Isolated Dental and Lower-Facial Pain Mimicking Trigeminal Neuropathy: An Indirect Carotid-Cavernous Fistula

Carotid-cavernous fistula (CCF) is a pathological arteriovenous communication in which carotid arterial flow is diverted into the cavernous sinus. Clinical manifestations typically include ocular signs, cranial neuropathies, and headache. Neurologic deficits most commonly reflect involvement of cranial nerves III, IV, V1/V2, and VI within or along the cavernous sinus; in contrast, isolated trigeminal presentations are rare, and V3 involvement is particularly uncommon. A 69-year-old woman presented with isolated V2/V3-territory pain, perceived as molar, gingival, and lower facial discomfort. Her symptoms were initially misattributed to trigeminal neuropathy or dental pathology. Subsequently, she developed horizontal diplopia, and bedside testing localized a right abducens palsy. Brain magnetic resonance imaging revealed findings suspicious for a CCF, which was angiographically confirmed as an indirect CCF. Following embolization, the patient’s pain markedly improved, implicating the CCF as the source of the V2/V3 symptoms. This case highlights that an atypical, trigeminal-predominant onset—even with pain limited to the V2/V3 distribution—may indicate an indirect CCF. When atypical trigeminal neuropathy is suspected and dental or other peripheral causes are excluded, clinicians should consider the possibility of a CCF.