To describe an atypical presentation of Guillain–Barré syndrome (GBS) manifesting as unilateral facial palsy, a rare variant that can closely mimic Bell’s palsy and delay appropriate diagnosis and treatment

The illness began with subtle fingertip numbness ascending to the elbows, followed by rapid progression to perioral numbness, dysarthria, and inability to close the right eye. On initial examination, he had diminished deep tendon reflexes but preserved muscle strength and sensation. Within several days, his reflexes became globally absent. Cerebrospinal fluid analysis revealed albuminocytologic dissociation. Initial electrophysiologic studies were unremarkable for cranial nerve involvement; however, repeat testing demonstrated bilateral facial and trigeminal neuropathies consistent with a demyelinating GBS variant. The patient was treated with intravenous immunoglobulin, resulting in marked improvement of facial weakness. 

This case highlights a rare but clinically important variant of Guillain–Barré syndrome presenting with unilateral facial palsy, an atypical manifestation that can be mistaken for idiopathic Bell’s palsy. Such overlap in presentation may delay recognition of the underlying immune-mediated neuropathy and postpone initiation of therapy. Awareness of this variant is essential, particularly when facial weakness develops after a recent infectious illness. Early identification of Guillain–Barré syndrome allows timely initiation of immunotherapy, which can improve outcomes. Clinicians should therefore consider GBS in the differential diagnosis of acute cranial neuropathies, even when the presentation resembles more common entities such as Bell’s palsy. Prompt diagnosis and management are crucial to prevent disease progression and complications, including respiratory involvement.