The pain, and presumably the ischemic process, appears to be very slowly progressive over time, with increasing pain, increasing frequency of pain and increasing areas of involvement. The pain is often intermittent and may vary in extent, location and character over time. It is often difficult for the patient to describe and localize. The pain in this disease can be produced by a variety of factors, such as ischemia of the nerves, fluid or gasseous pressures on the nerves, distended blood vessels, inflammatory mediators, damage to the nerves from chronic exposure to the toxins of dead or inflamed tissues. It should not be surprising, then, that a variety of types of pain occur.
Most patients feel a deep ache or sharp pain deep in the bone.
Pain episodes may be separated by days or weeks without pain. Another common pain type is a very sharp, lancinating pain shooting up to the eye or along the edge of the nose or back to the ear, perhaps with temporary secondary pain in those sites. This pain may or may not be triggered by touching a certain part of the alveolar bone or overlying facial skin. The latter phenomenon may have to do with the fact that intraosseous blood flow is so slowed in some individuals that the anesthetic remains in place for long periods of time. A third feature of NICO is that a local dental anesthetic injected into the periosteal tissues above the site of diseased marrow almost always reduces or completely eliminates the pain.