Delayed blink R1 latency in a patient with trigeminal neuralgia due to a contralateral vestibular schwannoma: An illustrative case

BACKGROUND: Although the blink reflex (BR) is effective in objectively evaluating trigeminal neuropathy, few studies have demonstrated its effect on trigeminal neuralgia (TN). The authors report a patient with TN due to contralateral vestibular schwannoma (VS) functionally diagnosed by delayed R1 latency of the BR. CASE DESCRIPTION: A 36-year-old man presented with left-sided deafness and paroxysmal facial pain in the right V1-3 area. Magnetic resonance imaging (MRI) showed a solid cystic mass compressing the right pons and left brainstem at the left cerebellopontine angle. Although preoperative BR evoked by right supraorbital nerve stimulation-induced delayed ipsilateral R1 latency and normal ipsilateral and contralateral R2 responses, the BR latency evoked by left supraorbital nerve stimulation was normal, indicating deficits in the principal nucleus of the trigeminal nerve in the right pons. The symptoms of TN disappeared after the removal of the VS. Postoperative MRI showed subtotal removal of the tumor and sufficient decompression of the pons and cerebellopontine cistern. The R1 latency returned to normal 50 days after surgery. CONCLUSION: The perioperative BR test was not only useful for objective evaluation of the localization of trigeminal neuropathy but also correlated with the symptoms of TN.