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Mitchell P. Wilson, Andrew S. Jack, Andrew Nataraj and Michael Chow

OBJECTIVE

Readmission to the hospital within 30 days of discharge is used as a surrogate marker for quality and value of care in the United States (US) healthcare system. Concern exists regarding the value of 30-day readmission as a quality of care metric in neurosurgical patients. Few studies have assessed 30-day readmission rates in neurosurgical patients outside the US. The authors performed a retrospective review of all adult neurosurgical patients admitted to a single Canadian neurosurgical academic center and who were discharged to home to assess for the all-cause 30-day readmission rate, unplanned 30-day readmission rate, and avoidable 30-day readmission rate.

METHODS

A retrospective review was performed assessing 30-day readmission rates after discharge to home in all neurosurgical patients admitted to a single academic neurosurgical center from January 1, 2011, to December 31, 2011. The primary outcomes included rates of all-cause, unplanned, and avoidable readmissions within 30 days of discharge. Secondary outcomes included factors associated with unplanned and avoidable 30-day readmissions.

RESULTS

A total of 184 of 950 patients (19.4%) were readmitted to the hospital within 30 days of discharge. One-hundred three patients (10.8%) were readmitted for an unplanned reason and 81 (8.5%) were readmitted for a planned or rescheduled operation. Only 19 readmissions (10%) were for a potentially avoidable reason. Univariate analysis identified factors associated with readmission for a complication or persistent/worsening symptom, including age (p = 0.009), length of stay (p = 0.007), general neurosurgery diagnosis (p < 0.001), cranial pathology (p < 0.001), intensive care unit (ICU) admission (p < 0.001), number of initial admission operations (p = 0.01), and shunt procedures (p < 0.001). Multivariate analysis identified predictive factors of readmission, including diagnosis (p = 0.002, OR 2.4, 95% CI 1.4–5.3), cranial pathology (p = 0.002, OR 2.7, 95% CI 1.4–5.3), ICU admission (p = 0.004, OR 2.4, 95% CI 1.3–4.2), and number of first admission operations (p = 0.01, OR 0.51, 95% CI 0.3–0.87). Univariate analysis performed to identify factors associated with potentially avoidable readmissions included length of stay (p = 0.03), diagnosis (p < 0.001), cranial pathology (p = 0.02), and shunt procedures (p < 0.001). Multivariate analysis identified only shunt procedures as a predictive factor for avoidable readmission (p = 0.02, OR 5.6, 95% CI 1.4–22.8).

CONCLUSIONS

Almost one-fifth of neurosurgical patients were readmitted within 30 days of discharge. However, only about half of these patients were admitted for an unplanned reason, and only 10% of all readmissions were potentially avoidable. This study demonstrates unique challenges encountered in a publicly funded healthcare setting and supports the growing literature suggesting 30-day readmission rates may serve as an inappropriate quality of care metric in neurosurgical patients. Potentially avoidable readmissions can be predicted, and further research assessing predictors of avoidable readmissions is warranted.

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Jason G. Mandell, Jack W. Langelaan, Andrew G. Webb and Steven J. Schiff

OBJECT

Accurate edge tracing segmentation remains an incompletely solved problem in brain image analysis. The authors propose a novel algorithm using a particle filter to follow the boundary of the brain in the style often used in autonomous air and ground vehicle navigation. Their goals were to create a versatile tool to segment brain and fluid in MRI and CT images of the developing brain, lay the foundation for an intelligent automated edge tracker that is modality independent, and segment normative data from MRI that can be applied to both MRI and CT.

METHODS

Simulated MRI data sets were used to train and evaluate the particle filter segmentation algorithm. The method was then applied to produce normative growth curves for children and adolescents from 0 to 18 years of age for brain and fluid from MR images from the National Institutes of Health pediatric database and these data were compared to historical results. The authors further adapted this method for use with CT images of pediatric hydrocephalus and compared the results with hand-segmented data.

