A report on neurosurgical workforce in the countries of the EU and associated states. Task Force "Workforce Planning", UEMS Section of Neurosurgery.

AIM: Aim of this report was to present recently collected data on neurosurgical workforce in the countries of the EU and associated states. METHODS: Data were obtained from 27 countries by means of a questionnaire developed by members of a working group of the UEMS Section of Neurosurgery (UEMS = Union Europénne des Médecins Spécialistes; European Union of Medical Specialists). Most data originate from 2005/2006. Results were discussed, amended, and approved by the countries' delegates of the UEMS Section of Neurosurgery. RESULTS: The number of Neurosurgeons (NS) per population varies considerably among these countries. The mean is one neurosurgeon per 99,152 population. The number of neurosurgical operations per population per year varies similarly with a mean of 1,642 operations per million population/year. Countries with fewer neurosurgeons per population tend to have less neurosurgical operations per population and vice versa. The average number of operations performed by one neurosurgeon per year (annual caseload) is between 56 and 300 with a mean of 154. A numerus clausus for neurosurgical training is reported in 13 countries, another 13 countries have no numerus clausus. The annual intake of new trainees is between 2.4 and 10.3% of the number of accredited neurosurgeons with a mean of approx. 5.2%. The average yearly loss rate due to retirement, sickness, other activities, etc. can only be estimated and lies in the range between 2.3 and 3.36% of the number of accredited NS. According to the figures provided by the countries, the total number of accredited NS in 2005/2006 was approx. 6,280 for a population of about 504.7 millions. These countries had an annual intake of approx. 332 new trainees.

Long-term toxicity studies in dogs support the safety of the special extract ERr 731 from the roots of Rheum rhaponticum.

The special extract ERr 731 from the roots of rhapontic rhubarb has been regularly prescribed for women with menopausal symptoms since 1993. As its constituents belong to the class of natural hydroxystilbenes, concerns have been raised about possible health risks similar to those known for the estrogenic diethylstilbestrol. To demonstrate the safety of the medical use of ERr 731, the extract was tested in long-term toxicity studies in dogs. In two independent studies, male and female beagle dogs were treated with 100, 300 and 1000 mg ERr 731/kg body weight (bw)/day and observed for 4 and 13 weeks followed by recovery periods. A histopathological examination of a full set of organs of all animals was examined. In both studies, all animals survived the scheduled treatment and recovery periods. The administration of ERr 731 resulted in increased incidences of feces with white particles due to an incomplete absorption of the extract. In the 13-week study, a slight decrease in glucose levels was recorded in both sexes at 1000 mg/kg bw/day. All other clinical changes were marginal and not related to ERr 731. Importantly, there was no increase in weight of organs of the genital tract due to ERr 731 intake. Based on these results, the no-observed-adverse-effect-level is 1000 mg/kg bw/day. No pathological findings where detected following ERr 731 treatment demonstrating that the toxicological risk for women taking ERr 731 regularly is extremely low.

Somatosensory evoked potentials modified by laser-induced lesions of the rat cortex.

The effect of focal application of laser energy on the modification of somatosensory evoked potentials (SEPs) was studied in sensory cortical fields of the rat. This article describes the methodological set-up for recording of SEPs and for determining location and size of the laser-induced lesion. The results show that both the size of the lesion of the somatosensory cortex, and the suppression and time of recovery of cortical SEPs varied depending on the laser energy dose. It remains to be analyzed by further experiments if the recovery of SEPs is due to a transient dysfunction of the somatosensory cortex or if it reflects cortical plasticity.

Primary glioblastoma multiforme of the oculomotor nerve. Case report.

Tumors of the oculomotor nerve are rare and most instances reported have been schwannomas. The authors present clinical, neuroradiological, and neuropathological findings in a 70-year-old woman with a glioblastoma multiforme (GBM) growing primarily in the proximal part of the left oculomotor nerve. The patient presented with a 1-month history of transient diplopia. Neurological examination revealed an incomplete left-sided oculomotor nerve palsy with no further signs of neurological dysfunction. Cranial computerized tomography and magnetic resonance imaging showed a tumor of the left oculomotor nerve without any obvious signs of penetration into the midbrain or upper pons. Following subtotal removal of the tumor, neuropathological examination of the operative specimen revealed a GBM that had grown diffusely within peripheral nerve tissue. Six weeks after surgery, the patient suddenly died of pulmonary thromboembolism. Postmortem examination of the brain confirmed a large leptomeningeal GBM at the left pontomesencephalic junction with complete destruction of the left oculomotor nerve. To the authors' knowledge, this represents the first case of a GBM of the oculomotor nerve, probably originating from glial cells within the most proximal part of the nerve or the adjacent leptomeninges.

