Tunçalp Özgen

Natural History of Brainstem Cavernous Malformations

OBJECTIVE: To review the natural history and determine the rates of intra- and extralesional hemorrhaging of brainstem cavernous malformations (cavernomas) monitored by one neuro-ophthalmology service. METHODS: A record review of all patients with brainstem cavernomas who were evaluated by a neuroophthalmology service between 1987 and 1999 was performed. We recorded the clinical symptoms and Rankin disability grade at presentation, during the worst clinical episode, and at the last follow-up examination. Magnetic resonance imaging scans were reviewed for evidence of intralesional hemorrhage (a bleeding episode), edema, or venous anomalies, and the cavernoma size was assessed. RESULTS: Thirty-seven patients (age range, 6-73 yr; mean age at presentation, 37.5 yr) underwent a mean of 4.9 years of follow-up monitoring. At presentation, there were 27 bleeding events and 8 nonhemorrhagic events; 2 patients did not exhibit symptoms. Patients who were at least 35 years of age exhibited a lower risk of bleeding episodes (odds ratio, 0.15; 95% confidence interval, 0.1-0.4). Cavernomas of at least 10 mm were associated with a higher risk of bleeding episodes (odds ratio, 3.48; 95% confidence interval, 1.3-9.4). Thirty-nine bleeding episodes occurred in 31 patients, yielding a bleeding rate of 2.46%/yr. There were eight rebleeding episodes, yielding a rebleeding rate of 5.1%/yr. Three patients experienced extralesional bleeding episodes; all of these patients experienced rebleeding. Of the 39 follow-up magnetic resonance imaging scans, the cavernoma size was unchanged in 66.7%, smaller in 18%, and larger in 15%. At the last follow-up examination, the mean Rankin grade was 1.0 for all patients, 0.6 for the 25 nonsurgically treated patients, and 1.4 for the 12 surgically treated patients. CONCLUSION: Rebleeding is not more common among patients who first present with bleeding, and it often has little effect on the neurological status of patients. Significant morbidity attributable to a brainstem cavernoma occurred in 8% of patients during follow-up monitoring of medium duration.

BRUCELLOSIS OF THE SPINE

The spinal form of brucellosis is still a disabling disease in many countries outside North America and northern and central Europe. Fifteen consecutive cases of spinal brucellosis diagnosed and treated over a 20-year period were reviewed retrospectively. Six patients were farmers, while 10 patients had a history of ingestion of unpasteurized milk or other dairy products. A high index of suspicion is necessary for the diagnosis, since there are no pathognomonic signs or symptoms. Radiological assessment of the disease was reviewed and highlights in the differential diagnoses were stressed. The diagnosis was based on actual culture of Brucella bacilli in seven patients. The principal treatment of brucellosis of the spine is conservative, namely, immobilization and antimicrobial therapy. We have found both a combination of ofloxacin and rifampin and ofloxacin monotherapy efficient as the early regimens used in this series. Three patients had to undergo surgery, since a diagnosis could not be made in any other way.

Spinal hydatid cysts

Eleven cases of spinal hydatid cyst are reported. The patients were admitted with symptoms of compression of the spinal cord. The cysts were localized epidurally in 10 patients and intradurally but extramedullarily in one, and were confirmed histopatholgically after surgical intervention. The results are compared with those reported in the literature. Six of the patients were female and five were male. Their ages ranged from 10 to 65 years. All of the patients were treated surgically, with an incidence of cyst recurrence of 18% and no mortality. Mebendazole (Vermox) was given to two of the patients after their operations.

Infection as a cause of spinal cord compression: a review of 36 spinal epidural abscess cases.

Summary¶ A retrospective survey of 36 cases treated in the Department of Neurosurgery, Hacettepe University Hospitals since 1970 was performed. Clinical presentation, aetiology and outcome of this rare disease compared to recently published series. All cases were admitted with signs of neural compression. Clinical and laboratory data suggesting an infectious origin were present only in 4 cases. Radiological investigation including magnetic resonance imaging in 10 patients, were not confirmative for an epidural abscess except for two cases. All cases underwent urgent surgical decompression and tuberculous abscess either in granulation or pus form was found in the majority. Overall mortality rate was 5.8%. Outcome was closely related to the neurological condition on admission rather than the underlying infectious origin. When compared with recently reported series, our cases demonstrated a significant divergence in terms of clinical presentation, pathogenesis and outcome. The most probable reason for this discrepancy is that risk factors for compromised immunity or systemic infection were much less than the other series and mycobacterium tuberculosis is the responsible agent in the majority which has a much more favourable outcome than non-spesific infections.

