[Not Available]

Gamma Knife treatments of arteriovenous malformations (AVM) are performed for about 40 years. This article presents the results of 123 patients treated for a brain AVM at the Gamma Knife Center ULB-Hôpital Erasme. Radiosurgical treatment is proposed following multidisciplinary discussion of the best therapeutic strategy based on specific parameters of the AVM. Gamma Knife irradiation was achieved for an AVM residue after endovascular embolization for 84% of patients, after microsurgery for 7% of patients, or after previous radiosurgical irradiation for 6% of patients. The whole volume of the nidus was irradiated in a single session for all patients. A mean margin dose of 22.3 Gy was delivered to the nidus, which had a mean volume of 3.3 cc. The maximum dose ranged from 30 Gy to 50 Gy (mean 44.1 Gy). All patients were prospectively followed after treatment with serial angio-MR and/or conventional angiography. A retrospective analysis shows complete obliteration of the AVM for 109 patients (89%) after 6 to 52 months (mean 32 months). For 14 patients the nidus was only partially obliterated from the radiosurgical procedure; for 9 patients a second irradiation was performed with subsequent complete occlusion of the AVM in all cases. So, 118 of 123 patients (96%) irradiated by Gamma Knife in 1 or 2 sessions were cured. Four patients bled after irradiation and before complete occlusion of the AVM, with neurological deficit for 2 patients. Transient neurological symptoms develop after treatment for 12 patients (10%), associated with postradic edema treated with corticoids. Permanent neurological worsening occurred in 5 patients (4%). Gamma Knife treatment of cerebral arteriovenous malformations is a highly efficient and low-risk therapy when used by a multidisciplinary team.

Hearing preservation and tumour control after radiosurgery for NF2-related vestibular schwannomas

OBJECTIVES

We analyzed the effects of stereotactic radiosurgery on tumour control and cranial nerve function in patients with vestibular schwannomas (VS) secondary to neurofibromatosis type 2 (NF2). Irradiation was performed with a Gamma Knife, model C equipped with a high-precision, robotized positioning system (APS).

METHODOLOGY

This study included 18 patients with 25 VSs secondary to NF2 that were treated from 2001 to 2010 with radiosurgery at our Gamma Knife Center. The radiosurgical procedure included high-resolution conformational dose-planning with multiple, small-diameter isocenters, a single-fraction, low-dose irradiation prescription, and highly accurate gamma rays delivery to the target with the APS.

RESULTS

The median follow-up time was 4.4 y. For 16 tumours in 12 patients with available follow-up data, we observed an actuarial tumour control of 87.5% at 2 y and 80.2% at 5 y, based on the Kaplan-Meier method. No patient developed facial weakness. Serviceable hearing was preserved in 78% of cases. Patients treated for bilateral and unilateral tumours had similar outcomes.

CONCLUSIONS

Radiosurgery could control tumour growth and preserve hearing function and facial weakness in patients with VS secondary to NF2. The enhanced techniques of radiosurgical irradiation provided with the Gamma Knife model C have improved the results of this treatment alternative to microsurgery.

[Non-functioning pituitary adenoma: is there an interest to treat a residue after surgery?]

Diagnosis of non-functioning pituitary adenoma is generally posted when there is a compression of the ophthalmic nerve or when a hypopituitarism occurred. Surgery will be the first treatment but complete removal can be achieved in less than 50% of the patients. In the great majority of the patients, there is a recurrence and a new treatment is proposed. The question is when we must treat a residue after surgery. We performed a retrospective study reviewing a series of 111 patients with a non-functioning pituitary adenoma. All patients had a pre- and post-operative MRI (1.5 T). A statistical analysis was done to determine the influence of the resection, the age of the patient on the recurrence. A complete removal was achieved for 45 patients and 11 of these present a recurrence. 39 patients out of 66 patients who had a partial removal presented also a recurrence. The mean age of the population is 53 years. The statistical analysis demonstrates that patients with a complete removal had less recurrence. Patient with an age below 60 years had more frequently a recurrence compared with older than 60 years old. In conclusion, treatment for non-functioning pituitary adenoma is a transsphenoidal approach surgery. A complete surgery must be the aim of the neurosurgeon. And when a residue is present, a secondary treatment must be given for patient with an age below 60 years old like radiosurgery or radiation therapy.

