Trigeminal nucleus caudalis dorsal root entry zone radiofrequency thermocoagulation for invalidating facial pain

Abstract

Introduction: Facial pain syndromes occasionally result in desperate clinical settings completely unresponsive to any known therapy. Trigeminal nucleus caudalis dorsal root entry zone (DREZ) lesion is reported to be of benefit in such cases. In 1982 Nashold performed the first DREZ caudalis lesion in a patient with anaesthesia dolorosa.

Patients and methods: From 1994 to 2002 we have performed six DREZ caudalis lesions on five patients with extremely invalidating facial pain resistant to multiple pharmacological and surgical therapies. Pain was secondary to previous craniofacial surgery in all but one case. Pain presented as anaesthesia dolorosa or atypical facial pain so severe as to interfere with personal hygiene and even to prevent patients from oral feeding. A midline suboccipital approach was used and radiofrequency lesions (at the trigeminal nucleus caudalis in the cervicomedullary junction) were made at 1-mm intervals, 75 (o)C for 15 seconds each along the ipsilateral posterolateral sulcus from the cervical DREZ up to the obex.

Results: Pain relief was complete and permanent in two patients. Three patients experienced significant improvement but pain recurred in two (weeks to a few months after the procedure). No patient's pain was made worse. A patient with persistent postoperative nasolabial pain was re-operated on (improving again but ultimately remaining unchanged). Air venous embolism related to the sitting position (3 patients) during surgery and bradycardia due to manipulation in medulla (2 patients) occurred during some of the procedures without any cardiovascular or neurological repercussion. Postoperative complications included mild and transient ataxia and monoparesia (3 patients).

Discussion: Facial pain secondary to craniofacial surgery is known to be among the least responsive to treatment and a true challenge for pain clinicians. Actual indications for this procedure, operative technical details and the results of our series compared to previous reports are reviewed.

Conclusion: Trigeminal nucleus caudalis radiofrequency thermocoagulation is an effective neurosurgical procedure for the treatment of chronically debilitating and desperate facial pain syndromes with acceptable morbidity.