APEA Neurology Practice Test 2026 - Free Neurology Exam Practice Questions and Study Guide

Dermatomal patterns come from nerve fibers supplying specific strips of skin mapped to each spinal nerve. Shingles is a classic example because it results from reactivation of varicella-zoster virus in a dorsal root ganglion, causing inflammation and viral spread along the sensory neurons of that single nerve. The rash and pain typically appear in one side of the body in a band-like distribution that follows a dermatome and usually does not cross the midline. This is why shingles presents as a localized, dermatomally confined eruption rather than widespread or symmetric patterns.

Fibromyalgia involves widespread musculoskeletal pain with no dermatomal limitation. Diabetic polyneuropathy usually shows a length-dependent, stocking-glove distribution and is symmetric rather than confined to a single dermatome. Referred pain is felt in a different location from the actual source and does not map to a single nerve’s dermatome.