RESUMO
Instrumentation during metastatic spine tumor surgery (MSTS) provides stability to the spinal column in patients with pathologic fracture or iatrogenic instability produced while undergoing extensive decompression. Titanium is the current implant material of choice in MSTS. However, it hinders radiotherapy planning and generates artifacts, with magnetic resonance imaging and computed tomography scans used for postoperative evaluation of tumor recurrence and/or complications. The high modulus of elasticity of titanium (110 GPa) results in stress shielding, which may lead to construct failure at the bone-implant interface. Polyether ether ketone (PEEK), a thermoplastic polymer, is an emerging alternative to titanium for use in MSTS. The modulus of elasticity of PEEK (3.6 GPa) is close to that of cortical bone (17-21 GPa), resulting in minimal stress shielding. Its radiolucent and nonmetallic properties cause minimal interference with magnetic resonance imaging and computed tomography scans. PEEK also causes low-dose perturbation for radiotherapy planning. However, PEEK has reduced bioactivity with bone and lacks sufficient rigidity to be used as rods in MSTS. The reduced bioactivity of PEEK may be addressed by 1) surface modification (introducing porosity or bioactive coating with hydroxyapatite [HA] or titanium) and 2) forming composites with HA/titanium. The mechanical properties of PEEK may be improved by forming composites with HA or carbon fiber. Despite these modifications, all PEEK and PEEK-based implants are difficult to handle and contour intraoperatively. Our review provides a comprehensive overview of PEEK and modified PEEK implants, with a description of their properties and limitations, potentially serving as a basis for their future development and use in MSTS.
Assuntos
Materiais Biocompatíveis , Cetonas , Osseointegração , Polietilenoglicóis , Próteses e Implantes , Neoplasias da Coluna Vertebral/cirurgia , Titânio , Artefatos , Benzofenonas , Fenômenos Biomecânicos , Fibra de Carbono , Descompressão Cirúrgica , Durapatita , Módulo de Elasticidade , Humanos , Imageamento por Ressonância Magnética , Fenômenos Mecânicos , Polímeros , Porosidade , Planejamento da Radioterapia Assistida por Computador , Neoplasias da Coluna Vertebral/secundário , Tomografia Computadorizada por Raios XRESUMO
OBJECTIVES: Pars repair is less explored in adults due to associated disc degeneration with advancing age. The aim of our systematic review was to define optimal characteristics of adults with spondylolysis/grade-I spondylolisthesis suitable for pars repair and evaluate the feasibility, effectiveness, and safety of standard repair techniques in these adults. METHODS: This systematic review is reported in line with PRISMA-P and protocol is registered with PROSPERO (CRD42020189208). Electronic searches were conducted in PubMed, Embase, Scopus, and Web of Science in June 2020 using systematic search strategy. Studies involving adults aged ≥18-years with spondylolysis/grade-1 isthmic spondylolisthesis treated with standard pars repair techniques were considered eligible. A two-staged (titles/abstracts and full-text) screening was conducted independently by three authors followed by quality assessment using the Joanna Briggs Institute critical appraisal checklist for selection of final articles for narrative synthesis. RESULTS: A total of 5,813-articles were retrieved using systematic search strategy. First screening followed by removal of duplicates resulted in 111-articles. Second (full-text) screening resulted in exclusion of 64-articles. A final 47-articles were considered for data extraction after quality assessment. A total of 590-adults were enrolled across 47-studies; 93% were 'young adults' (18-35 years); 82% were males. Persistent low back pain was the common presenting complaint. Lysis defect was primarily bilateral (96.4%) and L5 was the most involved level (68.5%). Majority had no disc degeneration (83.5%) and had spondylolysis as the primary diagnosis (86%); only 14% had grade-I spondylolisthesis. Pars infiltration test was conducted in 22-studies and discography in 8-studies. Duration of prior conservative therapy was 3 to 72-months. Buck's repair was the commonest technique (27-studies, 372-adults). Successful repair was reported in 86% of patients treated with Buck's and ≥90% treated with Scott's, Morscher's and pedicle-screw-based techniques. Improvement in pain/functional outcomes, union rate and rate-of-return to sports/activity was high and comparable across all techniques. Intraoperative blood loss was low with minimally invasive versus traditional repair. The overall complication rate was 11.9%, with implant failure being the major complication. CONCLUSIONS: Our systematic review establishes a definite place for lysis repair in carefully selected adults with spondylolysis/grade-I spondylolisthesis. We propose a treatment algorithm for optimizing patient selection and outcomes. We conclude that adults with age 18 to 45 years, no/mild disc or facet degenerative changes, positive diagnostic infiltration test, and normal preoperative discography will have successful outcomes with pars repair, regardless of the technique.
