Craniotomy tools: description of a test model for the evaluation of craniotome blade efficiency.

Craniotomes have shown to be fast and precise in performing bone flaps. Nevertheless, in everyday practice, the neurosurgeon can experience breakage of the blade and other complications like dural tears during cutting of the bone. We developed a test procedure for craniotomies and used it to compare two blade types. We used bovine scapulae to perform three tests. Five testers carried out every trial. Test 1: a 4-cm straight line was performed with both blades. Test 2: each tester performed a spiral cut. Test 3: a zig-zag cut with angles of 90° was performed by all testers with both blade types. The mean time needed to achieve the 4-cm cut in test 1 was 29.50 and 17.88 s, respectively, for the previous and new blade. In test 2, the calculated mean speed (cm/s) was 0.138 using the previous blade model and 0.178 using the new one. In test 3, the mean number of 90° angles per second performed with both blades is comparable with values of 0.058 and 0.063, respectively, for the previous and new blade. The variable considered: speed of cutting and resistance to breakage shows that the novel blade is faster in performing all the three types of cut and has higher compliance with stress.

Pediatric intracranial primary anaplastic ganglioglioma.

BACKGROUND: Primary intracranial anaplastic gangliogliomas are rare tumors in the pediatric patient group. Most of them present with symptoms of elevated pressure or symptomatic epilepsy. Extraaxial location is far more common than axial location. On MRI examination, they mimic pilocytic astrocytomas. The outcome after surgery depends mainly on the possible amount of surgical resection, and oncological therapy is necessary to prevent recurrence of the disease. CASE REPORT: An 11-year-old boy presented with headache and double vision due to obstructive hydrocephalus. MRI of the brain revealed an axial partially contrast enhancing lesion in the quadrigeminal plate extending from the cerebellum to the pineal gland and causing hydrocephalus. Subtotal removal of the lesion was performed, and the diagnosis of an anaplastic ganglioglioma was established and confirmed by the reference center. At the latest follow up (3 months), the boy is without any neurological symptoms and scheduled for radiation therapy as well as chemotherapy.

Cerebral Rosai-Dorfman disease.

BACKGROUND: Sinus histiocytosis (Rosai-Dorfman disease) with massive lymphadenopathy is a rare nonneoplastic and nonlangerhans cell proliferation disorder of the histiocytes. Extranodal location with or without lymphadenopathy occurs in about 40 % of the cases. Intracranial location is rare in children often mimicking meningiomas. The parasphenoidal region is more frequently involved though intraxial or intraventricular locations were described as well. Rarely, the surgical treatment allows the complete excision of the lesion; however, in symptomatic cases, partial resections of the tumor allow to counteract its mass effect. Long survivals are possible, even without radiotherapy or chemotherapy, due to the frequent spontaneous benign evolution of the lesions. CASE REPORT: A 2-year-10-month-old girl presented with high fever and vomiting. One year ago, she had a period of muscular weakness in both legs that recovered completely. MRI of the brain revealed an axial enhancing lesion with ventricular spreading mainly to the left occipital horn and bilateral frontal periventricular infiltration. After steroid therapy, all the symptoms recovered. Partial removal of the occipital intraventricular lesion was performed and the diagnosis of Rosai-Dorfman disease was established and confirmed by the reference center. At the latest follow-up (16 months), the girl is without any neurological symptoms and without any treatment.

Predictive factors for beneficial application of high-frequency electromagnetics for tumour vaporization and coagulation in neurosurgery.

