Extraosseous Thoracic Foraminal Osteoblastoma: Diagnostic Dilemma and Management with 3 Year Follow-Up

Osteoblastomas are bone forming lesions arising mainly from posterior elements of the vertebra. They are commonly encountered in the cervical and lumbar regions. We present a case of a thoracic osteoblastoma which is extra osseous and is not communicating with any part of the vertebra present intraforaminally. This is a rare presentation of an osteoblastoma. Imaging studies do not accurately diagnose the osteiod lesion. The size of the lesion and cortical erosion seen on the computed tomography scan help in differentiating the osteoid osteoma and osteoblastoma, but they are less sensitive and specific. Thus a histopathology is the investigation of choice to diagnose the osteoblastoma. Early and adequate removal of mass prevents malignant transformation, metastasis, and recurrence. In our case we excised the pars interarticularis unilaterally, removed the osteoid mass intact, and performed unilateral instrumented fusion. There was no recurrence and solid fusion was seen at 3 years follow up.

Change of the Intervertebral Foraminal Pressure after Removal of the Disc Material

OBJECTIVES: Spinal nerve root compression occurs commonly in conditions, such as herniated nucleus pulposus, spinal stenosis, intervertebral foraminal stenosis, and trauma. However, the pathophysiolosy of the symptoms and signs related to spinal nerve root compression is poorly understood. The purpose of the present study was to assess and compare the changes of various pressures of intervertebral foraminal pressure before and after decompression. METHOD: After laminetomy without foraminotomy was performed, pressure sensor tip of Camino parenchymal type was located at the middle-central portion of the intervertebral foramen and anterior portion of nerve root for the foraminal pressure before decompression of the intervertebral foramen. After laminectomy with foraminotomy, the same method was used for the foraminal pressure after decompression. The authors studied 40 consecutive patients (57 disc spaces) with severe constant root pain to the lower leg, pain unrelived by bed rest, and minimal tension signs, diagnosed by MRI. RESULTS: In patients with intervertebral foraminal stenosis, the intraforaminal pressure was decreased from 86+/-2.23mmHg to 17.1+/-1.51mmHg and in patients without stenosis, from 55.9+/-1.08mmHg to 11.9+/-1.25mmHg. All patients below 20mmHg after decompression showed good outcome, but 4 cases who showed poor outcome had foraminal stenosis, posterolateral type of the herniated disc, and above 30mmHg of foraminal pressure after decompression. CONCLUSION: These findings suggest that if the foraminal pressure falls below 20mmHg after decompression, good outcome can be anticipated. Central type of the herniated disc shows better outcome compared to the posterolateral type.