Hearing outcome after gamma knife radiosurgery for vestibular schwannoma: a prospective Belgian clinical study

INTRODUCTION

Leksel Gamma Knife (LGK) radiosurgery is a safe and efficient therapeutic approach for vestibular schwannoma (VS) with low side effects. The goal of radiosurgery is not necessarily to cause significant tumour necrosis or to obtain a complete radiographic response, but to halt the tumour's growth permanently through its biological elimination. The 2 major aims of radiosurgery for VS are long-term tumour control and functional hearing preservation. The purpose of this study is to report our experience with LGK radiosurgery in the management of VS and to evaluate the hearing preservation rate after a minimum one-year follow-up.

MATERIAL AND METHODS

Between January 2000 and January 2011, 415 patients with unilateral VS underwent LGK radiosurgery at the University Erasmus Hospital of Brussels. There were 349 patients with previously untreated VS (86 grade I, 96 grade II, 141 grade III, 9 grade IVa, 17 unknown grades, according to Koos) and 66 patients with post-operative residual tumour. All patients in our series underwent evaluation with high resolution neurodiagnostic imaging including computed tomography and magnetic resonance imaging, and clinical evaluation as well as audiological tests that included tonal and speech audiometries. The Gardner Robertson (GR) classification is used to report the results of this study. We identified 276 patients treated for VS with LGK, tested and retested with speech and tonal audiometries by the same team, and followed for a minimum of one year.

RESULTS

Before LGK, 144 patients had serviceable (85 GR class I and 59 GR class II) hearing; 95 (65.97%) of these patients had preservation of serviceable hearing (Pure tone average < or = 50 db and Speech discrimination > or = 50%) at minimum one-year audiological follow-up. It was observed that 44 of the 85 GR class I patients (51.76%) maintained their level of audition and 66 of these (74.64%) preserved serviceable hearing. In the 34 patients with preradiosurgery non-serviceable hearing (GR class III-IV) 25 of these patients (73.52%) maintained their hearing. The tumour was stable or declining in size in 90.44% of cases.

CONCLUSION

LGK radiosurgery provides excellent tumour control in vestibular schwannomas and has low toxicity even after long-term follow-up.

[Cranial nerve functional neurosurgery: evaluation of surgical practice]

We report the results of an investigation carried out on the activity of functional neurosurgery of the cranial nerves in the French-speaking countries, based on the analysis of a questionnaire addressed to all the members of the SNCLF. Eighteen centers responded to this questionnaire, which showed that activities and indications varied greatly from one unit to another. The results appear homogeneous and comparable with those reported in the literature. The questionnaire sought to provide a global perspective, open to the comments and questions of all responders on the various techniques raised, with the objective of establishing a common decisional tree for these pathologies and providing if possible to a consensus for better dissemination of these therapies.

[Surgical treatment of movement disorders]

Some movement disorders can be treated successfully by surgical procedures such as chronic deep brain stimulation of the subthalamic nucleus, the thalamus or the globus pallidus, as well as lesioning techniques of thalamotomy and pallidotomy, radiosurgical treatment with the Gamma Knife in the thalamus or globus pallidus, and cerebral graft in Parkinson's and Huntington's diseases. The major indications of these surgical techniques are Parkinson's disease, essential tremor, dystonia, Huntington's disease and tremor in multiple sclerosis.

[Intraoperative MRI and epilepsy surgery]

Intraoperative imaging, in particular intraoperative MRI, is a developing area in neurosurgery and its role is currently being evaluated. Its role in epilepsy surgery has not been defined yet and its use has been limited. In our experience with a compact and mobile low-field intraoperative MRI system, a few epilepsy surgeries have been performed using this technique. As the integration of imaging and functional data plays an important role in the planning of epilepsy surgery, intraoperative verification of the surgical result may be highly valuable. Therefore, teams that have access to intraoperative MRI should be encouraged to use this technique prospectively to evaluate its current relevance in epilepsy surgery.

