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Michael M. McDowell and Andrew F. Ducruet

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Nitin Agarwal, Ahmed Kashkoush, Michael M. McDowell, William R. Lariviere, Naveed Ismail and Robert M. Friedlander

OBJECTIVE

Ventricular shunt (VS) durability has been well studied in the pediatric population and in patients with normal pressure hydrocephalus; however, further evaluation in a more heterogeneous adult population is needed. This study aims to evaluate the effect of diagnosis and valve type—fixed versus programmable—on shunt durability and cost for placement of shunts in adult patients.

METHODS

The authors retrospectively reviewed the medical records of all patients who underwent implantation of a VS for hydrocephalus at their institution over a 3-year period between August 2013 and October 2016 with a minimum postoperative follow-up of 6 months. The primary outcome was shunt revision, which was defined as reoperation for any indication after the initial procedure. Supply costs, shunt durability, and hydrocephalus etiologies were compared between fixed and programmable valves.

RESULTS

A total of 417 patients underwent shunt placement during the index time frame, consisting of 62 fixed shunts (15%) and 355 programmable shunts (85%). The mean follow-up was 30 ± 12 (SD) months. The shunt revision rate was 22% for programmable pressure valves and 21% for fixed pressure valves (HR 1.1 [95% CI 0.6–1.8]). Shunt complications, such as valve failure, infection, and overdrainage, occurred with similar frequency across valve types. Kaplan-Meier survival curve analysis showed no difference in durability between fixed (mean 39 months) and programmable (mean 40 months) shunts (p = 0.980, log-rank test). The median shunt supply cost per index case and accounting for subsequent revisions was $3438 (interquartile range $2938–$3876) and $1504 (interquartile range $753–$1584) for programmable and fixed shunts, respectively (p < 0.001, Wilcoxon rank-sum test). Of all hydrocephalus etiologies, pseudotumor cerebri (HR 1.9 [95% CI 1.2–3.1]) and previous shunt malfunction (HR 1.8 [95% CI 1.2–2.7]) were found to significantly increase the risk of shunt revision. Within each diagnosis, there were no significant differences in revision rates between shunts with a fixed valve and shunts with a programmable valve.

CONCLUSIONS

Long-term shunt revision rates are similar for fixed and programmable shunt pressure valves in adult patients. Hydrocephalus etiology may play a significant role in predicting shunt revision, although programmable valves incur higher supply costs regardless of initial diagnosis. Utilization of fixed pressure valves versus programmable pressure valves may reduce supply costs while maintaining similar revision rates. Given the importance of developing cost-effective management protocols, this study highlights the critical need for large-scale prospective observational studies and randomized clinical trials of ventricular shunt valve revisions and additional patient-centered outcomes.

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Xiao Zhu, Michael M. McDowell, William C. Newman, Gary E. Mason, Stephanie Greene and Mandeep S. Tamber

Nivolumab is an immune checkpoint inhibitor (ICI) currently undergoing Phase III clinical trials for the treatment of glioblastoma. The authors present the case of a 10-year-old girl with glioblastoma treated with nivolumab under compassionate-use guidelines. After the first dose of nivolumab the patient developed hemiparesis, cerebral edema, and significant midline shift due to severe tumor necrosis. She was managed using intravenous dexamethasone and discharged on a dexamethasone taper. The patient's condition rapidly deteriorated after the second dose of nivolumab, demonstrating hemiplegia, seizures, and eventually unresponsiveness with a fixed and dilated left pupil. Computed tomography of her brain revealed malignant cerebral edema requiring emergency decompressive hemicraniectomy. Repeat imaging demonstrated increased size of the lesion, reflecting immune-mediated inflammation and tumor necrosis. The patient remained densely hemiplegic, but became progressively more interactive and was ultimately extubated. She resumed nivolumab several weeks later, but again her condition deteriorated with headache, vomiting, swelling at the craniectomy site, and limited right-sided facial movement following the sixth dose. MRI demonstrated severe midline shift and uncal herniation despite her craniectomy. Her condition gradually declined, and she died several days later under “do not resuscitate/do not intubate” orders. To the authors' knowledge, this represents the first case of malignant cerebral edema requiring operative intervention following nivolumab treatment for glioblastoma in a pediatric patient.

