Picoflare jets power the solar wind emerging from a coronal hole on the Sun

Coronal holes are areas on the Sun with open magnetic field lines. They are a source region of the solar wind, but how the wind emerges from coronal holes is not known. We observed a coronal hole using the Extreme Ultraviolet Imager on the Solar Orbiter spacecraft. We identified jets on scales of a few hundred kilometers, which last 20 to 100 seconds and reach speeds of ~100 kilometers per second. The jets are powered by magnetic reconnection and have kinetic energy in the picoflare range. They are intermittent but widespread within the observed coronal hole. We suggest that such picoflare jets could produce enough high-temperature plasma to sustain the solar wind and that the wind emerges from coronal holes as a highly intermittent outflow at small scales.

Geospatial analysis of time to HIV diagnosis and adult HIV testing coverage highlights areas for intervention in the U.S. Southeast

Background

In the U.S., 44% of people with HIV (PWH) live in the Southeastern census region; many PWH remain undiagnosed. Novel strategies to inform testing outreach in rural states with dispersed HIV-epidemics are needed.

Methods

Alabama state public health HIV testing surveillance data from 2013-2017 were used to estimate time from infection to HIV diagnosis using CD4 T-cell depletion modeling, mapped to county. Diagnostic HIV tests performed 2013-2021 by commercial testing entities were used to estimate HIV tests per 100,000 adults (15-65-year-old), mapped to client ZIP code tabulation area (ZCTA). We then defined testing “cold spots”: those with <10% adults tested plus either (a) within or bordering one of the 13 counties with HIV prevalence greater than 400 cases per 100,000 population or (b) within a county with average time to diagnosis greater than the state average to inform testing outreach.

Results

Time to HIV diagnosis is a median of 3.7 (IQR 0-9.2) years across Alabama, with a range from 0.06-12.25 years. Approximately 63% of counties (N=42) have a longer time-to-diagnosis compared to national U.S. estimates. 643 ZCTAs tested 17.3% (IQR: 10.3%,25.0%) of the adult population from 2013-2017. To prioritize areas for testing outreach, we generated maps to describe 47 areas of HIV-testing cold spots at the ZCTA level.

Conclusions

Combining public health surveillance with commercial testing data provides a more nuanced understanding of HIV testing gaps in a state with a rural HIV epidemic and identifies areas to prioritize for testing outreach.

Understanding the Role of Mass-Unloading in a Filament Eruption

We describe a partial filament eruption on 11 December 2011 that demonstrates that the inclusion of mass is an important next step for understanding solar eruptions. Observations from the Solar Terrestrial Relations Observatory-Behind (STEREO-B) and the Solar Dynamics Observatory (SDO) spacecraft were used to remove line-of-sight projection effects in filament motion and correlate the effect of plasma dynamics with the evolution of the filament height. Flux cancellation and nearby flux emergence are shown to have played a role in increasing the height of the filament prior to eruption. The two viewpoints allow the quantitative estimation of a large mass-unloading, the subsequent radial expansion, and the eruption of the filament to be investigated. A 1.8 to 4.1 lower-limit ratio between gravitational and magnetic-tension forces was found. We therefore conclude that following the loss-of-equilibrium of the flux-rope, the radial expansion of the flux-rope was restrained by the filamentary material until 70% of the mass had evacuated the structure through mass-unloading.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (10.1007/s11207-017-1224-y) contains supplementary material, which is available to authorised users.

Observations and Modelling of the Pre-flare Period of the 29 March 2014 X1 Flare

On 29 March 2014, NOAA Active Region (AR) 12017 produced an X1 flare that was simultaneously observed by an unprecedented number of observatories. We have investigated the pre-flare period of this flare from 14:00 UT until 19:00 UT using joint observations made by the Interface Region Imaging Spectrometer (IRIS) and the Hinode Extreme Ultraviolet Imaging Spectrometer (EIS). Spectral lines providing coverage of the solar atmosphere from the chromosphere to the corona were analysed to investigate pre-flare activity within the AR. The results of the investigation have revealed evidence of strongly blue-shifted plasma flows, with velocities up to 200 km s - 1 , being observed 40 minutes prior to flaring. These flows are located along the filament present in the active region and are both spatially discrete and transient. In order to constrain the possible explanations for this activity, we undertake non-potential magnetic field modelling of the active region. This modelling indicates the existence of a weakly twisted flux rope along the polarity inversion line in the region where a filament and the strong pre-flare flows are observed. We then discuss how these observations relate to the current models of flare triggering. We conclude that the most likely drivers of the observed activity are internal reconnection in the flux rope, early onset of the flare reconnection, or tether-cutting reconnection along the filament.

Understanding the Physical Nature of Coronal "EIT Waves"

For almost 20 years the physical nature of globally propagating waves in the solar corona (commonly called "EIT waves") has been controversial and subject to debate. Additional theories have been proposed over the years to explain observations that did not agree with the originally proposed fast-mode wave interpretation. However, the incompatibility of observations made using the Extreme-ultraviolet Imaging Telescope (EIT) onboard the Solar and Heliospheric Observatory with the fast-mode wave interpretation was challenged by differing viewpoints from the twin Solar Terrestrial Relations Observatory spacecraft and data with higher spatial and temporal resolution from the Solar Dynamics Observatory. In this article, we reexamine the theories proposed to explain EIT waves to identify measurable properties and behaviours that can be compared to current and future observations. Most of us conclude that the so-called EIT waves are best described as fast-mode large-amplitude waves or shocks that are initially driven by the impulsive expansion of an erupting coronal mass ejection in the low corona.

Treatment of 213 Patients with Symptomatic Tarlov Cysts by CT-Guided Percutaneous Injection of Fibrin Sealant

BACKGROUND AND PURPOSE

There has been a steady progression of case reports and a small surgical series that report successful surgical treatment of Tarlov cysts with concomitant relief of patients' symptoms and improvement in their neurological dysfunction, yet patients are still told that these lesions are asymptomatic by physicians. The purpose of this study was to analyze the efficacy and safety of intervention in 213 consecutive patients with symptomatic Tarlov cysts treated by CT-guided 2-needle cyst aspiration and fibrin sealing.