Information on heavy equipments and facilities in Belgium: gamma-knife

PURPOSE

To explain the principles and indications of gamma knife radiosurgery and to illustrate the correlated neuroimaging features.

METHODS AND MATERIAL

Between December 1999 and July 2007, 1620 patients were treated by GK for a large variety of indications (metastasis 26%, vascular malformations 7%, trigeminal neuralgia 14%, pituitary adenoma 3%, primary CNS tumour 8%, other tumours 6%, vestibular schwannoma 19%, meningioma 17%, functional disorders <1%). The patients benefited from MRI follow-ups.

RESULTS

MRI is the imaging technique of choice for Gamma knife radiosurgery (GKRS) in almost all indications. Computed Tomography, Digital Subtraction Angiography and Positron Emission Tomography have an additional role in some indications. Significant MRI data is illustrated in most indications. Evaluation of the treatment is mainly performed using MRI follow-up studies. The main features of these MRI follow-ups are described. Stabilisation or shrinking of the lesions volumes was generally observed. T2 relaxation times were also modified in and around the treated target areas, in patients responding to treatment and without any symptomatic complications. Modifications in contrast uptake were also observed in those patients. A few patients presented symptomatic complications associated with T2 signal anomalies. The interpretation of those modifications is discussed.

CONCLUSION

MRI is the method of choice for GKRS planning in most indications. Imaging changes after radiosurgery provide the best quality control available to assess the response to radiosurgical treatment and to identify and monitor potential complications.

Stereotactic comparison among cerebral blood volume, methionine uptake, and histopathology in brain glioma

BACKGROUND AND PURPOSE

Vascularity, metabolism, and histologic grade are related in gliomas but the exact determinants of these relationships are not fully defined. We used image coregistration and stereotactic biopsies to regionally compare cerebral blood volume (CBV) and (11)C-methionine (MET) uptake measurements in brain gliomas and to assess their relationship by histopathologic examination.

MATERIALS AND METHODS

Fourteen patients with brain gliomas underwent MR imaging, including dynamic susceptibility contrast-enhanced MR and positron-emission tomography (PET) using MET acquired in identical stereotactic conditions before biopsy. MR-based CBV maps were calculated and both CBV maps and PET images were coregistered to anatomic images. Sixty-five biopsy samples were obtained on trajectories targeted toward high MET uptake area. The following histopathologic features were semiquantified in each sample: mitotic activity, endothelial proliferation, cellular pleomorphism, and tumor necrosis. CBV and MET uptake values were measured in the biopsy area and normalized to contralateral white matter. CBV ratios were compared with MET uptake ratios, and both measurements were compared with histologic features of each sample.

RESULTS

CBV ratios ranged from 0.08 to 10.24 (median = 1.73), and MET uptake ratios ranged from 0.30 to 4.91 (median = 1.67). There was a positive correlation between CBV ratios and MET uptake ratios (r = 0.65, P < .001). Both CBV and MET uptake ratios were found to be significantly related to endothelial proliferation and mitotic activity (P < .01).

CONCLUSION

Within glial tumors, there is a local relationship between CBV and MET uptake measurements. Both provide indices of focal malignant activity.

11C-methionine PET for the diagnosis and management of recurrent pituitary adenomas

PURPOSE

The detection of recurrent pituitary adenoma by magnetic resonance imaging (MRI) is rendered uncertain by the tissue remodelling that follows surgery or radiotherapy. We aimed to evaluate the contribution of PET with 11C-methionine (MET-PET) in the detection and management of recurrent pituitary adenoma.

METHODS

Thirty-three patients with pituitary adenoma were evaluated postoperatively by MET-PET, either because of biological evidence of active residual tumour or because of MRI demonstration of non-functional adenoma growth. We studied 24 secreting adenomas and nine non-functional adenomas.

