Evidence for flow from hydrodynamic simulations of p-Pb collisions at 5.02 TeV from v2 mass splitting.

We show that a fluid dynamical scenario, already well tested against identified particle p(t) spectra, describes quantitatively the observed mass splitting of the elliptical flow coefficients v(2) for pions and protons. This provides a strong argument in favor of the existence of a fluid dynamical expansion in p-Pb collisions at 5.02 TeV.

Lifetime measurements of the neutron-rich N = 30 isotones 50Ca and 51Sc: orbital dependence of effective charges in the fp shell.

The lifetimes of the first excited states of the N = 30 isotones (50)Ca and (51)Sc have been determined using the Recoil Distance Doppler Shift method in combination with the CLARA-PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. This extends the lifetime knowledge beyond the f_{7/2} shell closure and allows us to derive the effective proton and neutron charges in the fp shell near the doubly magic nucleus (48)Ca, using large-scale, shell-model calculations. These results indicate an orbital dependence of the core polarization along the fp shell.

Factors predictive of surgical outcome for ossification of the posterior longitudinal ligament of the cervical spine.

AIM: Ossification of the posterior longitudinal ligament (OPLL) is a pathological ossification of the ligament that causes slowly progressive myelo-radiculopathy in adults. Because of long-standing compression of the spinal cord by OPLL, functional prognosis may not always be favorable. Efforts have been made in recent surgical series to identify prognostic factors, i.e., factors that are predictive of the outcome. The results are often inconclusive or conflicting, however. METHODS: A review of the pertinent literature published between 1966 and 2007 is conducted with the use of PUBMED. Potential prognostic factors are summarized and evaluated. These factors include: gender, age, history of head/neck trauma, type of OPLL, preoperative duration of symptoms, preoperative neurological score, occupying ratio, alignment of the cervical spine, presence of intramedullary high signal intensity (HSI) on magnetic resonance imaging, and morphometry of the spinal cord. RESULTS: A total of 15 studies, all of which are retrospective case series, are identified which statistically evaluate relationship between the potential prognostic factors and outcome. CONCLUSIONS: The history of head/neck trauma, preoperative duration of symptoms, and spinal cord morphometry seems to be the prognostic factors in patients with cervical OPLL. The results are inconclusive or divided among the studies regarding whether age, preoperative neurological score, or presence of intramedullary HSI is predictive of the outcome. The gender, type of OPLL, occupying ratio, and cervical spine alignment seem to be the factors that are unlikely to be predictive of the outcome.

Vascular injury and complication in neurosurgical spine surgery.

Vascular injury is an uncommon, but not rare complication of spine surgery. The consequence of vascular injury may be quite devastating, but its incidence can be reduced by understanding the mechanisms of injury. Properly managing vascular injury can reduce mortality and morbidity of patients. A review of the literature was conducted to provide an update on the etiology and management of vascular injury and complication in neurosurgical spine surgery. The vascular injuries were categorized according to each surgical procedure responsible for the injury, i.e., anterior screw fixation of the odontoid fracture, anterior cervical spine surgery, posterior C1-2 arthrodesis, posterior cervical spine surgery, anterolateral approach for thoracolumbar spine fracture, posterior thoracic spine surgery, scoliosis surgery, anterior lumbar interbody fusion (ALIF), lumbar disc arthroplasty, lumbar discectomy, and posterior lumbar spine surgery. The incidence, mechanisms of injury, and reparative measures were discussed for each surgical procedure. Detailed coverage was especially given to vascular injury associated with ALIF, which may have been underestimated. The accumulation of anatomical knowledge and advanced imaging studies has made complex spine surgery safer and more reliable. It is not clear, however, whether the incidence of vascular injury has been reduced significantly in all procedures of spine surgery. Emerging new techniques, such as microendoscopic discectomy and lumbar disc arthroplasty, seem to be promising, but we need to keep in mind their safety issues, including vascular injury and complication.

Iatrogenic vertebral artery injury.

Iatrogenic vertebral artery injury (VAI) results from various diagnostic and therapeutic procedures. The objective of this article is to provide an update on the mechanism of injury and management of this potentially devastating complication. A literature search was conducted using PubMed. The iatrogenic VAIs were categorized according to each diagnostic or therapeutic procedure responsible for the injury, i.e., central venous catheterization, cervical spine surgery, chiropractic manipulation, diagnostic cerebral angiography, percutaneous nerve block, and radiation therapy. The incidence, mechanisms of injury, and reparative procedures were discussed for each type of procedure. The type of VAI depends largely on the type of procedure. Laceration was the dominant type of acute injury in central venous catheterization and cervical spine surgery. Arteriovenous fistulae and pseudoaneurysms were the delayed complications. Arterial dissection was the dominant injury type in chiropractic manipulation and diagnostic cerebral angiography. Inadvertent arterial injection caused seizures or stroke in percutaneous nerve block. Radiation therapy was responsible for endothelial injury which in turn resulted in delayed stenosis and occlusion of the vertebral artery (VA). The proximal VA was the most vulnerable portion of the artery. Although iatrogenic VAIs are rare, they may actually be more prevalent than had previously been thought. Diagnosis of iatrogenic VAI may not always be easy because of its rarity and deep location, and a high level of suspicion is necessary for its early detection. A precise knowledge of the surgical anatomy of the VA is essential prior to each procedure to prevent its iatrogenic injury.