MATERIALS AND METHODS

This study was designed to assess outcomes in patients who underwent CT-guided aspiration and injection of ≥1 sacral Tarlov cyst at Johns Hopkins Hospital between 2003 and 2013. In all, 289 cysts were treated in 213 consecutive patients. All these patients were followed for at least 6 months, 90% were followed for 1 year, and 83% were followed for 3-6 years. The aspiration-injection procedure used 2 needles and was performed with the patients under local anesthesia and intravenous anesthesia. In the fibrin-injection stage of the procedure, a commercially available fibrin sealant was injected into the cyst through the deep needle (Tisseel VH).

RESULTS

One year postprocedure, excellent results were obtained in 104 patients (54.2% of patients followed), and good or satisfactory results were obtained in 53 patients (27.6%). Thus, 157 patients (81.8%) in all were initially satisfied with the outcome of treatment. At 3-6 years postprocedure, 74.0% of patients followed were satisfied with treatment. There were no clinically significant complications.

CONCLUSIONS

The aspiration-injection technique described herein constitutes a safe and efficacious treatment option that holds promise for relieving cyst-related symptoms in many patients with very little risk.

Perfusionist techniques of reducing acute kidney injury following cardiopulmonary bypass: an evidence-based review

Cardiac surgery utilizing cardiopulmonary bypass has come a long way since its introduction nearly 60 years ago. In the early days, end-organ damage was linked to contact of the blood with the extracorporeal circuit. One potential cardiac surgery complication known to result in significant morbidity and mortality is acute kidney injury (AKI). Causes of AKI are multifaceted, but most of them are associated with techniques that perfusionists employ during extracorporeal circuit management. These can cause patients to either go on dialysis or renal replacement therapy. Patients with AKI have longer lengths of stay and consume significant resources beyond those with normal kidney function. Few current evidence-based markers determine if the kidneys are adequately protected during surgery. Most relevant literature does not address perfusion-specific techniques that reduce the incidence of AKI. This paper reviews the pathophysiology of the kidney and focuses on perfusion techniques that may reduce the incidence of AKI.

Association of heterotopic neuroglial tissue with an arachnoid cyst in the internal auditory canal

An arachnoid cyst arising within the internal auditory canal, or within the cerebellopontine angle and subsequently extending into the internal meatus and enlarging it, is a rare occurrence. Nevertheless, the neurootologist and the neurosurgeon have an interest in its existence because its clinical manifestations are identical with the ones produced by a schwannoma, involving overwhelmingly the cochleovestibular nerve in that region. An equally rare observation in that location is the presence of ectopic neuroglial tissue. The two can occur independently or in combination. Examples of such lesions are presented, and their possible pathogenesis is discussed.

Clivus chordoma: a report of 12 recent cases and review of the literature

Twelve patients with histologically confirmed clivus chordoma were treated at the Johns Hopkins Hospital between 1971 and 1989. Eight of the patients were men and four were women. The mean age at first operation was 51 years (range, 10 to 80). The most common presenting symptoms were headache, diplopia, dysphagia and dysarthria, and facial sensory changes. Computed tomography, with and without contrast enhancement, proved adequate for tumor identification and localization. Magnetic resonance imaging and angiography were occasionally employed to localize the tumors further and to define tumor vascular supply and proximity to vascular structures. Twenty-two resections were performed in 11 patients, and another patient underwent biopsy only. Seven were also treated with radiation therapy. Tumors recurred in eight patients, six of whom underwent further operations. The mean time to first recurrence was 22 months (range 8 to 36 months). Six of the patients are still alive, with a mean follow-up of 31 months (range, 3 to 89 months) from first surgical resection. The mean survival time from first treatment was 31 months (range, 4 to 62 months) among those patients who died. There was no operative mortality. The 5-year cumulative survival rate was 20%. Six patients with long follow-up have had fair to good results, being free of recurrences for at least a year. However, none of the patients returned to their premorbid baseline of activities. Five of the patients had tumors with the histologic diagnosis of chondroid chordoma. Three of these patients are still alive. The mean age at first treatment was 44 (compared with 62 for typical chordomas). The mean time from symptoms to diagnosis was 29 months (typical chordomas, 18 months). The mean length of survival and time to tumor recurrence were not significantly different between chondroid and typical chordomas.

Rate of progression and severity of neuro-ophthalmologic manifestations of cavernous sinus meningiomas

The progression of neuro-ophthalmologic signs and symptoms caused by cavernous sinus meningiomas (CSMs) was evaluated in 24 patients. Ten patients had primary involvement of the cavernous sinus by meningioma, and 14 patients had extension of a sphenoid ridge meningioma into the cavernous sinus. Eighteen patients were followed after intradural meningioma debulking. Two of these patients underwent conventional radiation therapy after surgery. The other six patients were followed without treatment. Optic neuropathy caused by extension of the CSM was the most frequently (67%) seen manifestation at the beginning of the follow-up period. Proptosis (50%), ocular motor nerve palsies (46%), and trigeminal neuropathy (33%) were also common. During a mean follow-up period of 57 months, 14 patients (58%) had no change in neurologic status, four patients (17%) had improvement in one or more parameters and six patients (25%) worsened. The patients who worsened had progression of preexisting cranial nerve palsies (two patients), developed new cranial neuropathies (three patients), or both (one patient). Patients who worsened had a significantly longer mean follow-up (76 months) than patients who remained stable or improved (47 months) (p = 0.01). Although the signs and symptoms of CSMs may worsen with time, the rate is slow and the degree is mild. These factors are important when considering treatment options.

Pleomorphic Xanthoastrocytoma: Report of a Case with Light and Electron Microscopy

A case of pleomorphic xanthoastrocytoma is reported with light and electron microscopic findings. This unusual tumor arose in a 15-year-old male. The tumor consisted predominantly of nests of xanthomatous cells and plump spindle cells surrounded by a prominent reticulin network. There was considerable cellular pleomorphism with abundant bizarre giant cells and multinucleated cells. Occasional mitoses were present. Electron microscopy and immunoperoxidase localization of glial fibrillary acidic protein (GFAP) confirmed the glial nature of the tumor. Recognition of this tumor is important. Despite its "m alignant" appearance, the tumor characteristically has a relatively good prognosis and should not be confused with high-grade gliomas or meningeal sarcomas, which require aggressive therapy.