RESULTS

Segmentation of simulated MRI data with varied levels of noise (0%–9%) and spatial inhomogeneity (0%–40%) resulted in percent errors ranging from 0.06% to 5.38% for brain volume and 2.45% to 22.3% for fluid volume. The authors used this tool to create normal brain and CSF growth curves from MR images. The calculated growth curves showed excellent consistency with historical data. Additionally, compared with manual segmentation the particle filter accurately segmented brain and fluid volumes from CT scans of 5 pediatric patients with hydrocephalus (p < 0.001).

CONCLUSIONS

The authors have produced the first normative brain and CSF growth curves for children and adolescents 0–18 years of age. In addition, this study includes the first use of a particle filter as an edge tracker in image segmentation and offers a semiautomatic method to segment both pediatric and adult brain data from MR and CT images. The particle filter has the potential to be further automated toward a clinical rather than research tool with both of these modalities. Because of its modality independence, it has the capability to allow CT to be a more effective diagnostic tool for neurological disorders, a task of substantial importance in emergency settings and in developing countries where CT is often the only available method of brain imaging.

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Mitchell P. Wilson, Cian O’Kelly, Andrew S. Jack and Jeremy Rempel

OBJECTIVE

Freehand insertion of external ventricular drains (EVDs) using anatomical landmarks is considered the primary method for placement, although alternative techniques have shown improved accuracy in positioning. The purpose of this study was to retrospectively evaluate which features of the baseline clinical history and preprocedural CT scan predict EVD positioning into suboptimal and unsatisfactory locations when using the freehand insertion technique.

METHODS

A retrospective chart review was performed evaluating 189 consecutive adult patients who received an EVD via freehand technique through an anterior burr hole between January 1, 2014, and December 31, 2015, at a Level 1 trauma facility in Edmonton, Alberta, Canada. The primary outcome measures included features associated with suboptimal positioning (Kakarla grade 1 vs Kakarla grades 2 and 3). The secondary outcome measures were features associated with unsatisfactory positioning (Kakarla grades 1 and 2 vs Kakarla grade 3).

RESULTS

Fifty-one EVDs (27%) were suboptimally positioned. Fifteen (8%) EVDs were placed into eloquent cortex or nontarget CSF spaces. Admitting diagnosis, head height-to-width ratio in axial plane, and side of predominant pathology were found to be significantly associated with suboptimal placement (p = 0.02, 0.012, and 0.02, respectively). A decreased height-to-width ratio was also associated with placement into only eloquent cortex and/or nontarget CSF spaces (p = 0.003).

CONCLUSIONS

Freehand insertion of an EVD is associated with significant suboptimal positioning into parenchyma and nontarget CSF spaces. The likelihood of inaccurate EVD placement can be predicted with baseline clinical and radiographic features. The patient’s height-to-width ratio represents a novel potential radiographic predictor for malpositioning.

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Derek A. Mathis, Edward J. Stehel Jr., Joseph E. Beshay, Bruce E. Mickey, Andrew L. Folpe and Jack Raisanen

Hypophosphatemia with osteomalacia may be due to a neoplasm that produces fibroblast growth factor 23 (FGF-23), which inhibits phosphate reabsorption in the kidneys. Most of these tumors occur in bone or soft tissue and occasionally in the head, although intracranial occurrence is very rare. This report describes a tumor that caused hypophosphatemia and osteomalacia and was located entirely in the right anterior cranial fossa. Radiologically, the tumor resembled a meningioma; histologically, it was a low-grade phosphaturic mesenchymal tumor, mixed connective tissue variant (PMTMCT). After gross-total resection, the patient's symptoms abated and laboratory values normalized. The authors also studied another PMTMCT initially diagnosed as a hemangiopericytoma that involved the left anterior cranial fossa and ethmoid sinus, and reviewed reports of 6 other intracranial tumors that induced osteomalacia, 3 entirely in the anterior cranial fossa, 2 involving the anterior cranial fossa and ethmoid sinus, and 1 in the cavernous sinus. In older children or adults who have hypophosphatemia with osteomalacia and no personal or family history of metabolic, renal, or malabsorptive disease, a neoplasm should be suspected and an imaging workup that includes the brain is warranted, with particular attention to the anterior cranial fossa. Additionally, because there are some overlapping histological features between PMTMCTs and hemangiopericytomas, it may be helpful to assess tumoral FGF-23 expression by reverse transcriptase polymerase chain reaction or immunohistochemical analysis in patients with oncogenic osteomalacia from an intracranial tumor diagnosed as, or resembling, hemangiopericytoma.

