Satish Krishnamurthy

Resident duty hours reform: results of a national survey of the program directors and residents in neurosurgery training programs.

OBJECTIVE:The new Accreditation Council for Graduate Medical Education (ACGME) requirements regarding resident work hours have been implemented since July 2003. Neurological surgery training programs have been especially affected because of the limited number of residency positions and the residents’ long duty hours. The perceptions of program directors and residents may provide important insight into the evolution of new guidelines for improvement of resident training. METHODS:We conducted a nationwide survey of 93 program directors and 617 residents to characterize their perceptions regarding the changes in their training programs related to compliance with the ACGME requirements. The survey was conducted from July through September 2003 using electronic mail. RESULTS:The response rates were 45% and 23% among the program directors and residents, respectively. Most programs offered one (37%) or two (38%) resident training positions per year. Although 92% of programs had implemented the ACGME work hours requirements before or since July 2003, 8% had not yet implemented these guidelines. Sixty-eight percent of program directors indicated employment of ancillary health care professionals to fulfill the ACGME duty hours reform; 84% (95% confidence interval [CI], 64–94%) thought that this practice has not limited the residents’ clinical experience. Eleven percent of respondents (18 of 164 respondents) who provided Level I trauma coverage were unable to maintain compliance with the ACGME guidelines. Ninety-three percent (95% CI, 89–96%) of all respondents thought that the work hour reform has had a negative impact on the continuity of patient care. Fifty-five percent (95% CI, 46–63%) of the residents and only 33% (95% CI, 20–50%) of the program directors thought that the ACGME requirements are likely to result in improved American Board of Neurological Surgery written test scores. Twenty-nine percent (95% CI, 22–37%) of the residents and 17% (95% CI, 8–32%) of the program directors thought that resident attendance at national conferences would increase. Similarly, although 46% (95% CI, 37–54%) of residents perceived that these work hour limitations would facilitate residents’ research/publication-related activities, only 21% (95% CI, 11–37%) of program directors agreed. Forty-one percent (95% CI, 33–49%) of the residents and 74% (95% CI, 58–86%) of the program directors perceived that the chief residents operate on fewer complex cases since the institution of the ACGME duty hour guidelines. Seventy-five percent of residents think they are less familiar with their patients. Overall, 61% (95% CI, 53–69%) of the residents and 79% (95% CI, 63–89%) of the program directors noted that the ACGME guidelines have had a negative effect on their training programs. CONCLUSION:On the basis of their early experience, the majority of the residents and program directors think that the ACGME duty hour guidelines have had an adverse effect on continuity of patient care and resident training. The effects of these guidelines on neurosurgery programs should be carefully monitored, because more sophisticated solutions may be needed to address house staff fatigue. Strategies to enhance the educational content of the residents’ work hours and to preserve continuity of patient care are necessary.

Intraventricular infusion of hyperosmolar dextran induces hydrocephalus: a novel animal model of hydrocephalus

BackgroundPopular circulation theory of hydrocephalus assumes that the brain is impermeable to cerebrospinal fluid (CSF), and is therefore incapable of absorbing the CSF accumulating within the ventricles. However, the brain parenchyma is permeable to water due to the presence of specific ion channels as well as aquaporin channels. Thus, the movement of water into and out of the ventricles may be determined by the osmotic load of the CSF. If osmotic load determines the aqueous content of CSF in this manner, it is reasonable to hypothesize that hydrocephalus may be precipitated by pathologies and/or insults that produce sustained elevations of osmotic content within the ventricles.MethodsWe investigated this hypothesis by manipulating the osmotic content of CSF and assaying the development of hydrocephalus in the rat brain. This was achieved by continuously infusing artificial CSF (negative control; group I), fibroblast growth factor (FGF2) solution (positive control; group II) and hyperosmotic dextran solutions (10 KD and 40 KD as experimental solutions: groups III and IV) for 12 days at 0.5 μL/h. The osmolality of the fluid infused was 307, 664, 337 and 328 mOsm/L in Groups I, II, III and IV, respectively. Magnetic resonance imaging (MRI) was used to evaluate the ventricular volumes. Analysis of variance (ANOVA) with pairwise group comparisons was done to assess the differences in ventricular volumes among the four groups.ResultsGroup I had no hydrocephalus. Group II, group III and group IV animals exhibited significant enlargement of the ventricles (hydrocephalus) compared to group I. There was no statistically significant difference in the size of the ventricles between groups II, III and IV. None of the animals with hydrocephalus had obstruction of the aqueduct or other parts of CSF pathways on MRI.ConclusionInfusing hyperosmolar solutions of dextran, or FGF into the ventricles chronically, resulted in ventricular enlargement. These solutions increase the osmotic load in the ventricles. Water influx (through the choroid plexus CSF secretion and/or through the brain) into the ventricles to normalize this osmotic gradient results in hydrocephalus. We need to revise the popular theory of how fluid accumulates in the ventricles at least in some forms of hydrocephalus.