Neurologic deficits after cervical laminectomy in the prone position

New neurologic deficits are known to occur after spine surgery. We present four patients with cervical myeloradiculopathy who underwent cervical laminectomy, fusion, or both in the prone position, supported by chest rolls. Three patients were intubated and positioned while awake, whereas the fourth patient was positioned after induction. Surgeries were successfully carried out, except for transient episodes of relative hypotension intraoperatively. On recovery from anesthesia, all patients were noted to have new neurologic deficits. Immediate CT myelography or surgical reexploration was unremarkable. All patients improved gradually with administration of high-dose steroids and induction of hypertension. Use of the prone position with abdominal compression may compromise spinal cord perfusion and lead to spinal cord ischemia. The use of frames that prevent abdominal compression, as well as avoidance of perioperative arterial hypotension, is important in maintaining adequate spinal cord perfusion during and after decompressive spinal cord surgery.

Sine qua non: the formulation of a theory of neurosurgery

Fundamental postulates underlying the fabric of biomedicine are rarely discussed, much less seen in print. Scientific surgery and its subspecialties are relatively new fields, and their philosophical basis has received little attention since Halsted's day. During the last quarter century, we have "reinvented" neurosurgery, and a concatenation of forces is escalating that is further accelerated by technological change. Social, economic, political, and scientific climates concurrently exert unusually stressful influences on all practitioners, irrespective of the individual setting. This provides a reason to reexamine what neurosurgeons do and why, and to attempt to define the guidelines of theoretical basis for the specialty of neurosurgery and its procedures. This article examines the accomplishments of past generations in an effort to establish surgical substrata and proceeds to attempt to readdress elements of a theoretical basis of our current practice.

Two telomerase reverse transcriptases (TERTs) expressed in Candida albicans

The human pathogenic yeast Candida albicans contains two telomerase reverse transcriptase (TERT) genes. CaTERT1 and CaTERT2 appear either to be two alleles of the same gene or two entirely different genes that encode 867-residue proteins that differ by five amino acids. Both TERTs have a calculated pI of 9.5 and a M(r) of 100.9 kDa and are the smallest TERTs identified to date. Both genes appear to be expressed. Based on sequence similarity between CaTERT1 and the Saccharomyces cerevisiae orthologue Est2p, we suggest a revised alignment for motif E of Est2p. The identification of these TERT genes provides the first opportunity to study telomerase in an important human pathogen.

The treatment of meningiomas in the region of the cavernous sinus

The diagnosis and treatment of meningiomas of the cavernous sinus remains a controversial part of skull base surgery practice. The most common presenting symptom headache is nonspecific. Visual loss and oculomotor disturbance are the next likely symptoms and signs. It is possible to achieve total tumor removal in about 50% of patients, but an increase in cranial nerve dysfunction occurs in nearly as many. Improvement of neurological function, except for vision, is unusual. Because of the risk of complicating cranial nerve dysfunction by surgery, focused radiation as an alternative treatment has been explored in a small number of patients. Unfortunately, volume reduction is only seen in about one-third, but risks do appear to be low and nearly 60% of patients recorded have improvement in preoperative cranial nerve deficits. With these indolent tumors, much longer follow-ups are required before the role of focused radiation can be assessed.

Hemangioblastomas of the central nervous system in von Hippel-Lindau syndrome and sporadic disease

OBJECTIVE

The presentation, screening, management, and clinical outcomes of patients who presented to our institution from 1973 to 1999 with central nervous system (CNS) hemangioblastomas in von Hippel-Lindau (VHL) syndrome and sporadic disease were analyzed.

METHODS

The surgical pathology database of our institution was searched to identify all patients with histologically verified CNS hemangioblastomas occurring from 1973 to 1999. The medical, radiological, surgical, pathological, and autopsy records from these patients were reviewed retrospectively and statistically analyzed.

RESULTS

Forty patients (21 males and 19 females) presented with CNS hemangioblastomas. Twenty-five patients (62%) harbored sporadic hemangioblastomas. Fifteen patients (38%) had VHL syndrome. These 40 patients presented with 61 hemangioblastomas (8 patients had multiple lesions). Ten patients (25%) harbored spinal cord hemangioblastomas (5 patients had multiple lesions). Patients with VHL disease tended to present with neurological symptoms and signs at a younger age than patients with sporadic disease (P = 0.09), to present with multiple lesions (53%), and to develop new lesions (rate, 1 lesion/2.1 yr). Hemangioblastomas of the spinal cord were more prevalent in patients with VHL syndrome (P = 0.024). Neuroradiological screening of patients with VHL syndrome allowed identification of more than 75% of new lesions before they became symptomatic. Sixty-six surgical procedures were performed (12 patients required multiple operations). Six patients with VHL syndrome required surgery for new lesions. Surgical complications occurred in six patients (15%). Symptom resolution or arrest of progression at 1 year was documented in 88% of patients. Recurrence of symptoms from partially resected lesions occurred in eight patients (20%). No deaths associated with surgery occurred. One patient with sporadic disease and one patient with VHL syndrome (5%) died as a result of late medical complications from CNS hemangioblastomas.

CONCLUSION

Surgical outcomes for patients with CNS hemangioblastomas are favorable. However, management of hemangioblastomas is a more difficult and prolonged endeavor for patients with VHL syndrome. In patients with VHL syndrome, neuroradiological screening allows identification of lesions before they become symptomatic. Because patients with VHL syndrome are at risk for development of new lesions, they require lifelong follow-up.

Renoprotective effects of a novel inhibitor of advanced glycation

AIMS/HYPOTHESIS

ALT-946, an inhibitor of advanced glycation with a minimal inhibitory effect on nitric oxide synthase, was compared with aminoguanidine in experimental diabetic nephropathy.

