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Rohan Ramakrishna, Jeffrey C. Mai, Tanya Filardi, Samuel R. Browd and Richard G. Ellenbogen

This 18-year-old woman presented with symptoms of right upper-extremity ataxia and imaging evidence of syringomyelia and an acquired Chiari malformation after a previous suboccipital decompression for cerebellar hemorrhage. The patient underwent posterior fossa reexploration to detether any adhesions and release scar tissue in the fourth ventricular outlet. Her symptoms of syringomyelia resolved but she then developed symptoms of lethargy, confusion, and amnesia in addition to ataxia. Repeat neural axis imaging revealed resolution of the syrinx but prominent brainstem hypertrophy. Eventually, the placement of a ventriculoperitoneal shunt resulted in the resolution of both symptoms and brainstem hypertrophy. In the present article, the authors elaborate on this first reported case of a reversible brainstem hypertrophy responsive to CSF shunting.

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Rohan Ramakrishna, Shaan M. Raza, Michael Kupferman, Ehab Hanna and Franco DeMonte

OBJECT

Adenoid cystic carcinoma (ACC) is a locally aggressive tumor of salivary gland origin. Little data exist to guide treatment when this tumor extends to involve the structures of the skull base.

METHODS

Fifty-one patients with a diagnosis of ACC affecting the skull base were identified from a prospective database at MD Anderson Cancer Center (from 1992 to 2010).

RESULTS

Median follow-up for study patients was 6.75 years. The 5- and 10-year overall survival (OS) rates were 78% and 50%, respectively. Sixty-six percent of patients had progression of their disease. The 5- and 10-year progression-free survival (PFS) rates were 46.7% and 21.0%, respectively. Gross-total resection was achieved in 75% of patients, with 49% having microscopically negative margins at the time of first operation. On univariate analysis, resections with microscopically negative margins were associated with a significant OS advantage (20.1 ± 3.3 years) compared with resections that left residual disease, even if microscopic (10.3 ± 1.6 years, p = 0.035). In patients who underwent reoperation, the effect persisted, with improved OS in those with negative margins (21.4 ± 0.0 vs 16.7 ± 4.0 years, p = 0.06). The use of adjuvant radiotherapy was associated with an OS advantage (16.2 ± 2.5 vs 5.5 ± 2.2 years, p = 0.03) at initial diagnosis and improved PFS (7.8 ± 1.0 vs 2.1 ± 0.62 years, p = 0.005), whereas repeat irradiation provided no benefit. The use of adjuvant chemotherapy at diagnosis or at recurrence was not associated with any significant advantage. Multivariate analysis revealed margin-negative resection at initial operation and at recurrence retained OS significance, even after controlling for age, radiation therapy, and T stage.

CONCLUSIONS

ACC of the skull base is best treated with a multidisciplinary approach aimed at maximal, safe resection. Adjuvant radiotherapy should be offered, whereas chemotherapy does not confer benefit.

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Jonathan P. S. Knisely, Rohan Ramakrishna and Theodore H. Schwartz

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Ryan P. Morton, Renee M. Reynolds, Rohan Ramakrishna, Michael R. Levitt, Richard A. Hopper, Amy Lee and Samuel R. Browd

Object

In this study, the authors describe their experience with a low-dose head CT protocol for a preselected neurosurgical population at a dedicated pediatric hospital (Seattle Children's Hospital), the largest number of patients with this protocol reported to date.

Methods

All low-dose head CT scans between October 2011 and November 2012 were reviewed. Two different low-dose radiation dosages were used, at one-half or one-quarter the dose of a standard head CT scan, based on patient characteristics agreed upon by the neurosurgery and radiology departments. Patient information was also recorded, including diagnosis and indication for CT scan.

