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Anil Nanda, Boleslaw Liwnicz, Barbara F. Atkinson, Ben-Ami Sela, Hiroshi Takahashi, Paul H. Belser, Perry Black, Hilary Koprowski, and Dorothee Herlyn

✓ Monoclonal antibodies (MAb's) reactive with human malignant glioma cells were derived from mice inoculated with cells from fresh glioma tissue. Seven MAb's were selected for study based on their high-level binding in immunoperoxidase and immunofluorescence assay to most of the glioma tissues derived from various patients and based on the absence of binding to normal bone marrow cells. Four of the seven MAb's did not bind to any of the four normal brain tissues tested, whereas three MAb's bound to one or two of these tissues. Two MAb's bound to the surfaces of cultured glioma cells in radioimmunoassay. One of these MAb's (AS-AY1, immunoglobulin (Ig)G1) lysed cultured glioma cells with human lymphocytes or murine macrophages as effector cells; the other MAb (AS-AY2, IgM) was reactive in complement-dependent cytotoxicity assay. These two MAb's therefore seem especially promising reagents in approaches to immunotherapy of human malignant glioma.

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Laligam N. Sekhar, Anil Nanda, Chandra N. Sen, Carl N. Snyderman, and Ivo P. Janecka

✓ The extended frontal approach is a modification of the transbasal approach of Derome. The addition of a bilateral orbitofrontal or orbitofrontoethmoidal osteotomy improves the exposure of midline lesions of the anterior, middle, and posterior skull base, while minimizing the need for frontal lobe retraction. The authors present a 5-year experience with 49 patients operated on via the extended frontal approach. In seven patients, the extended frontal approach was used alone; in the remaining 42, it was combined with other skull base approaches. Highly malignant tumors were removed en bloc, whereas benign tumors and low-grade malignancies were removed either en bloc or piecemeal. Reconstruction was usually performed using fascia lata, a pericranial flap, and/or autologous fat. A temporalis muscle flap or a distant microvascular free flap was required for some patients.

One patient died 1 month postoperatively due to superior mesenteric artery thrombosis. Three patients had postoperative infections, two had cerebrospinal fluid leaks requiring reoperation, and four had brain contusions or hematomas. All but two patients recovered to their preoperative functional level. After an average follow-up period of 26 months (range 6 to 56 months), 64% of patients with benign lesions, 64% of patients with low-grade malignancies, and 44% of patients with high-grade lesions were alive with no evidence of disease.

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Prasad S. S. V. Vannemreddy, Marjorie Fowler, Richard S. Polin, John R. Todd, and Anil Nanda

✓ Malignant glioma is the most common primary brain neoplasm, but generally it is not included in the differential diagnosis of enhancing lesions of the central nervous system (CNS) in patients suffering from acquired immunodeficiency syndrome. We report a case of glioblastoma multiforme (GBM) in a 29-year-old man with human immunodeficiency virus (HIV). Primary CNS lymphoma was suspected, making a definitive histological diagnosis crucial. An initial stereotactic biopsy sample was insufficient to establish a diagnosis and a second biopsy of the lesion was obtained. The histopathological investigation confirmed GBM and adjuvant external radiation treatment was given to the patient, who survived for 4 months after the initial biopsy. A decline in the rate of Toxoplasma infection and the changing diseases observed in HIV infection indicate the importance of obtaining a biopsy in cases of CNS mass lesions.

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Richard S. Polin, David L. Lilien, Jose Menendez, and Anil Nanda

Any novel technological innovation is dependent more on the ingenuity of its users than its inherent properties and potential flaws. Positron emission tomography (PET) is unique in this regard because the limitations of this modality are defined by the ability of its users to identify tracers that will aid in the diagnosis of intracerebral processes. The limitations of PET scanning lay in the extent of tissue resolution and in the currently relatively small number centers equipped to perform PET scanning.

In this issue of Neurosurgical Focus , various applications of PET scanning are detailed. The traditional use of this technology in neurosurgery has been to determine the metabolic nature of cerebral neoplastic lesions so as to help differentiate neoplastic from benign or infectious processes. This determination, however, has not been foolproof, and the technique has been further refined to maximize diagnostic yield.

Nonetheless, the utility of PET scanning continues to grow. New applications have allowed for the precise measurements of cerebral blood flow, helping the neuroscientist understand the functional organization of cortex, the pathophysiology of normal-pressure hydrocephalus, and changes in cerebral blood flow following traumatic injury. Other radiotracers such as fluorodopa allow assessment of the metabolic state of cerebral tissue transplants in restorative neurosurgical procedures.