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Zachary L. Hickman, Michael M. McDowell, Sunjay M. Barton, Eric S. Sussman, Eli Grunstein and Richard C. E. Anderson

The endoscopic transnasal approach to the rostral pediatric spine and craniovertebral junction is a relatively new technique that provides an alternative to the traditional transoral approach to the anterior pediatric spine. In this case series, the authors provide 2 additional examples of patients undergoing endoscopic transnasal odontoidectomies for ventral decompression of the spinal cord. Both patients would have required transection of the palate to undergo an effective transoral operation, which can be a cause of significant morbidity. In one case, transnasal decompression was initially incomplete, and decompression was successfully achieved via a second endoscopic transnasal operation. Both cases resulted in significant neurological recovery and stable long-term spinal alignment. The transnasal approach benefits from entering into the posterior pharynx at an angle that often reduces the length of postoperative intubation and may speed a patient's return to oral intake. Higher reoperation rates are a concern for many endoscopic approaches, but there are insufficient data to conclude if this is the case for this procedure. Further experience with this technique will provide a better understanding of the indications for which it is most effective. Transcervical and transoral endoscopic approaches have also been reported and provide additional options for pediatric anterior cervical spine surgery.

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Nathan T. Zwagerman, Michael M. McDowell, Ronald L. Hamilton, Edward A. Monaco III, John C. Flickinger and Peter C. Gerszten

OBJECTIVE

Increased survival time after diagnosis of neoplastic disease has resulted in a gradual increase in spine tumor incidence. Radiosurgery is frequently a viable alternative to operative management in a population with severe medical comorbidities. The authors sought to assess the histopathological consequences of radiosurgery in the subset of patients progressing to operative intervention.

METHODS

Eighteen patients who underwent radiosurgery for spine tumors between 2008 and 2014 subsequently progressed to surgical treatment. A histopathological examination of these cases was performed. Indications for surgery included symptomatic compression fractures, radiographic instability, and symptoms of cord or cauda equina compression. Biopsy samples were obtained from the tumor within the radiosurgical zone in all cases and were permanently fixated. Viable tumor samples were stained for Ki 67.

RESULTS

Fifteen patients had metastatic lesions and 3 patients had neurofibromas. The mean patient age was 57 years. The operative indication was symptomatic compression in 10 cases (67%). The most frequent metastatic lesions were breast cancer (4 cases), renal cell carcinoma (3), prostate cancer (2), and endometrial cancer (2). In 9 (60%) of the 15 metastatic cases, histological examination of the lesions showed minimal evidence of inflammation. Viable tumor at the margins of the radiosurgery was seen in 9 (60%) of the metastatic cases. Necrosis in the tumor bed was frequent, as was fibrotic bone marrow. Vascular ectasia was seen in 2 of 15 metastatic cases, but sclerosis with ectasia was frequent. No evidence of malignant conversion was seen in the periphery of the lesions in the 3 neurofibroma cases. In 1 case of neurofibroma, the lesion demonstrated some small areas of remnant tumor in the radiosurgical target zone.

CONCLUSIONS

This case series demonstrates important histopathological characteristics of spinal lesions treated by SRS. Regions with the highest exposure to radiation appear to be densely necrotic and show little evidence of tumor growth, whereas peripheral regions distant from the radiation dosage are more likely to demonstrate viable tumor in malignant and benign neoplasms. Physiological tissue appears to be similarly affected. With additional investigation, a more homogenized field of hypofractionated radiation exposure may allow for tumor obliteration with relative preservation of critical anatomical structures.