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Andrew M. Baschnagel, Peter Y. Chen, Dennis Bojrab, Daniel Pieper, Jack Kartush, Oksana Didyuk, Ilka C. Naumann, Ann Maitz and Inga S. Grills

Object

Hearing loss after Gamma Knife surgery (GKS) in patients with vestibular schwannoma has been associated with radiation dose to the cochlea. The purpose of this study was to evaluate serviceable hearing preservation in patients with VS who were treated with GKS and to determine if serviceable hearing loss can be correlated with the dose to the cochlea.

Methods

Forty patients with vestibular schwannoma with serviceable hearing were treated using GKS with a median marginal dose of 12.5 Gy (range 12.5–13 Gy) to the 50% isodose volume. Audiometry was performed prospectively before and after GKS at 1, 3, and 6 months, and then every 6 months thereafter. Hearing preservation was based on pure tone average (PTA) and speech discrimination (SD). Serviceable hearing was defined as PTA less than 50 dB and SD greater than 50%.

Results

The median cochlear maximum and mean doses were 6.9 Gy (range 1.6–16 Gy) and 2.7 Gy (range 0.7–5.0 Gy), respectively. With a median audiological follow-up of 35 months (range 6–58 months), the 1-, 2-, and 3-year actuarial rates of maintaining serviceable hearing were 93%, 77%, and 74%, respectively. No patient who received a mean cochlear dose less than 2 Gy experienced serviceable hearing loss (p = 0.035). Patients who received a mean cochlear dose less than 3 Gy had a 2-year hearing preservation rate of 91% compared with 59% in those who received a mean cochlear dose of 3 Gy or greater (p = 0.029). Those who had more than 25% of their cochlea receiving 3 Gy or greater had a higher rate of hearing loss (p = 0.030). There was no statistically significant correlation between serviceable hearing loss and age, tumor size, pre-GKS PTA, pre-GKS SD, pre-GKS Gardner-Robertson class, maximum cochlear dose, or the percentage of cochlear volume receiving 5 Gy. On multivariate analysis there was a trend toward significance for serviceable hearing loss with a mean cochlear dose of 3 Gy or greater (p = 0.074). Local control was 100% at 24 months. No patient developed facial or trigeminal nerve dysfunction.

Conclusions

With a median mean cochlear dose of 2.7 Gy, the majority of patients with serviceable hearing retained serviceable hearing 3 years after GKS. A mean cochlear dose less than 3 Gy was associated with higher serviceable hearing preservation.

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Andrew S. Jack, Michael M. Chow, Loretta Fiorillo, Thea Chibuk, Jerome Y. Yager and Vivek Mehta

The acronym PHACE has been used to denote a constellation of abnormalities: posterior fossa anomalies, facial hemangiomas, arterial anomalies, cardiac anomalies, and eye abnormalities. Approximately 30% of patients with large facial hemangiomas have PHACE syndrome, with the vast majority having intracranial arteriopathy. Few reports characterize neurological deterioration from this intracranial arteriopathy, and even fewer report successful treatment thereof. The authors report on a case of a child with PHACE syndrome who presented with an ischemic stroke from a progressive intracranial arteriopathy and describe her successful treatment with bilateral pial synangiosis.

An 8-month old girl diagnosed with PHACE syndrome was found to have bilateral internal carotid artery stenosis. Although initially asymptomatic, a few months after diagnosis she suffered a right frontal and parietal stroke. MRI and cerebral angiography investigations demonstrated progressive intracranial arterial stenosis and occlusion. The patient then underwent indirect cerebral revascularization surgery. At 2-year follow-up, she exhibited clinical improvement with persistent speech and motor developmental delay. Follow-up MRI and cerebral angiography showed no new ischemic events and robust extensive vascular collateralization from surgery.

