Objective: Analysis of the use of polyetheretherketone (PEEK) cages for atlantoaxial facet realignment and distraction for treatment of basilar invagination by Goel technique. Method: Retrospective descriptive statistical analysis of the neurological status, pain, presence of subsidence and bone fusion with the use of PEEK cages in 8 atlantoaxial joints of 4 patients with basilar invagination. All patients were treated with atlantoaxial facet distraction and realignment and subsequent arthrodesis C1-C2 by the technique of Goel modified by the use of PEEK cage. Results: All patients showed improvement in Nurick neurological assessment scale and Visual Analogue Scale (VAS) of pain. There were no cases of subsidence, migration, or damage to the vertebral artery during the insertion of the cage. All joints evolved with bone fusion, assessed by dynamic radiographs, and computed tomography. Two patients developed neuropathic pain in dermatome of C2 and one patient had unilateral vertebral artery injury during C2 instrumentation treated with insertion of pedicle screw to control the bleeding. Conclusion: The results of the treatment of basilar invagination by the Goel technique with the use of PEEK cages shown to be effective and safe although further studies are needed to confirm this use.Keywords: Platybasia; Skull base; Atlanto-axial joint. RESUMO

Objective: Evaluate the results after decompression and stabilization of craniocervical junction in patients with mucopolysaccharidosis (MPS). Method: Retrospective study of 10 patients with MPS through the analysis of medical records and additional tests. Result: All patients with mid-term and long-term follow-up achieved consolidation of the arthrodesis and 87.5% had neurological improvement of Nurick score. Conclusion: Early diagnosis and intervention in cases of stenosis and/or craniocervical instability of patients with MPS provide patients a good recovery of neurological function, despite the great technical difficulty and risk of complications.

Objective To establish the statistical interobserver and intraobserver concordance of thoracic pedicle screw placement in scoliosis surgery, with a 4-week interval between the two analyses. Methods Of 55 patients that evaluated the intra- and interobserver concordances of the screw positions (according to the Abul-Kasim classification) using the Kappa coefficient. Results The intraobserver concordance ranged from a Kappa coefficient of 0.516 to 0.889 (“moderate” to “almost perfect”) between the two analyses performed four weeks apart. Interobserver concordance ranged from 0.379 to 0.633 (“reasonable” to “strong”). Conclusion The intraobserver concordance was always greater than the interobserver concordance. No concordance coefficient was classified as “insignificant” or “weak”. Level of Evidence III; Retrospective study.

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The literature estimates that between 70 and 80% of dural ectasia occur in patients with Neurofibromatosis type I, also known as von Recklinghausen's disease. 1 Autosomal dominant disease of changerelated etiology on chromosome 17(17q11.2), in the gene NF1 2 responsible for the production of the protein neurofibromin, 3 being inherited in 50% of the cases, and by spontaneous mutation in the other 50%. It presents an incidence of 1: 3000, varying the statistic according to the region of the planet. 4 According to the NIH-National Institute of Health-the diagnosis is established by the presence of two or more characteristics within the seven: (1) six or more coffeewith-milk stains, (2) two or more neurofibromas; or a plexiform neurofibroma, (3) inguinal or axillary ephelides, (4) Lisch nodules in the iris, (5) optic glioma, (6) first-degree relative carrying the disease, and (7) typical skeletal alteration of the disease spectrum. 5 With a lower incidence, dural ectasia may also be present in patients with Marfan syndrome, Ehlers-Danlos syndrome and ankylosing spondylitis. 6