Hypertrophic pachymeningitis is an uncommon inflammatory process with thickening of the dura mater and may be idiopathic or secondary to various conditions such as vasculitis, Sjögren syndrome, rheumatoid arthritis, sarcoidosis, and infections. A 67-year-old man who presented with bilateral hearing loss, vision loss in the left eye, right-sided facial paralysis, and right-side headache underwent 18 F-FDG PET/CT for further evaluation. Herein, we have presented a patient who showed diffuse increased radiotracer uptake in the cranial nerves and intracranial dura mater on 18 F-FDG PET/CT and was diagnosed as idiopathic hypertrophic pachymeningitis based on laboratory and MRI findings.