Interpretation of increased anterior cerebral artery flow velocity on transcranial Doppler ultrasound.

Trigeminal neuralgia (TN) is classified into classical, secondary, and idiopathic forms, but the pathophysiology and optimal surgical management of idiopathic TN remain controversial, especially in the absence of definite neurovascular compression. We report two cases of idiopathic TN successfully treated with nerve combing combined with posterior fossa exploration. A 44-year-old woman and a 73-year-old man presented with medically refractory paroxysmal facial pain, and preoperative MRI demonstrated vascular contact without clear compression. Intraoperatively, thickened arachnoid adhesions and axial torsion of the trigeminal nerve root were identified. Meticulous arachnoid dissection restored normal nerve alignment, followed by nerve combing. In one case, intraoperative compound nerve action potential monitoring suggested reduced neural hyperexcitability. Both patients achieved complete postoperative pain relief with only transient sensory disturbances. These cases indicate that axial torsion of the trigeminal nerve root caused by arachnoid adhesions may play a role in the pathophysiology of idiopathic TN. A diagnostic trial of carbamazepine can serve as a valuable adjunct for the clinical diagnosis of orofacial pain disorders suggestive of trigeminal neuralgia, even in the absence of neurovascular compression on MRI. Furthermore, nerve combing combined with meticulous arachnoid dissection may represent an effective surgical strategy for select patients.