Results

Six hundred twenty-four low-dose head CT procedures were performed within the 12-month study period. Although indications for the CT scans varied, the most common reason was to evaluate the ventricles and catheter placement in hydrocephalic patients with shunts (70%), followed by postoperative craniosynostosis imaging (12%). These scans provided adequate diagnostic imaging, and no patient required a follow-up full-dose CT scan as a result of poor image quality on a low-dose CT scan. Overall physician comfort and satisfaction with interpretation of the images was high. An additional 2150 full-dose head CT scans were performed during the same 12-month time period, making the total number of CT scans 2774. This value compares to 3730 full-dose head CT scans obtained during the year prior to the study when low-dose CT and rapid-sequence MRI was not a reliable option at Seattle Children's Hospital. Thus, over a 1-year period, 22% of the total CT scans were able to be converted to low-dose scans, and full-dose CT scans were able to be reduced by 42%.

Conclusions

The implementation of a low-dose head CT protocol substantially reduced the amount of ionizing radiation exposure in a preselected population of pediatric neurosurgical patients. Image quality and diagnostic utility were not significantly compromised.

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Erratum

Brain oxygen tension and outcome in patients with aneurysmal subarachnoid hemorrhage

Rohan Ramakrishna, Michael Stiefel, Joshua Udoetuk, Alejandro Spiotta, Joshua M. Levine, W. Andrew Kofke, Eric Zager, Wei Yang and Peter Le Roux

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Shaan M. Raza, Rohan Ramakrishna, Randal S. Weber, Michael E. Kupferman, Paul W. Gidley, Ehab Y. Hanna and Franco DeMonte

OBJECT

A relative paucity of information exists regarding outcomes from craniofacial resection for advanced nonmelanoma skin cancers involving the skull base. In light of advances in surgical technique and adjuvant therapy protocols, the authors reviewed their surgical experience to determine disease control rates, overall survival (OS), morbidity, and mortality.

METHODS

A retrospective review of 24 patients with nonmelanoma cutaneous cancers with skull base involvement treated with craniofacial resection at The University of Texas MD Anderson Cancer Center from 1994 to 2012 was performed. Of these patients, 19 (79%) had squamous cell carcinoma (SCC), 4 (17%) had basosquamous carcinoma (BSCC), and 1 patient (4%) had adenocarcinoma. Factors as assessed were prior treatment, TNM staging, tumor involvement, extent of intracranial extension, margin status, postoperative complications, recurrence, disease status at last follow-up, and long-term survival. The majority of tumors were T4 (67%) according to the TNM classification; perineural extension was noted in 58%, cavernous sinus involvement in 25%, and dural involvement in 29%.

RESULTS

Postoperative complications occurred in 4 patients (17%) including 1 death. Kaplan-Meier estimates were calculated for OS and progression-free survival (PFS). Median OS was 43.2 months with an 82% 1-year OS and 37% 5-year OS; the median PFS was 91.2 months. Margin status was positively associated with median OS in SCC (91 months [for negative margins] vs 57 months, p = 0.8) and in BSCC (23.7 vs 3.2 months, p < 0.05). Postoperative radiotherapy was associated with improved median OS (43.2 vs 22 months, p = 0.6). Brain involvement was uniformly fatal after 1 year, while cavernous sinus involvement (31 vs 43 months, p = 0.82), perineural disease (31 vs 54 months, p = 0.30), and T4 stage (22 vs 91.2 months, p = 0.09) were associated with worsened OS. Similar associations were found with median PFS.

CONCLUSIONS

Aggressive multimodality management with surgery and postoperative radiotherapy can positively impact locoregional control and OS. With improvements in technique and adjuvant therapy protocols, treatment can still be considered in situations of perineural disease and cavernous sinus involvement and as a salvage option for patients in whom prior treatment has failed. As patients with advanced NMSCs often have few options, craniofacial resection, as part of a coordinated multimodal management plan, is justified if it can be performed safely.

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Iyan Younus, Mina M. Gerges, Saniya S. Godil, Rafael Uribe-Cardenas, Georgiana A. Dobri, Rohan Ramakrishna and Theodore H. Schwartz

OBJECTIVE

Postoperative sellar hematoma is an uncommon complication of endonasal endoscopic transsphenoidal surgery (EETS) for pituitary adenoma that often requires emergency surgical evacuation. Sellar hematomas can cause mass effect and compress parasellar structures, leading to clinically significant symptoms such as visual impairment and severe headache. The objective of this study was to determine the incidence and risk factors associated with reoperation for postoperative hematoma after EETS for pituitary adenoma.

