Diphtheria Presenting With Cranial Neuropathy: The Patch Unseen

Diphtheria is a vaccine-preventable disease that remains endemic in several developing countries. Neurological complications, such as polyneuropathy, are rare but serious, often mimicking other neuromuscular disorders and leading to delayed diagnosis. Herein, we report the case of a 20-year-old incompletely immunised woman who presented with bilateral ptosis, multiple cranial neuropathies, and mild limb weakness following a prodrome of fever, headache, and peri-orbital pain. Initial investigations revealed albumin-cytologic dissociation in the cerebrospinal fluid, raising suspicion of Guillain-Barré syndrome, for which intravenous immunoglobulin was administered; however, there was no clinical improvement. Myasthenia gravis and botulism were also considered but excluded based on clinical and laboratory findings. Throat swab culture indicated the presence of Corynebacterium diphtheriae, confirming the diagnosis of diphtheritic polyneuropathy. The patient was treated with diphtheria antitoxin and erythromycin, resulting in an improvement of bulbar symptoms; nonetheless, ptosis persisted at discharge. Prophylaxis was provided to close contacts, and the patient was scheduled for diphtheria vaccination. This case highlights the significance of considering diphtheria in the differential diagnosis of acute cranial neuropathies in endemic regions and the role of vaccination in preventing such life-threatening complications.