A rash and a rare cause of unilateral diaphragmatic paralysis

A 61-year-old man who was an ex-heavy smoker presented to our ambulatory care centre with a 4-week history of dyspnoea on mild exertion. 2 weeks prior to his symptoms, he had developed right-sided cervical herpes zoster for which he was prescribed oral acyclovir by his general practitioner. On examination, a rash over the right C4-5 dermatomes was noted and dullness on percussion of the right mid and lower zones with markedly reduced air entry. His chest radiograph showed a raised right hemi-diaphragm with associated right middle and lower lobe collapse. Further investigation with CT and bronchoscopy did not identify a cause and showed no evidence of underlying malignancy or endobronchial obstruction. An ultrasound 'sniff test' was performed to confirm diaphragmatic paralysis. We present a rare case of cervical herpes-induced diaphragmatic paralysis, and summarise our approach and the current understanding of this interesting condition.