METHODS

In vitro and in vivo assays were used to assess the ability of ALT-946 to inhibit AGE-protein cross-link formation. Diabetic animals were randomly allocated into groups receiving aminoguanidine for 32 weeks, ALT-946 or vehicle (untreated). As a delayed intervention protocol, an additional diabetic group was treated with ALT-946 from week 16 to week 32 of the study. Non-diabetic rats were studied concurrently. Systolic blood pressure, body weight, plasma glucose, glycated haemoglobin and urinary albumin excretion were measured serially. Accumulation of advanced-glycation end products in the kidney was assessed by immunohistochemistry.

RESULTS

The ALT-946 inhibitor was more potent than aminoguanidine in inhibiting AGE-protein cross-linking both in vitro and in vivo. Increased albuminuria observed in diabetic rats was attenuated in all three treatment groups. We found no difference in body weight, blood pressure or glycaemic control with any of the treatments. The untreated diabetic group had a twofold increase in glomerular staining for advanced-glycation end products compared with the diabetic groups which received treatment.

CONCLUSION/INTERPRETATION

ALT-946 is a potent inhibitor of advanced renal glycation end-product accumulation and reproduces the renoprotective effects of aminoguanidine. Therefore, ALT-946 should be considered as a treatment for preventing or retarding diabetic nephropathy.

Competency-based residency training: the next advance in graduate medical education

The goal of all graduate medical education is to ensure that the graduating physician is competent to practice in his or her chosen field of medicine. The evaluation of a resident's competency to practice, however, has never been clearly defined, nor has the fixed period of time given for residency training in each specialty been shown to be the right amount of time for each individual resident to achieve competency. To better ensure that new physicians have the competencies they need, the author proposes the replacement of the current approach to residents' education, which specifies a fixed number of years in training, with competency-based training, in which each resident remains in training until he or she has been shown to have the required knowledge and skills and can apply them independently. Such programs, in addition to tailoring the training time to each individual, would make it possible to devise and test schemes to evaluate competency more surely than is now possible. The author reviews the basis of traditional residency training and the problems with the current training approach, both its fixed amount of time for training and the uncertainty of the methods of evaluation used. He then explains competency-based residency education, notes that it is possible, indeed probable, that some trainees will become competent considerably sooner than they would in the current required years of training, quotes a study in which this was the case, and explains the implications. He describes the encouraging experience of his neurosurgery department, which has used competency-based training for its residents since 1994. He then discusses issues of demonstrating competency in procedural and nonprocedural fields, as well as the evaluation of competency in traditional and competency-based training, emphasizing that the latter approach offers hope for better ways of assessing competency.

The Atlanta Urban Networks Study: a blueprint for endemic transmission

OBJECTIVE

To study prospectively social networks and behavior in a group of persons at risk for HIV because of their drug-using and sexual practices, with particular emphasis on the interaction of risks and concomitant network structure.

METHODS

A longitudinal study was conducted of 228 respondents in Atlanta, Georgia in six inner-city community chains of connected persons, interviewing primary respondents and a sample of their contacts every 6 months for 2 years. Ascertained were: HIV and immunologic status; demographic, medical, and behavioral factors; and the composition of the social, sexual, and drug-using networks.

RESULTS

The prevalence of HIV in this group was 13.3% and the incidence density was 1.8% per year. Substantial simultaneity of risk-taking was observed, with a high level of both non-injecting (crack, 82%) and injecting (heroin, cocaine or both, 16 30%) drug use, the exchange of sex or money for drugs by men (approximately 35%) and women (57-71%), and high frequency of same-sex sexual activity by men (9.4%) and women (33%). The intensity of interaction, as measured by network features such as microstructures and concurrency, was significantly greater than that observed in a low prevalence area with little endemic transmission.

CONCLUSION

The traditional hierarchical classification of risk for HIV may impede our understanding of transmission dynamics, which, in the setting of an inner-city population, is characterized by simultaneity of risk-taking, and moderately intense network interactions. The study provides further evidence for the relationship of network structure to transmission dynamics, but highlights the difficulties of using network information for prediction of individual seroconversion.

Long-term visual outcome after nonradical microsurgery patients with parasellar and cavernous sinus meningiomas

OBJECTIVE

To determine the long-term visual outcome in patients with parasellar and cavernous sinus meningiomas treated with nonradical surgery.

METHODS

Retrospective clinical review of 29 patients with parasellar or cavernous sinus meningiomas and visual sensory or ocular motor dysfunction at presentation, all of whom had at least 10 years of follow-up after initial diagnosis and treatment with nonradical surgery.

RESULTS

Nineteen of 29 patients had a unilateral or bilateral optic neuropathy at presentation, and 7 patients developed a unilateral or bilateral optic neuropathy during a mean follow-up period of 13.6 years. However, 27 (93%) of 29 patients retained vision of 20/40 or better in at least one eye, and 14 patients (48%) retained vision of 20/40 or better in both eyes. New ocular motility deficits developed in 3 (10%) of 29 patients during the follow-up period.

CONCLUSION

Radical surgery is not required to achieve long-term useful visual function for patients with parasellar or cavernous sinus meningiomas.

Intracanalicular schwannoma of the facial nerve: a manifestation of neurofibromatosis type 2

Primary facial nerve tumors, which are relatively uncommon, can present a diagnostic dilemma based on their location and variable pattern of symptoms. Of primary cranial nerve tumors, schwannomas of the facial nerve rank third in frequency after those of the eighth and fifth cranial nerves. We report an illustrative case of an intracanalicular schwannoma associated with several central nervous system tumors, consistent with neurofibromatosis type 2. Initially assumed to be an eighth cranial nerve tumor, the schwannoma was found intraoperatively to arise from the facial nerve. Early diagnosis and treatment enabled excision of the tumor without sacrifice of the facial nerve. Facial nerve schwannomas can resemble acoustic schwannomas in their clinical presentation. Only a heightened level of clinical vigilance will point to the correct diagnosis and result in an optimal therapeutic outcome for patients with these rare tumors.

Neodymium:YAG laser posterior capsulotomies performed by residents at a Veterans Administration Hospital

PURPOSE

To assess the initial efficacy of neodymium:YAG (Nd:YAG) laser posterior capsulotomies performed by residents at a teaching institution and to evaluate the associated complications over an extended follow-up.

SETTING

Department of Ophthalmology, Edward Hines, Jr. Veterans Administration Hospital, Hines, Illinois, USA.