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Jennifer L. Perez, Michael M. McDowell, Benjamin Zussman, Ashutosh P. Jadhav, Yosuke Miyashita, Patrick McKiernan and Stephanie Greene

Aneurysmal rupture can result in devastating neurological consequences and can be complicated by comorbid disease processes. Patients with autosomal recessive polycystic kidney disease (ARPKD) have a low rate of reported aneurysms, but this may be due to the relative high rate of end-stage illnesses early in childhood. Authors here report the case of a 10-year-old boy with ARPKD who presented with a Hunt and Hess grade V subarachnoid hemorrhage requiring emergency ventriculostomy, embolization, and decompressive craniectomy. Despite initial improvements in his neurological status, the patient succumbed to hepatic failure. Given the catastrophic outcomes of subarachnoid hemorrhage in young patients, early radiographic screening in those with ARPKD may be warranted.

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Michael M. McDowell, Simon J. Hanft, Sophie A. Greenberg, Rahmatullah Rahmati, Vincent Carrao, Sidney Eisig and Richard C. E. Anderson

The authors report on the surgical management of an extensive lesion of the upper cervical spine that required an uncommon transmandibular approach to facilitate exposure, resection, and stabilization in a pediatric patient. A 6-year-old boy with a large aneurysmal bone cyst of the C-2 vertebra presented with progressive weakness and right-sided neck pain. The lesion extended laterally into the soft tissue of the neck, inferiorly to C-4, and posteriorly around the spinal cord. A transmandibular osteotomy was performed to provide adequate exposure for complete resection of the mass and anterior C1–3 instrumentation and fusion. Subsequently, the patient underwent occiput to C-4 posterior instrumentation and fusion. The patient tolerated the operation well and had regained all function at 3 and 11 months' follow-up. No neurological complications or problems of speech, swallowing, or respiration occurred. Even in pediatric patients, the transmandibular approach for the treatment of upper cervical spine lesions is an effective method of maximizing exposure for complex lesions requiring resection and stabilization.

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Michael M. McDowell, Jason E. Blatt, Christopher P. Deibert, Nathan T. Zwagerman, Zachary J. Tempel and Stephanie Greene

OBJECTIVE

Chiari malformation type II (CM-II) in myelomeningocele is associated with a significant rate of mortality and poor outcome. Death is frequently heralded by the onset or progression of neurological symptoms. The authors sought to identify predictors of poor outcome and mortality within the myelomeningocele population at Children’s Hospital of Pittsburgh.

METHODS

A retrospective chart and radiology review was performed on all infants who underwent primary closure of a myelomeningocele defect at Children’s Hospital of Pittsburgh between the years of 1995 and 2015. Preoperative symptoms and signs leading to CM-II decompression, as well as operative details and postoperative changes in these symptoms and signs, were investigated in detail and correlated to outcome. Poor outcome was defined as death, stridor, or ventilator dependence. Deceased patients were separately assessed within this subgroup.

RESULTS

Thirty-two (21%) of 153 patients were found to have symptomatic CM-II. Of the 32 patients meeting inclusion criteria, 12 (38%) had poor outcomes. Eight patients (25%) died since initial presentation; 5 of these patients (16% of the overall cohort) died within the 1st year of life and 3 (9%) died during adolescence. Seven (88%) of the 8 patients who died had central apnea on presentation (p = 0.001) and 7 (44%) of the 16 patients who developed symptoms in the first 3 months of life died, compared with 1 (6.3%) of 16 who developed symptoms later in childhood (p = 0.04). The median Apgar score at 1 minute was 4.5 for patients who died and 8 for surviving patients (p = 0.006). The median diameter of the myelomeningocele defect was 5.75 cm for patients who died and 5 for those who survived (p = 0.01). The anatomical level of defect trended toward higher levels in patients who died, with 4 patients in that group having an anatomical level at L-2 or higher compared with 5 of the surviving patients (p = 0.001). The median initial head circumference for the 5 patients dying in the 1st year of life was 41.5 cm, versus 34 cm for all other patients (p = 0.01).

