Therapeutic Failure in Trigeminal Neuralgia: from a Clarification of Trigeminal Nerve Somatotopy to a Targeted Partial Sensory Rhizotomy

Abstract

Trigeminal neuralgia (TN) is a severe unilateral facial pain involving 1 or more branches of the trigeminal nerve (CNV). Microvascular decompression is a standard curative treatment of pharmacoresistant classic TN. Alternative procedures used for secondary or idiopathic TN usually lead to a high rate of pain recurrence and sensitive deficits. Partial sensory rhizotomy (PSR) is one of these ablative procedures. However, thelack of anatomic knowledge about the somatotopy ofCNV lead to variable results in pain relief and hypoesthesia. To refine the somatotopy of CNV and bring new anatomic landmarks for PSR, studying a cohort of patients treated by a targeted PSR (TPSR). Retrospective and consecutive cases of adult patients treated in our institution between March 2000 and June 2015 for pharmacoresistant TN without vascular compression were collected. Our surgical procedure was performed using a precision map of the somatotopy of CNV. We compared our results with other surgical and nonsurgical therapies. Twenty-two patients had undergone TPSR. Fourteen had an idiopathic TN without compression of the nerve root, 6 had a secondary TN caused by multiple sclerosis, and 2 had a trigeminal conflict by inoperable tumor. Complete pain relief was achieved in 86.4% of the patients. Postoperative hypoesthesia was partial and focalized (22.7%). TN recurrence rate at 5 years was 31.5% (standard deviation, 10.9%). We clarified the functional somatotopy of CNV in its juxtapontine portion. TPSR is an interesting alternative to other ablative procedures to treat pharmacoresistant TN without vascular compression.