OBJECTIVE: To identify preoperative and intraoperative factors and conditions that predicts the beneficial application of a high-frequency electromagnetic field (EMF) system for tumor vaporization and coagulation. METHODS: One hundred three subsequent patients with brain tumors were microsurgically treated using the EMF system in addition to the standard neurosurgical instrumentarium. A multivariate analysis was performed regarding the usefulness (ineffective/useful/very helpful/essential) of the new technology for tumor vaporization and coagulation, with respect to tumor histology and location, tissue consistency and texture, patients' age and sex. RESULTS: The EMF system could be used effectively during tumor surgery in 83 cases with an essential contribution to the overall success in 14 cases. In the advanced category of effectiveness (very helpful/essential), there was a significant difference between hard and soft tissue consistency (50 of 66 cases vs. 3 of 37 cases). The coagulation function worked well (very helpful/essential) for surface (73 of 103 cases) and spot (46 of 103 cases) coagulation when vessels with a diameter of less than one millimeter were involved. The light-weight bayonet hand piece and long malleable electrodes made the system especially suited for the resection of deep-seated lesions (34 of 52 cases) compared to superficial tumors (19 of 50 cases). The EMF system was less effective than traditional electrosurgical devices in reducing soft glial tumors. Standard methods where also required for coagulation of larger vessels. CONCLUSION: It is possible to identify factors and conditions that predict a beneficial application of high-frequency electromagnetics for tumor vaporization and coagulation. This allows focusing the use of this technology on selective indications.

Identification of venous variants in the pineal region with 3D preoperative computed tomography and magnetic resonance imaging navigation. A statistical study of venous anatomy in living patients.

OBJECT: The purpose of this study was to determine the ability of software-assisted 3D reconstruction performed using a neuronavigation system to delineate the anatomy and variation patterns of the pineal region venous complex, and then to compare these data with previous anatomical findings. METHODS: The authors retrospectively reviewed the neuroimages obtained in 100 patients with intracranial lesions (50 computed tomography [CT] scans obtained with contrast agents and 50 magnetic resonance [MR] images obtained with gadolinium) by using a neuronavigation workstation for 3D reconstruction. Particular attention was given to the internal cerebral vein, basal vein (BV), and the vein of Galen. The various connection patterns between the major vessels were classified and statistically analyzed. CONCLUSIONS: The venous system of the pineal region shows a wide range of sex-related variations. In the female patient the absence of a BV (Type 0) is significantly more frequent than in the male. In this study the authors illustrate the ability to depict the venous drainage patterns in the pineal region for all cases studied by using 3D neuronavigation software without the need for additional examinations. This simple tool provides important information for surgical planning and may be of significant help intraoperatively.

Treatment of Hyponatremia with Tolvaptan in a Patient after Neurosurgical Treatment of a Pituitary Tumor: Case Report and Review of Literature.

Hyponatremia is a frequent complication following pituitary surgery. We report a case with hyponatremia after surgery of a pituitary adenoma that was successfully treated with tolvaptan. A 68-year-old man with a pituitary tumor presented with mild hyponatremia (133 mEq/L) before surgery. The patient developed hyponatremia (125 mEq) 4 days postsurgery, and 10% sodium chloride was infused. Seven 7 days postsurgery, hyponatremia was improved (132 mEq/L), and tolvaptan 15 mg was given orally as a single dose instead of the 10% sodium chloride infusion. His serum sodium remained within normal limits. The syndrome of inappropriate antidiuretic hormone secretion (SIADH) after pituitary surgery most probably led to the hyponatremia, and tolvaptan was effective because it is an oral vasopressin receptor antagonist.

Prevention of venous thromboembolic complications with and without intermittent pneumatic compression in neurosurgical cranial procedures using intraoperative magnetic resonance imaging. A retrospective analysis.