METHODS

This retrospective noncomparative case review comprised 212 pseudophakic eyes having Nd:YAG laser posterior capsulotomies from April 1992 through March 1995. Evaluated were postoperative changes in best corrected visual acuity (BCVA), intraocular pressure (IOP) elevations, and complications related to the procedure.

RESULTS

In all 212 eyes, Snellen visual acuity was obtained at least 1 week after the capsulotomy. The BCVA in 96 eyes (45.3%) improved by 3 or more lines, in 43 (20.3%) by 2 lines, and in 51 (24.1%) by 1 line. Nineteen eyes (9.0%) did not improve by 1 or more lines, and 3 eyes (1.4%) had decreased Snellen acuity. All but 4 eyes with less than 1 line of improvement had underlying ocular pathology or a previous incomplete capsulotomy. For evaluation of postoperative complications, long-term follow-up was available for 133 of 212 eyes (62.7%). The mean follow-up for this group was 3.18 years. Postoperative complications were found in 14 of these eyes (10.5%). Nine (6.8%) had a rise in IOP greater than 10 mm Hg after the capsulotomy. One eye (0.8%) developed a persistent iritis, 2 (1.5%) had vitreous prolapse into the anterior chamber, and 2 (1.5%) developed rhegmatogenous retinal detachments.

CONCLUSION

Postoperative Snellen acuity results and complication rates compare favorably with those in previous studies. The results indicate that Nd:YAG laser posterior capsulotomies performed by residents with attending supervision are safe, effective, and carry a low associated complication rate over a long follow-up.

The Hunterian Neurosurgical Laboratory: the first 100 years of neurosurgical research

Modern neurosurgery has long had a strong laboratory foundation, and much of this tradition can be traced to the Hunterian Neurosurgical Laboratory of the Johns Hopkins Hospital. Founded with the basic goals of investigating the causes and symptoms of disease and establishing the crucial role that surgeons may play in the treatment of disease, the Hunterian laboratory has adhered to these tenets, despite the dramatic changes in neurosurgery that have occurred in the last 100 years. Named for the famous English surgeon John Hunter (1728-1793), the Hunterian laboratory was conceived by William Welch and William Halsted as a special laboratory for experimental work in surgery and pathology. In 1904, Harvey Cushing was appointed by Halsted to direct the laboratory. With the three primary goals of student education, veterinary surgery that stressed surgical techniques, and meticulous surgical and laboratory record-keeping, the laboratory was quite productive, introducing the use of physiological saline solutions, describing the anatomic features and function of the pituitary gland, and establishing the field of endocrinology. In addition, the original development of hanging drop tissue culture, fundamental investigations into cerebrospinal fluid, and countless contributions to otolaryngology by Samuel Crowe all occurred during this "crucible" period. In 1912, Cushing was succeeded by Walter Dandy, whose work on experimental hydrocephalus and cerebrospinal fluid circulation led to the development of pneumoencephalography. The early days of neurosurgery evolved with close ties to general surgery, and so did the Hunterian laboratory. After Dandy began devoting his time to clinical work, general surgeons (first Jay McLean and then, in 1922, Ferdinand Lee) became the directors of the laboratory. Between 1928 and 1942, more than 150 original articles were issued from the Hunterian laboratory; these articles described significant advances in surgery, including pioneering research on calcium metabolism by William MacCallum and Carl Voegtlin and seminal preclinical work by Alfred Blalock and Vivian Thomas that led to the famous "blue baby" operation in 1944. With the introduction of the operating microscope in the 1950s, much of the focus in neurosurgical science shifted from the laboratory to the operating room. The old Hunterian building was demolished in 1956. The Hunterian laboratory for surgical and pathological research was rebuilt on its original site in 1987, and the Hunterian Neurosurgical Laboratory was reestablished in 1991, with a focus on novel treatments for brain tumors. The strong tradition of performing basic research with clinical relevance has continued.

Microanatomical variations in the cerebellopontine angle associated with vestibular schwannomas (acoustic neuromas): a retrospective study of 1006 consecutive cases

OBJECT

Great advances in neuroimaging, intraoperative cranial nerve monitoring, and microsurgical technique have shifted the focus of acoustic neuroma surgery from prolonging life to preserving cranial nerve function in patients. An appreciation of the vascular and cranial nerve microanatomy and the intimate relationship between neurovascular structures and the tumor is essential to achieve optimum results. In this paper the authors analyze the microanatomical variations in location of the facial and cochlear nerves in the cerebellopontine angle (CPA) associated with acoustic neuromas and, additionally, describe the frequency of involvement of surrounding neural and vascular structures with acoustic tumors of varying size. The authors base these findings on their experience with 1006 consecutive patients who underwent surgery via a retrosigmoid or translabyrinthine approach.

METHODS

Between July 1969 and January 1998, the senior author (D.M.L.) performed surgery in 1022 patients for acoustic neuroma: 705 (69%) via the retrosigmoid (suboccipital); 301 (29%) via the translabyrinthine; and 16 (2%) via the middle fossa approach. Patients undergoing the middle fossa approach were excluded from the study. The remaining 1006 patients were subdivided into three groups based on tumor size: Group I tumors (609 patients [61%]) were smaller than 2.5 cm; Group II tumors (244 patients [24%]) were between 2.5 and 4 cm; and Group III tumors (153 patients [15%]) were larger than 4 cm. The senior author's operative notes were analyzed for each patient. Relevant cranial nerve and vascular "involvement" as well as anatomical location with respect to the tumor in the CPA were noted. "Involvement" was defined as adherence between neurovascular structure and tumor (or capsule), for which surgical dissection was required to free the structure. Seventh and eighth cranial nerve involvement was divided into anterior, posterior, and polar (around the upper or lower pole) locations. Anterior and posterior locations were further subdivided into upper, middle, or lower thirds of the tumor. The most common location of the seventh cranial nerve (facial) was the anterior middle third of the tumor for all groups, although a significant number were found on the anterior superior portion. The posterior location was exceedingly rare (< 1%). Interestingly, patients with smaller tumors (Group I) had an incidence (3.4%) of the seventh cranial nerve passing through the tumor itself, equal to that of patients with larger tumors. The most common location of the eighth cranial nerve complex was the anterior inferior portion of the tumor. Not surprisingly, larger tumors (Group III) had a higher incidence of involvement of fourth cranial nerve (41%), fifth cranial nerve (100%), ninth-11th cranial nerve complex (99%), and 12th cranial nerve (31%), as well as superior cerebellar artery (79%), anterior inferior cerebellar artery (AICA) trunk (91.5%), AICA branches (100%), posterior inferior cerebellar artery (PICA) trunk (59.5%), PICA branches (79%), and the vertebral artery (VA) (93.5%). A small number of patients in Group III also had AICA (3.3%), PICA (3.3%), or VA (1.3%) vessels within the tumor itself.

