難治性頭蓋顔面痛に対するスフェノパラチン神経節の二段階神経刺激療法：後向き研究

The sphenopalatine ganglion (SPG) represents an important neuroanatomical structure in the pathophysiology of various craniofacial pain syndromes. Its strategic anatomical position has made the SPG an attractive therapeutic target for over a century, with interventions ranging from pharmacologic blockade to implanted neuromodulation. Although SPG neurostimulation has indicated efficacy for chronic cluster headache, optimal patient selection strategies and efficacy in other craniofacial pain conditions remain undefined.

This study aimed to evaluate the feasibility and safety of a two-stage SPG neurostimulation protocol for patient selection across heterogeneous refractory craniofacial pain syndromes.

This retrospective case series analyzed nine patients with medication-refractory chronic craniofacial pain who underwent SPG electrode trial implantation through a lateral infrazygomatic approach under fluoroscopic guidance. The cohort included chronic cluster headache (n = 4) and secondary neuropathic facial pain (n = 5). Primary outcomes included technical feasibility, safety profile, and clinical effectiveness (Numeric Rating Scale [NRS], attack frequency, and functional improvement). Primary headache diagnoses in study cohort population were verified according to International Classification of Headache Disorders-3 criteria and neuropathic pain was confirmed by clinical features and etiology.

Seven of nine patients (78%) achieved a positive trial response with pain reduction ranging from 30% to 90%. Six patients underwent permanent implantation. At 12-month follow-up, five patients (83.3%) maintained therapeutic benefit. Mean NRS scores decreased from 9 (9-10) at baseline to 2 (2-3). Painful trigeminal neuropathy showed superior outcomes (mean 85% reduction, n = 4) compared with those in chronic cluster headache (mean 65% reduction, n = 2). Two major complications had occurred: maxillary artery hemorrhage during trial (n = 2, managed conservatively) and device explantation due to suspected infection (n = 1, day 10) and decubitus ulcer (n = 1, month 18).

Two-stage SPG neurostimulation effectively identifies appropriate candidates for permanent implantation. The differential response between neuropathic pain and cluster headache suggests the need for condition-specific trial protocols, with extended trial periods potentially beneficial for episodic pain syndromes. This approach represents a valuable strategy for optimizing patient selection in SPG neuromodulation therapy.