Impact of international research fellows in neurosurgery: results from a single academic center.

OBJECTIVE: International research fellows have been historically involved in academic neurosurgery in the United States (US). To date, the contribution of international research fellows has been underreported. Herein, the authors aimed to quantify the academic output of international research fellows in the Department of Neurosurgery at The Johns Hopkins University School of Medicine. METHODS: Research fellows with Doctor of Medicine (MD), Doctor of Philosophy (PhD), or MD/PhD degrees from a non-US institution who worked in the Hopkins Department of Neurosurgery for at least 6 months over the past decade (2010-2020) were included in this study. Publications produced during fellowship, number of citations, and journal impact factors (IFs) were analyzed using ANOVA. A survey was sent to collect information on personal background, demographics, and academic activities. RESULTS: Sixty-four international research fellows were included, with 42 (65.6%) having MD degrees, 17 (26.6%) having PhD degrees, and 5 (7.8%) having MD/PhD degrees. During an average 27.9 months of fellowship, 460 publications were produced in 136 unique journals, with 8628 citations and a cumulative journal IF of 1665.73. There was no significant difference in total number of publications, first-author publications, and total citations per person among the different degree holders. Persons holding MD/PhDs had a higher number of citations per publication per person (p = 0.027), whereas those with MDs had higher total IFs per person (p = 0.048). Among the 43 (67.2%) survey responders, 34 (79.1%) had nonimmigrant visas at the start of the fellowship, 16 (37.2%) were self-paid or funded by their country of origin, and 35 (81.4%) had mentored at least one US medical student, nonmedical graduate student, or undergraduate student. CONCLUSIONS: International research fellows at the authors' institution have contributed significantly to academic neurosurgery. Although they have faced major challenges like maintaining nonimmigrant visas, negotiating cultural/language differences, and managing self-sustainability, their scientific productivity has been substantial. Additionally, the majority of fellows have provided reciprocal mentorship to US students.

Health Care Expenditures of Medicare Beneficiaries with Normal Pressure Hydrocephalus.

BACKGROUND: Normal pressure hydrocephalus (NPH) is an underdiagnosed and undertreated condition affecting the elderly population and with costs associated with its surgical management reported to be less than those associated with conservative management. OBJECTIVE: To determine if the rate of diagnosis of NPH has improved over the last decade, the rate of treatment has increased, and if surgical treatment costs and socioeconomic factors related to receipt of treatment have changed over time compared with conservative therapy. METHODS: A retrospective study based on data from a nationally representative random sample of 2,378,637 Medicare beneficiaries (2006-2010) was performed. Shunt surgery, shunt revision, replacement, and removal were analyzed as independent variables. RESULTS: A total of 2321 patients with NPH were included, with 580 (24.99%) receiving a first shunt procedure. The adjusted effect of the procedure is that total 5-year expenditures are $11,676 more per patient (P < 0.001) than expenditures associated with nonsurgical management. Shunt revision ($22,715, P < 0.01) and/or replacement ($46,607, P < 0.001) add significantly to 5-year expenditures. Socioeconomic factors including African American race (P = 0.006); age 75-79 years (P = 0.024), 80-84 years (P < 0.001), and ≥85 years (P < 0.001); and Medicaid (P < 0.001) have significant negative associations with shunt surgery. CONCLUSIONS: There was a 1.66-fold increase in the rate of diagnosis of NPH, from 0.12% in 1999 to 0.2% in 2008. The total costs per surgical patient rose by approximately 145% to 160% comparing 2001 and 2010. This increase was mainly due to hospital (by 167% to 168%) and home health costs (by 118% to 148%). Providing appropriate care across the socioeconomic spectrum warrants further study and requires identifying the factors that limit access to care.

Ultrasound for the assessment of distal shunt malfunction in adults with internal ventricular shunts.

Shunts that are used for the treatment of hydrocephalus have a propensity towards malfunction, however, diagnosing a shunt malfunction can sometimes be a challenge. The purpose of this study was to investigate whether ultrasound technology can be safely and effectively used to assess for distal shunt malfunction. This was a prospective cohort study at a single institution. Eighteen adult patients that received a radionuclide shunt patency study also underwent an ultrasound shunt patency study. Ultrasound with Doppler technology was used to visualize flow through the shunt tubing following manual compression of the shunt reservoir. A peak flow speed was recorded and the results were compared to the results of the radionuclide shunt patency study. A Receiver Operating Characteristic (ROC) curve comparing the ultrasound to the radionuclide shunt patency study was generated, revealing an Area Under the Curve (AUC) of 0.95 (95% CI: 0.84-1.00). The ultrasound test performed maximally with a cutoff speed of ≤10cm/s as the criteria for malfunction, with a sensitivity of 100.00%, specificity of 90.91%, accuracy of 94.44%, positive likelihood ratio of 11.000 and negative likelihood ratio of 0.000 using the radionuclide study results as criteria for comparison. Overall, ultrasound has the potential to be a safe, quick, available and cost-effective screening test for patients with suspected distal shunt malfunction. The high sensitivity of the test makes it an attractive option for use as a screening method that could potentially reduce the number of cases requiring radionuclide shunt patency study.

