Facial lymphatic malformation: the root cause of trigeminal neuralgia is not its root. Illustrative case

BACKGROUND: Trigeminal neuralgia (TN) is commonly caused by a vascular compression of the trigeminal nerve (classical TN). Due to the high frequency of this compression at the nerve's root entry zone, a misunderstanding has arisen in the literature that this location is the only site that can cause TN. The present case demonstrates that TN can be caused by compression anywhere along the nerve-even in the face. OBSERVATIONS: A 15-year-old female presented with medically refractory left TN. MRI revealed no neurovascular conflict at the root entry zone, but ultrasound revealed a lymphatic malformation in her face. After the lesion was sclerosed with bleomycin, her TN pain improved significantly. LESSONS: Trigeminal nerve compression distal to the root entry zone, although uncommon, is a treatable cause of TN. Treatment for classical TN should consider the full anatomical course of the nerve and potential compression points. This case challenges the conventional understanding that TN is exclusively caused by compression at its more vulnerable root entry zone. https://thejns.org/doi/10.3171/CASE25973.