OBJECT: To evaluate the introduction of intraoperative and postoperative pneumatic compression additionally to the use of compression stockings, low molecular weight heparin-LMWH and early mobilization, a retrospective study in cranial neurosurgery using intraoperative MRI was performed. METHODS: A retrospective analysis of 207 neurosurgical patients using intraoperative MRI was performed. A group of 86 patients was treated with the additional use of intraoperative and postoperative pneumatic compression until mobilization out of bed. One hundred twenty-one patients were treated without the use of additional pneumatic compression. Postoperatively the patients were screened for deep venous thrombosis by ultrasound and pulmonary embolism by CT-scan if suspicious. Statistical analysis was performed. RESULTS: The development of deep venous thrombosis was reduced from 9.9% to 3.5% in our patients with the additional use of intraoperative and postoperative pneumatic compression. That is a 64.6% relative risk reduction to develop deep venous thrombosis with the use of intraoperative and postoperative pneumatic compression. An additional 52% relative risk reduction was found for the chance of developing pulmonary embolism. In the 15 patients with detected deep venous thrombosis, the OR-time was more than 100 min longer than in the 192 patients without detected deep venous thrombosis. The difference between both groups was significant. CONCLUSION: This study demonstrates the benefit of pneumatic compression with a risk reduction for the development of thromboembolic complications. OR-time is another risk factor that attributes to a significant risk for the development of thromboembolic complications.

Alterations in brain metabolism, CNS morphology and CSF dynamics in adult rats with kaolin-induced hydrocephalus.

The present study describes the biochemical changes, morphological development and the cerebrospinal fluid dynamics of the kaolin-induced hydrocephalus in the adult rat. Two, 4 and 6 weeks after microsurgical kaolin instillation into the rat cisterna magna the basal intracranial pressure and the cerebrospinal fluid outflow resistance were measured. To determine possible biochemical changes in the rat cerebrum, brain stem and cerebellum the concentrations of glutamine, glutamate, glutathione, aspartate, GABA, alanine and taurine were measured by high pressure liquid chromatography. In addition, ventriculomegaly and syringomyelia were assessed, measuring the lateral ventricles and central canals by means of an image-processing computer program. It could be shown that the acute phase of kaolin-induced hydrocephalus in the first 4 weeks is characterised by a high basal intracranial pressure, a considerably increased CSF outflow resistance and a rise in brain water content in the fourth week. The changes in the concentrations of amino acids were moderate. Glutamine was increased and taurine was decreased in the cerebrum and alanine was increased in the brain stem. The chronic phase, however, is defined by normal basal pressure, declining outflow resistance, progression of ventriculomegaly and distinct changes in the biochemical parameters such as a remarkable decrease of glutamate, glutamine and taurine in the cerebellum, a decrease of taurine and alanine plus an increase in glutamine in the cerebrum and an increase of alanine in the brain stem. Moreover, cerebral metabolism in the adult rat seems to be more resistant to the effects of hydrocephalus than metabolism in neonatal and infantile rats.

De novo development of a cavernous malformation of the brain: significance of factors with paracrine and endocrine activity: case report.

OBJECTIVE AND IMPORTANCE: De novo development of cavernous malformations is poorly documented in the literature. CLINICAL PRESENTATION: We report the case of a 37-year old woman with de novo growth of a cavernous malformation of the brain. The patient presented with a 12-month history of nonspecific headaches and paresthesias after two pregnancies. After computed tomographic scanning of the cranium, a cavernous malformation located parieto-occipitally within the right brain hemisphere was diagnosed. Control magnetic resonance imaging scans obtained 12 years earlier did not reveal a similar lesion. INTERVENTION: Surgery was performed, and the specimen was analyzed histopathologically. CONCLUSION: Immunohistochemistry demonstrated lack of expression of pituitary hormones as well as of androgen, estrogen, and progesterone hormone receptors. However, strong expression of both basic fibroblast growth factor and CD44 was detected in surrounding tissue, and expression of CD44 was noted within the matrix of the cavernous malformation.

Effect of celecoxib and dexamethasone on postoperative pain after lumbar disc surgery.