Assuntos
Fusão Vertebral , Espondilolistese , Espondilólise , Adolescente , Adulto , Algoritmos , Humanos , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/cirurgia , Masculino , Metanálise como Assunto , Pessoa de Meia-Idade , Espondilolistese/diagnóstico por imagem , Espondilolistese/cirurgia , Espondilólise/diagnóstico por imagem , Espondilólise/cirurgia , Resultado do Tratamento , Adulto JovemRESUMO
The authors tested the null hypothesis that published literature with a high level of evidence does not support the assertion that subarachnoid hemorrhage (SAH) causes cerebral vasospasm, which in turn causes cerebral infarction and poor outcome after aneurysmal SAH. The medical literature on SAH was searched in MEDLINE. The author's personal files of all published literature on SAH were reviewed. References cited in Cochrane reviews as well as the published papers that were reviewed were also retrieved. There is no question that SAH causes what the authors have chosen to call "angiographic vasospasm." However, the incidence and severity of vasospasm in recent series of patients is not well defined. There is reasonable evidence that vasospasm causes infarction, but again, accurate data on how severe and how diffuse vasospasm has to be to cause infarction and how often vasospasm is the primary cause of infarction are not available. There are good data on the incidence of cerebral infarction after SAH, and these data indicate that it is highly associated with poor outcome. The link between angiographic vasospasm and poor outcome is particularly poorly described in terms of what would be considered data of a high level of evidence. The question as to whether there is a clear pathway from SAH to vasospasm to cerebral infarction to poor outcome seems so obvious to neurosurgeons as to make it one not worth asking. Nevertheless, the obvious is not always true or accurate, so it is important to note that published literature only weakly supports the causative association of vasospasm with infarction and poor outcome after SAH. It behooves neurosurgeons to document this seemingly straightforward pathway with high-quality evidence acceptable to the proponents of evidence-based medicine.
Assuntos
Angiografia Cerebral/métodos , Infarto Cerebral/patologia , Vasoespasmo Intracraniano/patologia , Infarto Cerebral/etiologia , Humanos , MEDLINE/estatística & dados numéricos , Neurocirurgia/métodos , Literatura de Revisão como Assunto , Hemorragia Subaracnóidea/complicações , Resultado do Tratamento , Vasoespasmo Intracraniano/etiologia , Vasoespasmo Intracraniano/radioterapia , Vasoespasmo Intracraniano/cirurgiaRESUMO
Cerebral vasospasm and delayed cerebral ischemia remain common complications of aneurysmal subarachnoid hemorrhage (SAH), and yet therapies for cerebral vasospasm are limited. Despite a large number of clinical trials, only calcium antagonists have strong evidence supporting their effectiveness. The purpose of this work was to perform a systematic review of the literature on the treatment of cerebral vasospasm. A literature search for randomized controlled trials of therapies used for prevention or treatment of cerebral vasospasm and/or delayed cerebral ischemia was conducted, and 41 articles meeting the review criteria were found. Study characteristics and primary results of these articles are reviewed. Key indicators of quality were poor when averaged across all studies, but have improved greatly over time. The only proven therapy for vasospasm is nimodipine. Tirilazad is not effective, and studies of hemodynamic maneuvers, magnesium, statin medications, endothelin antagonists, steroid drugs, anticoagulant/antiplatelet agents, and intrathecal fibrinolytic drugs have yielded inconclusive results. The following conclusions were made: nimodipine is indicated after SAH and tirilazad is not effective. More study of hemodynamic maneuvers, the effectiveness of other calcium channel antagonists such as nicardipine delivered by other routes (for example intrathecally), magnesium, statin drugs, endothelin antagonists, and intrathecal fibrinolytic therapy is warranted. There is less enthusiasm for the study of steroid drugs and anticoagulant/antiplatelet agents because they entail more risks and investigations so far have shown little evidence of efficacy. The study of rescue therapy such as balloon angioplasty and intraarterial vasodilating agents will be difficult. The quality of clinical trials should be improved.
Assuntos
Medicina Baseada em Evidências , Hemorragia Subaracnóidea/terapia , Vasoespasmo Intracraniano/terapia , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , MEDLINE/estatística & dados numéricos , Magnésio/uso terapêutico , Peptídeos Cíclicos/uso terapêutico , Ensaios Clínicos Controlados Aleatórios como Assunto , Literatura de Revisão como AssuntoRESUMO
Meningiomas are usually low-grade, solitary lesions that rarely metastasize. In this group of central nervous system tumours, the higher grade subtypes are notorious for resistance to conventional chemo-radiation therapies. Recent studies have shown efficacy in the use of bevacizumab in patients with recurrent and, or progressive anaplastic meningioma. The authors report a case of a young patient with recurrent anaplastic meningioma who despite being treated with bevacizumab, progressed with disease dissemination to multiple extracranial sites. Although the majority of meningiomas are amendable to treatment, the higher grade subtypes remain therapeutically challenging. The unexpected resistance to anti-angiogenic therapy in this patient adds another layer of complexity to an elusive subset of a supposedly benign disease. This patient report reflects the need for in-depth studies, molecular characterization and overall, better disease understanding in order to improve prognosis for affected patients.