Primary afferents of trigeminal autonomic reflex may not be nociceptive: A case report.

INTRODUCTION: Autonomic symptoms have been long recognized to occur with pain in the head, e.g., trigeminal neuralgia and trigeminal autonomic cephalalgias. Symptoms occur during pain attacks, so they are assumed to be activated by nociceptive afferents of the trigeminal nerve. Herein, we present a patient with hypersalivation that occurred following percutaneous balloon compression for trigeminal neuralgia, although being pain-free after the treatment.

CASE PRESENTATION: The patient was a 71-year-old woman who experienced excessive salivation on the affected side after percutaneous balloon compression. She underwent microvascular decompression several years ago, and both microvascular decompression and preoperative imaging confirmed the absence of an offending vessel at the root entry zone of the trigeminal nerve. After percutaneous balloon compression, the patient was free of pain, but the autonomic symptom (hypersalivation) occurred. Autonomic symptoms that usually emerge along with pain presented only after percutaneous balloon compression in this patient.

CONCLUSIONS: Contrary to popular belief, in the patient who was pain-free after percutaneous balloon compression, the transiently overactivated nerve fibers that led to hypersalivation were not nociceptive afferents of the trigeminal nerve.