To describe a case of sudden-onset, isolated cranial nerve (CN) X palsy without typical rash caused by VZV infection. This abstract aims to highlight VZV as an important, albeit rare, consideration in the differential diagnosis of acute vagal nerve dysfunction.

Neurological involvement secondary to VZV infection is a known complication, sometimes manifesting as cranial neuropathies, commonly CN V, VII, and VIII. Clinical signs such as dysphonia, dysphagia, upper esophageal sphincter (UES) dysfunction, and a hypomobile vocal cord raise suspicion for CN X involvement. This specific presentation requires timely recognition due to the potential for serious morbidity.

An 81-year-old male presented with one week of persistent dysphagia and dysphonia that began suddenly upon waking, following a recent upper respiratory infection. A modified barium swallow study demonstrated UES dysfunction and reduced right lateral pharyngeal contraction. A nasopharyngolaryngoscopy revealed a right, hypomobile vocal cord, indicating potential vagal nerve involvement. The patient also reported new onset, "excruciating" right-sided headaches, and associated pain/tenderness to the right side of his face, ear, and behind the ear with erythema and edema. MRI brain was unremarkable. Lumbar puncture revealed lymphocytic pleocytosis and mildly elevated protein in the cerebrospinal fluid. Crucially, VZV DNA PCR via the meningitis panel was positive, confirming the diagnosis. The patient was started on acyclovir for varicella-zoster meningoencephalitis treatment. Additionally, electrodiagnostic studies were completed but were unrevealing.

VZV infection should be recognized as a possible, though rare, cause of acute CN X palsy. Clinicians should suspect this etiology in patients presenting with sudden, potentially severe symptoms like dysphagia and dysphonia in the setting of negative brain imaging despite absence of typical skin findings. Confirmation via positive VZV DNA in the CSF, along with CSF pleocytosis, is critical for timely initiation of appropriate antiviral therapy for conditions like zoster meningoencephalitis.