PHACE syndrome is an uncommon disease, and affected patients often have cerebral arteriopathy. Although the underlying natural history of cerebral arteriopathy in PHACE remains unclear, cerebral revascularization may represent a potential therapy for symptomatic patients.

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Panagiotis G. Simos, Eduardo M. Castillo, Jack M. Fletcher, David J. Francis, Fernando Maestu, Joshua I. Breier, William W. Maggio and Andrew C. Papanicolaou

Object. There are conflicting claims in the functional imaging literature concerning whether different languages are represented by distinct brain mechanisms in individuals who are proficient in more than one language. This interesting theoretical issue has practical implications when functional imaging methods are used for presurgical language mapping. To address this issue the authors compared the location and extent of receptive language cortex specific to English and Spanish in neurologically intact bilingual volunteers by using magnetic source imaging.

Methods. Areas of the cortex that were specialized for receptive language functions were identified separately for each language in 11 healthy adults who were bilingual in English and Spanish. The authors performed exactly the same procedures used routinely for presurgical receptive language mapping. In each bilingual individual, the receptive language—specific map always encompassed the posterior portion of the superior temporal gyrus. In every case, however, substantial differences in the receptive language maps were also observed for the two languages, regardless of whether each participant's first language was English or Spanish.

Conclusions. Although the reasons for such differences and their ultimate significance in identifying the cerebral mechanisms of language are subject to continuing investigation, their presence is noteworthy and has practical implications for the surgical management of patients with lesions in the temporal and parietal regions of the dominant hemisphere.

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Wyatt L. Ramey, Alexander von Glinski, Andrew Jack, Ronen Blecher, Rod J. Oskouian and Jens R. Chapman

OBJECTIVE

The surgical treatment of osteomyelitis and discitis of the spine often represents a challenging clinical entity for a multitude of reasons, including progression of infection despite debridement, development of spinal deformity and instability, bony destruction, and seeding of hardware. Despite advancement in spinal hardware and implantation techniques, these aforementioned challenges not uncommonly result in treatment failure, especially in instances of heavy disease burden with enough bony endplate destruction as to not allow support of a modern titanium cage implant. While antibiotic-infused polymethylmethacrylate (aPMMA) has been used in orthopedic surgery in joints of the extremities, its use has not been extensively described in the spine literature. Herein, the authors describe for the first time a series of patients treated with a novel surgical technique for the treatment of spinal osteomyelitis and discitis using aPMMA strut grafts with posterior segmental fusion.

METHODS

Over the course of 3 years, all patients with spinal osteomyelitis and discitis at a single institution were identified and included in the retrospective cohort if they were surgically treated with spinal fusion and implantation of an aPMMA strut graft at the nidus of infection. Basic demographics, surgical techniques, levels treated, complications, and return to the operating room for removal of the aPMMA strut graft and placement of a traditional cage were examined. The surgical technique consisted of performing a discectomy and/or corpectomy at the level of osteomyelitis and discitis followed by placement of aPMMA impregnated with vancomycin and/or tobramycin into the cavity. Depending on the patient’s condition during follow-up and other deciding clinical and radiographic factors, the patient may return to the operating room nonurgently for removal of the PMMA spacer and implantation of a permanent cage with allograft to ultimately promote fusion.

RESULTS

Fifteen patients were identified who were treated with an aPMMA strut graft for spinal osteomyelitis and discitis. Of these, 9 patients returned to the operating room for aPMMA strut graft removal and insertion of a cage with allograft at an average of 19 weeks following the index procedure. The most common infections were methicillin-sensitive Staphylococcus aureus (n = 6) and methicillin-resistant S. aureus (n = 5). There were 13 lumbosacral infections and 1 each of cervical and thoracic infection. Eleven patients were cured of their infection, while 2 had recurrence of their infection; 2 patients were lost to follow-up. Three patients required unplanned return trips to the operating room, two of which were for wound complications, with the third being for recurrent infection.

