Footnotes

• Contributors MRN provided clinical care and drafted the manuscript. SP provided mentorship and revised the manuscript for intellectual content.

• Competing interests None declared.

• Provenance and peer review Not commissioned; externally peer reviewed.

• Referee's commentary Neagu and Prasad provide a neat and valuable lesson in facial nerve anatomy, based on the distribution of the rash in a patient with a lower motor neurone facial nerve palsy associated with herpes zoster infection. The viral infection elegantly uncovers areas, not routinely tested on clinical examination, as belonging to the boundary zones of the involved facial nerve. This is a compelling example of a treatable disease briefly delineating, for observant clinicians, the normal but little known anatomy of an otherwise familiar nerve. Tom Hughes, Cardiff, UK Tom.Hughes2@wales.nhs.uk