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Posterior vault distraction osteogenesis (DO) is an emerging treatment option for craniosynostosis. Operative nuances detailing surgical management are being described with increasing use and experience. In this article, we discuss the surgical management of an 8-month-old male with a ventriculoperitoneal shunt (VPS) diagnosed with bilateral lambdoid craniosynostosis and Chiari I malformation. The patient underwent successful bilateral posterior fossa DO without surgical re-implantation of the shunt. Pre- and post-operative imaging confirmed no migration of the VPS. Intracranial volume increased by 20.1% and posterior fossa volume increased by 39.9%. Our experience illustrates that posterior vault DO can be done safely in the setting of a parieto-occipital VPS, in a single operative setting, without the need of additional procedures.

Tenosynovial giant cell tumor (TGCT) is a rare entity that is not well described in the neurosurgical literature. We present a case of a 37-year-old woman with a diffuse subtype TGCT of the cervical spine, affecting the left cervical 6-7 facet joint, with co-incidental cervical trauma. Initial management consisted of subtotal resection and cervical stabilization with cervical 6 to 7 laminectomy, and cervical 4 to thoracic 2 posterior instrumented fusion. Gross total resection was achieved at a later date with a plan for postoperative radiation to prevent a recurrence. The patient was lost to follow-up for radiation treatment and returned 2.5 years later with minor symptoms and recurrence at the surgical site.

Glycerol rhizotomy was originally described as an initial surgical treatment for trigeminal neuralgia after the failure of medical therapy. Here we describe its use as a salvage procedure, typically after failure of multiple other modalities including microvascular decompression, stereotactic radiosurgery, and/or other percutaneous procedures. Foramen ovale cannulation as a "salvage procedure" may be complicated by lack of cerebrospinal fluid (CSF) return despite adequate cannulation of the foramen ovale, making conventional fluoroscopic confirmation of adequate needle placement less certain. In this article, we describe the application of intraoperative CT, fused with high-resolution preoperative CT/MRI for neuronavigation to accurately cannulate the foramen ovale and Meckel's cave for glycerol rhizotomy. Intraoperative CT, again fused with high-resolution preoperative CT and MRI studies, was then used to confirm accurate trajectory through the foramen ovale and the adequate location of the needle tip in Meckel's cave before injecting glycerol. We present our initial experience with 14 patients who underwent glycerol rhizotomy by these techniques depending on intraoperative CT. It appears that intraoperative CT-guided neuronavigation provides a practical, reliable, and accurate route to the foramen ovale and aids in the confirmation of adequate needle placement even when there is a lack of CSF return. These methods may be especially useful for difficult cannulations typical in salvage procedures. In an era of feasible intraoperative guidance, with advanced stereotactic planning software allowing the fusion of intraoperative CT with high-resolution preoperative CT and MRI datasets, these techniques can be applied to foramen ovale cannulation for glycerol rhizotomy without major modification.

OBJECT Distraction osteogenesis (DO) may allow for maximal volumetric expansion in the posterior vault (PV) by overcoming viscoelastic forces of overlying soft tissues. Little evidence exists regarding surgical planning and anticipated 3D volumetric changes pre- and post-operatively. We aim to study the volumetric changes occurring in PV distraction in lambdoid craniosynostosis. METHODS From 2007 to 2019, a single institution retrospective review revealed 232 craniosynostosis patients. Fourteen demonstrated lambdoid synostosis (6%), and of those, 11 patients were included in the study due to treatment with PVDO or representative sample. Six patients had unilateral synostosis and 5 had bilateral synostosis. Imaging protocol for PVDO patients included preoperative head CT within 1 month of surgery and 8 weeks following distraction cessation with weekly skull plain films. 3D volumetric analyses were performed on pre and postoperative head CT using 3D Slicer software. RESULTS Posterior fossa volume (PFV) increased by 38.7% and foramen magnum area increased by 26.9% postoperatively. Unilateral lambdoid craniosynostosis patients had greater increases in PFV versus bilateral lambdoid craniosynostosis patients (63.5% versus 8.9%, P = 0.007). Osteotomy to the asterion was more effective in increasing PFV versus osteotomy to foramen magnum (P = 0.050). Placement of distractor in the inferior third of the lambdoid suture is more effective in increasing PFV versus placement in the middle or top third of the suture (P = 0.041). CONCLUSIONS Highest volumetric increases are seen in unilateral lambdoid synostosis. Extending osteotomy beyond the asterion is not necessary for maximal PV volumetric gain. Placement of distractor in the inferior third of the suture leads to maximal PV volumetric gains.