CONCLUSIONS

In cases of severe infection with considerable bony destruction, insertion of an aPMMA strut graft is a novel technique that should be considered in order to provide strong anterior-column support while directly delivering antibiotics to the infection bed. While the active infection is being treated medically, this structural aPMMA support bridges the time it takes for the patient to be converted from a catabolic to an anabolic state, when it is ultimately safe to perform a definitive, curative fusion surgery.

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Paul S. Echlin, Elaine N. Skopelja, Rachel Worsley, Shiroy B. Dadachanji, D. Rob Lloyd-Smith, Jack A. Taunton, Lorie A. Forwell and Andrew M. Johnson

Object

The primary objective of this study was to measure the incidence of concussion according to a relative number of athlete exposures among 25 male and 20 female varsity ice hockey players. The secondary objective was to present neuropsychological test results between preseason and postseason play and at 72 hours, 2 weeks, and 2 months after concussion.

Methods

Every player underwent baseline assessments using the Sport Concussion Assessment Tool-2 (SCAT2), Immediate Post-Concussion Assessment and Cognitive Test (ImPACT), and MRI. Each regular season and postseason game was observed by 2 independent observers (a physician and a nonphysician observer). Players with a diagnosed concussion were removed from the game, examined in the team physician's office using the SCAT2 and ImPACT, and sent to undergo MRI.

Results

Eleven concussions occurred during the 55 physician-observed games (20%). The incidence of concussion, expressed as number of concussions per 1000 athlete exposures, was 10.70 for men and women combined in regular season play, 11.76 for men and women combined across both the regular season and playoff season, 7.50 for men and 14.93 for women in regular season play, and 8.47 for men across both the regular season and playoff season. One male player experienced repeat concussions. No concussions were reported during practice sessions, and 1 concussion was observed and diagnosed in an exhibition game. Neuropsychological testing suggested no statistically significant preseason/postseason differences between athletes who sustained a physician-diagnosed concussion and athletes who did not sustain a physician-diagnosed concussion on either the ImPACT or SCAT2. The athletes who sustained a physician-diagnosed concussion demonstrated few reliable changes postinjury.

Conclusions

Although the incidence of game-related concussions per 1000 athlete exposures in this study was half the highest rate reported in the authors' previous research, it was 3 times higher than the incidence reported by other authors within the literature concerning men's collegiate ice hockey and 5 times higher than the highest rate previously reported for woman's collegiate ice hockey. Interestingly, the present results suggest a substantively higher incidence of concussion among women (14.93) than men (7.50). The reproducible and significantly higher incidence of concussion among both men and woman ice hockey players, when compared with nonphysician-observed games, suggests a significant underestimation of sports concussion in the scientific literature.

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Edward M. Marchan, Raymond F. Sekula Jr., Andrew Ku, Robert Williams, Brent R. O'Neill, Jack E. Wilberger and Matthew R. Quigley

Object

Because of high recanalization rates associated with wide-necked intracranial aneurysms treated with bare platinum coils, hydrogel coils (HydroCoil, MicroVention, Inc.) have been developed. Hydrogel coils undergo progressive expansion once exposed to the physiological environment of blood and increase overall aneurysm filling.

Methods

The authors retrospectively reviewed their series of patients with unruptured aneurysms treated between 1998 and 2006 and who underwent placement of bare platinum and hydrogel coils for cerebral aneurysms. They examined the incidence of delayed hydrocephalus as related to coil type. In a subgroup of patients in which preand postprocedure CT and MR imaging studies were available, the authors quantitatively analyzed the ventricular size change after hydrogel coils were placed.

Results

Four of 29 patients treated with hydrogel coils developed symptomatic hydrocephalus 2–6 months after the intervention compared with 0 of 26 treated with bare platinum coils alone. The difference in ventricular size between the subgroups in which pre- and postprocedure imaging was performed was found to be statistically significant (p < 0.05). All 4 HydroCoil-treated patients in whom hydrocephalus developed required placement of a shunt.

Conclusions

A 14% incidence (95% confidence interval 3.9–31.7%) of hydrocephalus in patients with unruptured aneurysm undergoing embolization with hydrogel coils was discovered. This incidence is much higher than previously reported. The mechanism by which hydrogel coils may induce hydrocephalus remains poorly understood.