Herpes Zoster primarily affects which branch of the trigeminal nerve?

Herpes Zoster, also known as shingles, is caused by the reactivation of the varicella-zoster virus. When it reactivates, it follows the distribution of a specific nerve branch. In the case of the trigeminal nerve, the V1 branch, also known as the ophthalmic division, is primarily affected. This is significant because the lesions from Herpes Zoster in the V1 region can lead to conditions such as herpes zoster ophthalmicus, which can potentially cause serious ocular complications.

The V1 branch innervates areas such as the forehead, scalp, and upper eyelids. Because the distribution of the rash and pain typically follows the sensory dermatomes corresponding to these areas, it makes sense that V1 is the area most commonly involved when Herpes Zoster reactivates in the trigeminal nerve.

In contrast, while V2 (maxillary) and V3 (mandibular) branches can also be affected, they are less commonly involved in the classic presentation of Herpes Zoster. The statement regarding all branches being equally affected is incorrect, as the distribution of Herpes Zoster is typically unilateral and corresponds to the specific dermatome of the trigeminal nerve where the virus has re