The indication for gamma probe-guided surgery of spinal osteoid osteomas.

The standard treatment for osteoid osteomas is CT-guided radiofrequency ablation (RFA). This minimally invasive procedure is effective in terms of pain reduction as well as the recurrence rate. Nevertheless, the use for spinal lesions is limited due to a possible thermal damage of neural structures. Although the literature is contradictory, RFA should only be used when a cortical shell between the lesion and the spinal canal is existent. We present seven cases (five males, two females, mean age 23 years) with spinal osteoid osteoma in which RFA was not applicable and open resection with the use of probe-guided surgery (PGS) was performed. The principle of PGS is that after preoperative bone scintigraphy, a handheld radiation probe is used intraoperatively for tumour localisation. Here, exposure and bone resection can be minimised and completeness of tumour excision may be estimated. At the initial measurement we found a hot-spot (maximum count-rate) in all patients and after tumour resection, the signal decreased by a mean of 68% in the operative field. After a mean follow-up of 17 months one patient had residual pain but no patient had signs of tumour recurrence. The authors recommend to use PGS for those spinal osteoid osteomas where RFA is not applicable and intraoperative localisation--and here complete resection--of the tumour is difficult.