The true prevalence of PNI in various malignancies still has not been established. Lack of a concise, universal definition for PNI across all disciplines has resulted in significant confusion and probably is a reason for the seemingly slow progress. In fact, in a recent editorial, Doctor Ginsberg, a professor of neuroradiology at M.D. Anderson Cancer Center, wrote “Misinterpretation of head and neck imaging studies is so prevalent, that some radiologic diagnoses such as the perineural spread of head and neck cancer are far more commonly missed than made. It may even be that the standard of care is actually to miss perineural tumor spread radiologically.” Common causes for missing the diagnosis of PNS include lack of familiarity with the head and neck cancers that cause PNS, lack of knowledge of the anatomy of their common routes of spread, suboptimal imaging, and lack of familiarity with the imaging criteria of PNS.