Efficacy of neurosurgery resident education in the new millennium: the 2008 Council of State Neurosurgical Societies post-residency survey results.

BACKGROUNDNeurosurgical residency training paradigms have changed in response to Accreditation Council for Graduate Medical Education mandates and demands for quality patient care. Little has been done to assess resident education from the perspective of readiness to practice. OBJECTIVETo assess the efficacy of resident training in preparing young neurosurgeons for practice. METHODSIn response to Resolution V-2007F of the Council of State Neurosurgical Societies, a survey was developed for neurosurgeons who applied for oral examination, Part II of the American Board of Neurological Surgery boards, in 2002 through 2007 (N = 800). The survey was constructed in “survey monkey” format and sent to 775 of 800 (97%) neurosurgeons for whom e-mail addresses were available. RESULTSThe response rate was 30% (233/775). Most neurosurgeons were board certified (n = 226, 97%). General neurosurgical training was judged as adequate by a large majority (n = 188, 80%). Sixty-percent chose to pursue at least 1 additional year of fellowship training (n = 138, 60%). Surgical skills training was acceptable, but 6 skill-technique areas were reported to be inadequate (endovascular techniques, neurosurgical treatment of pain, stereotactic radiosurgery, epilepsy surgery, cranial base surgery, and stereotactic neurosurgery). Respondents also noted inadequate education in contract negotiation, practice evaluation, and management. CONCLUSIONThe study suggests that neurosurgeons believed that they were well trained in their surgical skills except for some areas of subspecialization. However, there is a significant need for improvement of resident training in the areas of socioeconomic and medicolegal education. Continued evaluation of the efficacy of neurosurgical education is important.

Influence of Fever and Hospital-Acquired Infection on the Incidence of Delayed Neurological Deficit and Poor Outcome after Aneurysmal Subarachnoid Hemorrhage

Although fever and infection have been implicated in the causation of delayed neurological deficits (DND) and poor outcome after aneurysmal subarachnoid hemorrhage (SAH), the relationship between these two often related events has not been extensively studied. We reviewed these events through of our retrospective database of patients with SAH. Multivariate logistic regression was used to determine independent predictors of DND and poor outcome. A total of 186 patients were analyzed. DND was noted in 76 patients (45%). Fever was recorded in 102 patients (55%); infection was noted in 87 patients (47%). A patient with one infection was more likely to experience DND compared to a patient with no infections (adjusted OR 3.73, 95% CI 1.62, 8.59). For those with more than two infections the likelihood of DND was even greater (adjusted OR 4.24, 95% CI 1.55, 11.56). Patients with 1-2 days of fever were less likely to have a favorable outcome when compared to their counterparts with no fever (adjusted OR 0.19, 95% CI 0.06, 0.62). This trend worsened as the number of days febrile increased. These data suggest that the presence of infection is associated with DND, but that fever may have a stronger independent association with overall outcome.

Effects of tobacco dose and length of exposure on delayed neurological deterioration and overall clinical outcome after aneurysmal subarachnoid hemorrhage.