OBJECTIVE: This study was designed to assess the efficacy of perioperative administration of celecoxib (Celebrex; Pharmacia GmbH, Erlangen, Germany) in reducing pain and opioid requirements after single-level lumbar microdiscectomy. METHODS: We studied 34 patients (mean age, 44.26 yr; standard deviation [SD], 13.09 yr) allocated randomly to receive celecoxib 200 mg twice a day for 72 hours starting on the evening before surgery or placebo capsules in a double-blind study. Fourteen patients received 20 to 80 mg dexamethasone intravenously during surgery (mean, 40 mg; SD, 19.22 mg) because of visible signs of compression of the affected nerve root. After lumbar disc surgery, patients were monitored for visual analog scores for pain at rest and on movement, patient-controlled analgesia (PCA) piritramide requirements, and von Frey thresholds in the wound area. RESULTS: Pain scores decreased and wound von Frey thresholds increased continuously until discharge, with no intergroup differences. Mean 24-hour PCA piritramide requirements were 22.63 mg (SD, 23.72 mg) and 26.14 mg (SD, 22.57 mg) in the celecoxib and placebo groups, respectively (P = not significant). However, patients with intraoperative dexamethasone (n = 14) required only 10.29 mg (SD, 8.55 mg) 24-hour PCA piritramide, in contrast to the 34.25 mg (SD, 24.69 mg) needed in those who did not receive intraoperative dexamethasone (P = 0.001). In addition, 24 hours after the operation, pain scores on movement were significantly lower in the dexamethasone subgroup (P = 0.003). CONCLUSION: Celecoxib has no effect on postoperative pain scores and PCA piritramide requirements. The intraoperative use of 20 to 80 mg dexamethasone is able to significantly decrease postoperative piritramide consumption and pain scores on the first day after surgery.

Seeding of malignant meningioma along a surgical trajectory on the scalp. Case report and review of the literature.

The authors report the case of an 11-year-old boy with a malignant meningioma of the right frontal meninges. The tumor was asymptomatic, despite visible exophytic extracranial growth. Neuroimaging demonstrated an en plaque meningioma bulging into the brain. Six months after the tumor had been totally removed by surgery, an isolated subcutaneous metastasis developed at the right preauricular area of the scalp, originating at the scar left by the first surgery. After removal of this metastasis, radiotherapy was conducted. To date the follow-up examinations have not revealed any additional metastases. To the best of the authors' knowledge, this is the first report of a seeding of a subcutaneous metastasis in a child with a malignant meningioma. The authors review the literature with reference to malignant meningiomas and their formation of metastasis. In cases of malignant meningiomas, piecemeal tumor removal carries the risk of iatrogenic cell dissemination even when precautions are taken.

How obliteration of petrosal air cells by vestibular schwannoma influences the risk of postoperative CSF fistula.

INTRODUCTION: For postoperative CSF-fistula prevention a better understanding of its origins and risk factors is necessary. To identify the role of the tumor growth for the risk to develop CSF-fistula we performed a retrospective analysis. METHODS: 519 patients between the years 2000 and 2007 had a retrosigmoidal surgical removal of vestibular schwannoma in a standardized procedure. 22 CSF-fistula-patients were chosen for evaluation. 78 patients were randomly selected as control group in four equally sized cohorts: male/female with small/large tumors. Preoperative CT-scans were analyzed regarding IAC-length, diameter of the IAC porus (IAP), tumor size and pneumatization of the posterior wall (PW) of the IAC. RESULTS: The mean length of the IAC was 1.2 cm, SD 0.17. There was a significant difference between the diameter of the IAP in cases of small tumors and those of large tumors. Patients with small tumors also showed a larger fraction with visible pneumatization of the PW (34.88%) in the CT-scan than patients with large tumors (24.07%). There is a positive correlation between tumor grade and diameter of the IAP. At the same time there is an inverse correlation between tumor grade and pneumatization of the PW. CONCLUSIONS: Widening of the IAC by tumor growth may leads to obliteration of air cells in the PW and therefore can be protective concerning CSF-fistula. At the same time patients with small tumors and a visible pneumatization in the PW must be expected to have a higher risk of CSF-fistula.