RESULTS

In 30 patients, MET-PET detected abnormally hypermetabolic tissue. In 14 out of these, MRI did not differentiate between residual tumour and scar formation. In nine of these 14 cases, major therapeutic decisions were undertaken (radiosurgery and surgery). In another group of 16 patients, both MET-PET and MRI detected abnormal tissue. In one case, neither MRI nor MET-PET detected adenomatous tissue. Finally, abnormal tissue was detected in two patients on MRI solely. In these two cases, failure of MET-PET to reveal the adenoma was attributable to concomitant inhibitory therapy. The sensitivity of MET-PET and MRI varied as a function of the tumour type: all non-functional adenomas were localised by both modalities, while MET-PET detected all adrenocorticotropic hormone-secreting adenomas whereas MRI depicted only one of these eight lesions. Fifteen out of 17 patients treated by radiosurgery showed clinical improvement after treatment.

CONCLUSION

We suggest that MET-PET is a sensitive technique complementary to MRI for the detection of residual or recurrent pituitary adenomas. It should gain a place in the efficient management of these tumours.

Modern multimodal neuroimaging for radiosurgery: the example of PET scan integration

Radiosurgery relies critically on medical imaging modalities. Leksell Gamma Knife (LGK) radiosurgery presents the highest requirements in terms of imaging accuracy as the treatment is applied in a single high-dose session with no other spatial control than medical imaging. The advent of new imaging modalities opens challenges for LGK planning strategies. The integration of stereotactic PET in LGK represents an example of such application of modern multimodality imaging in radiosurgery. Our experience consists of 80 patients treated with the combination of MR/CT and PET guidance. In order to analyze the specific contribution of PET findings, we developed a classification reflecting the strategy used to define the target volume. When combining PET and MR information, 102 target volumes were defined, because some patients presented with multiple lesions or multifocal tumor areas. Abnormal PET uptake was found in 86% of the lesions, and this information altered significantly the MR-defined tumor in 73%. In conclusion, integration of PET in radiosurgery provides additional information opening new perspectives for the treatment of brain tumors. The use of a standardized classification allows to assess the relative role of PET. A similar approach could be useful and may serve as a template for the evaluation of the integration of other new imaging modalities in radiosurgery.

[In vivo evaluation of tumor response to radiosurgery: application to vestibular schwannomas]

Imaging follow-up of vestibular schwannomas (VS), such as CT or MR, does not allow assessing the response of the tumor tIssue to radiosurgery. Changes in contrast enhancement are frequently observed, with a loss of contrast enhancement within the treated VS. However, this typical aspect does not anticipate the long-term success of radiosurgery for VS. New functional and metabolic image modalities could be useful to assess in vivo radiosurgery-induced tIssue changes. Such data already exist, using techniques such as MR spectroscopy, positron emission tomography (PET) and SPECT, but they concern almost exclusively the evaluation of primary SNC tumors and metastases of systemic cancers. There are, however, very sparse metabolic and functional data concerning the in vivo evaluation of the response of the tumor tIssue to radiosurgery. Moreover, such information is only anecdotal in VS. In other disorders, PET and MR spectroscopy data suggest interesting new directions for the assessment of radiosurgery follow-up. Based on the predictive information provided by PET and MR spectroscopy in primary CNS tumors, it would be worthwhile to design a prospective study evaluating the role of these imaging modalities for in vivo assessment of radiosurgery-treated SV.

[Usefulness of PET scan guidance in stereotaxic radioneurosurgery using a gamma knife]

Integration of the metabolic data of PET in the dosimetry planning of radiosurgical treatment with the Gamma Knife, can optimize the definition of the target volume for infiltrating or ill-defined brain tumors. Our experience of twenty patients treated with this technique demonstrates the interest of this original approach that should improve the results of radiosurgical treatment of cerebral tumors.

Preservation of hearing in vestibular schwannomas treated by radiosurgery using Leksell Gamma Knife: preliminary report of a prospective Belgian clinical study

INTRODUCTION

Radiosurgery is an alternative to the microsurgical resection of vestibular schwannoma (VS). Since its introduction, radiosurgery has been used in more than 8000 patients with VS worldwide and the long term tumor control rates are reported to be 86 to 100%. The aim of this study is to report our experience with Leksell Gamma Knife (LGK) radiosurgery in the management of VS and to evaluate the serviceable hearing preservation rate after one-year follow-up.