OBJECTIVEThe association between smoking and intracranial aneurysms is now well recognized. However, the relationship between tobacco use and outcome after aneurysmal subarachnoid hemorrhage (SAH) is not as well understood and published results are contradictory. The purpose of this study is to examine the degree to which the amount of tobacco exposure/dose impacts delayed neurological deterioration and overall clinical outcome after aneurysmal SAH. METHODSWe reviewed our retrospective database of patients with aneurysmal SAH. We assessed the impact of four independent tobacco variables: smoker (ever smoked), current smoker (actively smoking within the past yr and with at least a 10 pack per yr history of smoking), long-term smoker (at least a 20 pack per yr history), and salient (combination of current and long-term) smoker as well as tobacco dose (categorized according to number of packs per yr) on two outcome variables, delayed neurological deterioration and dichotomized Glasgow Outcome Scale score. Covariates included in the analysis were age, sex, Hunt and Hess grade, Fisher grade, and medical comorbidities. Stepwise elimination with logistic regression was used to arrive at a final multivariate model for each outcome and independent tobacco variable in the presence of covariates. RESULTSA total of 320 patients were analyzed. As expected, Hunt and Hess grade was a significant predictor of both delayed neurological deterioration and clinical outcome. Tobacco use (smoker variable) showed an independent association with the development of delayed neurological deterioration (P = 0.0409; odds ratio, 1.78; 95% confidence interval, 1.02–3.08). In addition, patients who were long-term or current smokers (salient smoker variable) showed a trend toward a slightly stronger association with the occurrence of delayed neurological deterioration (P = 0.0229; odds ratio, 1.85; 95% confidence interval, 1.09–3.14). No tobacco use variable was associated with clinical outcome (Glasgow Outcome Scale) in the multivariate analysis. CONCLUSIONThe duration and timing of tobacco use, rather than the dose of tobacco per se, seem to be risk factors for delayed neurological deterioration after aneurysmal SAH. Although we did not find an association between tobacco use and overall clinical outcome after aneurysmal SAH, these results suggest that the distribution of various patterns of tobacco use within a given data set may influence the overall results.

Strategic Placement of Bedside Ventriculostomies Using Ultrasound Image Guidance: Report of three Cases

BackgroundThe blind free-hand technique for external ventricular drain (EVD) placement sometimes requires multiple attempts, and catheter location is often less than ideal. Our institution has adapted an intraoperative ultrasound-guided ventriculostomy technique for the placement of EVDs at the bedside. Our experience with ultrasound at the bedside has proven to be invaluable in certain circumstances. We present three cases of strategic EVD catheter trajectories that were made possible at the bedside with the use of ultrasound.MethodsIllustrative cases were chosen from a larger prospective study investigating the ultrasound-guided EVD technique. A portable ultrasound with a “burr hole” probe was used with modification of the standard surgical technique for placement of EVDs at the bedside.ResultsCase 1 describes an unexpected re-hemorrhage that was first realized by the ultrasound image obtained during the bedside EVD placement procedure. The catheter was purposefully directed across midline to the more prominent ventricle on the contralateral side based on this real-time finding. Case 2 describes how ultrasound was used to salvage the failed free-hand procedure and cannulate an extremely small ventricular space at the bedside. Case 3 describes an unconventionally placed burr hole that provided a customized trajectory in which the EVD catheter was placed just laterally and inferior to a large frontal hematoma.ConclusionUltrasound-guided bedside EVD placement allows EVD trajectories to be customized based on real-time information to accommodate for distorted and dynamic anatomy of the brain and its ventricles.

Increased CSF osmolarity reversibly induces hydrocephalus in the normal rat brain

BackgroundHydrocephalus is a central nervous system (CNS) disorder characterized by the abnormal accumulation of cerebrospinal fluid (CSF) in cerebral ventricles, resulting in their dilatation and associated brain tissue injury. The pathogenesis of hydrocephalus remains unclear; however, recent reports suggest the possible involvement of abnormal osmotic gradients. Here we explore the kinetics associated with manipulating CSF osmolarity on ventricle volume (VV) in the normal rat brain.MethodsCSF was made hyper-osmotic by introducing 10KD dextran into the lateral ventricle, either by acute injection at different concentrations or by chronic infusion at a single concentration. The induction and withdrawal kinetics of dextran infusion on VV were explored in both contexts.ResultsAcute intraventricular injection of dextran caused a rapid increase in VV which completely reversed within 24 hours. These kinetics are seemingly independent of CSF osmolarity across a range spanning an order of magnitude; however, the magnitude of the transient increase in VV was proportional to CSF osmolarity. By contrast, continuous intraventricular infusion of dextran at a relatively low concentration caused a more gradual increase in VV which was very slow to reverse when infusion was suspended after five days.ConclusionWe conclude that hyperosmolar CSF is sufficient to produce a proportional degree of hydrocephalus in the normal rat brain, and that this phenomenon exhibits hysteresis if CSF hyperosmolarity is persistent. Thus pathologically-induced increases in CSF osmolarity may be similarly associated with certain forms of clinical hydrocephalus. An improved understanding of this phenomenon and its kinetics may facilitate the development of novel therapies for the treatment of clinical hydrocephalus.

