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Per K. Eide, Benjamin I. Rapoport, William B. Gormley and Joseph R. Madsen

Object

In the search for optimal monitoring and predictive tools in neurocritical care, the relationship of the pulsatile component of intracranial pressure (ICP) and the pressure itself has long been of great interest. Higher pressure often correlates with a higher pulsatile response to the heartbeat, interpreted as a type of compliance curve. Various mathematical approaches have been used, but regardless of the formula used, it is implicitly assumed that a reproducible curve exists. The authors investigated the stability of the correlation between static and pulsatile ICPs in patients with subarachnoid hemorrhage (SAH) who were observed for several hours by using data sets large enough to allow such calculations to be made.

Methods

The ICP recordings were obtained in 39 patients with SAH and were parsed into 6-second time windows (1,998,944 windows in 197 recordings). The ICP parameters were computed for each window as follows: static ICP was defined as the mean ICP, and pulsatile ICP was characterized by mean ICP wave amplitude, rise time, and rise time coefficient.

Results

The mean ICP and ICP wave amplitudes were simultaneously high or low (the expected correlation) in only ~ 60% of observations. Furthermore, static and pulsatile ICP correlated well only over short intervals; the degree of correlation weakened over periods of hours and was inconsistent across patients and within individual patients over time. Decorrelation originated with abrupt shifting and gradual drifting of mean ICP and ICP wave amplitude over several hours.

Conclusions

The relationship between the static and pulsatile components of ICPs changes over time. It evolves, even in individual patients, over a number of hours. This can be one reason the observation of high pulsatile ICP (indicative of reduced intracranial compliance) despite normal mean ICP that is seen in some patients with SAH. The meaning and potential clinical usefulness of such changes in the curves is uncertain, but it implies that clinical events result not only from moving further out on a compliance curve; in practice, the curve, and the biological system that underlies the curve, may itself change.

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Ryan Brewster, Wenya Linda Bi, Timothy R. Smith, William B. Gormley, Ian F. Dunn and Edward R. Laws Jr.

Baseball maintains one of the highest impact injury rates in all athletics. A principal causative factor is the “beanball,” referring to a pitch thrown directly at a batter’s head. Frequent morbidities elicited demand for the development of protective gear development in the 20th century. In this setting, Dr. Walter Dandy was commissioned to design a “protective cap” in 1941. His invention became widely adopted by professional baseball and inspired subsequent generations of batting helmets. As a baseball aficionado since his youth, Walter Dandy identified a natural partnership between baseball and medical practice for the reduction of beaning-related brain injuries. This history further supports the unique position of neurosurgeons to leverage clinical insights, inform innovation, and expand service to society.

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Panagiotis G. Simos, Andrew C. Papanicolaou, Joshua I. Breier, James W. Wheless, Jules E. C. Constantinou, William B. Gormley and William W. Maggio

Object. In this paper the authors demonstrate the concordance between magnetic source (MS) imaging and direct cortical stimulation for mapping receptive language cortex.

Methods. In 13 consecutive surgical patients, cortex specialized for receptive language functions was identified noninvasively by obtaining activation maps aided by MS imaging in the context of visual and auditory word-recognition tasks. Surgery was then performed for treatment of medically intractable seizure disorder (eight patients), and for resection of tumor (four), or angioma (one). Mapping of language areas with cortical stimulation was performed intraoperatively in 10 patients and extraoperatively in three. Cortical stimulation mapping verified the accuracy of the MS imaging—based localization in all cases.

Conclusions. Information provided by MS imaging can be especially helpful in cases of atypical language representation, including bihemispheric representation, and location of language in areas other than those expected within the dominant hemisphere, such as the anterior portion of the superior temporal gyrus, the posteroinferior portion of the middle temporal gyrus, the basal temporal cortex, and the lateral temporooccipital cortex.

