-Its term is derived from the latin term “cingulum” meaning girdle.
-Is caused by the Herpes Zoster virus following its reactivation in the geniculate, trigeminal or dorsal ganglia following a dormant state after an old episode of chicken pox.
-The cause of the reactivation is not known but it is associated with advanced age (over 50), immunosuppressive illness, physical stress or new medical treatments.
-The most affected dermatome is by descending order: thoracic, cervical, trigeminal nerve, lumbar, sacral…and opthalmic.
-Usually a single dermatome is involved, but if multiple dermatomes are involved, an immunosuppressive state (such as HIV infection…) should be suspected.
-Lesions on the tip of the nose implies involvement of the ophtalmic branch of the trigeminal nerve (V.1) and is called Hutchinson’s sign.