CONCLUSIONS

In this study, the authors show the great variation in anatomical location and involvement of neurovascular structures in the CPA. With this knowledge, they present certain technical lessons that may be useful in preserving nerve function during surgery and, in doing so, hope to provide neurosurgeons and neurootologists with valuable information that may help to achieve optimum outcomes in patients.

Harvey Cushing at Johns Hopkins

Harvey Cushing began surgical training with William Halsted at Johns Hopkins in 1896. Cushing joined the Johns Hopkins faculty in 1900 and spent 1 year in Europe in the laboratory of Theodore Kocher. He returned to Johns Hopkins, where he founded neurosurgery as an independent specialty, established the concept of the clinician scientist, discovered the hormonal properties of the pituitary gland and founded endocrinology, introduced intraoperative x-rays into surgical practice, introduced blood pressure monitoring into the operating room, and wrote the first definitive text on neurosurgery. Although there have been many pioneers in our field, Cushing, more than anyone else, developed neurosurgery as a specialty and left a legacy of talented neurosurgeons to develop and expand the field.

Acoustic neuroma: outcome of surgical resection and study on the anatomy of facial and cochlear nerves

The treatment of acoustic neuroma (vestibular schwannoma) has evolved greatly. In this report, we studied the history of acoustic tumour surgery, and documented the value of technical advances in benefiting patients. We also present our outcome of surgery for this benign tumour in support of its use as the treatment of choice. In 611 patients undergoing initial surgery at Johns Hopkins from 1973-1994, complete resection was obtained in all but one case (intentional), and permanent morbidity and mortality rate was 0.3%. Including temporary morbidity, the rate was 3.8%. Tumour recurrence was seen in only 0.8% of cases. The facial nerve was preserved in 97.6% and function at one-year was House-Brackmann grade 1 or 2 in 89.7%. Lastly, we present results of an anatomical study localizing the nerves and vessels, and the frequency of involvement by tumour, associated with acoustic neuromas in 1006 surgical cases. We continue to offer surgery as the best treatment option for the majority of our patients, and prefer the suboccipital route because of its unrestricted access to all posterior fossa structures, and ability to preserve hearing.

Association between peridural scar and activity-related pain after lumbar discectomy

The purpose of this study was to investigate the correlation between activity-related pain six months after first surgery for herniated lumbar disc, and the extent of lumbar epidural fibrosis present at the surgical site, assessed by magnetic resonance imaging. The 298 patients who underwent surgery for lumbar disc herniation were studied in a randomized, controlled, double-blind multicenter clinical trial to test the effectiveness of the scar-inhibiting device ADCON-L. Clinical assessments were conducted pre-operatively and at 1, 3, and 6 month intervals post-operatively, and included wound examination, magnetic resonance imaging scar assessment, and the Johns Hopkins activity-related pain questionnaire. In addition, a longer-term follow-up assessment was conducted at 12 months post-operatively. The association between the presence of epidural scar and activity-related pain was analyzed at the 6-month interval, when successful surgical excision of protruding disc material should have eliminated chronic pain. Logistic regression analysis demonstrated a significant association (p = 0.02, odds ratio = 0.7) whereby the odds of extensive scar decreased by 30% for every 31% decrease in activity-related pain score. In addition, those patients receiving ADCON-L at surgery developed significantly less scar in the months following operation (p = 0.01, 6 and 12 months post-operatively). Repeated measures analysis demonstrated that patients who received treatment with ADCON-L at the time of surgery experienced less activity-related pain through the 12-month assessment (p = 0.05). A significant association between extensive epidural scar and activity-related pain is demonstrated. Patients with less scar had less activity related pain, confirming the finding that the use of the scar inhibitor ADCON-L has a positive effect on surgical outcome.

The operating room of the future

The operating room of the future will be designed to have peri-operative integration of all imaging capabilities. Pre-operative planning will become increasingly important, as will integrated intra-operative neuro-navigation. The operative work space will be redesigned to have robotic capabilities. Operating rooms will be isolated. Self-contained modular and robotic monitoring will become remote through improved sensors. The operating microscope will disappear. Light and magnification will be supplied by means other than optical microscopes.

Late-onset facial nerve degeneration after vestibular schwannoma surgery: incidence, putative mechanisms, and prevention

Delayed facial nerve dysfunction after vestibular schwannoma surgery is a poorly understood phenomenon that has been reported to occur in 15 to 29% of patients undergoing microsurgery. It is a condition characterized by spontaneous deterioration of facial nerve function in a patient who has otherwise normal or near-normal facial function in the immediate postoperative period. This delayed paralysis is generally reported to occur in the first few days postsurgery, with the majority of patients eventually recovering their immediate postoperative facial function. However, infrequently, it can also occur more than 1 week after surgery (so-called late-onset facial nerve palsy). The authors reviewed facial nerve outcome in 611 patients who underwent microsurgery between 1973 and 1994. The facial nerve was anatomically preserved in 596 patients (97.5%), and 90% of patients had House-Brackmann[6] Grade 1 or 2 function 1 year after surgery. Late-onset facial dysfunction was seen in 13 patients (2.1%). All of these had significant deterioration in facial nerve function between 1 and 4 weeks postoperatively, and all showed improvement by 1 year. In this study, the focus on these patients who developed late-onset facial palsy. The incidence, treatment strategies, and outcomes will be discussed with emphasis on possible pathophysiological mechanisms that contribute to this relatively rare condition.

