124 Endoscopic Trigeminal Nucleus Caudalis Doral Root Entry Zone Lesioning for Atypical Facial Pain

Abstract

INTRODUCTION: While many chronic pain conditions are challenging to treat, atypical facial pain including conditions such as anesthesia dolorosa and trigeminal deafferentation are among the most difficult. Patients experience numbness in facial areas that also have constant severe, burning pain. The condition results from traumatic or surgical deafferentation injuries of the first-order trigeminal nerve. Anesthesia dolorosa occurs in up to 4% of patients who have undergone prior trigeminal procedures. Deafferentation releases second-order neurons along the trigeminal pain pathway to generate spontaneous pain signals, without a nociceptive stimulus. Medications used for neuropathic pain are firstline but often ineffective. METHODS: Trigeminal tractotomy/nucleotomy and open nucleus caudalis dorsal root entry zone (NC DREZ) lesioning are 2 ablative procedures that have been performed over the past several decades targeting the descending trigeminal tractus and the spinal trigeminal nucleus. Here, we present the technical details of a novel operative technique performed in 5 patients, with the use of a percutaneous, endoscopic technique with neuromonitoring that allows direct visualization of the brainstem and physiological confirmation of stimulation and ablation. We believe direct endoscopic visualization of the surrounding anatomy, including the vertebral artery, posterior inferior cerebellar artery, accessory nerve rootlets, C1, C2 roots, and pial vessels, affords greater accuracy and safety. RESULTS: Four of the 5 patients had immediate, significant relief of their facial pain postoperatively. Upper and lower extremity strength and sensation remained intact. One patient did experience transient spinocerebellar ataxia that resolved by the following week. At 3-month follow-up, 4 of the patients had significant pain relief compared to their pre-operative pain scores. CONCLUSION: Endoscopic NC DREZ lesioning is a safe, effective, and minimally invasive approach for reducing neural hyper-excitability in second order neurons in patients with intractable atypical facial pain. Longer-term studies and follow-up are needed for these challenging types of craniofacial pain.