Pituitary adenomas: results of 684 surgically treated patients and review of the literature

BACKGROUND The outcome of patients with pituitary adenomas who were treated surgically with or without postoperative radiotherapy was analyzed. The purpose of this study was to determine the factors that strongly influence (A) tumor control, (B) the efficacy of surgery, and (C) radiotherapy based on the hormonal activity of adenomas and its invasion characteristics. METHODS Between 1982-1996, 684 patients with the diagnosis of pituitary adenoma were operated on. The mean age was 38 years and the mean follow-up time was 40.5 months. A total of 516 patients who were followed for more than 1 year were studied to analyze the effect of treatment modalities and invasion characteristics on tumor control. There were 297 patients with prolactinomas, 118 patients with somatotropinomas, 45 with corticotropinomas, 17 with mixed adenomas, two with thyrotropinomas, and 205 with null cell adenomas. All patients were classified according to Hardys modified radiological classification scheme and analyzed in invasive and noninvasive groups individually based on this classification system. In the early postoperative period, 230 of these patients were given conventional radiotherapy with a mean dose of 4400 cGy. The following factors were analyzed for prognostic significance in tumor control: the effects of surgery and radiotherapy based on tumor types and invasion characteristics, the existence of histologically proven invasion of the dura mater overlying the sellar floor, and the early results of topical bromocriptine application in macroprolactinoma patients. RESULTS Overall surgical complications and mortality rate were similar to those of large series reported in the literature. Except for the invasive somatotropinomas and null cell adenomas, statistical analysis demonstrated the ineffectiveness of radiotherapy on tumor control. We did not detect any positive correlation between the recurrence rate and mean recurrence time or dural invasion of the sellar floor. Topical bromocriptine application seemed to improve tumor control in 21 selected macroprolactinoma patients. CONCLUSION Conventional radiotherapy is not as effective as expected, considering its adverse effects. The increased side effects of radiotherapy in cases with supra-parasellar extension, especially to the optic pathway and hypothalamus, limit its benefits, which could be demonstrated only in invasive somatotropinomas and null cell adenomas. In contrast with our current beliefs, tumoral infiltration of the sellar dura mater is not a prognostic factor for recurrence and therefore should not be a criterion for radiotherapy after surgery. Topical application of bromocriptine into the sellar cavity after tumor removal seems to provide superior results compared with the conventional treatment modalities.

Aneurysms of the distal anterior cerebral artery: Report of 14 cases and a review of the literature

BACKGROUND Distal anterior cerebral artery aneurysms are rare and compose about 4.5% of all intracranial aneurysms. They generally arise at the bifurcation of the pericallosal and callosomarginal arteries. Their surgical approach is different from those of other anterior circulation aneurysms. These aneurysms present some special difficulties for neurosurgeons, including narrow exposure in the interhemispheric fissure, dense adhesions between the cingulate gyri, difficulty in controlling the parent artery, and the association of multiple aneurysms and vascular anomalies. METHODS Between January 1975 and May 1996, 14 cases of saccular aneurysms of the distal anterior cerebral artery were operated at the University of Hacettepe. The clinical presentations, neuroradiological findings, and operative approaches of these aneurysms were analyzed. In addition, the clinical series and isolated case reports in the English literature were also extensively reviewed. RESULTS The incidence of the aneurysms in this location was 2.8% of a total of 494 surgically treated cases in our center. Of 14 patients, eight were women and six were men. Multiple aneurysms were found in five patients (35%). All patients were operated via the interhemispheric route. Thirteen patients had good outcome and one patient died. CONCLUSIONS We believe that all difficulties related to distal anterior cerebral artery aneurysms can be minimized with sufficient knowledge of microsurgery and surgical anatomy, using microtechniques and experience.

Microanatomy of the central myelin-peripheral myelin transition zone of the trigeminal nerve.