In vivo addition of telomeric repeats to foreign DNA generates extrachromosomal DNAs in the taxol-producing fungus Pestalotiopsis microspora

Transformation of the taxol-producing filamentous fungus Pestalotiopsis microspora with a plasmid containing the bacterial hygromycin resistance gene fused to Aspergillus regulatory sequences resulted in the in vivo formation of extrachromosomal DNAs with telomeric repeats in the majority of transformants. Repeats of the telomeric sequence 5'-TTAGGG-3' were appended to nontelomeric transforming DNA termini. No fungal sequences other than telomeric repeats were detected in extrachromosomal DNAs. Transformants contained three to six different sizes or conformational forms of extrachromosomal DNAs. The DNAs showed no change in size or internal structure during 6 months of growth with selection, but were lost after 20 days of growth without selection. Transformation of wild-type P. microspora with a PCR-amplified extrachromosomal DNA having terminal telomeric repeats produced up to 50-fold more transformants than the original transformation vector. The addition of telomeric repeats to foreign DNA is unusual among fungi and may have important adaptive or developmental implications.

The current status of electrical stimulation of the nervous system for the relief of chronic pain

Neuroaugmentation techniques have been in common use for nearly 30 years. Spinal stimulation is the most important treatment mode for many patients with failed back syndrome. Stimulation can replace or supplement reoperation. Stimulation has been shown to be useful in many other chronic pain states and deserves wider application. However, it is not a technique to be used casually. Effective use requires a thorough understanding of the pain states to be treated, appreciation of the comorbidities that accompany chronic pain, an infrastructure to support the patient and the surgeon, and a dedication to lifelong care for the patient with the implant. All of these mean that patients are better handled by a few dedicated individuals than by wide dispersion of the technique among neurosurgeons who see only a few such patients each year. Peripheral nerve stimulation is very effective, but the number of potential candidates is small. Brain stimulation remains investigative and has not yet found a clearly defined place in pain management. If these techniques are to continue to evolve, more basic research on the mechanisms of action will be necessary if efficacy is to be improved. Most of the research to date has been in clinical efficacy. Defining the mechanisms of action will be the next important step.

Personality traits, pain duration and severity, functional impairment, and psychological distress in patients with persistent low back pain

The relationships between psychological distress, pain duration, neuroticism, extraversion, pain severity, and functional impairment were examined in a large group of patients with persistent complaints of low back pain. We evaluated patients on a host of relevant variables before treatment and at 1 year and 2 years after treatment which permitted assessment of the stability of the relationships over time. We found that the levels of psychological distress reported by patients were not related to the duration of their complaint. Rather, levels of psychological distress are related to both aspects of the patients' personalities, and characteristics of their illness. Patients who scored high on neuroticism reported higher levels of psychological distress than patients who scored low on this trait. Similarly, patients who had more severe pain and were more functionally impaired also reported higher levels of psychological distress due to pain. The relative strengths of these relationships varied with treatment status. Before treatment, psychological distress and neuroticism were strongly related, but after treatment, the relationship was moderate. In contrast, the relationship of psychological distress to pain severity and functional impairment was significantly strengthened after treatment. We attributed this shift in the relative strengths of the relationships to change in the patient perception of their illness.

Patient characteristics associated with diagnostic imaging evaluation of persistent low back problems

STUDY DESIGN

Post hoc analysis of data from the National Low Back Pain Study, a prospective observational multicenter study of patients referred for the evaluation and treatment of persistent low back problems.

OBJECTIVE

To identify patient characteristics associated with use of particular diagnostic imaging examinations in patients with persistent low back problems.

SUMMARY OF BACKGROUND DATA

The Agency for Health Care Policy and Research clinical practice guidelines on low back problems suggest that the use of particular diagnostic imaging tests for a given patient should be based on specific characteristics of that patient.

METHODS

Use of diagnostic imaging examinations in 2,374 patients with persistent low back problems who were enrolled in the National Low Back Pain Study from 1986 to 1991 was analyzed. Stepwise logistic regression was used to identify patient characteristics that distinguish between enrollees who underwent particular imaging studies.

RESULTS

Characteristics that distinguished patients who had undergone magnetic resonance imaging from those who had received only lumbo-sacral spine radiographs included higher socioeconomic status, greater resource use in the preceding 12 months, more functional impairment, presence of sciatica, and presence of neurologic signs/symptoms suggestive of nerve root compromise. Suspected soft tissue involvement was characteristic of enrollees who had undergone magnetic resonance imaging, whereas suspected structural involvement characterized patients who received noncontrast computed tomography. Only nonclinical factors, such as higher annual household income, disability compensation, and male gender distinguished enrollees who had undergone both magnetic resonance imaging and computed tomography-myelography from those who received only computed tomography-myelography.

CONCLUSION

Particular patient socioeconomic and clinical characteristics are associated with receipt of specific imaging studies in evaluation of persistent low back problems.

Facial nerve injury in acoustic neuroma (vestibular schwannoma) surgery: etiology and prevention

Facial nerve injury associated with acoustic neuroma surgery has declined in incidence but remains a clinical concern. A retrospective analysis of 611 patients surgically treated for acoustic neuroma between 1973 and 1994 was undertaken to understand patterns of facial nerve injury more clearly and to identify factors that influence facial nerve outcome. Anatomical preservation of the facial nerve was achieved in 596 patients (97.5%). In the immediate postoperative period, 62.1% of patients displayed normal or near-normal facial nerve function (House-Brackmann Grade 1 or 2). This number rose to 85.3% of patients at 6 months after surgery and by 1 year, 89.7% of patients who had undergone acoustic neuroma surgery demonstrated normal or near-normal facial nerve function. The surgical approach appeared to have no effect on the incidence of facial nerve injury. Poor facial nerve outcome (House-Brackmann Grade 5 or 6) was seen in 1.58% of patients treated via the suboccipital approach and in 2.6% of patients treated via the translabyrinthine approach. When facial nerve outcome was examined with respect to tumor size, there clearly was an increased incidence of facial nerve palsy seen in the immediate postoperative period in cases of larger tumors: 60.8% of patients with tumors smaller than 2.5 cm had normal facial nerve function, whereas only 37.5% of patients with tumors larger than 4 cm had normal function. This difference was less pronounced, however, 6 months after surgery, when 92.1% of patients with tumors smaller than 2.5 cm had normal or near normal facial function, versus 75% of patients with tumors larger than 4 cm. The etiology of facial nerve injury is discussed with emphasis on the pathophysiology of facial nerve palsy. In addition, on the basis of the authors' experience with these complex tumors, techniques of preventing facial nerve injury are discussed.

