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Samuel Moscovici, Felix Umansky and Sergey Spektor

The far-lateral approach (FLA) has become a mainstay for skull base surgeries involving the anterior foramen magnum and lower clivus. The authors present a surgical technique using the FLA for the management of lesions of the anterior/ anterolateral foramen magnum and lower clivus. The authors consider this modification a “lazy” FLA. The vertebral artery (VA) is both a critical anatomical structure and a barrier that limits access to this region. The most important nuance of this FLA technique is the management of this critical vessel. When the lazy FLA is used, the VA is reflected laterally, encased in its periosteal sheath and wrapped in the dura, greatly minimizing the risk for vertebral injury while preserving a wide working space. To accomplish this step, drilling is performed lateral to the point where the VA pierces the dura. The dura is incised medial to the VA entry point by using a slightly curved longitudinal cut. Drilling of the condyle and the C-1 lateral mass is performed in a manner that preserves craniocervical stability. The lazy FLA is a true FLA that is based on manipulation of the VA and lateral bone removal to obtain excellent exposure ventral to the spinal cord and medulla, yet it is among the most conservative FLA techniques for management of the VA and provides a safer window for bone work and lesion management. Among 44 patients for whom this technique was used to resect 42 neoplasms and clip 2 posterior inferior cerebral artery aneurysms, there was no surgical mortality and no injury to the VA.

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Sergey Spektor, Samuel Agus, Vladimir Merkin and Shlomo Constantini

Object. The goal of this paper was to investigate a possible relationship between the consumption of low-dose aspirin (LDA) and traumatic intracranial hemorrhage in an attempt to determine whether older patients receiving prophylactic LDA require special treatment following an incidence of mild-to-moderate head trauma.

Methods. Two hundred thirty-one patients older than 60 years of age, who arrived at the emergency department with a mild or moderate head injury (Glasgow Coma Scale [GCS] Scores 13–15 and 9–12, respectively), were included in the study. One hundred ten patients were receiving prophylactic LDA (100 mg/day) and these formed the aspirin-treated group. One hundred twenty-one patients were receiving no aspirin, and these formed the control group. There was no statistically significant difference between the two groups with respect to age, sex, mechanism of trauma, or GCS score on arrival at the emergency department. Most of the patients sustained the head injury from falls (88.2% of patients in the aspirin-treated group and 85.1% of patients in the control group), and had external signs of head trauma such as bruising or scalp laceration (80.9% of patients in the aspirin-treated group and 86.8% of patients in the control group). All patients underwent similar neurological examinations and computerized tomography (CT) scanning of the head.

The CT scans revealed evidence of traumatic intracranial hemorrhage in 27 (24.5%) patients in the aspirin-treated group and in 31 patients (25.6%) in the control group. Surgical intervention was required for five patients in each group (4.5% of patients in the aspirin-treated group and 4.1% of patients in the control group). A surprising number of the patients who arrived with GCS Score 15 were found to have traumatic intracranial hemorrhage, as revealed by CT scanning (11.5% of patients in the aspirin-treated group and 16.5% of patients in the control group). Surgery, however, was not necessary for any of these patients.

Conclusions. There was no statistically significant difference in the frequency or types of traumatic intracranial hemorrhage between patients who had received aspirin prophylaxis and those who had not. The authors conclude that LDA does not increase surgically relevant parenchymal or meningeal bleeding following moderate and minor head injury in patients older than 60 years of age.

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Sergey Spektor, John M. Gomori, Liana Beni-Adani and Shlomo Constantini

✓ A multilocular extradural cervical spinal hydatid cyst that causes severe spinal cord compression and quadriplegia is relatively rare and difficult to treat. In a patient with this disorder, computerized tomography—guided needle aspiration of the cyst loculations and irrigation using hypertonic saline eliminated the need for emergency surgery and provided complete resolution of the patient's quadriplegia. The subsequent course of the disease was controlled by treatment with albendazole. Magnetic resonance imaging performed 4 months after the procedure demonstrated collapsed cysts and absence of spinal cord compression.

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Felix Umansky, Yigal Shoshan, Guy Rosenthal, Shifra Fraifeld and Sergey Spektor

✓ The long-term or delayed side effects of irradiation on neural tissue are now known to include the induction of new central nervous system neoplasms. However, during the first half of the 20th century, human neural tissue was generally considered relatively resistant to the carcinogenic and other ill effects of ionizing radiation. As a result, exposure to relatively high doses of x-rays from diagnostic examinations and therapeutic treatment was common.