[The selective arterial and venous MR angiography of intracranial arteriovenous malformations]. / Selektive arterielle und venöse MR-Angiographie intrakranieller arteriovenöser Malformationen.

This study evaluates the usefulness of MR angiography (MRA) in analysing cerebral arterial blood supply and venous drainage in patients with intracranial arteriovenous malformations (AVM). Selective MRA of the carotid, middle cerebral or vertebrobasilar territories was performed by means of presaturation of up to three of the brain-supplying arteries at the level of the middle or lower neck (angled presaturation slabs). Results obtained with selective, non-selective arterial, as well as venous MRA in 13 consecutive patients were compared with the findings at intraarterial angiography, the latter serving as the "gold standard". Sensitivity in identifying major feeding arteries was 100%. Determination of the absolute and relative AVM sizes at selective MRA corresponded with IAA. The mean difference was 17.6 and 3.9% respectively. Both display of superficial and deep venous drainage was provided by 2-dimensional venous MRA. The authors conclude that selective MRA of cerebral arteries as used here is a powerful non-invasive method to demonstrate blood supply by single feeding vessels in intracranial malformations. 2D venous MRA permits an accurate evaluation of the venous drainage pattern.

Transoral transclival removal of anteriorly placed cavernous malformations of the brainstem.

BACKGROUND: The natural history of brain stem cavernous malformations is unfavorable because of their high hemorrhage rate and resulting neurological deterioration among patients. However, direct surgery of intrinsic and anteriorly situated cavernomas is hazardous and leads to a bad postoperative outcome because of trauma to lateral and dorsally situated eloquent areas of the brain stem. METHODS: We review the cases of two patients with symptomatic cavernous malformations of the anterior brain stem and describe the usefulness of a transoral-transclival approach. A 23-year-old man developed progressive hemihypaesthesia and paraesthesia, hemiparesis with gait ataxia, dysarthria, dysphonia, and dysphagia. A 38-year-old woman suffered from an acute onset of vertigo with nausea and vomiting, diplopia, and paraesthesia of the left hand and foot. In both patients, computed tomography demonstrated the presence of brain stem hemorrhage, because of cavernous malformation. Magnetic resonance imaging showed a close proximity of the lesions to the pia mater only on the ventral surface of the brain stem. RESULTS: In both patients, the cavernomas could be safely approached and completely resected via a transoral transclival route. Three months after surgery, neurological examination revealed marked neurological improvement. The 23-year-old patient showed slight gait ataxia, no hemiparesis, no cranial nerve palsies; the 38-year-old woman demonstrated no neurological symptoms except for minimal motor dysfunction of the left hand. In both cases, under perioperative prophylactic antibiotics, no meningitis was observed. The patients could subsequently return to their previous employment. CONCLUSION: The transoral transclival approach for ventrally situated brain stem cavernomas allows a largely atraumatic resection of the lesion.

The Miethke dual switch valve: experience in 169 adult patients with different kinds of hydrocephalus: an open field study.

OBJECT: In spite of the development of approximately 200 different shunt systems within the last 50 years, overdrainage and valve obstructions are still major problems in the current treatment of hydrocephalus. In 1994, a new gravitational valve with different opening pressures (depending upon the patient's posture) and a big contact area to CSF was introduced by Miethke and co-workers (DSV). We report about a single institution's experience in the treatment of 169 adult patients with different kinds of hydrocephalus with this valve. METHODS: We retrospectively reviewed the clinical and radiological data of all patients who were treated with a DSV between 1998 and 2005 at our institution. A telephone interview was perfomed at the end of the study, to determine the overall shunt survival. We analysed the outcome and the shunt-related complications. RESULTS: Among 169 patients with DSV, we had 70 patients with normal pressure hydrocephalus (NPH), 40 patients with communicating hydrocephalus due to SAH, 31 patients with communicating hydrocephalus not due to SAH and 28 patients with occlusive hydrocephalus. We had a rate of shunt responders of 93.2%, an overdrainage rate of 3.2% and no valve obstruction in the whole series. The overall shunt survival was 81% after 82 months (mean follow-up: 47.6 months). All implantations were performed by the whole staff, as well as by residents of the neurosurgical department. DISCUSSION: Among the currently available shunt systems, this series is one with the lowest complication rates due to overdrainage and valve obstructions. In patients with NPH, where low opening pressures are essential, the DSV seems to bear an advantage because of a high drainage rate and, in spite of this, a low rate of overdrainage. Even in patients with relatively high CSF protein content, we did not observe any valve obstruction. This study was an open field analysis providing data about the current complication rates of hydrocephalus treatment with this shunt system, outside of a specialized hydrocephalus team or a prospective study trial. However, this study is a retrospective analysis and a prospective randomized controlled trial is required for the comparison of these valves with other shunt systems, such as programmable and flow-controlled ones is required for the future.

