Learning Curve for Robot-Assisted Percutaneous Pedicle Screw Placement in Thoracolumbar Surgery.

STUDY DESIGN: Retrospective review of an initial cohort of consecutive patients undergoing robot-assisted pedicle screw placement. PURPOSE: We aimed to evaluate the learning curve, if any, of this new technology over the course of our experience. OVERVIEW OF LITERATURE: Percutaneous pedicle screws have specific advantages over open freehand screws. However, they require intraoperative imaging for their placement (e.g., fluoroscopy and navigation) and require increased surgeon training and skill with the learning curve estimated at approximately 20-30 cases. To our knowledge, this is the first study that measures the learning curve of robot-guided purely percutaneous pedicle screw placement with comprehensive objective postoperative computed tomography (CT) scoring, time per screw placement, and fluoroscopy time. METHODS: We included the first 80 consecutive patients undergoing robot-assisted spinal surgery at Melbourne Private Hospital. Data were collected for pedicle screw placement accuracy, placement time, fluoroscopy time, and revision rate. Patient demographic and relevant perioperative and procedural data were also collected. The patients were divided equally into four sub-groups as per their chronological date of surgery to evaluate how the learning curve affected screw placement outcomes. RESULTS: Total 80 patients were included; 73 (91%) had complete data and postoperative CT imaging that could help assess that placement of 352 thoracolumbar pedicle screws. The rate of clinically acceptable screw placement was high (96.6%, 95.4%, 95.6%, and 90.7%, in groups 1 to 4, respectively, p=0.314) over time. The median time per screw was 7.0 minutes (6.5, 7.0, 6.0, and 6.0 minutes in groups 1 to 4, respectively, p=0.605). Intraoperative revision occurred in only 1 of the 352 screws (0.3%). CONCLUSIONS: We found that robot-assisted screw placement had high accuracy, low placement time, low fluoroscopy time, and a low complication rate. However, there were no significant differences in these parameters at the initial experience and the practiced, experience placement (after approximately 1 year), indicating that robot-assisted pedicle screw placement has a very short (almost no) learning curve.

Metastatic olfactory neuroblastoma invading a radiation-induced meningioma.

Olfactory neuroblastomas are malignant, neuroectodermal nasal tumours. We describe a 62-year-old patient with a recurrent olfactory neuroblastoma invading a radiation-induced meningioma. Given the temporal and spatial relationship between the primary lesion and the described recurrence, this was due to metastatic rather than direct contiguous spread, fulfilling all the criteria for true tumour-to-tumour metastasis. To our knowledge, this is the first description of an olfactory neuroblastoma metastasising to a meningioma.

Thyroid carcinoma metastasis to the choroid plexus of the lateral ventricle.

We present a rare case of a lateral ventricle choroid plexus metastasis arising from thyroid carcinoma in a 62-year-old man. The patient underwent subtotal excision of the intracranial tumour followed by total thyroidectomy with good outcome. We review previous reports of intracranial thyroid metastases and discuss the role of surgical resection, radiosurgery, whole brain radiotherapy and radioactive iodine therapy. There is no consensus regarding treatment in the literature due to small numbers of patients reported. We recommend surgical resection for single accessible lesions.

Promising survival in patients with high-grade gliomas following therapy with a novel boronated porphyrin.

Current treatment strategies for high-grade gliomas are inadequate with high rates of disease recurrence and poor overall survival. Photodynamic therapy has been extensively investigated for a variety of tumours including high-grade gliomas. We have previously described a novel boronated porphyrin (BOPP) which has highly selective uptake by tumour cells. A Phase I study documented that BOPP at a dose of 4mg/kg was well tolerated. We report here the survival data arising from this Phase I study. Overall 28 patients (pts) with high-grade gliomas were treated with BOPP photodynamic therapy with a median overall survival (OS) of 14 months (2-48+ months). Sixteen pts had glioblastoma multiforme (GBM) with a median OS of 8 months (2-38+). Of 9 pts with recurrent GBM, the median OS was 11 months (3-38+), with 56% surviving at least 12 months. In conclusion, BOPP photodynamic therapy was associated with encouraging survival particularly in the recurrent GBM setting.