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Philip E. Stieg

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Kai U. Frerichs, Philip E. Stieg and Robert M. Friedlander

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Alireza Shoakazemi, Alexander I. Evins, Justin C. Burrell, Philip E. Stieg and Antonio Bernardo

OBJECT

Surgical approaches to deep-seated brain pathologies, specifically lesions of the third ventricle, have always been a challenge for neurosurgeons. In certain cases, the transcallosal approach remains the most suitable option for targeting lesions of the third ventricle, although retraction of the fornices and wall of the third ventricle have been associated with neuropsychological and hypothalamic deficits. The authors investigated the feasibility of an interhemispheric 3D endoscopic transcallosal approach through a minimally invasive tubular retractor system for the management of third ventricular lesions.

METHODS

Three-dimensional endoscopic transtubular transcallosal approaches were performed on 5 preserved cadaveric heads (10 sides). A parasagittal bur hole was placed using neuronavigation, and a tubular retractor was inserted under direct endoscopic visualization. Following observation of the vascular structures, fenestration of the corpus callosum was performed and the retractor was advanced through the opening. Transforaminal, interforniceal, and transchoroidal modifications were all performed and evaluated by 3 surgeons.

RESULTS

This approach provided enhanced visualization of the third ventricle and more stable retraction of corpus callosum and fornices. Bayonetted instruments were used through the retractor without difficulty, and the retractor applied rigid, constant, and equally distributed pressure on the corpus callosum.

CONCLUSIONS

A transtubular approach to the third ventricle is feasible and facilitates blunt dissection of the corpus callosum that may minimize retraction injury. This technique also provides an added degree of safety by limiting the free range of instrumental movement. The combination of 3D endoscopic visualization with a clear plastic retractor facilitates safe and direct monitoring of the surgical corridor.

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Malte Ottenhausen, Imithri Bodhinayake, Matei A. Banu, Philip E. Stieg and Theodore H. Schwartz

In 1955, Vincent du Vigneaud (1901–1978), the chairman of the Department of Biochemistry at Cornell University Medical College, was awarded the Nobel Prize for Chemistry for his research on insulin and for the first synthesis of the posterior pituitary hormones—oxytocin and vasopressin. His tremendous contribution to organic chemistry, which began as an interest in sulfur-containing compounds, paved the way for a better understanding of the pituitary gland and for the development of diagnostic and therapeutic tools for diseases of the pituitary. His seminal research continues to impact neurologists, endocrinologists, and neurosurgeons, and enables them to treat patients who had no alternatives prior to du Vigneaud’s breakthroughs in peptide structure and synthesis. The ability of neurosurgeons to aggressively operate on parasellar pathology was directly impacted and related to the ability to replace these hormones after surgery. The authors review the life and career of Vincent du Vigneaud, his groundbreaking discoveries, and his legacy of the understanding and treatment of the pituitary gland in health and disease.

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Peter F. Morgenstern, Caitlin E. Hoffman, Gary Kocharian, Ranjodh Singh, Philip E. Stieg and Mark M. Souweidane

OBJECT

The optimal method for detecting recurrent arteriovenous malformations (AVMs) in children is unknown. An inherent preference exists for MR angiography (MRA) surveillance rather than arteriography. The validity of this strategy is uncertain.

METHODS

A retrospective chart review was performed on pediatric patients treated for cerebral AVMs at a single institution from 1998 to 2012. Patients with complete obliteration of the AVM nidus after treatment and more than 12 months of follow-up were included in the analysis. Data collection focused on recurrence rates, associated risk factors, and surveillance methods.

RESULTS

A total of 45 patients with a mean age of 11.7 years (range 0.5–18 years) were treated for AVMs via surgical, endovascular, radiosurgical, or combined approaches. Total AVM obliteration on posttreatment digital subtraction angiography (DSA) was confirmed in 27 patients, of whom the 20 with more than 12 months of follow-up were included in subsequent analysis. The mean follow-up duration in this cohort was 5.75 years (median 5.53 years, range 1.11–10.64 years). Recurrence occurred in 3 of 20 patients (15%). Two recurrences were detected by surveillance DSA and 1 at the time of rehemorrhage. No recurrences were detected by MRA. Median time to recurrence was 33.6 months (range 19–71 months). Two patients (10%) underwent follow-up DSA, 5 (25%) had DSA and MRI/MRA, 9 (45%) had MRI/MRA only, 1 (5%) had CT angiography only, and 3 (15%) had no imaging within the first 3 years of follow-up. After 5 years posttreatment, 2 patients (10%) were followed with MRI/MRA only, 2 (10%) with DSA only, and 10 (50%) with continued DSA and MRI/MRA.

CONCLUSIONS

AVM recurrence in children occurred at a median of 33.6 months, when MRA was more commonly used for surveillance, but failed to detect any recurrences. A recurrence rate of 15% may be an underestimate given the reliance on surveillance MRA over angiography. A new surveillance strategy is proposed, taking into account exposure to diagnostic radiation and the potential for catastrophic rehemorrhage.

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Michael A. Cohen, Alexander I. Evins, Gennaro Lapadula, Leopold Arko, Philip E. Stieg and Antonio Bernardo

OBJECTIVE

The rectus capitis lateralis (RCL) is a small posterior cervical muscle that originates from the transverse process of C-1 and inserts onto the jugular process of the occipital bone. The authors describe the RCL and its anatomical relationships, and discuss its utility as a surgical landmark for safe exposure of the jugular foramen in extended or combined skull base approaches. In addition, the condylar triangle is defined as a landmark for localizing the vertebral artery (VA) and occipital condyle.