Laparoscopic anterior lumbar interbody fusion: a review of outcome studies.

Laparoscopic anterior lumbar interbody fusion (LALIF) was first reported in 1995. It was expected to reduce the morbidity of an open ALIF, while maintaining its advantages. About a decade after its debut, the feasibility and short-term efficacy of the LALIF has been recognized. Currently, other minimally-invasive surgical options have been made available for the treatment of lumbar degenerative disc disease, and thus the role of LALIF has not been established in view of these other methods. The authors aim to clarify this, by conducting a review of the literature particularly on the outcome studies of LALIF. Several comparative studies showed that at the L5-S1 disc level, there was no marked difference between LALIF and the open or mini-open ALIF in terms of short-term efficacy, i. e., operative time, blood loss, and length of hospital stay. With regard to the complication rate, however, there was a higher incidence of retrograde ejaculation in LALIF. At the L4-L5 and L4-L5/L5-S1 disc levels, the complication rate and conversion rate to open surgery was high in LALIF, and many authors were not impressed with the LALIF at these levels. Several case series showed that the LALIF yielded excellent perioperative outcomes in the hands of experienced endoscopic spine surgeons at both the L5-S1 and L4-L5 disc levels. No conclusion regarding either the superiority or inferiority of LALIF to the open or mini-open ALIF can be drawn, because of the lack of data with a high-level of evidence. It cannot be denied, however, that some spine surgeons are abandoning this procedure and switching to the mini-open ALIF. Treatment of lumbar degenerative disc disease itself has been changing rapidly, as represented by the recent emergence of the lumbar artificial disc, and the future role of LALIF remains to be followed closely.

Molecular biology of degenerative disc disease.

The intervertebral disc is a complex anatomic and biochemical structure. It is composed primarily of fibrocytes and chondrocytes that are anatomically segregated in an elaborate avascular macromolecular matrix of collagen and proteoglycans. Degenerative processes associated with aging and trauma result in morphological and molecular changes to the disc. Morphological changes are observed as dehydration, fissuring, and tearing of the nucleus, annulus and endplates. On the molecular level, degenerative changes include decreased diffusion, decreased cell viability, decreased proteoglycan synthesis, and alteration in collagen distribution. The role of inflammatory mediators in these processes, and the potential use of growth factors to delay or reverse the degenerative cascade, is poorly understood. However, these areas are under active investigation, the results of which may soon contribute significantly to our understanding of degenerative disc disease.

Lumbar radiculopathy secondary to gouty tophi in the filum terminale in a patient without systemic gout: case report.

OBJECTIVE AND IMPORTANCE: Gouty arthritis and gouty tophi of the spine are very rare. We present a patient with the clinical manifestations of an intradural tumor and histologically proven gouty deposits in the filum terminale. CLINICAL PRESENTATION: The patient presented with typical symptoms of lumbar radiculopathy and neurogenic claudication. There was no evidence of peripheral gout. INTERVENTION: Imaging studies, including computed tomography and magnetic resonance imaging, demonstrated a 1-cm, round, intradural, calcified lesion at the L3 vertebral level, causing moderate spinal stenosis. The patient underwent a two-level laminectomy and removal of the mass. A pathological examination of the specimen revealed gouty deposits in the region of the filum terminale. CONCLUSION: Spinal involvement in gout is very rare, and intradural gouty deposits have not been previously described. Intradural gout should be considered in the differential diagnosis of intradural masses.

Complex atlantoaxial fractures.

OBJECT: The authors conducted a retrospective study to evaluate the treatment of complex C1-2 fractures. METHODS: There were 10 cases of complex C1-2 fractures. Six patients were men (median age 58 years) and four patients were women (median age 55.5 years). Injuries resulted from seven falls, two motor vehicle accidents, and one diving incident. Three patients suffered from upper-extremity weakness. Neurological function in seven patients was intact preoperatively. Fracture combinations included six Jefferson/Type II odontoid, two anterior ring/Type II odontoid, one posterior ring/Type II odontoid, and one posterior ring/Type III odontoid/Type III hangman's fracture. All patients underwent surgery, five after halo immobilization for an average of 4 months failed to provide stability. Treatment included placement of six odontoid screws, one posterior C1-2 transarticular screw, one odontoid screw with anterior C1-2 transarticular screw fixation, one C1-2 transarticular screw with C1-2 Songer cable fusion, and one odontoid screw with bilateral C-2 pedicle screw fixation. Specific treatment was determined by the combination of fractures. Postoperatively, all patients were immobilized in a hard collar for 3 months. There were no intraoperative surgery-related complications. The mean follow-up period was 28.5 months. Neurological recovery was observed in one of three patients who presented with neurological deficits. Fusion occurred in all cases. CONCLUSIONS: The goals in treating these complex fractures are to achieve early maximum stability and minimum reduction in range of motion. These are often competing phenomena. Frequently in cases of atlas-axis fracture, odontoid screw fixation combined with hard collar immobilization is the best therapy, provided the transverse atlantal ligament is competent. If not, C1-2 stabilization with placement of transarticular screws is required for best results.