METHODS

The authors reviewed a prospectively acquired database of EETS for pituitary adenoma over 13 years at Weill Cornell Medicine, NewYork-Presbyterian Hospital and identified cases that required reoperation for confirmed hematoma. They also reviewed clinical and radiographic data of a consecutive series of patients undergoing EETS for pituitary adenoma who did not have postoperative hematoma, which served as the control group. Demographic data and risk factors were compared between the groups using univariate and multivariate analyses via binary logistic regression.

RESULTS

Among a cohort of 583 patients undergoing EETS for pituitary adenoma, 9 patients (1.5%) required operation for sellar hematoma evacuation. All 9 patients with reoperation for sellar hematoma presented with worsening in their vision, and severe headache was present in 67%. New postoperative endocrine dysfunction developed in 78%. Clot evacuation improved vision in 88%. The mean time to hematoma evacuation was 4.5 days. The median length of stay for patients with sellar hematoma was 8 days (range 4–210 days) compared with a median length of stay of 3 days (range 1–32 days) for the control patients (p < 0.005). Significant risk factors in univariate analysis were tumor diameter ≥ 30 mm (p < 0.005), suprasellar extension (p < 0.005), tumor volume (p < 0.005), cavernous sinus invasion (p < 0.05), gonadotroph histology (p < 0.05), antiplatelet use (p < 0.05), and elevated BMI (p < 0.05). On multivariate analysis, tumor diameter ≥ 30 mm (OR 4.555, CI 1.30–28.90; p < 0.05) and suprasellar extension (OR 1.048, CI 1.01–1.10; p < 0.05) were found to be the only independent predictors of sellar hematoma. The incidence of hematoma in tumors ≥ 30 mm was 5% (7/139).

CONCLUSIONS

Postoperative sellar hematoma requiring reoperation is a rare phenomenon after transsphenoidal surgery, often presenting with visual loss and headache. Clot evacuation results in improvement in vision, but long-term endocrinopathy often ensues. Tumor diameter ≥ 30 mm and suprasellar extent are the most reliable risk factors. Close postoperative scrutiny should be given to patients at high risk.

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Swathi Chidambaram, Susan C. Pannullo, Michelle Roytman, David J. Pisapia, Benjamin Liechty, Rajiv S. Magge, Rohan Ramakrishna, Philip E. Stieg, Theodore H. Schwartz and Jana Ivanidze

OBJECTIVE

There is a need for advanced imaging biomarkers to improve radiation treatment planning and response assessment. T1-weighted dynamic contrast-enhanced perfusion MRI (DCE MRI) allows quantitative assessment of tissue perfusion and blood-brain barrier dysfunction and has entered clinical practice in the management of primary and secondary brain neoplasms. The authors sought to retrospectively investigate DCE MRI parameters in meningiomas treated with resection and adjuvant radiation therapy using volumetric segmentation.

METHODS

A retrospective review of more than 300 patients with meningiomas resected between January 2015 and December 2018 identified 14 eligible patients with 18 meningiomas who underwent resection and adjuvant radiotherapy. Patients were excluded if they did not undergo adjuvant radiation therapy or DCE MRI. Demographic and clinical characteristics were obtained and compared to DCE perfusion metrics, including mean plasma volume (v p), extracellular volume (v e), volume transfer constant (K trans), rate constant (k ep), and wash-in rate of contrast into the tissue, which were derived from volumetric analysis of the enhancing volumes of interest.