In this introduction, all of these issues will be considered, and a historical perspective and the potential future uses of this technology will be provided. Technology moves so quickly that new instruments are routinely introduced. The authors will try to assess what properties, in the 25-year history of PET scanning, will need to be improved to keep it as a cutting-edge technology and expand its clinical role.

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Richard S. Polin, Volker A. Coenen, Carolyn Apperson Hansen, Peter Shin, Mustafa K. Baskaya, Anil Nanda, and Neal F. Kassell

Object. Transluminal angioplasty has become a widely used adjunct therapy to medical management of symptomatic cerebral vasospasm following subarachnoid hemorrhage (SAH). Despite anecdotal reports of universal, angiographically confirmed reversal of vasospasm and high rates of clinical improvement, no rigorous examination of the efficacy of this procedure has been conducted. In this study the authors assess the efficacy of the aforementioned procedure.

Methods. Thirty-eight patients enrolled as part of the North American trial of tirilazad in aneurysmal SAH underwent transluminal angioplasty for symptomatic cerebral vasospasm. Fifty-three percent of these patients showed good recovery or moderate disability based on their 3-month Glasgow Outcome Scale score.

Among the 38 patients who underwent angioplasty, the severity and type of vasospasm, use of papaverine in addition to balloon angioplasty, timing of treatment, and dose of study drug did not have an effect on the outcome. The results of their neurological examinations improved in only four of the 38 patients immediately after the procedure. A conditional logistic regression analysis was performed in which these patients were compared with individuals matched for age, sex, dose of study drug, admission neurological grade, and modified Glasgow Coma Scale score at the time of angioplasty. No effect on favorable outcomes was found for this procedure.

Conclusions. Transluminal cerebral angioplasty is very effective in reversing angiographically confirmed vasospasm, and anecdotal reports of its clinical utility are numerous. However, in this report the authors conclude that its superiority to medical management for symptomatic cerebral vasospasm is questionable.

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Jose A. Menendez, David L Lilien, Anil Nanda, and Richard S. Polin

Intracranial mass lesions comprise approximately half of all acquired immune deficiency syndrome (AIDS)–related neurological complications. Although toxoplasmosis and lymphoma are the most common causes of these lesions, diagnosis and treatment can be delayed because computerized tomography and magnetic resonance imaging studies cannot accurately differentiate between them.

The authors retrospectively studied nine patients with AIDS in whom, after a 6-hour fast, [18F]-fluorodeoxyglucose (FDG)–positron emission tomography (PET) scanning demonstrated intracranial mass lesions. The FDG uptake within each lesion was classified as either increased or not increased. In six patients there was no increase in FDG uptake, which suggested a diagnosis of toxoplasmosis, and lymphoma was suggested in two patients in whom increased FDG uptake was demonstrated. In a patient with two lesions, one lesion was shown to have increased FDG uptake whereas the other was shown to have no increased FDG uptake. All patients in whom a diagnosis of toxoplasmosis was made were started on antimicrobial therapy. Two patients died of other AIDS-related complications before repeated neuroimaging could be performed to assess treatment response, one patient refused to undergo further treatment or follow up, and two patients responded well to treatment. One patient with toxoplasmosis did not respond to the drugs. Analysis of a biopsy sample of the lesion confirmed the diagnosis; however, the patient died shortly thereafter. The two patients with FDG-PET–diagnosed lymphoma began corticosteroid therapy and improved considerably. In the patient in whom PET demonstrated two different FDG uptakes, a biopsy sample was obtained that confirmed the diagnosis of lymphoma; this patient was started on corticosteroid therapy and improved. A safe and reliable diagnostic tool, FDG-PET scanning can be used to differentiate causes of human immunodeficiency virus-related intracranial mass lesions. When available, this diagnostic study should be conducted before initiating empirical treatment or obtaining a stereotactically guided brain biopsy sample.

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Anil Nanda, David A. Vincent, Prasad S. S. V. Vannemreddy, Mustafa K. Baskaya, and Amitabha Chanda

Object. The goal of this study was to determine whether drilling out the occipital condyle facilitates surgery via the far-lateral approach by comparing data from 10 clinical cases with that from studies of eight cadaver heads.

