It is said that the first doctor who used Wu Ling San for trigeminal neuralgia was Dr. Keisetsu Otsuka (1900-1970) in Japan.
A housemaid of Dr. Otsuka’s neighbor came to see him for severe pain on her face on the left. It was along the first branch of the trigeminal nerve. Her pulse was floating and small. He gave her Ge Gen Tang for two days. No effect. Then he gave her Xiang Xiong Tang for two days. No effect. Then he realized that she has severe thirst, and she urinated only 1-2 times per day. He gave her Wu Ling San. Her pain was reduced significantly within two days, and it was completely cured in four days.
Keisetu Otsuka “Practical Kampo Treatment Illustrated by Cases” 5th edition Nanzando (2000) p.31 (in Japanese) Translated by Hiromi Kagawa