Identification of venous variants in the pineal region with three-dimensional preoperative magnetic resonance imaging navigation in patients harbouring tumors in this area: significance for surgical approach to the lesion.

OBJECT: The purpose of this study was to identify the anatomy of pineal region venous complex using neuronavigation software when distorted by the presence of a space-occupying lesion and to describe the anatomical relationship between lesion and veins. Moreover we discuss its influence on the choice of the surgical strategy. METHODS: Of the 33 patients treated at our Institute for pineal region tumors between 2003 and 2008 we used the neuronavigation software to depict the venous system of the pineal region in 14 patients. We focused on depiction of the basal vein of Rosenthal (BV), the internal cerebral vein (ICV) and the vein of Galen: connection patterns between the veins and the type of anatomical distortion caused by the lesion were investigated and classified. RESULTS: Using the neuronavigation software for three-dimensional (3D) reconstruction of MRI images the ICV was clearly depicted in all patients on both sides (100%). Last segment of the BV was identified in 25 sides on a total of 28 (89.3%) and absent in 3 of the 28 sides (10.7%). Studying the distortion effect of the tumor on the galenic venous system, three directions of displacement were observed: craniocaudal, anteroposterior and lateral. Seven patients presented a cranial dislocation, 5 patients caudal dislocation and there was no craniocaudal shift in 2 patients. Considering the anteroposterior displacement: 3 subjects showed an anterior shift of the veins, 5 subjects posterior shift and no anterioposterior shift was present in 6 patients. Only 2 of the 14 patients presented lateral displacement of the veins. The principal approaches used in this series were: supracerebellar infratentorial and interhemispheric parieto-occipital. The craniocaudal displacement of the pineal veins seems to be the most important for the choice of the approach. CONCLUSION: The galenic venous system has a central role in the surgery pineal region tumors. Our study demonstrates that the architecture of the pineal veins and their anatomical relationship with the lesion can be depicted with great accuracy by using 3D neuronavigation software in order to facilitate surgical planning and intraoperative orientation.

Optic radiation fiber tracking using anteriorly angulated diffusion tensor imaging: a tested algorithm for quick application.

BACKGROUND: Fiber tracking (FT) of the optic pathways (OPs) is difficult because there is no standard for the parameters of diffusion tensor imaging (DTI), placement of seed volumes, or interpreting the results. OBJECTIVE: To determine optimal conditions and parameters for DTI and FT of the optic radiation under intraoperative conditions, we performed a multivariate prospective study. METHODS: A healthy man underwent magnetic resonance imaging and DTI scans using various scan parameters. The slice thicknesses were 2.7 mm, 5 mm, and 7 mm, and the gantry of the slices was 0 degrees and 44 degrees. The OPs were tracked using different settings for focal anisotropy and minimal length of the visualized fibers. The time needed for DTI, image processing, and uploading as well as the difficulty of depicting the OPs, the time needed for FT, quality, and volume of the tracked fiber object were registered and analyzed. RESULTS: The DTI took between 2 minutes 14 seconds for the axial scan with 7-mm slice thickness and 6 minutes 14 seconds for the 44-degree angulated scan with 2.7-mm slice thickness. Splitting the data into a 3-dimensional mosaic data set took between 1 minute 42 seconds (44 degrees, 7 mm; 0 degrees, 7 mm) and 4 minutes 21 seconds (44 degrees, 2.7 mm). The best results were achieved using 44-degree, 2.7-mm DTI. The optimal setting for focal anisotropy was 0.1 and 11 mm for minimal length. Using these parameters, tracking of the OPs was possible in 1 minute 22 seconds and with high quality and correlating with anatomic studies. CONCLUSION: The use of anteriorly angulated DTI improves the FT work flow and the results of tractography of the OP. The quality of the resulting objects can be judged by anatomic landmarks.

