A Placebo-Controlled, Single-Blind Study Evaluating the Safety and Efficacy of Nasal Carbon Dioxide for the Symptomatic Treatment of Classical Trigeminal Neuralgia

• Male and female, 18 years of age and older.

• History of classical trigeminal neuralgia with or without persistent background facial pain, not secondary, as defined by International Classification of Headache Disorders (ICHD), third edition, beta version (ICHD-3 beta, Cephalalgia 2013).

• Diagnosis of trigeminal neuralgia (TN) for at least 60 days prior to enrollment.

• Experience pain with a score of at least 5 on a 0-10 scale during a typical TN episode as reported by subject. Note: Prior to treatment pain score must a 5 or greater on a VAS.

• History of unilateral typical TN pain predominantly in the V2 branch of the trigeminal nerve.

• Absence of a significant structural lesion (e.g., a tumor) as the cause of pain as shown in at least one neuro-imaging study.

• On stable dose of all medications, including those for the treatment of TN prevention/prophylaxis, for at least 14 days prior to baseline (including, but not limited to, verapamil, lithium, melatonin, any anticonvulsant, any systemic corticosteroid or steroid injection, occipital nerve block, other cranial or extracranial nerve block, or any neurostimulation treatment). Note: Subjects are allowed to use their usual standard of care for the acute/abortive treatment of trigeminal neuralgia attacks 60 or more minutes after the initial dose, provided it is approved by the investigator.

• Capable of completing a diary.

• Able to provide written Informed Consent.