In the present article the authors review the literature relating to radiation-induced meningiomas (RIMs). Emphasis is placed on meningiomas resulting from childhood treatment for primary brain tumor or tinea capitis, exposure to dental x-rays, and exposure to atomic explosions in Hiroshima and Nagasaki. The incidence and natural history of RIMs following exposure to high- and low-dose radiation is presented, including latency, multiplicity, histopathological features, and recurrence rates. The authors review the typical presentation of patients with RIMs and discuss unique aspects of the surgical management of these tumors compared with sporadic meningioma, based on their clinical experience in treating these lesions.

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Moshe Attia, Felix Umansky, Iddo Paldor, Shlomo Dotan, Yigal Shoshan and Sergey Spektor

Object

Surgery for giant anterior clinoidal meningiomas that invade vital neurovascular structures surrounding the anterior clinoid process is challenging. The authors present their skull base technique for the treatment of giant anterior clinoidal meningiomas, defined here as globular tumors with a maximum diameter of 5 cm or larger, centered around the anterior clinoid process, which is usually hyperostotic.

Methods

Between 2000 and 2010, the authors performed 23 surgeries in 22 patients with giant anterior clinoidal meningiomas. They used a skull base approach with extradural unroofing of the optic canal, extradural clinoidectomy (Dolenc technique), transdural debulking of the tumor, early optic nerve decompression, and early identification and control of key neurovascular structures.

Results

The mean age at surgery was 53.8 years. The mean tumor diameter was 59.2 mm (range 50–85 mm) with cavernous sinus involvement in 59.1% (13 of 22 patients). The tumor involved the prechiasmatic segment of the optic nerve in all patients, invaded the optic canal in 77.3% (17 of 22 patients), and caused visual impairment in 86.4% (19 of 22 patients). Total resection (Simpson Grade I or II) was achieved in 30.4% of surgeries (7 of 23); subtotal and partial resections were each achieved in 34.8% of surgeries (8 of 23). The main factor precluding total removal was cavernous sinus involvement. There were no deaths. The mean Glasgow Outcome Scale score was 4.8 (median 5) at a mean of 56 months of follow-up. Vision improved in 66.7% (12 of 18 patients) with consecutive neuroophthalmological examinations, was stable in 22.2% (4 of 18), and deteriorated in 11.1% (2 of 18). New deficits in cranial nerve III or IV remained after 8.7% of surgeries (2 of 23).

Conclusions

This modified surgical protocol has provided both a good extent of resection and a good neurological and visual outcome in patients with giant anterior clinoidal meningiomas.

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Reuben R. Shamir, Moti Freiman, Leo Joskowicz, Sergey Spektor and Yigal Shoshan

Object

Surface-based registration (SBR) with facial surface scans has been proposed as an alternative for the commonly used fiducial-based registration in image-guided neurosurgery. Recent studies comparing the accuracy of SBR and fiducial-based registration have been based on a few targets located on the head surface rather than inside the brain and have yielded contradictory conclusions. Moreover, no visual feedback is provided with either method to inform the surgeon about the estimated target registration error (TRE) at various target locations. The goals in the present study were: 1) to quantify the SBR error in a clinical setup, 2) to estimate the targeting error for many target locations inside the brain, and 3) to create a map of the estimated TRE values superimposed on a patient's head image.

Methods

The authors randomly selected 12 patients (8 supine and 4 in a lateral position) who underwent neurosurgery with a commercial navigation system. Intraoperatively, scans of the patients' faces were acquired using a fast 3D surface scanner and aligned with their preoperative MR or CT head image. In the laboratory, the SBR accuracy was measured on the facial zone and estimated at various intracranial target locations. Contours related to different TREs were superimposed on the patient's head image and informed the surgeon about the expected anisotropic error distribution.

Results

The mean surface registration error in the face zone was 0.9 ± 0.35 mm. The mean estimated TREs for targets located 60, 105, and 150 mm from the facial surface were 2.0, 3.2, and 4.5 mm, respectively. There was no difference in the estimated TRE between the lateral and supine positions. The entire registration procedure, including positioning of the scanner, surface data acquisition, and the registration computation usually required < 5 minutes.

Conclusions

Surface-based registration accuracy is better in the face and frontal zones, and error increases as the target location lies further from the face. Visualization of the anisotropic TRE distribution may help the surgeon to make clinical decisions. The observed and estimated accuracies and the intraoperative registration time show that SBR using the fast surface scanner is practical and feasible in a clinical setup.

