much rarer occurrence of the glossopharyngeal neuralgia in comparison with the trigeminal neuralgia.