Persistent low back pain in patients suspected of having herniated nucleus pulposus: radiologic predictors of functional outcome--implications for treatment selection

PURPOSE

To assess the relationship between imaging findings, therapy, and functional outcome in patients with persistent low back pain who are suspected of having herniated nucleus pulposus.

MATERIALS AND METHODS

Data collected during a multicenter, longitudinal study were retrospectively analyzed (n = 1,084). Multivariate regression was used to determine the association between imaging findings, therapy, and functional outcome. The patient outcome measure was disability days: the number of days the patient was unable to perform work-related activities.

RESULTS

In patients with at least one normal advanced (imaging other than plain radiography) diagnostic study or with an unconfirmed diagnosis of herniated nucleus pulposus, outcome at 2-year follow-up was no better in patients who were treated than in those who were not. In patients with only abnormal advanced imaging results or with a concordant diagnosis based on clinical and imaging findings, outcome was better in patients who underwent surgery than in those treated nonsurgically. Patients with a free fragment, protrusion, or extrusion that was treated surgically had fewer disability days than patients treated nonsurgically.

CONCLUSION

Advanced diagnostic imaging studies can play an important role in treatment selection in patients with persistent low back pain who are suspected of having herniated nucleus pulposus.

Trends in diagnostic imaging for low back pain: has MR imaging been a substitute or add-on?

PURPOSE

To assess whether magnetic resonance (MR) imaging has replaced other diagnostic imaging modalities in the evaluation of persistent low back pain.

MATERIALS AND METHODS

Data on diagnostic imaging use in 2,374 adult patients with persistent low back pain in 1987-1990 were analyzed. Multiple logistic regression was used to estimate the annual adjusted odds of lumbosacral spine radiography, MR imaging, unenhanced computed tomography (CT), or CT myelography use. The national cost of diagnostic imaging for persistent low back pain in 1990 relative to 1987 was estimated.

RESULTS

The adjusted odds of performing MR imaging in 1990 relative to 1987 was 3.44 (95% confidence interval, 2.63, 4.51), which reflects an estimated increase from 22 studies per 100 enrollees in 1987 to 75 studies per 100 enrollees in 1990. Use of MR imaging in combination with radiography, unenhanced CT, or CT myelography increased. The additional national cost of diagnostic imaging for persistent low back pain in 1990 relative to 1987 was estimated at $70-$176 million.

CONCLUSION

MR imaging was used primarily as an add-on rather than a substitute for other imaging modalities in the evaluation of persistent low back pain. Thus, the volume and cost of diagnostic imaging for persistent low back pain have increased.

Enzymatic assay of beta-lactamase using circular dichroism spectropolarimetry

A method for measuring the rates of enzymatic hydrolysis of beta-lactam antibiotics based on circular dichroism spectropolarimetry is described. Unhydrolyzed beta-lactam antibiotics have high molar ellipticities, but the hydrolyzed compounds are circular dichroism (CD) inactive in the case of penams or have significantly different CD spectra in the case of cephems. By measuring CD at constant wavelength as a function of time for reaction mixtures containing beta-lactamase and beta-lactam antibiotics, rates of hydrolysis and steady-state enzyme kinetic constants can be derived. The method was applied to measurement of a wide range of enzymatic reaction constants for wild-type and four mutant RTEM-1 beta-lactamases. Compared to the commonly employed assay based on ultraviolet spectroscopy, the new method offers several advantages. These include the ability to measure larger enzymatic Michaelis-Menten constants, less interference from high concentrations of beta-lactamase, higher sensitivity, and potentially less interference from other uv-absorbing components of complex reaction mixtures.

State legislation related to breast cancer: 1980-1994

Increased screening mammography usage is important for reducing breast cancer mortality in the United States. This article summarizes state breast cancer screening legislation enacted between 1980-1994. Forty-three laws were identified and analyzed based on five categories: screening/education programs; third-party reimbursement for screening; third-party reimbursement for reconstruction/prosthesis; mammography facility accreditation; and alternative therapy information. Third-party reimbursement mandates were subdivided into Medicaid/public assistance; state employee health benefits; Medicare supplement insurance; age/frequency provisions; and screening based on risk factors besides age. The larger context of breast cancer screening needs for the present and future are discussed.

In vivo accuracy testing and clinical experience with the ISG Viewing Wand

OBJECTIVE

A frameless stereotactic system (the Viewing Wand; Elekta Instruments, Atlanta, GA) has been developed for use with preoperative computed tomography, magnetic resonance imaging, and positron emission tomography as an adjunct for surgical planning and intraoperative navigation. This clinical study was designed to evaluate the safety, efficacy, and accuracy of the Viewing Wand in a variety of intracranial procedures.

METHODS

We used this system in 250 patients undergoing a wide range of neurosurgical procedures from July 1990 to July 1994, to assess its clinical usefulness and safety. In a subset of 45 neurosurgical patients studied between March 1993 and March 1994, a battery of objective accuracy measurements was obtained before and during surgery.

RESULTS

In this series, there were no instances of adverse outcomes attributable to the use of this system. A comparison of two alternative patient-image registration techniques established that the fiducial-fit method was slightly more accurate than the surface-fit method (geometric means = 2.51 and 3.03 mm, respectively). The clinical accuracy achieved with magnetic resonance imaging was nearly equivalent to that with computed tomography.

CONCLUSIONS

On the basis of this clinical series, recommendations are made regarding preoperative scanning parameters, registration techniques, and methods for reestablishing registration if needed during the course of surgery. The primary clinical benefits of the wand in this series were improved intraoperative navigation and surgical safety. For most cases, the wand was also useful in planning the location and size of the scalp incision, craniotomy, or corticotomy, as well as the extent of surgical resection.