Case Report: Isolated lingual pain: a rare and atypical presentation of trigeminal neuralgia successfully treated with microvascular decompression.

Background: Trigeminal neuralgia (TN) typically presents with paroxysmal, shock-like, or stabbing pain in the unilateral facial region corresponding to the trigeminal nerve distribution. However, cases manifesting solely as isolated tongue pain are exceedingly rare. Case presentation: A 63-year-old female presented with a two-year history of left-sided tongue pain. She was initially suspected of having glossopharyngeal neuralgia (GPN) and treated with oxcarbazepine at the local hospital, which provided suboptimal relief. Over the past two months, her pain intensified significantly. Upon referral to our department, a comprehensive evaluation was conducted-including a detailed history, neurological examination and high-resolution magnetic resonance imaging (MRI). However, we ruled out the diagnosis of glossopharyngeal neuralgia and strongly believe the patient suffered from trigeminal neuralgia. First, MRI imaging revealed vascular compression of the trigeminal nerve. Then, glossopharyngeal nerve block helped rule out glossopharyngeal neuralgia. Most importantly, intraoperative exploration confirmed definite vascular compression of the trigeminal nerve, while vessels were observed adjacent to the glossopharyngeal nerve without significant compression. The patient subsequently underwent left microvascular decompression (MVD) of the trigeminal nerve. Postoperatively, her pain resolved completely. Discussion and conclusion: Trigeminal neuralgia and glossopharyngeal neuralgia share overlapping clinical features, pathogenesis, imaging findings and triggering factors. These two diseases are typically distinguished by their characteristic pain locations. This case illustrates a diagnostically challenging presentation of TN, with pain confined exclusively to the tongue, which is highly prone to being misdiagnosed as glossopharyngeal neuralgia. The definitive identification of neurovascular compression on imaging, coupled with the complete resolution of pain following MVD, conclusively confirmed the diagnosis of TN. This report emphasizes that clinicians should meticulously analyze pain distribution and correlate it with imaging evidence of vascular compression to accurately differentiate between these two entities, thereby avoiding misdiagnosis and mitigating the risk of unnecessary interventions or secondary injury.