NPH Log: Validation of a New Assessment Tool Leading to Earlier Diagnosis of Normal Pressure Hydrocephalus.

INTRODUCTION: Early treatment of normal pressure hydrocephalus (NPH) yields better postoperative outcomes. Our current tests often fail to detect significant changes at early stages. We developed a new scoring system (LP log score) to determine if this tool is more sensitive in detecting clinical differences than current tests. MATERIAL AND METHODS: Sixty-two consecutive new patients with suspected idiopathic NPH were studied. Secondary, previously treated and obstructive cases were not included. We collected age, pre- and post-lumbar puncture (LP) Tinetti, Timed Up and Go (TUG) Test, European NPH scale, and LP log scores. The LP log score is recorded at baseline and for seven consecutive days after removing 40 cc of cerebrospinal fluid (CSF) via LP. We studied the diagnostic accuracy of the tests for surgical indication. RESULTS: The post-LP log showed improvement in 90% of people with good baseline gait tests and in 93% of people who did not show any pre-LP and post-LP change in gait tests. Sensitivity, specificity, and accuracy to detect intention to treat when positive post-LP improvements were 4%, 100%, and 24%, respectively, for TUG, 21%, 86%, and 34%, respectively, for the Tinetti Mobility Test, 66%, 29%, and 58%, respectively, for Medical College of Virginia (MCV) grade, and 98%, 33%, and 85%, respectively, for LP log score. Pre-LP and post-LP TUG improvement and pre-LP and post-LP Tinetti improvement were not associated with a surgical indication (p > 0.05). LP log improvement was associated with surgical indication odds ratio (OR): 24.5 95% CI (2.4-248.12) (p = 0.007). CONCLUSIONS: LP log showed better sensitivity, diagnostic accuracy, and association with surgical indication than the current diagnostic approach. An LP log may be useful detecting NPH patients at earlier stages and, therefore, yield better surgical outcomes.

The Utility of Computed Tomography in Shunted Patients with Idiopathic Intracranial Hypertension Presenting to the Emergency Department.

BACKGROUND: Shunted patients with idiopathic intracranial hypertension (IIH) often present to the emergency department (ED) for symptoms related to their disease. Although brain imaging with computed tomography (CT) is often performed, particularly in the current medicolegal environment, its utility during these ED visits is unclear. METHODS: The ED visits of all shunted adult patients with IIH from 2003-2015 were retrospectively reviewed. ED visits not related to IIH were excluded from our study. RESULTS: Thirty-one patients visited the ED 171 times for IIH symptoms. Five patients had greater than 10 ED visits. Twenty-five (81%) patients had 131 visits involving a CT scan, while six (19%) patients were not scanned. The majority of scans (n = 126, 96%) showed no change; five (4%) scans detected new noncritical pathologies. On the basis of CT findings alone, treatment changes occurred in three (2.3%) instances. Of the 131 visits with a CT scan, twenty-five (19%) visits resulted in management changes; of the 40 ED visits without a CT scan, four (10%) visits resulted in a management change (P = 0.23). CONCLUSIONS: In our cohort, CT imaging rarely showed a change in pathology or affected the management of patients with IIH. There was no difference in the rate of management changes between those patients who underwent a CT scan and those who did not. Given the risk of cumulative radiation exposure and cost of CT scans, CT imaging should be used when there is concern for visual dysfunction and the utility of CT imaging in the ED for the workup of other symptoms related to IIH must be explored further.

Cost analysis of antibiotic-impregnated catheters in the treatment of hydrocephalus in adult patients.

OBJECTIVE: To determine if use of antibiotic-impregnated shunt (AIS) systems to reduce cerebrospinal fluid (CSF) shunt infections in adult patients with hydrocephalus has been cost-effective at one institution. METHODS: All adult patients undergoing CSF shunt insertion over a 7-year period at the Johns Hopkins Hospital were retrospectively reviewed (2004-2009). In 2006, a categorical switch to AIS catheters was made. Before 2006, standard nonimpregnated shunt catheters were used. The 1-year incidence of shunt infection was retrospectively assessed and accounting and billing records were reviewed to determine shunt infection-related medical costs for patients undergoing AIS vs non-AIS shunt surgery. RESULTS: A total of 500 (250 AIS, 250 non-AIS) shunt surgeries were performed for normal-pressure hydrocephalus (NPH) (n = 378 [76%]), pseudotumor cerebri (n = 83 [17%]), and various obstructive and communicating hydrocephalus etiologies (n = 40 [8%]). The incidence of shunt infection was decreased in the AIS (1.2%) vs non-AIS (4.0%) cohorts (P = .0492. Overall, the mean cost per shunt infection was $40,371. Per 250 shunts placed, the total infection-related cost was reduced from $321,407 to $203,424 after the conversion to AIS catheters. AIS catheters were associated with direct cost savings of $47,193 per 100 shunt surgeries performed. CONCLUSIONS: In a retrospective cohort study of 500 CSF shunt surgeries performed in adult patients with hydrocephalus, this institution's categorical conversion to AIS catheters was associated with a significant reduction in infection-related medical costs within the first year after surgery. Although prospective randomized cost-utility studies are needed to confirm these observations, these results suggest that AIS catheters are cost-effective in the treatment of hydrocephalus in adult patients.