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Aditya V. Karhade, Viren S. Vasudeva, Hormuzdiyar H. Dasenbrock, Yi Lu, William B. Gormley, Michael W. Groff, John H. Chi and Timothy R. Smith

OBJECTIVE

The goal of this study was to use a large national registry to evaluate the 30-day cumulative incidence and predictors of adverse events, readmissions, and reoperations after surgery for primary and secondary spinal tumors.

METHODS

Data from adult patients who underwent surgery for spinal tumors (2011–2014) were extracted from the prospective National Surgical Quality Improvement Program (NSQIP) registry. Multivariable logistic regression was used to evaluate predictors of reoperation, readmission, and major complications (death, neurological, cardiopulmonary, venous thromboembolism [VTE], surgical site infection [SSI], and sepsis). Variables screened included patient age, sex, tumor location, American Society of Anesthesiologists (ASA) physical classification, preoperative functional status, comorbidities, preoperative laboratory values, case urgency, and operative time. Additional variables that were evaluated when analyzing readmission included complications during the surgical hospitalization, hospital length of stay (LOS), and discharge disposition.

RESULTS

Among the 2207 patients evaluated, 51.4% had extradural tumors, 36.4% had intradural extramedullary tumors, and 12.3% had intramedullary tumors. By spinal level, 20.7% were cervical lesions, 47.4% were thoracic lesions, 29.1% were lumbar lesions, and 2.8% were sacral lesions. Readmission occurred in 10.2% of patients at a median of 18 days (interquartile range [IQR] 12–23 days); the most common reasons for readmission were SSIs (23.7%), systemic infections (17.8%), VTE (12.7%), and CNS complications (11.9%). Predictors of readmission were comorbidities (dyspnea, hypertension, and anemia), disseminated cancer, preoperative steroid use, and an extended hospitalization. Reoperation occurred in 5.3% of patients at a median of 13 days (IQR 8–20 days) postoperatively and was associated with preoperative steroid use and ASA Class 4–5 designation. Major complications occurred in 14.4% of patients: the most common complications and their median time to occurrence were VTE (4.5%) at 9 days (IQR 4–19 days) postoperatively, SSIs (3.6%) at 18 days (IQR 14–25 days), and sepsis (2.9%) at 13 days (IQR 7–21 days). Predictors of major complications included dependent functional status, emergency case status, male sex, comorbidities (dyspnea, bleeding disorders, preoperative systemic inflammatory response syndrome, preoperative leukocytosis), and ASA Class 3–5 designation (p < 0.05). The median hospital LOS was 5 days (IQR 3–9 days), the 30-day mortality rate was 3.3%, and the median time to death was 20 days (IQR 12.5–26 days).

CONCLUSIONS

In this NSQIP analysis, 10.2% of patients undergoing surgery for spinal tumors were readmitted within 30 days, 5.3% underwent a reoperation, and 14.4% experienced a major complication. The most common complications were SSIs, systemic infections, and VTE, which often occurred late (after discharge from the surgical hospitalization). Patients were primarily readmitted for new complications that developed following discharge rather than exacerbation of complications from the surgical hospital stay. The strongest predictors of adverse events were comorbidities, preoperative steroid use, and higher ASA classification. These models can be used by surgeons to risk-stratify patients preoperatively and identify those who may benefit from increased surveillance following hospital discharge.

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Hormuzdiyar H. Dasenbrock, Kevin X. Liu, Christopher A. Devine, Vamsidhar Chavakula, Timothy R. Smith, William B. Gormley and Ian F. Dunn

OBJECT

Although the length of hospital stay is often used as a measure of quality of care, data evaluating the predictors of extended hospital stay after craniotomy for tumor are limited. The goals of this study were to use multivariate regression to examine which preoperative characteristics and postoperative complications predict a prolonged hospital stay and to assess the impact of length of stay on unplanned hospital readmission.