The value of micro-Doppler in stereotactic brain biopsy.

OBJECTIVE: The aim of this study was to analyse the value of intraoperative micro-Doppler in stereotactic brain biopsy (SBB). So far, only a few studies have reported about the usefulness of micro-Doppler in stereotactic brain biopsy. METHODS: Between 1998 and 2003, 155 SBBs were performed in 153 patients with micro-Doppler (81 males, 72 females, mean age: 59 years). All operations were performed using a ZD-frame and a multiplanar computer tomography-guided trajectory planning system (Leibinger SPP). A 16 MHz micro-Doppler probe (diameter 1 mm, DWL) was used in all cases to explore the area of biopsy before the tissue probes were taken. Serial biopsies (mean, 6 samples) were taken with the Sedan side-cutting cannula (n = 145) or the small forceps (n = 10). We evaluated the number of intraoperative detectable vessel signals by micro-Doppler, intraoperative bleedings as well as bleedings detected by postoperative CT (which was performed in all cases). We compared our results according to bleeding-related complications with the data of stereotactic biopsy series from the recent literature. RESULTS: A conclusive histopathological diagnosis was achieved in 150/153 patients (98 %). A re-biopsy had to be undertaken in 2 cases. In 98 biopsies (63 %), no vessel could be detected with the micro-Doppler. In the remainder, a signal of arterial vessels was detected in 22 (14 %) and a signal of venous vessels in 35 cases (23 %). Detection of a vessel in the micro-Doppler led to a change of the biopsy site in each case within the same trajectory. Biopsy-related bleedings were detected in 4 cases (2.6 %). Among these, the only bleeding which occurred without any signs of vessels in the micro-Doppler happened in a case of a melanoma. The overall biopsy-related permanent morbidity was 0.6 % (n = 1). The biopsy-related mortality was 0. CONCLUSIONS: Despite the overall high security of SBB, the use of intraoperative micro-Doppler may lead to an additional reduction of the risk for a biopsy-related bleeding without enormous expense.

Paragangliomas of the parasellar region.

Parasellar paragangliomas are rare tumors. As far as we know, only ten cases are described in the literature. Their clinical, pathological, and radiological features and possible origin are discussed in this article and a review of the literature is given. Additionally, we report a new case of a 51-year-old woman with paraganglioma growing in the anterior, middle, and posterior cranial fossa with extended destruction of the skull base. The patient had been suffering from long-standing headaches and facial nerve paresis. Preoperatively, this tumor was suspected to be a meningioma.

Fine structure of zonal changes in experimental Nd:YAG laser-induced interstitial hyperthermia.

Interstitial thermotherapy using Nd:YAG-laser induced hyperthermia is a new stereotactic method for the treatment of brain tumors in poorly accessible regions. To provide a basis for the underlying tissue alterations, we have analyzed the spatial and temporal pattern of interstitial laser hyperthermia lesions in the normal rat brain by histological, immunohistochemical, and electron microscopical methods. The acute changes corresponded to the temperature gradient surrounding the laser probe and showed a distinct zonal architecture. Membrane destruction on a cellular and subcellular level appears to be of major significance in the pathogenesis of the laser lesion. The tissue reaction followed the course known for coagulation necrosis and resulted in a well-defined defect. These results, although limited by the choice of the experimental model, may be helpful in the interpretation of images obtained in future applications of interstitial thermotherapy.

Monostotic lumbar manifestation of fibrous dysplasia--a rare entity.

Monostotic manifestation of fibrous dysplasia in the spine is exceedingly rare. We report the case of a 30 year-old woman suffering from slowly increasing low back pain. Radiologically a polycyclic, slightly gadolinium-enhancing, solitary lesion within the first lumbar vertebral body was detected. The lesion was removed and stabilized with bone marrow transplant. We describe the radiological and histopathological findings.

[Laser-induced interstitial induced hyperthermia of cerebral tumors with nuclear magnetic resonance tomography control]. / Laserinduzierte interstitielle Thermotherapie von zerebralen Tumoren unter kernspintomographischer Kontrolle.

