Pontine infarction isolated to trigeminal sensory fibers: a case report

Background Brainstem infarction involving the trigeminal nerve is not uncommon in clinical practice. However, isolated infarction that selectively damages the sensory fibers of the trigeminal nerve while sparing motor function is extremely rare. Due to its atypical presentation—distinct from complete nerve infarction—this condition is prone to misdiagnosis, posing a significant clinical challenge. Case report We report a 59-year-old male with a history of hyperlipidemia, fatty liver disease, and hyperuricemia who presented with progressive swelling and numbness of the left gingiva and face for 20 days. He was initially misdiagnosed with trigeminal neuritis at an external dental clinic and treated with prednisone without symptom relief. Neurological examination revealed decreased pinprick and temperature sensation in the left trigeminal nerve distribution, with normal masseter muscle strength. Brain magnetic resonance imaging showed a diffusion-restricted lesion along the trigeminal sensory pathway in the left pontine tegmentum. A diagnosis of subacute pontine infarction selectively involving the trigeminal sensory fibers was made. Treatment consisted of dual antiplatelet therapy (aspirin 0.1 g at bedtime plus clopidogrel 75 mg once daily), rosuvastatin 20 mg at bedtime, gabapentin 0.3 g three times daily for numbness relief, and loratadine 10 mg once daily for angioneurotic edema. Three-week in-hospital follow-up showed marked improvement of facial swelling and partial relief of numbness. Conclusion Isolated infarction of the trigeminal sensory fibers resulting from occlusion of small penetrating pontine arteries is a rare stroke subtype. Early recognition and targeted neuroimaging are crucial for accurate diagnosis and timely intervention.