Intracranial solitary fibrous tumor with delayed symptomatic metastasis to the lumbar spine: illustrative case.

BACKGROUND: Intracranial solitary fibrous tumors (SFTs), formerly known as hemangiopericytomas, are rare, aggressive mesenchymal extra-axial tumors typically treated via resection, often with preoperative embolization and postoperative radiation and/or antiangiogenic therapy. Although surgery confers a significant survival benefit, local recurrence and distant metastasis are not uncommon and may occur in a delayed fashion. OBSERVATIONS: The authors describe the case of a 29-year-old male who initially presented with headache, visual disturbance, and ataxia, and was found to have a large right tentorial lesion with mass effect on surrounding structures. He underwent tumor embolization and resection with gross total resection achieved and pathology consistent with World Health Organization grade 2 hemangiopericytoma. The patient recovered well, but 6 years later presented with low back pain and lower extremity radiculopathy and was found to have metastatic disease within the L4 vertebral body causing moderate central canal stenosis. This was successfully treated with tumor embolization followed by spinal decompression and posterolateral instrumented fusion. Metastasis of intracranial SFT to vertebral bone is exceedingly rare. To our knowledge this is only the 16th reported case. LESSONS: Serial surveillance for metastatic disease is imperative in patients with intracranial SFTs given their propensity and unpredictable time course for distant spread.

Catastrophic acute failure of pelvic fixation in adult spinal deformity requiring revision surgery: a multicenter review of incidence, failure mechanisms, and risk factors.

OBJECTIVE: There are few prior reports of acute pelvic instrumentation failure in spinal deformity surgery. The objective of this study was to determine if a previously identified mechanism and rate of pelvic fixation failure were present across multiple institutions, and to determine risk factors for these types of failures. METHODS: Thirteen academic medical centers performed a retrospective review of 18 months of consecutive adult spinal fusions extending 3 or more levels, which included new pelvic screws at the time of surgery. Acute pelvic fixation failure was defined as occurring within 6 months of the index surgery and requiring surgical revision. RESULTS: Failure occurred in 37 (5%) of 779 cases and consisted of either slippage of the rods or displacement of the set screws from the screw tulip head (17 cases), screw shaft fracture (9 cases), screw loosening (9 cases), and/or resultant kyphotic fracture of the sacrum (6 cases). Revision strategies involved new pelvic fixation and/or multiple rod constructs. Six patients (16%) who underwent revision with fewer than 4 rods to the pelvis sustained a second acute failure, but no secondary failures occurred when at least 4 rods were used. In the univariate analysis, the magnitude of surgical correction was higher in the failure cohort (higher preoperative T1-pelvic angle [T1PA], presence of a 3-column osteotomy; p < 0.05). Uncorrected postoperative deformity increased failure risk (pelvic incidence-lumbar lordosis mismatch > 10°, higher postoperative T1PA; p < 0.05). Use of pelvic screws less than 8.5 mm in diameter also increased the likelihood of failure (p < 0.05). In the multivariate analysis, a larger preoperative global deformity as measured by T1PA was associated with failure, male patients were more likely to experience failure than female patients, and there was a strong association with implant manufacturer (p < 0.05). Anterior column support with an L5-S1 interbody fusion was protective against failure (p < 0.05). CONCLUSIONS: Acute catastrophic failures involved large-magnitude surgical corrections and likely resulted from high mechanical strain on the pelvic instrumentation. Patients with large corrections may benefit from anterior structural support placed at the most caudal motion segment and multiple rods connecting to more than 2 pelvic fixation points. If failure occurs, salvage with a minimum of 4 rods and 4 pelvic fixation points can be successful.

Severe Chin-on-Chest Cervical Spine Deformity in the Setting of Stiff-Person Syndrome: A Case Report.

CASE: Stiff-person syndrome (SPS) presents with progressive muscle rigidity, postural instability, and periodic debilitating spasms. Reports of axial hyperextension exist, but kyphotic deformities have not been described. We surgically treated a patient with debilitating SPS and severe cervicothoracic hyperkyphosis with posterior spinal fusion and instrumentation. At 1-year follow-up, the patient displayed better upright gait and forward gaze, 18° cervical lordosis, and improved patient-reported outcome scores. CONCLUSION: SPS can lead to extreme spinal deformity and disease, including hyperkyphosis of the cervicothoracic spine, and can successfully be managed with a multidisciplinary team and a posterior-only correction with spinal instrumentation and fusion.

The bi-directional translocation of MARCKS between membrane and cytosol regulates integrin-mediated muscle cell spreading.

The regulation of the cytoskeleton is critical to normal cell function during tissue morphogenesis. Cell-matrix interactions mediated by integrins regulate cytoskeletal dynamics, but the signaling cascades that control these processes remain largely unknown. Here we show that myristoylated alanine-rich C-kinase substrate (MARCKS) a specific substrate of protein kinase C (PKC), is regulated by alpha5beta1 integrin-mediated activation of PKC and is critical to the regulation of actin stress fiber formation during muscle cell spreading. Using MARCKS mutants that are defective in membrane association or responsiveness to PKC-dependent phosphorylation, we demonstrate that the translocation of MARCKS from the membrane to the cytosol in a PKC-dependent manner permits the initial phases of cell adhesion. The dephosphorylation of MARCKS and its translocation back to the membrane permits the later stages of cell spreading during the polymerization and cross-linking of actin and the maturation of the cytoskeleton. All of these processes are directly dependent on the binding of alpha5beta1 integrin to its extracellular matrix receptor, fibronectin. These results demonstrate a direct biochemical pathway linking alpha5beta1 integrin signaling to cytoskeletal dynamics and involving bi-directional translocation of MARCKS during the dramatic changes in cellular morphology that occur during cell migration and tissue morphogenesis.