PURPOSE: The purpose of our study was to determine the value of MRI in monitoring laser-induced interstitial thermotherapy (LITT) of cerebral neoplasms. MATERIALS AND METHODS: Sixteen patients with brain tumors were treated with LITT. The laser irradiation was performed within the MR unit and monitored with a temperature-sensitive T1-weighted 2D-FLASH sequence. RESULTS: During irradiation a gradually increasing central zone of high signal intensity was surrounded by an increasing area of reduced signal intensity. After therapy, the diameter of an enhancing rim at the outer border of the peripheral zone indicated total lesion size. On T2-weighted images the signal intensities were reversed. Total lesion size decreased during follow-up. CONCLUSION: MRI is suitable for monitoring LITT. However, the role of LITT in the treatment of brain tumors has still to be defined.

Frameless neuronavigation applied to endoscopic neurosurgery.

OBJECTIVE: We retrospectively analyzed the indications, surgical techniques, and applicability of frameless neuronavigation to endoscopic procedures in a heterogeneous group of 15 patients. MATERIAL AND METHODS: In 8 patients indications for surgery were cystic lesions, in 3 patients intraventricular tumors, and in 4 patients occlusive hydrocephalus. The mean age was 39 years (range 9-76 years). The follow-up period ranged from 5-24 months (mean 10 months). Frameless neuronavigation was accomplished with the "operating arm system" in 10 cases and with the "optical tracking system" in 5 cases (RADIONICS, Burlington, USA). RESULTS: In all 15 cases, neuronavigation sufficiently provided anatomical orientation, preoperative planning, and intraoperative realization of the approach. The calculated mean calibration error was 2.1 mm. There have been no permanent morbidities and no mortalities related to the use of endoscopes and neuronavigation. CONCLUSION: In endoscopic neurosurgery, frameless neuronavigation is a useful tool in planning and realizing the approach and improving intraoperative orientation in selected cases. Indications are small or hidden lesions, impaired visual conditions, abnormal anatomy, and narrow ventricles. Endoscopic procedures include fenestration and resection of intraventricular or intraparenchymal cysts, biopsy of intraventricular tumors, and third ventriculostomy in selected cases.

MRI-guided laser-induced interstitial thermotherapy of cerebral neoplasms.

OBJECTIVE: Laser-induced interstitial thermotherapy (LITT) using a neodymium:yttrium aluminum garnet (Nd: YAG) laser is a new therapeutic approach in the treatment of brain tumors. The purpose of our study was to determine the value of MRI in monitoring LITT. MATERIALS AND METHODS: Eight patients with intracerebral tumors were treated with LITT. The light guide was inserted via an applicator sheath that was implanted stereotaxically with CT guidance. The laser irradiation was performed within the MR unit and monitored by repetitive measurements of a T1-weighted 2D-FLASH sequence. RESULTS: During therapy in all patients, typical changes of signal intensity were seen. A gradually increasing central zone of high signal intensity was surrounded by an increasing peripheral area of reduced signal intensity. The diameter of an enhancing rim at the outer border of the peripheral area after Gd-DTPA was considered as the total lesion size. The lesion size as determined on 2D-FLASH scans during LITT accounted for 88-100% (mean 93.5%) of total lesion size on T1-weighted images after Gd-DTPA acquired immediately after therapy. On T2-weighted images the signal intensities of the two zones were vice versa. Follow-up studies showed a decrease of total lesion size (15-87%). CONCLUSION: Our results demonstrate that MRI is feasible and effective in monitoring LITT. However, the role of LITT in the therapeutic workup of brain tumors still has to be defined in future clinical studies.

Is a combination of Tc-SPECT or perfusion weighted magnetic resonance imaging with spinal tap test helpful in the diagnosis of normal pressure hydrocephalus?

OBJECTIVE: The aim of this study was to evaluate the combination of spinal tap test (STT) with cerebral perfusion measurement assessed either by Tc-bicisate-SPECT (Tc-SPECT) or perfusion weighted MRI (pwMRI), or both, for a better preoperative selection of promising candidates for shunt operations in suspected idiopathic normal pressure hydrocephalus. METHODS: 27 consecutive patients were examined with a standard clinical protocol (assessed by the Homburg Hydrocephalus Scale (HHS)) as well as with 99m Tc-bicisate-SPECT (n=27) or additionally by pwMRI (n=12) before and after STT. The results of these examinations were compared preoperatively for each patient and correlated with postoperative clinical outcome after shunt surgery. RESULTS: Nine patients showed both, a clinical improvement, and increased cerebral perfusion after STT. They underwent shunt surgery with good to excellent results. In another nine patients increasing cerebral perfusion was detected although they did not show a clear clinical improvement after STT. Six of them also received a shunt operation with good to excellent outcome. Three patients of the last group could have an operation. Nine patients did not show any clinical improvement or any kind of increasing cerebral perfusion after STT. Therefore, they did not undergo surgery. The results of SPECT and pwMRI correlated in 92 % of the patients (11 of 12). CONCLUSION: It is concluded that a combination of clinical assessment with SPECT or pwMRI is helpful in the preoperative selection of patients for shunting procedures with suspected NPH syndrome. This combination is a minimal invasive and objective test modality that is superior to STT alone. Further studies are necessary for a comparison of the described imaging techniques with different diagnostic tests in this difficult field of cerebral disease.

