[Vertebral osteoid osteoma--peroperative detection of its nidus using a surgical gamma probe].

The case of a vertebral osteoid osteoma localized in the arch and pedicle of the fourth lumbar vertebra in a young girl is described. The condition was manifested by the development of scoliosis, which was also the initial diagnosis. Because of painful muscle contractions and persistent pain at night, osteoid osteoma was suspected and then confirmed by scintigraphy. In order to minimize resection of the posterior stabilizing structures and to ensure removal of the complete nidus, surgery was carried out with the use of a surgical gamma probe. The method is based on administration of a radionuclide (99m Techneciumlabeled methylenediphosphonate) 2 to 3 h before the operation and intraoperative detection of the intensity of radiation directly in the operative wound. The values of impulses recorded over the nidus were more than ten-times higher than the background values, i.e., the impulses over the surrounding, unaffected bone. The nidus was exactly localized and removed as a whole. Posterolateral fusion without instrumentation was carried out. The patient was almost immediately free from night pain. After fixation with TLSO for 3 months, the patient started physical therapy. One year later she was without any complaints, fusion was healed and she had no relapse. The aim of this study was to draw attention to this less known and therefore less frequently employed method that may enable the surgeon to detect conditions otherwise difficult to localize. This method can also be used for other body sites if the lesion treated accumulates radionuclides.