MATERIAL AND METHODS

Between January 2000 and October 2002, 95 patients with unilateral VS underwent LGK radiosurgery at the University Erasmus Hospital of Brussels with the first worldwide installed LGK C. All patients in our series underwent evaluation with high resolution neurodiagnostic imaging including computed tomography and MRI, and clinical evaluation as well as audiological tests that included tonal and vocal audiometries. The Gardner Robertson (GR) classification is used to report the results of this study. We identified 48 patients treated for VS with LGK, tested and retested with vocal and tonal audiometries by the same team, and followed for a minimum of one year. There were 38 patients with previously untreated VS (9 grade I, 9 grade II, 20 grade III according to Koos) and 10 patients with postoperative evolutive residual tumor.

RESULTS

Before LGK, 24 patients had serviceable (17 GR class I and 7 GR class II) hearing; 16 (67%) of these patients had preservation of serviceable hearing (Pure tone average < 50 db and Speech discrimination > 50%) at the one-year audiological follow-up. It was observed that 9 of the 17 GR class I patients (52.9%) maintained their level of audition and 14 of these (82.3%) preserved serviceable hearing. No deterioration of hearing occurred in the 7 patients with preradiosurgery radiosurgery nonserviceable hearing (GR class III) at the one-year follow-up. One patient improved from GR class V to III after LGK. No patient developed trigeminal neuropathy and only one patient who had preradiosurgery facial nerve dysfunction experienced deterioration at one-year follow-up.

CONCLUSIONS

In view of the high tumor control rate and excellent long-term cranial nerve preservation rates, LGK radiosurgery should now be considered as an excellent alternative strategy to microsurgery for the management of VS grade I to III as well as in cases of residual tumor after microsurgery. Compared to results obtained in centers with long-term experience, our data suggest that LGK radiosurgery is an efficient reproducible therapeutic approach that offers high rate of hearing preservation. This justifies the choice of radiosurgery as the first treatment option in VS.

[The neurosurgery department]

Opened on November 1st, 2001, the Department of Neurosurgery has progressively grown to become worldwide renown in a few years. All the pathologies are covered, from lumbar disc hernia to intracranial tumors and vascular malformations. But the originality stays into the exceptional environment by the concentration of logistic resources and the ability of clinician and researchers who daily collaborate with the neurosurgical team. The Department of Neurosurgery has a strong reputation in several fields like intraspinal cord tumors or Pet-guided Neurosurgery in stereotactic biopsies, neuronavigation and Gamma Knife and, generally speaking, in the original approach of the treatment and follow-up of brain tumors. Neurodegenerative diseases also benefit of modern approaches trough the Gamma Knife, deep brain stimulation or fetal cell grafting into the brain in Parkinson and soon in Huntington diseases. Last but not least, the arrival for the 25th anniversary of Erasme Hospital of an interventional MRI will allow to follow in real-time the resection of brain tumors with an obvious benefit for the surgical performances and the quality of life of the patients. It will also open a new window for neurosurgical research through combination with functional MRI and Pet-Scan, reinforcing the reputation of Erasme Neurosurgical Department who has been distinguished in 1997 by the World Health Organisation as "WHO Collaborating Center for Research and Training in Neurosurgery" and nominated again in 2002 for a new 4-year period, which is unique in the Neurosurgical World.

The Zeiss-MKM system for frameless image-guided approach in epidural motor cortex stimulation for central neuropathic pain

Object

Twelve patients (seven female, and five male, mean age 55.6 years) suffering from refractory central (ischemic/traumatic [eight cases]) and neuropathic pain (trigeminal neuropathy [four cases]) underwent surgery for the implantation of an epidural motor cortex stimulation (MCS) device in which the authors used a frameless neuronavigation system, the Zeiss-MKM microscope.