METHODS

Data were extracted from the National Surgical Quality Improvement Program (NSQIP) database from 2007 to 2013. Patients who underwent craniotomy for resection of a brain tumor were included. Stratification was based on length of hospital stay, which was dichotomized by the upper quartile of the interquartile range (IQR) for the entire population. Covariates included patient age, sex, race, tumor histology, comorbidities, American Society of Anesthesiologists (ASA) class, functional status, preoperative laboratory values, preoperative neurological deficits, operative time, and postoperative complications. Multivariate logistic regression with forward prediction was used to evaluate independent predictors of extended hospitalization. Thereafter, hierarchical multivariate logistic regression assessed the impact of length of stay on unplanned readmission.

RESULTS

The study included 11,510 patients. The median hospital stay was 4 days (IQR 3-8 days), and 27.7% (n = 3185) had a hospital stay of at least 8 days. Independent predictors of extended hospital stay included age greater than 70 years (OR 1.53, 95% CI 1.28%-1.83%, p < 0.001); African American (OR 1.75, 95% CI 1.44%-2.14%, p < 0.001) and Hispanic (OR 1.68, 95% CI 1.36%-2.08%) race or ethnicity; ASA class 3 (OR 1.52, 95% CI 1.34%-1.73%) or 4-5 (OR 2.18, 95% CI 1.82%-2.62%) designation; partially (OR 1.94, 95% CI 1.61%-2.35%) or totally dependent (OR 3.30, 95% CI 1.95%-5.55%) functional status; insulin-dependent diabetes mellitus (OR 1.46, 95% CI 1.16%-1.84%); hematological comorbidities (OR 1.68, 95% CI 1.25%-2.24%); and preoperative hypoalbuminemia (OR 1.78, 95% CI 1.51%-2.09%, all p ≤ 0.009). Several postoperative complications were additional independent predictors of prolonged hospitalization including pulmonary emboli (OR 13.75, 95% CI 4.73%-39.99%), pneumonia (OR 5.40, 95% CI 2.89%-10.07%), and urinary tract infections (OR 11.87, 95% CI 7.09%-19.87%, all p < 0.001). The C-statistic of the model based on preoperative characteristics was 0.79, which increased to 0.83 after the addition of postoperative complications. A length of stay after craniotomy for tumor score was created based on preoperative factors significant in regression models, with a moderate correlation with length of stay (p = 0.43, p < 0.001). Extended hospital stay was not associated with differential odds of an unplanned hospital readmission (OR 0.97, 95% CI 0.89%-1.06%, p = 0.55).

CONCLUSIONS

In this NSQIP analysis that evaluated patients who underwent craniotomy for tumor, much of the variance in hospital stay was attributable to baseline patient characteristics, suggesting length of stay may be an imperfect proxy for quality. Additionally, longer hospitalizations were not found to be associated with differential rates of unplanned readmission.

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Faith C. Robertson, Muhammad M. Abd-El-Barr, Srinivasan Mukundan Jr. and William B. Gormley

OBJECTIVE

Ventriculostomy entry sites are commonly selected by freehand estimation of Kocher's point or approximations from skull landmarks and a trajectory toward the ipsilateral frontal horn of the lateral ventricles. A recognized ventriculostomy complication is intracranial hemorrhage from cortical vessel damage; reported rates range from 1% to 41%. In this report, the authors assess hemorrhagic risk by simulating traditional ventriculostomy trajectories and using CT angiography (CTA) with venography (CTV) data to identify potential complications, specifically from cortical draining veins.

METHODS

Radiographic analysis was completed on 50 consecutive dynamic CTA/CTV studies obtained at a tertiary-care academic neurosurgery department. Image sections were 0.5 mm thick, and analysis was performed on a venous phase that demonstrated high-quality opacification of the cortical veins and sagittal sinus. Virtual ventriculostomy trajectories were determined for right and left sides using medical diagnostic imaging software. Entry points were measured along the skull surface, 10 cm posteriorly from the nasion, and 3 cm laterally for both left and right sides. Cannulation was simulated perpendicular to the skull surface. Distances between the software-traced cortical vessels and the virtual catheter were measured. To approximate vessel injury by twist drill and ventricular catheter placement, veins within a 3-mm radius were considered a hemorrhage risk.