OBJECTIVE:The aim of this study was to evaluate the microanatomy of the central myelin-peripheral myelin transitional zone (TZ) in trigeminal nerves from cadavers. METHODS:One hundred trigeminal nerves from 50 cadaver heads were examined. The cisternal portion of the nerve (from the pons to Meckel’s cave) was measured. Horizontal sections were stained and photographed. The photomicrographs were used to measure the extent of central myelin on the medial and lateral aspects of the nerve and to classify TZ shapes. RESULTS:The cisternal portions of the specimens ranged from 8 to 15 mm long (mean, 12.3 mm; median, 11.9 mm). The data from the photomicrographs revealed that the extent of central myelin (distance from pons to TZ) on the medial aspect of the nerve (range, 0.1–2.5 mm; mean, 1.13 mm; median, 1 mm) was shorter than that on the lateral aspect (range, 0.17–6.75 mm; mean, 2.47 mm; median, 2.12 mm). CONCLUSION:The data definitively prove that the root entry zone (REZ, nerve-pons junction) and TZ of the trigeminal nerve are distinct sites and that these terms should never be used interchangeably. The measurements showed that the central myelin occupies only the initial one-fourth of the trigeminal nerve length. If trigeminal neuralgia is caused exclusively by vascular compression of the central myelin, the problem vessel would always have to be located in this region. However, it is well known that pain from trigeminal neuralgia can resolve after vascular decompression at more distal sites. This suggests that the effects of surgical decompression are caused by another mechanism.

The efficacy of silver-embedded polypropylene-grafted polyethylene glycol-coated ventricular catheters on prevention of shunt catheter infection in rats

PurposeCatheter-related infection is a major complication of ventriculoperitoneal shunt in children. The aim of this study is to determine inflammatory response and the efficacy of polypropylene-grafted polyethylene glycol (PP-g-PEG) copolymer and silver nanoparticle-embedded PP-g-PEG (Ag-PP-g-PEG) polymer-coated ventricular catheters on the prevention of catheter-related infections on a new experimental model of ventriculoperitoneal shunt in rats.MethodsThirty six Wistar albino rats were divided into six groups: group 1, unprocessed sterile silicone catheter-embedded group; group 2, sterile PP-g-PEG-coated catheter group; group 3, sterile Ag-PP-g-PEG-coated catheter group; group 4, infected unprocessed catheter group; group 5, infected PP-g-PEG-coated catheter group; and group 6, infected Ag-PP-g-PEG-coated catheter group, respectively. In all groups, 1-cm piece of designated catheters were placed into the cisterna magna. In groups 4, 5, and 6, all rats were infected with 0.2 mL of 10 × 106 colony forming units (CFU)/mL Staphylococcus epidermidis colonies before the catheters were placed. Thirty days after implantation, bacterial colonization in cerebrospinal fluid and on catheter pieces with inflammatory reaction in the brain parenchyma was analyzed quantitatively.ResultsSterile and infected Ag-PP-g-PEG-covered groups revealed significantly lower bacteria colony count on the catheter surface (ANOVA, 0 ± 0, p < 0.001; 1.08 ± 0.18, p < 0.05, respectively). There was moderate inflammatory response in the parenchyma in group 4, but in groups 5 and 6, it was similar to that of the sterile group (ANOVA, 16.33 ± 3.02, p < 0.001; 4.00 ± 0.68, p < 0.001, respectively).ConclusionsThe PP-g-PEG, especially Ag-PP-g-PEG polymer-coated ventricular catheters are more effective in preventing the catheter-related infection and created the least inflammatory reaction in the periventricular parenchyma.

Benign extramedullary tumors in the foramen magnum region

We present 16 cases of benign extramedullary tumors of the foramen magnum region who were operated on between the years 1984 and 1992. On admission, no case was neurologically intact and over 50% had had symptoms for more than 1 year. Nine patients had erroneous diagnoses initially. CT myelography and magnetic resonance (MR) imaging were the most appropriate diagnostic tools in visualizing tumors of this region. All operations except one, were performed by the posterior approach without surgical mortality. Histopathological examination revealed 8 meningiomas, 6 neurinomas, one tuberculous abscess and one neurenteric cyst which has not been reported at this location before. Patients with minor to moderate disability on admission showed good functional results without any recurrences during follow-up.

Subependymal giant cell astrocytoma associated with tuberous sclerosis: diagnostic and surgical characteristics of five cases with unusual features

Five children with tuberous sclerosis and intracranial tumors were surgically treated at Neurosurgery Department of Hacettepe University School of Medicine. Two of the five patients presented with the giant cell astrocytoma filling the third ventricle. Direct surgical intervention and tumor removal was carried out in all four patients (three with a total surgical resection and one with a subtotal resection) and cerebrospinal fluid shunting procedure in one. Histopathological examination revealed giant cell astrocytomas in four patients. Postoperatively, one died and the rest four patients survived with minor focal neurologic difficulties. The surgical results and the changing concepts in the treatment of tuberous sclerosis are discussed and the literature is reviewed.