As recently as 1979, a newly described pain disorder was reported. This disorder, which came to be known as osteocavitational lesions, produced pain similar to trigeminal neuralgia, both the typical and atypical types. In fact, usually these patients are diagnosed with trigeminal neuralgia. The diagnosis is complicated by the fact that the x-ray examination of the bone is usually normal.

These bony lesions oftentimes develop in jaws and produce little or no pain whatsoever. They may lie dormant for years and sometimes never become painful or cause a problem. Those that produce pain are termed NICO (Neuralgia Inducing Cavitational Osteonecrosis) lesions.

NICO lesions produce referred pain patterns which also serve to confuse both patient and doctor. However, just like trigeminal neuralgia, there are trigger areas that, when pressed, produce pain. These trigger areas develop directly over the areas of affected bone.

The mandible, or lower jaw, is affected more often than the maxilla, or upper jaw.

One important aspect of NICO is a history of tooth extraction usually years earlier. Any tooth area may be involved. However, lower back teeth seem to be most common. Small areas of bone actually die, producing neuralgia-like pain symptoms. It appears that after a tooth extraction, a NICO lesion may develop due to injury of the blood vessels in the area which ultimately results in poor circulation, resulting in bone death in some cases.

Other common bones affected are the hips and knees.