Objective assessment of gait in normal-pressure hydrocephalus.

OBJECTIVES: Gait abnormalities are an early clinical symptom in normal pressure hydrocephalus (NPH), and subjective improvement in gait after temporary removal of CSF is often used to decide to perform shunt surgery. We investigated objective measures to compare gait before and after CSF drainage and shunt surgery. DESIGN: Twenty patients and nine controls were studied. Quantitative gait measures were obtained at baseline, after 3 days of controlled CSF drainage, and after shunt surgery. Decision to perform surgery was based on response to drainage, and patients were assigned to shunted or unshunted groups for comparison. RESULTS: There was no improvement after CSF drainage in the unshunted group (n = 4). In the shunted group (n = 15) velocity, double-support time, and cadence improved significantly after drainage, and improved further after shunt surgery. The degree of improvement after drainage significantly correlated to the degree of improvement postshunt for velocity, double-support time, cadence, and stride length. CONCLUSIONS: There are significant, quantifiable changes in gait after CSF drainage that correspond to improvement after shunt surgery for patients with NPH. Use of objective gait assessment may improve the process of identifying these candidates when response to CSF removal is used as a supplemental prognostic test for shunt surgery.

Extrapyramidal signs in normal pressure hydrocephalus: an objective assessment.

BACKGROUND: Beyond the classic Normal Pressure Hydrocephalus (NPH) triad of gait disturbance, incontinence, and dementia are characteristic signs of motor dysfunction in NPH patients. We used highly sensitive and objective methods to characterize upper limb extrapyramidal signs in a series of NPH subjects compared with controls. Concentrated evaluation of these profound, yet underappreciated movement disorders of NPH before and after techniques of therapeutic intervention may lead to improved diagnosis, insight into pathophysiology, and targeted treatment. METHODS: Twenty-two (22) consecutive NPH patients and 17 controls performed an upper limb motor task battery where highly sensitive and objective measures of akinesia/bradykinesia, tone, and tremor were conducted. NPH subjects performed this test battery before and more than 36 h after continuous CSF drainage via a spinal catheter over 72 h and, in those subjects undergoing permanent ventriculo-peritoneal shunt placement, at least 12 weeks later. Control subjects performed the task battery at the same dates as the NPH subjects. Statistical analyses were applied to group populations of NPH and control subjects and repeated measures for within subject performance. RESULTS: Twenty (20) NPH subjects remained in the study following CSF drainage as did 14 controls. NPH subjects demonstrated akinesia/bradykinesia (prolonged reaction and movement times) and increased resting tone compared with controls. Furthermore, the NPH group demonstrated increased difficulty with self-initiated tasks compared with stimulus-initiated tasks. Following CSF drainage, some NPH subjects demonstrated reduced movement times with greater improvement in self- versus stimulus-initiated tasks. Group reaction time was unchanged. Resting tremor present in one NPH subject resolved following shunt placement. Tone measures were consistent for all subjects throughout the study. CONCLUSION: Clinical motor signs of NPH subjects extend beyond gait deficits and include extrapyramidal manifestations of bradykinesia, akinesia, rigidity, and propensity to perform more poorly when external cues to move are absent. Objective improvement of some but not all of these features was seen following temporary or permanent CSF diversion.

Influence of shunt surgery on healthcare expenditures of elderly fee-for-service Medicare beneficiaries with hydrocephalus.

OBJECT: The goal in this study was to determine the percentage of patients with hydrocephalus who were treated with shunt surgery and to assess Medicare expenditures for those with and without shunt surgery. METHODS: Retrospective cost analyses were performed using the Standard Analytic Files of paid claims for beneficiaries enrolled in both Parts A (Inpatient) and B (Outpatient) of the Medicare program for 1997 through 2001. The main outcome measures were 5-year total payments and 5-year payments for separate types of service; for example, acute hospital (inpatient and outpatient), skilled nursing facility, home health, and physician/supplier services. RESULTS: Of 1441 patients with hydrocephalus, 25.1% underwent shunt surgery during the study period. The effect of a shunt procedure on 5-year Medicare expenditures is a cost difference of $25,477 (p < 0.0001) less per patient, which is equal to a potential -$184.3 million difference in 5-year Medicare expenditures. The following three factors had a negative association with whether shunt surgery was performed: (1) age 80 to 84 years (odds ratio [OR] 0.619, confidence interval [CI] 0.390-0.984); (2) age 85 years or older (OR 0.201, CI 0.110-0.366); and (3) African-American race (OR 0.506, CI 0.295-0.869). The effect of age on the likelihood of shunt surgery persisted after adjusting for the propensity to die score. CONCLUSIONS: Medicare expenditures for patients with hydrocephalus treated with shunt surgery are significantly lower than expenditures for untreated patients. Research to improve the diagnosis and treatment of hydrocephalus has the potential to improve outcomes and reduce health care expenditures further.