Methods

The authors assessed the spatial accuracy of the neuronavigation system and its potential contribution to improve the quality of targeting pain. In these patients, the positions of the central sulcus, defined by stereotactic magnetic resonance MR imaging, intraoperative somatosensory evoked potentials (SSEPs) and subdural visual verification, were correlated into the stereotactic neuronavigation planning procedure. The mean spatial accuracy of distance between (MR) imaging–defined and actual central sulcus was 2.4 mm (range 5–10 mm). The intraoperative SSEP-defined central sulcus was close to that defined by MR imaging (mean distance 6.4 mm). Although very precise, intra-operative SSEP recordings were impaired by artifacts and wave attenuation in six of the 12 patients. Stereotactic correlations between anatomical and functional data in the navigation system corrected final targeting in 10 of 12 cases. Pain relief was obtained in eight patients. Indeed, inappropriate targeting probably explains the reported variable success rate of MCS and certainly underestimates the actual efficacy.

Conclusions

Since intraoperative SSEP monitoring has, for many years, been considered the standard procedure to approach motor target, the development of an accurate stereotactic image guidance system could help to increase the efficacy of MCS on the alleviation of pain. The excellent spatial accuracy provided by the Zeiss-MKM navigation system allows precise data correlations that represent a remarkable means to validate functional MR imaging as an alternative to SSEP. The authors believe that developing stereotactic image guidance with such a navigation system could improve the success rate of MCS.

[Gamma-knife radiosurgery for brainstem arteriovenous malformations. Preliminary results]

BACKGROUND AND PURPOSE

Microsurgical resection have the advantage to be immediately effective according to bleeding risk and is the reference treatment for cerebral arteriovenous malformations. For cerebral arteriovenous malformations located in the brainstem gamma-knife radiosurgery due to its low invasivity is classically a first line treatment. We reviewed the Marseilles experience to assess the efficacy and safety of gamma-knife radiosurgery for brain stem arteriovenous malformations.

METHODS

We analyzed retrospectively data of 45 patients with an arteriovenous malformation located in the brain stem treated in Marseilles by gamma-knife radiosurgery by between 07/92 and 12/99. Mean age was 42 years, there were 5 children. Arteriovenous malformations were located in the pons or midbrain for the majority of the patients. Intraaxial lesion was found in 82% of patients. Hemorrhage prior to radiosurgery occurred in 75% of the patients. Gamma-knife procedure was the first treatment of the arteriovenous malformations for 29 patients (65%); previous surgery was performed in 34 patients (15%). Mean nidus volume was 550 mm(3) (32-14 196 mm(3)). Mean margin dose was of 23 Gy (range 15-30 Gy). Follow up was available for 25 patients (mean 18 months).

RESULTS

One patient presented a transient worsening of his neurological status, and 2 patients developed a fixed deficit. Two patients underwent rebleeding at an interval of 12 to 36 months after the gamma-knife procedure. At last angiographic follow-up (13 patients), the obliteration rate was 82% of the arteriovenous malformations. A second procedure was proposed to a patient with only partial occlusion at 3 years.

CONCLUSIONS

Gamma-knife radiosurgery can achieve good obliteration rate of brain stem arteriovenous malformations with low morbidity and may be a valuable first-choice therapy for such arteriovenous malformations. A larger population and longer follow up are mandatory in order to confirm these preliminary results.

Trigeminal neuralgia. Pathophysiology and treatment

Trigeminal neuralgia is a very peculiar disease. The pain, also known as "tic douloureux", is paroxystic and very severe. It can be triggered by a light cutaneous stimulus on a very localized spot on the face (the so-called "trigger zone"). The patient can sometimes benefit from long remissions without any treatment. With the exception of multiple sclerosis and of uncommon cases of posterior fossa tumours or other lesions impinging on the trigeminal nerve, ganglion or root, trigeminal neuralgia is considered as "idiopathic". Some benign abnormality had for long been suspected. The current opinion is now in favour of a "neurovascular conflict": an artery, most often a loop of the superior or anteroinferior cerebellar artery, has an offending contact with the trigeminal nerve root, which results in localized demyelination and ectopic triggering of neuronal discharges. This hypothesis is in agreement with the relief provided by antiepileptic drugs and is supported by recent neuroimaging data. Therapeutic options are reviewed: very efficient drugs are available but fail to provide a significant relief and/or have important side effects in many cases. Surgical alternatives are available, for which guidelines are proposed.

