Non-invasive brain stimulation for neuropathic orofacial pain: a mini-review

Neuropathic orofacial pain (NOP) can seriously affect the quality of life of patients. Due to the concentration of pain in the central area of the craniofacial region, it is not only highly invasive but also easily distracts the patient's attention, resulting in its destructive nature far exceeding that of distal limb pain. As emerging non-invasive therapies, Repetitive Transcranial Magnetic Stimulation (rTMS) and Transcranial Direct Current Stimulation (tDCS) are bringing hope for the treatment of NOP. This brief review summarizes existing evidence on their efficacy, highlighting that pain phenotype may be a key determinant of treatment response and warrants further investigation. High-frequency (10-20 Hz) rTMS over the primary motor cortex (M1) reduces trigeminal and postherpetic neuralgia pain by 30%-45%, with effects lasting weeks to months. Non-somatotopic hand M1 stimulation appears to produce comparable facial analgesia via descending pain pathways. For tDCS, preliminary evidence suggests pure paroxysmal pain may respond more robustly than persistent pain, implicating central sensitization as a potential negative predictor. Current evidence is limited by small samples and heterogeneous protocols. Future research should prioritize phenotype-stratified trials, optimal parameters, and synergy with pharmacotherapy.