RESULTS

In 100 virtual lines through Kocher's point toward the ipsilateral ventricle, 19% were predicted to cause cortical vein injury and suspected hemorrhage (radius ≤ 3 mm). Little difference existed between cerebral hemispheres (right 18%, left 20%). The average (± SD) distance from the trajectory line and a cortical vein was 7.23 ± 4.52 mm. In all 19 images that predicted vessel injury, a site of entry for an avascular zone near Kocher's point could be achieved by moving the trajectory less than 1.0 cm laterally and less than 1.0 cm along the anterior/posterior axis, suggesting that empirical measures are suboptimal, and that patient-specific coordinates based on preprocedural CTA/CVA imaging may optimize ventriculostomy in the future.

CONCLUSIONS

In this institutional radiographic imaging analysis, traditional methods of ventriculostomy site selection predicted significant rates of cortical vein injury, matching described rates in the literature. CTA/CTV imaging potentiates identification of patient-specific cannulation sites and custom trajectories that avoid cortical vessels, which may lessen the risk of intracranial hemorrhage during ventriculostomy placement. Further development of this software is underway to facilitate stereotactic ventriculostomy and improve outcomes.

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Matthew L. Vestal, Emily B. Wong, Dan A. Milner Jr., William B. Gormley and Ian F. Dunn

This report is the first published case of cerebral melioidosis in the western hemisphere. In this paper the authors review the literature on neurological melioidosis and its presentation and treatment in endemic areas, describe the clinical course of this unique case of a presentation of the disease with cranial abscess in the US, review the pathological and radiological findings associated with this seminal case, and put forth recommendations for recognizing and treating possible future instances of the disease within the western hemisphere.

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Hormuzdiyar H. Dasenbrock, Robert F. Rudy, Pui Man Rosalind Lai, Timothy R. Smith, Kai U. Frerichs, William B. Gormley, M. Ali Aziz-Sultan and Rose Du

OBJECTIVE

Although cigarette smoking is one of the strongest risk factors for cerebral aneurysm development and rupture, there are limited data evaluating the impact of smoking on outcomes after aneurysmal subarachnoid hemorrhage (SAH). Additionally, two recent studies suggested that nicotine replacement therapy was associated with improved neurological outcomes among smokers who had sustained an SAH compared with smokers who did not receive nicotine.

METHODS

Patients who underwent endovascular or microsurgical repair of a ruptured cerebral aneurysm were extracted from the Nationwide Inpatient Sample (NIS, 2009–2011) and stratified by cigarette smoking. Multivariable logistic regression analyzed in-hospital mortality, complications, tracheostomy or gastrostomy placement, and discharge to institutional care (a nursing or an extended care facility). Additionally, the composite NIS-SAH outcome measure (based on mortality, tracheostomy or gastrostomy, and discharge disposition) was evaluated, which has been shown to have excellent agreement with a modified Rankin Scale score greater than 3. Covariates included in regression constructs were patient age, sex, race/ethnicity, insurance status, socioeconomic status, comorbidities (including hypertension, drug and alcohol abuse), the NIS-SAH severity scale (previously validated against the Hunt and Hess grade), treatment modality used for aneurysm repair, and hospital characteristics. A sensitivity analysis was performed matching smokers to nonsmokers on age, sex, number of comorbidities, and NIS-SAH severity scale score.

