ABSTRACT
Cerebral arteriovenous malformations (AVMs) are a leading cause of intracerebral hemorrhage in both children and young adults. With the continued advancement of science and technology, the understanding of the pathophysiology behind the development of these lesions has evolved. From early theory published by Harvey Cushing and Percival Bailey in 1928, Tumors Arising from the Blood-vessels of the Brain: Angiomatous Malformations and Hemangioblastoma, which regarded AVMs as tumors arising from blood vessels, to the meticulous artistry of Dorcas Padget's embryological cataloguing of the cerebral vasculature in 1948, to the proliferative capillaropathy theory of Yasargil in 1987, to Ramey's 2014 hierarchical model of vascular development, there have been multiple hypotheses of congenital, developmental, and genetic two-hit theories in the pathogenesis of AVMs. Most recent evidence implicates somatic KRAS mutations in the cerebral endothelium, producing an important understanding of the pathogenesis of this disease, which is critical to the development of targeted therapeutics. The authors present the historical progression of their understanding of AVM pathogenesis. They focus on the foundation laid by early pioneers, discussing embryological anatomy and vasculogenesis, the prominent theories of AVM development that have emerged over time, and culminate in an overview of the most current understanding of the pathogenesis of these complex vascular lesions and the clinical implications of our scientific progress.
ABSTRACT
STUDY DESIGN: Retrospective analysis of clinical data from a single institution. OBJECTIVE: To assess the day of surgery during the week as a possible predictor of length of stay (LOS) following anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA: Surgeries later in the week may result in longer LOS and higher costs for joint arthroplasty, yet this is unclear following spine surgery. Procedures performed later in the week may lead to weekend admissions when there are limited services that may contribute to an extended LOS. We attempt to identify associations between day of surgery and LOS, readmission, and complications following single- and multilevel ACDF. MATERIALS AND METHODS: Patients at a single institution undergoing ACDF by 7 primary surgeons in both orthopedic and neurosurgery spine departments between 2015 and 2019 were retrospectively reviewed. Patients were stratified by surgery day at either the beginning (Monday/Tuesday) or end (Thursday/Friday) of the week and by single- or multilevel ACDF. Surgery for trauma, infections, adjacent level disease, or revision were excluded. Patient demographics, Charlson Comorbidity Index (CCI), LOS, postoperative complications, and readmission rates were assessed. RESULTS: Six hundred fifty-two patients underwent ACDF. For single-level ACDF, 222 were reviewed, with 112 having surgery at the beginning and 110 at the end of the week. For multilevel ACDF, 431 were reviewed, with 192 having surgery at the beginning and 239 at the end of the week. No differences in pre- or postoperative variables were determined for single-level ACDF. Despite no differences in pre-operative variables, CCI, operative duration, or number of levels, late-week multilevel ACDF had longer average LOS (2.8±3.0 days) compared to early-week surgery (2.0±2.0 days) (P=0.018). CONCLUSIONS: Late-week multilevel ACDF was associated with an increased LOS, as it may prove beneficial to surgical planning. This conflicts with previous reports that day of week was not associated with LOS following ACDF. LEVEL OF EVIDENCE: III.
ABSTRACT
Rationale: Severe TBI (sTBI) is a devastating neurological injury that comprises a significant global trauma burden. Early comprehensive neurocritical care and rehabilitation improve outcomes for such patients, although better diagnostic and prognostic tools are necessary to guide personalized treatment plans. Methods: In this study, we explored the feasibility of conducting resting state magnetoencephalography (MEG) in a case series of sTBI patients acutely after injury (~7 days), and then about 1.5 and 8 months after injury. Synthetic aperture magnetometry (SAM) was utilized to localize source power in the canonical frequency bands of delta, theta, alpha, beta, and gamma, as well as DC-80 Hz. Results: At the first scan, SAM source maps revealed zones of hypofunction, islands of preserved activity, and hemispheric asymmetry across bandwidths, with markedly reduced power on the side of injury for each patient. GCS scores improved at scan 2 and by scan 3 the patients were ambulatory. The SAM maps for scans 2 and 3 varied, with most patients showing increasing power over time, especially in gamma, but a continued reduction in power in damaged areas and hemispheric asymmetry and/or relative diminishment in power at the site of injury. At the group level for scan 1, there was a large excess of neural generators operating within the delta band relative to control participants, while the number of neural generators for beta and gamma were significantly reduced. At scan 2 there was increased beta power relative to controls. At scan 3 there was increased group-wise delta power in comparison to controls. Conclusion: In summary, this pilot study shows that MEG can be safely used to monitor and track the recovery of brain function in patients with severe TBI as well as to identify patient-specific regions of decreased or altered brain function. Such MEG maps of brain function may be used in the future to tailor patient-specific rehabilitation plans to target regions of altered spectral power with neurostimulation and other treatments.