Stereotactic laser therapy in cerebral gliomas.

The 1.06 micron Nd:YAG laser and a new fiberoptic delivery system, the Interstitial Thermo-Therapy (ITT) laser fibre, allows stereotactic interstitial irradiation of cerebral tumours. In experimental rat brain studies we found typical laser-tissue effects with a central necrosis and a sharply demarcated oedema towards the normal brain. The size of the lesion depended on the energy and exposure time applied. In a pilot series we treated 5 patients with cerebral gliomas WHO grade II-III in functionally important regions and monitored the therapeutic effects by MR imaging and PET scan. Early post-operative results showed irreversible necrotic changes in the tumour centre and reversible oedematous changes at the tumour margin. Long-term results will show if stereotactic interstitial laser therapy is a useful supplementary method in the treatment of malignant cerebral tumours.

Preliminary experience with the application of gadolinium-DTPA before MR imaging-guided laser-induced interstitial thermotherapy of brain tumors.

The purpose of this study was to investigate the potential value of i.v. gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) applied before MRI-guided laser-induced interstitial thermotherapy (LITT) of brain tumors without original enhancement, especially in defining total lesion size during therapy. MRI-guided LITT was performed on two patients with astrocytoma WHO II. For both patients, Gd-DTPA was administered intravenously after a first irradiation period and LITT was continued after pulling back the light guide to coagulate the upper parts of the tumor. In both patients, the whole irreversible damaged zone of the second irradiation period after Gd-DTPA showed an intense increase of signal intensity. The spatial expansion correlated with the diameter of an enhancing rim after Gd-DTPA on follow-up studies. Our preliminary results indicate that the application of Gd-DTPA before MRI-guided LITT may be of value in defining exactly the size of the irreversible damaged zone during therapy in nonenhancing brain tumors.

Mapping of the cortical motor hand area with functional MR imaging and MR imaging-guided laser-induced interstitial thermotherapy of brain tumors. Work in progress.

PURPOSE: To localize the cortical motor hand area with functional magnetic resonance (MR) imaging before and after MR imaging--guided laser-induced interstitial thermotherapy of tumors in the precentral brain region to control energy delivery and to improve safety. MATERIALS AND METHODS: Functional MR images were obtained in eight patients (five men, three women; aged 27-63 years) while they flexed their fingers. MR imaging--guided laser-induced interstitial thermotherapy was terminated when there was less than 8-12 mm between the border of the laser-induced lesion and the motor hand area anterior aspect. RESULTS: Seven patients had a statistically significant localized change in signal intensity in the central region of the contralateral hemisphere. This area was a spotlike circumscribed focus in three patients and scattered over a larger zone in four patients. Persistent deficits did not occur after thermotherapy in any patient. In three patients, onset of reversible perifocal edema in the motor hand area coincided with the development of hemiparesis, which completely resolved. No patient had activity within the tumor on functional MR images. CONCLUSION: Functional MR imaging findings can be used to prevent neurologic damage during MR imaging--guided laser-induced interstitial thermotherapy.

Representational cortical plasticity associated with brain tumours: evidence from laser-induced interstitial thermotherapy.

OBJECTIVES: To test the hypothesis that cortical plasticity related to destructive tumour growth is functionally relevant. This hypothesis predicts that function is dependent on the intactness of tissue surrounding the tumour. MATERIAL AND METHODS: Eight patients underwent laser-induced interstitial thermotherapy (LITT) for minimally invasive palliative treatment of brain tumours located in eloquent frontal motor regions including the primary motor cortex. A multimodal approach was used to assess the functional outcome of patients after LITT in detail. RESULTS: Following LITT, motor function deteriorated in four patients. In three of these four patients the LITT-induced lesion involved minimal parts of adjacent non-tumorous tissue. By contrast, the other four patients whose LITT-induced signal changes were confined to the tumour, showed no functional deficits. CONCLUSION: These findings support the idea that peri-tumorous neuronal circuitry in motor competent areas may permanently take over those functions that were formerly represented in the neuronal tissue destroyed by the tumour.