Which of the following is NOT a recognised complication of infection with Corynebacterium diphtheriae?

Correct answer: C. Trigeminal neuralgia

• A. ACUTE CIRCULATORY FAILURE follows from toxic myocarditis and from the systemic toxaemia of severe disease.
• B. MYOCARDITIS is the leading cause of death in diphtheria. The exotoxin inhibits protein synthesis by ADP-ribosylating elongation factor 2, and cardiac muscle is particularly vulnerable — producing arrhythmias, conduction block and heart failure in the second week of illness.
• C. CORRECT — this is the exception. TRIGEMINAL NEURALGIA is a distinct disorder characterised by paroxysmal lancinating facial pain, most often caused by vascular compression of the trigeminal root or, in younger patients, by multiple sclerosis. It has no relationship to diphtheria. The neuropathy that diphtheria toxin DOES cause is quite different: a descending, largely MOTOR polyneuropathy beginning with palatal paralysis (nasal speech, regurgitation) and blurred accommodation, progressing to limb weakness.
• D. OTITIS MEDIA and extension of the pharyngeal infection into adjacent structures are recognised local complications, along with the pathognomonic grey PSEUDOMEMBRANE that can obstruct the airway.

Note: The two lethal features of diphtheria are AIRWAY OBSTRUCTION by the pseudomembrane and TOXIC MYOCARDITIS. Treatment is antitoxin plus penicillin or erythromycin, and the disease is prevented by the toxoid in DTaP.