Patient acceptance of awake craniotomy.

OBJECTIVES: The aim of this study was to objectively assess the patients' acceptance for awake craniotomy in a group of neurosurgical patients, who underwent this procedure for removal of lesions in or close to eloquent brain areas. PATIENTS AND METHODS: Patients acceptance for awake craniotomy under local anesthesia and conscious sedation was assessed by a formal questionnaire (PPP33), initially developed for general surgery patients. The results are compared to a group of patients who had brain surgery under general anesthesia and to previously published data. RESULTS: The awake craniotomy (AC) group consisted of 37 male and 9 female patients (48 craniotomies) with age ranging from 18 to 71 years. The general anesthesia (GA) group consisted of 26 male and 15 female patients (43 craniotomies) with age ranging from 26 to 83 years. All patients in the study were included in the questionnaire analysis. In comparison to GA the overall PPP33 score for AC was higher (p=0.07), suggesting better overall acceptance for AC. The subscale scores for AC were also significantly better compared to GA for the two subscales "postoperative pain" (p=0.02) and "physical disorders" (p=0.01) and equal for the other 6 subscales. The results of the overall mean score and the scores for the subscales of the PPP33 questionnaire verify good patients' acceptance for AC. CONCLUSION: Previous studies have shown good patients' acceptance for awake craniotomy, but only a few times using formal approaches. By utilizing a formal questionnaire we could verify good patient acceptance for awake craniotomy for the treatment of brain tumors in or close to eloquent areas. This is a novel approach that substantiates previously published experiences.

Petrous bone pneumatization is a risk factor for cerebrospinal fluid fistula following vestibular schwannoma surgery.

BACKGROUND: For the prevention of postoperative CSF fistula a better understanding of origins and risk factors is necessary. OBJECTIVE: To identify the petrous bone air cell volume as a risk factor for developing CSF fistula, we performed a retrospective analysis. METHODS: From 2000 to 2007 519 patients had a retrosigmoidal surgical removal of a vestibular schwannoma. The 22 who had a postoperative CSF fistula were chosen for evaluation in addition to 78 patients who were randomly selected in 4 equally sized cohorts: male/female with small/large tumors. Preoperative CT scans were analyzed regarding petrous bone air cell volume, area of visible pneumatization at the level of the internal auditory canal (IAC), tumor grade, and sex. RESULTS: : Women developed nearly half as many CSF fistulas (2.7%) as men (5.2%). The mean volume of the petrous bone air cells was 10.97 mL (SD, 4.9; range, 1.38-27.25). It was significantly lower for women (mean, 9.23 mL; SD, 3.8) than for men (mean, 12.5 mL; SD, 5.28; P = .0008). The mean air cell volume of CSF-fistula patients was 13.72 mL (SD, 5.22). The difference concerning the air cell volume between patients who developed CSF fistulas and patients from the control group was significant (P = .0042). There was a significant positive correlation between the air cell volume and the area of pneumatization in one CT slide at the level of the IAC. CONCLUSION: The higher incidence of CSF fistulas in men compared with women can be explained by means of differently pneumatized petrous bones. A high amount of petrous bone pneumatization has to be considered as a risk factor for the development of postoperative CSF fistula after vestibular schwannoma surgery.

Microvascular decompression for trigeminal neuralgia in the elderly: long-term treatment outcome and comparison with younger patients.

