Background and Purpose: Cases of pain mimicking trigeminal neuralgia (TN) induced by ischemic stroke in the brainstem have been sparsely reported. The study was to determine the characteristics of symptomatic TN in patients with acute ischemic stroke in the medulla oblongata and pons, and to determine the location of the ischemic lesion associated with the pain.
Patients and Methods: A total of 6/21 (28.5%) patients with medullary ischemic stroke and 3/34 (8.8%) patients with pontine ischemic stroke who experienced pain mimicking TN between 1 week before and 2 weeks after the stroke onset were enrolled in the study. All patients accepted neuroimaging examinations to determine the location of the ischemic lesion and the etiology of ischemic stroke. The characteristics of pain were recorded and analyzed.
Results: Ischemic lesions of patients who experienced pain mimicking TN were located in the lateral medulla oblongata (n=6), nerve root entry zoo (n=2), and areas involved with the spinal trigeminal tract (n=1) in the pons. Half of the instances of pain induced by medullary ischemic stroke occurred prior to the stroke onset. The branch of V1 was exclusively involved in patients with lateral medullary infarction and the branches of V2 and V3 were typically involved in patients with pontine infarction. The pain was relieved spontaneously (n=4, 44.4%) or was controlled with drugs for neuropathic pain treatment (n=5, 55.5%).
Conclusion: Half of the instances of pain induced by medullary ischemic stroke occurred prior to the stroke onset. Pain mimicking TN might be a premonitory symptom of the medullary ischemic stroke. Pain mimicking TN induced by brainstem infarction has a good prognosis.
Keywords: trigeminal neuralgia, lateral medullary infarction, pontine infarction, brainstem infarction, ischemic stroke