METHODS

Four cadaveric heads (8 sides) were used to perform far-lateral, extended far-lateral, combined transmastoid infralabyrinthine transcervical, and combined far-lateral transmastoid infralabyrinthine transcervical approaches to the jugular foramen. On each side, the RCL was dissected, and its musculoskeletal, vascular, and neural relationships were examined.

RESULTS

The RCL lies directly posterior to the internal jugular vein—only separated by the carotid sheath and in some cases cranial nerve (CN) XI. The occipital artery travels between the RCL and the posterior belly of the digastric muscle, and the VA passes medially to the RCL as it exits the C-1 foramen transversarium and courses posteriorly toward its dural entrance. CNs IX–XI exit the jugular foramen directly anterior to the RCL. To provide a landmark for identification of the occipital condyle and the extradural VA without exposure of the suboccipital triangle, the authors propose and define a condylar triangle that is formed by the RCL anteriorly, the superior oblique posteriorly, and the occipital bone superiorly.

CONCLUSIONS

The RCL is an important surgical landmark that allows for early identification of the critical neurovascular structures when approaching the jugular foramen, especially in the presence of anatomically displacing tumors. The condylar triangle is a novel and useful landmark for identifying the terminal segment of the hypoglossal canal as well as the superior aspect of the VA at its exit from the C-1 foramen transversarium, without performing a far-lateral exposure.

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J. Levi Chazen, Harini Sarva, Philip E. Stieg, Robert J. Min, Douglas J. Ballon, Kane O. Pryor, Paul M. Riegelhaupt and Michael G. Kaplitt

OBJECTIVE

The objective of this study was to evaluate the utility of diffusion tensor imaging (DTI) tractography–based targeting of the dentatorubrothalamic tract (DRT) for magnetic resonance–guided focused ultrasound (MRgFUS) thalamotomy in patients with essential tremor (ET) and correlate postprocedural tract disruption with clinical outcomes.

METHODS

Four patients received preprocedural and immediate postprocedural DTI in addition to traditional anatomical MRI sequences for MRgFUS thalamotomy. Optimal ablation sites were selected based on the patient-specific location of the DRT as demonstrated by DTI (direct targeting) and correlated with traditional atlas-based measurements for thalamic ventral intermediate nucleus (Vim) lesioning (indirect targeting). Fiber tracts were displayed three-dimensionally during the procedure and used in conjunction with clinical signs of tremor control for fine correction of the ablation site. Immediately following the conclusion of the procedure, the MRgFUS head frame was removed and patients were placed in a 32-channel MRI head coil for follow-up DTI and anatomical MRI sequences.

RESULTS

All patients had excellent postoperative tremor control and successful pre- and postprocedural DTI fiber tracking of the corticospinal tract, medial lemniscus, and DRT. Immediate postprocedure DTI failed to track the DRT ipsilateral to the lesion site with a preserved contralateral DRT, coincident with substantial resolution of contralateral tremor.

CONCLUSIONS

DTI can reliably identify the optimal ablation target and demonstrates tract disruption on immediate postprocedural imaging. A clinical improvement of ET was observed immediately following the procedure, correlating with DRT disruption and suggesting that interruption of the DRT is a consequence of clinically successful MRgFUS thalamotomy. These findings may have utility for both MRgFUS procedure planning in surgically naive patients and retreatment of patients who have previously undergone unsuccessful thalamic Vim lesioning.

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Sacit Bulent Omay, Yu-Ning Chen, Joao Paulo Almeida, Armando Saul Ruiz-Treviño, John A. Boockvar, Philip E. Stieg, Jeffrey P. Greenfield, Mark M. Souweidane, Ashutosh Kacker, David J. Pisapia, Vijay K. Anand and Theodore H. Schwartz

OBJECTIVE

Exome sequencing studies have recently demonstrated that papillary craniopharyngiomas (PCPs) and adamantinomatous craniopharyngiomas (ACPs) have distinct genetic origins, each primarily driven by mutually exclusive alterations: either BRAF (V600E), observed in 95% of PCPs, or CTNNB1, observed in 75%–96% of ACPs. How the presence of these molecular signatures, or their absence, correlates with clinical, radiographic, and outcome variables is unknown.

METHODS

The pathology records for patients who underwent surgery for craniopharyngiomas between May 2000 and March 2015 at Weill Cornell Medical College were reviewed. Craniopharyngiomas were identified and classified as PCP or ACP. Patients were placed into 1 of 3 groups based on their genomic mutations: BRAF mutation only, CTNNB1 mutation only, and tumors with neither of these mutations detected (not detected [ND]). Demographic, radiological, and clinical variables were collected, and their correlation with each genomic group was tested.

RESULTS

Histology correlated strongly with mutation group. All BRAF tumors with mutations were PCPs, and all CTNNB1 with mutations and ND tumors were ACPs. Preoperative and postoperative clinical symptoms and radiographic features did not correlate with any mutation group. There was a statistically significant relationship (p = 0.0323) between the age group (pediatric vs adult) and the mutation groups. The ND group tumors were more likely to involve the sella (p = 0.0065).

CONCLUSIONS

The mutation signature in craniopharyngioma is highly predictive of histology. The subgroup of tumors in which these 2 mutations are not detected is more likely to occur in children, be located in the sella, and be of ACP histology.

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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.