OBJECTIVE: Multiple studies have proved that microvascular decompression (MVD) is the treatment of choice in cases of medically refractory trigeminal neuralgia (TN). In the elderly, however, the surgical risks related to MVD are assumed to be unacceptably high and various alternative therapies have been proposed. We evaluated the outcomes of MVD in patients aged older than 65 years of age and compared them with the outcomes in a matched group of younger patients. The focus was on procedure-related morbidity rate and long-term outcome. METHODS: This was a retrospective study of 112 patients with TN operated on consecutively over 22 years. The main outcome measures were immediate and long-term postoperative pain relief and neurological status, especially function of trigeminal, facial, and cochlear nerves, as well as surgical complications. A questionnaire was used to assess long-term outcome: pain relief, duration of a pain-free period, need for pain medications, time to recurrence, pain severity, and need for additional treatment. RESULTS: The mean age was 70.35 years. The second and third branches of the trigeminal nerve were most frequently affected (37.3%). The mean follow-up period was 90 months (range, 48-295 months). Seventy-five percent of the patients were completely pain free, 11% were never pain free, and 14% experienced recurrences. No statistically significant differences existed in the outcome between the younger and older patient groups. Postoperative morbidity included trigeminal hypesthesia in 6.25%, hypacusis in 5.4%, and complete hearing loss, vertigo, and partial facial nerve palsy in 0.89% each. Cerebrospinal fluid leak and meningitis occurred in 1 patient each. There were no mortalities in both groups. CONCLUSION: MVD for TN is a safe procedure even in the elderly. The risk of serious morbidity or mortality is similar to that in younger patients. Furthermore, no significant differences in short- and long-term outcome were found. Thus, MVD is the treatment of choice in patients with medically refractory TN, unless their general condition prohibits it.

Fat implant is superior to muscle implant in vestibular schwannoma surgery for the prevention of cerebrospinal fluid fistulae.

OBJECTIVE: Meticulous sealing of opened air cells in the petrous bone is necessary for the prevention of cerebrospinal fluid (CSF) fistulae after vestibular schwannoma surgery. We performed a retrospective analysis to determine whether muscle or fat tissue is superior for this purpose. METHODS: Between January 2001 and December 2006, 420 patients underwent retrosigmoidal microsurgical removal by a standardized procedure. The opened air cells at the inner auditory canal and the mastoid bone were sealed with muscle in 283 patients and with fat tissue in 137 patients. Analysis was performed regarding the incidence of postoperative CSF fistulae and correlation with the patient's sex and tumor grade. RESULTS: The rate of postoperative CSF leak after application of fat tissue was lower (2.2%) than after use of muscle (5.7%). Women had less postoperative CSF leakage (3.4%) than men (5.6%). There was an inverse correlation with tumor grade. Patients with smaller tumors seemed to have a higher rate of CSF leakage than those with large tumors without hydrocephalus. Only large tumors with severe dislocation of the brainstem causing hydrocephalus showed a higher incidence of CSF leaks. CONCLUSION: Fat implantation is superior to muscle implantation for the prevention of CSF leakage after vestibular schwannoma surgery and should, therefore, be used for the sealing of opened air cells in cranial base surgery.

A ferritin tracer study of compensatory spinal CSF outflow pathways in kaolin-induced hydrocephalus.

Spinal drainage of cerebrospinal fluid (CSF) into the lymphatic system is important in physiological and pathological conditions in both humans and rodents. However, in hydrocephalus and syringomyelia the exact CSF pathway from the central canal into the lymphatic tissue around the spinal nerves remains obscure. We therefore induced syringomyelia and hydrocephalus in 36 Lewis rats by injection of 0.1 ml kaolin into the cisterna magna. At 2, 4 and 6 weeks later cationized ferritin was stereotactically infused into the cisterna magna of controls and into the lateral ventricles of hydrocephalic animals followed by dissection of brain, spinal cord and spinal nerves. CSF pathway and tracer flow were studied by light and electron microscopy. We found that in rats with kaolin-induced CSF outflow obstruction, CSF passes from central canal syringes through ruptured ependyma and dorsal columns into the spinal subarachnoid space, from where it is absorbed along spinal nerves into extradural lymphatic vessels. Taken into account that spinal hydrostatic pressure in humans differs significantly from pressure in animals due to the upright gait, we conclude that spinal compensatory CSF outflow pathways might be of even greater importance in human hydrocephalus.