Neuralgia-inducing cavitational osteonecrosis (NICO) is a controversial diagnosis whereby a putative jawbone cavitation causes chronic facial neuralgia; this is different from osteonecrosis of the jaw. In NICO the pain is said to result from the degenerating nerve ("neuralagia"). The condition is probably rare, if it does exist. Also called Ratner's bone cavity, a neuralgia-inducing cavitational osteonecrosis was first described in dental literature by G V Black in 1920. Several decades later, oral pathologist Jerry E Bouquot took especial interest in NICO.