Early carotid endarterectomy after ischemic stroke improves diffusion/perfusion mismatch on magnetic resonance imaging: report of two cases.

OBJECTIVE AND IMPORTANCEThe functional magnetic resonance imaging techniques of diffusion-weighted imaging and perfusion-weighted imaging allow for ultra-early detection of brain infarction and concomitant identification of blood flow abnormalities in surrounding regions, which may represent brain “at risk.” CLINICAL PRESENTATIONWe report two patients with acute ischemic stroke associated with ipsilateral high-grade carotid stenosis. The first patient, a 64-year-old woman with a remote history of ischemic stroke and a vertebral artery aneurysm, presented with worsening of her preexisting right hemiparesis. The second patient, another 64-year-old woman with known multiple intracranial aneurysms and bilateral high-grade internal carotid artery stenosis, was admitted for the elective microsurgical clipping of an enlarging giant left carotid-ophthalmic artery aneurysm. Postoperatively, she developed right hemiparesis and mild aphasia. Both patients showed progressive worsening of their neurological deficits in the setting of small or undetected diffusion-weighted imaging abnormalities and large perfusion-weighted imaging defects. INTERVENTIONAfter prompt carotid endarterectomy, symptoms in both patients resolved or improved. Follow-up magnetic resonance imaging scans demonstrated resolution or significant improvement in the perfusion abnormalities in both patients. CONCLUSIONCarotid endarterectomy in the setting of diffusion-weighted/perfusion-weighted imaging mismatch can lead to improvement in cerebral perfusion as evidenced by resolution of the perfusion-weighted imaging lesion. Diffusion/perfusion magnetic resonance imaging may be useful in identifying patients with severe neurological deficits but without large territories of infarction who may safely undergo early surgical revascularization.

Primitive Neuroectodermal Tumor of Cerebrum With Adipose Tissue

Primitive neuroectodermal tumors (PNETs) of the central nervous system are uncommon embryonal neoplasms, rarely occurring in adults. Differentiation into specific mesenchymal tissues, such as cartilage, bone, skeletal muscle, smooth muscle, or adipose tissue, is rare. We report a case of a 51-year-old woman with a PNET of cerebrum that showed extensive mature adipose tissue differentiation. This is the second case, to our knowledge, of PNET of cerebrum with adipose tissue elements that has been described.

Bedside External Ventricular Drain Placement: Can Multiple Passes Be Predicted on the Computed Tomography Scan Before the Procedure?

OBJECTIVEnBedside external ventricular drain (EVD) placement is less than perfect and often requires multiple passes to achieve cerebrospinal fluid flow. We conducted this prospective study to understand why multiple passes are necessary and whether this affects the incidence of hemorrhage.nnnMETHODSnWe compared the number of passes in 47 EVD placement procedures to the incidence of hemorrhage after the procedure. We also analyzed computed tomography scans before the procedure to identify variables that correlate with multiple passes.nnnRESULTSnOf the procedures analyzed, 72% (34/47) were single pass whereas 28% (13/47) required multiple passes. Average number of passes was 1.85 (± 1.8), but average number of passes when multiple passes were made was 4.1 (± 2.29; range, 2-9). Incidence of tract hemorrhage was 10.6% (5/47). Of those, 11.8% (4/34) were in the single-pass group and 7.7% (1/13) from the multiple-pass group. There was no statistical relationship between the number of passes and hemorrhage (P > 0.99). Subarachnoid hemorrhage, intraventricular hemorrhage, and midline shift were not found to be statistically significant in relation to the number of passes. The presence of midline rostral hematoma significantly correlated with multiple passes. One of 34 patients (2.9%) needed a single pass and 5/13 (38.5%) needed multiple passes in the presence of midline rostral hematoma (P = 0.0011). The average targeted frontal horn volume was larger in patients who needed single pass EVD (12.4 ± 6.3 cm(2) vs. 8.0 ± 4.7 cm(2); P = 0.035).nnnCONCLUSIONSnMultiple passes are inherent to the bedside EVD procedure, but did not increase the rate of intracranial hemorrhage.