perineural,a.|pɛrɪˈnjʊərəl| [f.Gr. περί around + νεῦρ-ον nerve + -al1: cf.neural.] Surrounding or investing a nerve, or a bundle of nerve-fibres. 1899Allbutt's Syst.Med. VI. 501 There is in all these cases..leucocytal infiltration of the perineural sheath.