RESULTS

Among the 5784 admissions evaluated, 37.1% (n = 2148) had a diagnosis of tobacco use, of which 31.1% (n = 1800) were current and 6.0% (n = 348) prior tobacco users. Smokers were significantly younger (mean age 51.4 vs 56.2 years) and had more comorbidities compared with nonsmokers (p < 0.001). There were no significant differences in mortality, total complications, or neurological complications by smoking status. However, compared with nonsmokers, smokers had significantly decreased adjusted odds of tracheostomy or gastrostomy placement (11.9% vs 22.7%, odds ratio [OR] 0.63, 95% confidence interval [CI] 0.51–0.78, p < 0.001), discharge to institutional care (OR 0.71, 95% CI 0.57–0.89, p = 0.002), and a poor outcome (OR 0.65, 95% CI 0.55–0.77, p < 0.001). Similar statistical associations were noted in the matched-pairs sensitivity analysis and in a subgroup of poor-grade patients (the upper quartile of the NIS-SAH severity scale).

CONCLUSIONS

In this nationwide study, smokers experienced SAH at a younger age and had a greater number of comorbidities compared with nonsmokers, highlighting the negative ramifications of cigarette smoking among patients with cerebral aneurysms. However, smoking was also associated with paradoxical superior outcomes on some measures, and future research to confirm and further understand the basis of this relationship is needed.

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Hormuzdiyar H. Dasenbrock, Timothy R. Smith, Robert F. Rudy, William B. Gormley, M. Ali Aziz-Sultan and Rose Du

OBJECTIVE

Although reoperation and readmission have been used as quality metrics, there are limited data evaluating the rate of, reasons for, and predictors of reoperation and readmission after microsurgical clipping of unruptured aneurysms.

METHODS

Adult patients who underwent craniotomy for clipping of an unruptured aneurysm electively were extracted from the prospective National Surgical Quality Improvement Program registry (2011–2014). Multivariable logistic regression and recursive partitioning analysis evaluated the independent predictors of nonroutine hospital discharge, unplanned 30-day reoperation, and readmission. Predictors screened included patient age, sex, comorbidities, American Society of Anesthesiologists (ASA) classification, functional status, aneurysm location, preoperative laboratory values, operative time, and postoperative complications.

RESULTS

Among the 460 patients evaluated, 4.2% underwent any reoperation at a median of 7 days (interquartile range [IQR] 2–17 days) postoperatively, and 1.1% required a cranial reoperation. The most common reoperation was ventricular shunt placement (23.5%); other reoperations were tracheostomy, craniotomy for hematoma evacuation, and decompressive hemicraniectomy. Independent predictors of any unplanned reoperation were age greater than 51 years and longer operative time (p ≤ 0.04). Readmission occurred in 6.3% of patients at a median of 6 days (IQR 5–13 days) after discharge from the surgical hospitalization; 59.1% of patients were readmitted within 1 week and 86.4% within 2 weeks of discharge. The most common reason for readmission was seizure (26.7%); other causes of readmission included hydrocephalus, cerebrovascular accidents, and headache. Unplanned readmission was independently associated with age greater than 65 years, Class II or III obesity (body mass index > 35 kg/m2), preoperative hyponatremia, and preoperative anemia (p ≤ 0.04). Readmission was not associated with operative time, complications during the surgical hospitalization, length of stay, or discharge disposition. Recursive partitioning analysis identified the same 4 variables, as well as ASA classification, as associated with unplanned readmission. The most potent predictors of nonroutine hospital discharge (16.7%) were postoperative neurological and cardiopulmonary complications; other predictors were age greater than 51 years, preoperative hyponatremia, African American and Asian race, and a complex vertebrobasilar circulation aneurysm.

CONCLUSIONS

In this national analysis, patient age greater than 65 years, Class II or III obesity, preoperative hyponatremia, and anemia were associated with adverse events, highlighting patients who may be at risk for complications after clipping of unruptured cerebral aneurysms. The preponderance of early readmissions highlights the importance of early surveillance and follow-up after discharge; the frequency of readmission for seizure emphasizes the need for additional data evaluating the utility and duration of postcraniotomy seizure prophylaxis. Moreover, readmission was primarily associated with preoperative characteristics rather than metrics of perioperative care, suggesting that readmission may be a suboptimal indicator of the quality of care received during the surgical hospitalization in this patient population.