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Ziv Gil, Avraham Abergel, Sergey Spektor, Esther Shabtai, Avi Khafif and Dan M. Fliss

Object. The goal of this study was to develop a disease-specific, multidimensional quality of life (QOL) assessment instrument for patients undergoing surgical extirpation of anterior skull base tumors.

Methods. This investigation included 35 patients who had been surgically treated for more than 3 months before the study was begun. Relevant QOL questions were generated from a review of the literature and interviews with health professionals, patients, and their caregivers. The initial multidimensional, 80-item questionnaire was reduced to a 35-item questionnaire by using standard psychometric criteria. Six relevant domains were identified using factor analysis: performance, physical function, vitality, pain, specific symptoms, and influence on emotions. The internal consistency of the instrument had a correlation coefficient of 0.8 and a reliability coefficient (test—retest reliability) of 0.9. The validity of the construct was assessed by testing whether the clinical variable of the patient influenced his QOL domain score as hypothesized. Patients older than 60 years of age had significantly poorer scores in the domains of performance and physical function than younger patients. Patients with malignant tumors had significantly poorer scores in the domains of specific symptoms, influence on emotions, physical function, and performance compared with patients with benign tumors. Radiotherapy was associated with poorer scores in the domains of specific symptoms and influence on emotions. Comorbidity was associated with poor physical function scores. Using the final questionnaire, we prospectively evaluated the QOL of 12 additional patients before they underwent surgery and again between 5 and 6 months postoperatively to test the utility and validity of the instrument further. Again, significantly poorer QOL scores were recorded for patients with malignancy.

Conclusions. The proposed questionnaire appears to be sufficiently reliable and valid in estimating a patient's QOL after extirpation of anterior skull base tumors. The instrument can be used in face-to-face interviews and via electronic or regular mail.

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Sergey Spektor, Gerald Weinberger, Shlomo Constantini, John M. Gomori and Liana Beni-Adani

✓ A case of giant lateral sinus pericranii, which presented in a patient during early childhood as a soft, collapsible mass and gradually grew until it reached 13 × 9 cm when the patient was 36 years of age, is reported. The patient underwent successful surgery and the lesion was totally excised. The results of diagnostic tests (computerized tomography scanning, magnetic resonance imaging, cerebral angiography, and sinusography) and surgery-related problems are presented and discussed.

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Sergey Spektor, Gregory J. Anderson, Sean O. McMenomey, Michael A. Horgan, Jordi X. Kellogg and Johnny B. Delashaw Jr.

Object. The purpose of this study was to evaluate the far-lateral transcondylar transtubercular approach (complete FLA) based on quantitative measurements of the exposure of the foramen magnum and petroclival area obtained after each successive step of this approach.

Methods. The complete FLA was reproduced in eight specially prepared cadaveric heads (a total of 15 sides). The approach was divided into six steps: 1) C-1 hemilaminectomy and suboccipital craniectomy with unroofing of the sigmoid sinus (basic FLA); 2) partial resection of the occipital condyle (up to the hypoglossal canal); 3) removal of the jugular tuberculum; 4) mastoidectomy (limited to the labyrinth and the fallopian canal) and retraction of the sigmoid sinus; 5) resection of the lateral mass of C-1 with mobilization of the vertebral artery; and 6) resection of the remaining portion of the occipital condyle. After each successive step, a standard set of measurements was obtained using a frameless stereotactic device. The measurements were used to estimate two parameters: the size of the exposed petroclival area and the size of a spatial cone directed toward the anterior rim of the foramen magnum, which depicts the amount of surgical freedom available for manipulation of instruments.

The initial basic FLA provided exposure of only 21 ± 6% of the petroclival area that was exposed with the full, six-step maximally aggressive (complete) FLA. Likewise, only 18 ± 9% of the final surgical freedom was obtained after the basic FLA was performed. Each subsequent step of the approach increased both petroclival exposure and surgical freedom. The most dramatic increase in petroclival exposure was noted after removal of the jugular tuberculum (71 ± 12% of final exposure), whereas the least improvement in exposure occurred after the final step, which consisted of total condyle resection.

Conclusions. The complete FLA provides wide and sufficient exposure of the foramen magnum and lower to middle clivus. The complete FLA consists of several steps, each of which contributes to increasing petroclival exposure and surgical freedom. However, the FLA may be limited to the less aggressive steps, while still achieving significant exposure and surgical freedom. The choice of complete or basic FLA thus depends on the underlying pathological condition and the degree of exposure required for effective surgical treatment.