The thalamus in trigeminal neuralgia: structural and metabolic abnormalities, and influence on surgical response

Abstract Background Medically-refractory trigeminal neuralgia (TN) can be treated successfully with operative intervention, but a significant proportion of patients are non-responders despite undergoing technically successful surgery. The thalamus is key component the sensory pathway involved in transmitting facial pain, role TN, and its influence on durability pain relief after TN surgery, relatively understudied. We aimed to test hypothesis that variations thalamic structure metabolism related surgical non-response TN. Methods performed longitudinal, peri-operative neuroimaging study medically-refractory microvascular decompression or percutaneous balloon compression rhizotomy. Patients underwent structural MRI MR spectroscopy scans pre-operatively at 1-week following were classified as responders based 1-year post-operative outcome. Thalamus volume, shape, metabolite concentration (choline/creatine [Cho/Cr] N-acetylaspartate/creatine [NAA/Cr]) evaluated baseline 1-week, compared between responders, non-responders, healthy controls. Results Twenty controls 23 surgically (17 6 non-responders) included. Pre-operatively, group showed significantly larger volume contralateral side pain. However, vertex-wise shape analysis reduction an axially-oriented band spanning outer circumference (peak p = 0.019). Further, while pre-operative concentrations did not differ early long-term distinct decrease Cho/Cr NAA/Cr, irrespective surgery type, which was observed responders. Conclusions Atrophy consistent feature across Regional alterations preoperative structure, very metabolic changes thalamus, both appear