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Ezequiel Goldschmidt, Amir H. Faraji, Brian T. Jankowitz, Paul Gardner and Robert M. Friedlander

Near-infrared (NIR) light is commonly used to map venous anatomy in the upper extremities to gain intravenous access for line placement. In this report, the authors describe the use of a common and commercially available NIR vein finder to delineate the cortical venous anatomy prior to dural opening.

During a variety of cranial approaches, the dura was directly visualized using an NIR vein finder. The NIR light source allowed for recognition of the underlying cortical venous anatomy, dural sinuses, and underlying pathology before the dura was opened. This information was considered when tailoring the dural opening. When the dura was illuminated with the NIR vein finder, the underlying cortical and sinus venous anatomy was evident and correlated with the observed cortical anatomy. The vein finder was also accurate in locating superficial lesions and pathological dural veins. A complete accordance in the findings on the pre– and post–dural opening images was observed in all cases.

This simple, inexpensive procedure is readily compatible with operative room workflow, necessitates no head fixation, and offers a real-time image independent of brain shift.

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Samuel S. Shin, Geoffrey Murdoch, Ronald L. Hamilton, Amir H. Faraji, Hideyuki Kano, Nathan T. Zwagerman, Paul A. Gardner, L. Dade Lunsford and Robert M. Friedlander

OBJECT

Stereotactic radiosurgery (SRS) is a therapeutic option for repeatedly hemorrhagic cavernous malformations (CMs) located in areas deemed to be high risk for resection. During the latency period of 2 or more years after SRS, recurrent hemorrhage remains a persistent risk until the obliterative process has finished. The pathological response to SRS has been studied in relatively few patients. The authors of the present study aimed to gain insight into the effect of SRS on CM and to propose possible mechanisms leading to recurrent hemorrhages following SRS.

METHODS

During a 13-year interval between 2001 and 2013, bleeding recurred in 9 patients with CMs that had been treated using Gamma Knife surgery at the authors' institution. Microsurgical removal was subsequently performed in 5 of these patients, who had recurrent hemorrhages between 4 months and 7 years after SRS. Specimens from 4 patients were available for analysis and used for this report.

RESULTS

Histopathological analysis demonstrated that vascular sclerosis develops as early as 4 months after SRS. In the samples from 2 to 7 years after SRS, sclerotic vessels were prominent, but there were also vessels with incomplete sclerosis as well as some foci of neovascularization.

CONCLUSIONS

Recurrent bleeding after SRS for CM could be related to incomplete sclerosis of the vessels, but neovascularization may also play a role.

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Amir H. Faraji, Kumar Abhinav, Kevin Jarbo, Fang-Cheng Yeh, Samuel S. Shin, Sudhir Pathak, Barry E. Hirsch, Walter Schneider, Juan C. Fernandez-Miranda and Robert M. Friedlander

OBJECT

Brainstem cavernous malformations (CMs) are challenging due to a higher symptomatic hemorrhage rate and potential morbidity associated with their resection. The authors aimed to preoperatively define the relationship of CMs to the perilesional corticospinal tracts (CSTs) by obtaining qualitative and quantitative data using high-definition fiber tractography. These data were examined postoperatively by using longitudinal scans and in relation to patients’ symptomatology. The extent of involvement of the CST was further evaluated longitudinally using the automated “diffusion connectometry” analysis.

METHODS

Fiber tractography was performed with DSI Studio using a quantitative anisotropy (QA)-based generalized deterministic tracking algorithm. Qualitatively, CST was classified as being “disrupted” and/or “displaced.” Quantitative analysis involved obtaining mean QA values for the CST and its perilesional and nonperilesional segments. The contralateral CST was used for comparison. Diffusion connectometry analysis included comparison of patients’ data with a template from 90 normal subjects.

RESULTS

Three patients (mean age 22 years) with symptomatic pontomesencephalic hemorrhagic CMs and varying degrees of hemiparesis were identified. The mean follow-up period was 37.3 months. Qualitatively, CST was partially disrupted and displaced in all. Direction of the displacement was different in each case and progressively improved corresponding with the patient’s neurological status. No patient experienced neurological decline related to the resection. The perilesional mean QA percentage decreases supported tract disruption and decreased further over the follow-up period (Case 1, 26%–49%; Case 2, 35%–66%; and Case 3, 63%–78%). Diffusion connectometry demonstrated rostrocaudal involvement of the CST consistent with the quantitative data.

CONCLUSIONS

Hemorrhagic brainstem CMs can disrupt and displace perilesional white matter tracts with the latter occurring in unpredictable directions. This requires the use of tractography to accurately define their orientation to optimize surgical entry point, minimize morbidity, and enhance neurological outcomes. Observed anisotropy decreases in the perilesional segments are consistent with neural injury following hemorrhagic insults. A model using these values in different CST segments can be used to longitudinally monitor its craniocaudal integrity. Diffusion connectometry is a complementary approach providing longitudinal information on the rostrocaudal involvement of the CST.