CONCLUSIONS

CM-II in spina bifida is associated with a significant mortality rate even when surgical intervention is performed. Death is more frequent in symptomatic patients presenting prior to 1 year of age. Late deaths are associated with symptom progression despite aggressive surgical and medical intervention. In this patient cohort, death was more likely in patients with symptomatic presentation during the first 3 months of life, low Apgar scores, large myelomeningocele defects, early central apnea, and large head circumference at birth.

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Benjamin C. Kennedy, Kathleen M. Kelly, Michelle Q. Phan, Samuel S. Bruce, Michael M. McDowell, Richard C. E. Anderson and Neil A. Feldstein

OBJECT

Symptomatic pediatric Chiari malformation Type I (CM-I) is most often treated with posterior fossa decompression (PFD), but controversy exists over whether the dura needs to be opened during PFD. While dural opening as a part of PFD has been suggested to result in a higher rate of resolution of CM symptoms, it has also been shown to lead to more frequent complications. In this paper, the authors present the largest reported series of outcomes after PFD without dural opening surgery, as well as identify risk factors for recurrence.

METHODS

The authors performed a retrospective review of 156 consecutive pediatric patients in whom the senior authors performed PFD without dural opening from 2003 to 2013. Patient demographics, clinical symptoms and signs, radiographic findings, intraoperative ultrasound results, and neuromonitoring findings were reviewed. Univariate and multivariate regression analyses were performed to determine risk factors for recurrence of symptoms and the need for reoperation.

RESULTS

Over 90% of patients had a good clinical outcome, with improvement or resolution of their symptoms at last follow-up (mean 32 months). There were no major complications. The mean length of hospital stay was 2.0 days. In a multivariate regression model, partial C-2 laminectomy was an independent risk factor associated with reoperation (p = 0.037). Motor weakness on presentation was also associated with reoperation but only with trend-level significance (p = 0.075). No patient with < 8 mm of tonsillar herniation required reoperation.

CONCLUSIONS

The vast majority (> 90%) of children with symptomatic CM-I will have improvement or resolution of symptoms after a PFD without dural opening. A non–dural opening approach avoids major complications. While no patient with tonsillar herniation < 8 mm required reoperation, children with tonsillar herniation at or below C-2 have a higher risk for failure when this approach is used.

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Benjamin C. Kennedy, Taylor B. Nelp, Kathleen M. Kelly, Michelle Q. Phan, Samuel S. Bruce, Michael M. McDowell, Neil A. Feldstein and Richard C. E. Anderson

OBJECT

Chiari malformation Type I (CM-I) is associated with a syrinx in 25%–85% of patients. Although posterior fossa decompression (PFD) without dural opening is an accepted treatment option for children with symptomatic CM-I, many surgeons prefer to open the dura if a syrinx exists. The purpose of this study was to investigate the frequency and timing of syrinx resolution in children undergoing PFD without dural opening for CM-I.

METHODS

A retrospective review of 68 consecutive pediatric patients with CM-I and syringomyelia who underwent PFD without dural opening was conducted. Patient demographics, presenting symptoms and signs, radiographic findings, and intraoperative ultrasound and neuromonitoring findings were studied as well as the patients’ clinical and radiographic follow-up.

RESULTS

During the mean radiographic follow-up period of 32 months, 70% of the syringes improved. Syrinx improvement occurred at a mean of 31 months postoperatively. All patients experienced symptom improvement within the 1st year, despite only 26% of patients showing radiographic improvement during that period. Patients presenting with sensory symptoms or motor weakness had a higher likelihood of having radiographic syrinx improvement postoperatively.

CONCLUSIONS

In children with CM-I and a syrinx undergoing PFD without dural opening, syrinx resolution occurs in approximately 70% of patients. Radiographic improvement of the syrinx is delayed, but this does not correlate temporally with symptom improvement. Sensory symptoms or motor weakness on presentation are associated with syrinx resolution after surgery.