RESULTS

The mean patient age was 64 years (range 49–86 years), and 50% of patients (7/14) were female. The average tumor volume was 8.07 cm3 (range 0.21–27.89 cm3). The median Ki-67 in the cohort was 15%. When stratified by median Ki-67, patients with Ki-67 greater than 15% had lower median v p (0.02 vs 0.10, p = 0.002), and lower median wash-in rate (1.27 vs 4.08 sec−1, p = 0.04) than patients with Ki-67 of 15% or below. Logistic regression analysis demonstrated a statistically significant, moderate positive correlation between v e and time to progression (r = 0.49, p < 0.05). Furthermore, there was a moderate positive correlation between K trans and time to progression, which approached, but did not reach, statistical significance (r = 0.48, p = 0.05).

CONCLUSIONS

This study demonstrates a potential role for DCE MRI in the preoperative characterization and stratification of meningiomas, laying the foundation for future prospective studies incorporating DCE as a biomarker in meningioma diagnosis and treatment planning.

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M. Nathan Nair, Rohan Ramakrishna, Kit Song, Gregory Kinney, Jefferson Slimp, Andrew L. Ko and Anthony M. Avellino

Motor evoked potential (MEP) monitoring has been used increasingly in conjunction with somatosensory evoked potential monitoring to monitor neurological changes during complex spinal operations. No published report has demonstrated the effects of segmental spinal cord transection on MEP monitoring.

The authors describe the case of an 11-year-old girl with lumbar myelomeningocele and worsening thoracolumbar scoliosis who underwent a T11–L5 fusion and spinal transection to prevent tethering. Intraoperative MEP and somatosensory evoked potential monitoring were performed, and the spinal cord was transected in 4 quadrants. The MEPs were lost unilaterally as each anterior quadrant was sectioned.

This is the first reported case that demonstrates the link between spinal cord transection and MEP signaling characteristics. Furthermore, it demonstrates the relatively minor input of the ipsilateral ventral corticospinal tract in MEP physiology at the thoracolumbar junction. Finally, this study further supports the use of MEPs as a specific intraoperative neuromonitoring tool.

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A. Gabriella Wernicke, Andrew W. Smith, Shoshana Taube, Menachem Z. Yondorf, Bhupesh Parashar, Samuel Trichter, Lucy Nedialkova, Albert Sabbas, Paul Christos, Rohan Ramakrishna, Susan C. Pannullo, Philip E. Stieg and Theodore H. Schwartz

OBJECTIVE

Managing patients whose intraparenchymal brain metastases recur after radiotherapy remains a challenge. Intraoperative cesium-131 (Cs-131) brachytherapy performed at the time of neurosurgical resection may represent an excellent salvage treatment option. The authors evaluated the outcomes of this novel treatment with permanent intraoperative Cs-131 brachytherapy.

METHODS

Thirteen patients with 15 metastases to the brain that recurred after stereotactic radiosurgery and/or whole brain radiotherapy were treated between 2010 and 2015. Stranded Cs-131 seeds were placed as a permanent volume implant. Prescription dose was 80 Gy at 5-mm depth from the resection cavity surface. The primary end point was resection cavity freedom from progression (FFP). Resection cavity freedom from progression (FFP), regional FFP, distant FFP, median survival, overall survival (OS), and toxicity were assessed.

RESULTS

The median duration of follow-up after salvage treatment was 5 months (range 0.5–18 months). The patients' median age was 64 years (range 51–74 years). The median resected tumor diameter was 2.9 cm (range 1.0–5.6 cm). The median number of seeds implanted was 19 (range 10–40), with a median activity per seed of 2.25 U (range 1.98–3.01 U) and median total activity of 39.6 U (range 20.0–95.2 U). The 1-year actuarial local FFP was 83.3%. The median OS was 7 months, and 1-year OS was 24.7%. Complications included infection (3), pseudomeningocele (1), seizure (1), and asymptomatic radionecrosis (RN) (1).

CONCLUSIONS

After failure of prior irradiation of brain metastases, re-irradiation with intraoperative Cs-131 brachytherapy implants provides durable local control and limits the risk of RN. The authors' initial experience demonstrates that this treatment approach is well tolerated and safe for patients with previously irradiated tumors after failure of more than 1 radiotherapy regimen and that it results in excellent response rates and minimal toxicity.