Methods. During the last 6 years at Louisiana State University Health Sciences Center—Shreveport, 10 patients underwent surgery via the far-lateral approach to the foramen magnum. Six of these patients harbored anterior foramen magnum meningiomas, one patient a dermoid cyst, two patients vertebral artery (VA) aneurysms, and an additional patient suffered from rheumatoid disease of the craniocervical junction. The surgical approach consisted of retromastoid craniectomy and C-1 laminectomy.

The seven tumors and the pannus of rheumatoid disease were completely excised, and the two aneurysms were clipped without drilling the occipital condyle. In one patient a chronic subdural hematoma was found 3 months after surgery, but no patient displayed any complication associated with surgery. It is significant that in no patient was a cerebrospinal fluid leak present. All patients experienced improved neurological function postoperatively.

To compare surgical visibility, eight cadaveric specimens (16 sides) were studied, including delineation of the VA and its segments around the craniocervical junction. Increase in visibility as a function of fractional removal of the occipital condyle was quantified by measuring the degrees of visibility gained by removing one third and one half of the occipital condyle. Removal of one third of the occipital condyle produced a mean increase of 15.9° visibility, and removal of one half produced a mean increase of 19.9°.

Conclusions. On the basis of their findings the authors conclude that removal of the occipital condyle is not necessary for the safe and complete resection of anterior intradural foramen magnum tumors.

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Amitabha Chanda, Donald R. Smith, and Anil Nanda

Object. The authors used a modern cell saver technique to perform autotransfusion in patients undergoing instrument-assisted lumbar and/or thoracic spinal fusion, in whom significant blood loss was anticipated. The safety and benefits of this procedure as well as its cost effectiveness were analyzed.

Methods. The authors studied 50 patients who underwent lumbar and/or thoracic spinal fusion in which instrumentation was placed between January 1998 and June 2000 and in whom an estimated blood loss of 500 ml or more was expected. All surgeries were conducted by a single neurosurgeon (D.R.S.). During surgery, the Brat 2 cell saver system was used to salvage the autologous blood. The anesthesiologist and surgeon jointly decided, on the basis of hematocrit and clinical stability, whether transfusion was necessary in each patient. Various parameters (hematocrit, plasma and urine hemoglobin, platelet counts, coagulation profile, and serum bilirubin) were measured pre-, intra-, and postoperatively.

Thirty-three patients (66%) required transfusion. The mean blood loss in these patients was 1046 ml. The most important factor affecting blood loss was the number of levels fused (p < 0.0001). Only two patients required postoperative homologous transfusion. The mean decrease in hematocrit was 7.82%. The maximum reduction of platelet count was limited to 80,000/mm3. Major complications such as hemoglobinuria, coagulopathy, cardiopulmonary problems, air embolism, and major sepsis were not observed in this study.

Conclusions. Autotransfusion performed using a modern cell saver technique is safe and has many advantages over homologous transfusion. It conserves the homologous blood resources. The costs of the two modes are statistically comparable when greater than 500 ml of red blood cell transfusion is necessary.

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Amitabha Chanda and Anil Nanda

Object. An anatomical study in which measurements were obtained was undertaken to demonstrate that the orbitozygomatic transcavernous—transclinoidal approach provides excellent exposure of the trunk of the basilar artery (BA) and its bifurcation.

Methods. Bilateral stepwise dissections were performed on 10 fixed cadaver heads with the aid of × 3 to × 40 magnifications. A frontotemporal craniotomy was made, followed by an orbitozygomatic osteotomy. After the dura mater had been opened, the sylvian fissure was widely separated. The anteromedial triangle of the cavernous sinus was opened to mobilize the internal carotid artery medially. The sella turcica and the dorsum sellae were exposed. The posterior clinoid process and the dorsum sellae were drilled to expose a length of BA that included its bifurcation. Measurements were obtained following the frontotemporal craniotomy, orbitozygomatic osteotomy, and drilling of the posterior clinoid process to quantify the exposures provided by these procedures.

Excellent exposure of the trunk of the BA and its bifurcation was achieved. The structures in the interpeduncular cistern and the prepontine cistern were also exposed. There was an average gain of a 13.4-mm-long segment of the BA, which in some surgeries can be invaluable. The angle of exposure that was achieved with the BA bifurcation located at the apex increased markedly. Moreover, this method widened the oculomotor nerve—carotid artery corridor for easier access to the BA bifurcation region.

Conclusions. This approach combines the advantages granted by most conventional approaches to aneurysms of the BA bifurcation. The approach is suitable for aneurysms situated at a high, normal, or low position on the BA bifurcation. It exposes a sufficient length of the BA trunk to place a temporary clip.