Combined magnetic resonance imaging- and positron emission tomography-guided stereotactic biopsy in brainstem mass lesions: diagnostic yield in a series of 30 patients

OBJECT

In the management of brainstem lesions, the place of stereotactic biopsy sampling remains debatable. The authors compared the results of magnetic resonance (MR) imaging, positron emission tomography (PET) scanning, and histological studies obtained in 30 patients who underwent MR imaging- and PET-guided stereotactic biopsy procedures for a brainstem mass lesion.

METHODS

Between July 1991 and December 1998, 30 patients harboring brainstem mass lesions underwent a stereotactic procedure in which combined MR imaging and PET scanning guidance were used. Positron emission tomography scanning was performed using [18F]fluorodeoxyglucose in 16 patients, methionine in two patients, and both tracers in 12 patients. Definite diagnosis was established on histological examination of the biopsy samples. Interpretation of MR imaging findings only or PET findings only was in agreement with the histological diagnosis in 63% and 73% of cases, respectively. Magnetic resonance imaging and PET findings were concordant in 19 of the 30 cases; in those cases, imaging data correlated with histological findings in 79%. Treatment based on information derived from MR imaging was concordant with therapy based on histological findings in only 17 patients (57%). Combining MR imaging and PET scanning data, the concordance between the neuroimaging-based treatment and treatments based on histological findings increased to 19 patients (63%). In seven patients who underwent biopsy procedures with one PET-defined and one MR imaging-defined trajectory, at histological examination the PET-guided samples were more representative of the tumor's nature and grade than the MR imaging-guided samples in four cases (57%). In 18 patients PET scanning was used to define a biopsy target and provided a diagnostic yield in 100% of the cases.

CONCLUSIONS

Although the use of combined PET and MR imaging improves radiological interpretation of a mass lesion in the brainstem, it does not accurately replace histological diagnosis that is provided by a stereotactically obtained biopsy sample. Combining information provided by MR imaging and PET scanning in stereotactic conditions improves the accuracy of targeting and the diagnostic yield of the biopsy sample; an MR imaging- and PET-guided stereotactic biopsy procedure is a safe and efficient modality for the management of mass lesions of the brainstem.

Statistical parametric mapping of regional glucose metabolism in mesial temporal lobe epilepsy

We investigated statistical parametric mapping (SPM) use for positron emission tomography (PET) with [(18)F]fluorodeoxyglucose (FDG) data analysis in mesial temporal lobe epilepsy. The study involved 14 patients with temporal lobe epilepsy ultimately treated by anterior temporal lobectomy. Surgical outcome in terms of seizure control was favorable in 12 patients. Two different SPM approaches were designed to analyze each FDG-PET scan: a direct comparison with a control group (n = 27) and a search for significant interhemispheric asymmetry considering the asymmetry existing in the control group. Statistical inference was performed, first, without correction for multiple comparisons (making the hypothesis of temporal hypometabolism) and, second, after correction for multiple comparisons. Search for temporal interhemispheric asymmetry under the hypothesis of temporal hypometabolism was the most reliable SPM approach: hypometabolism was identified on the side chosen for resection in most cases (sensitivity, 71%; specificity, 100%) and was predictive of favorable postsurgical outcome in 90% of the patients. There was no false-positive result within the control group using this approach. After correction for multiple comparisons, SPM also identified in some patients temporal hypermetabolic areas as well as extratemporal cortical and subcortical hypometabolic areas on the side of resection but also on the contralateral side. In a further step, SPM was used for a group analysis of patients with favorable outcome after reversing scans when needed to set an identical lateralization in all patients. This analysis identified multiple ipsilateral temporal and extratemporal hypometabolic regions; when temporal metabolic changes were specifically assessed, the contralateral mesiotemporal region was found hypermetabolic, possibly as a manifestation of compensatory mechanisms in the presence of a unilateral epileptogenic lesion.

[Primary malignant lymphoma of the spine: clinical aspects and therapeutic advances]

Malignant lymphomas are occasionally encountered in the spine, where they are usually secondary deposits. The authors report the case of a primary non-Hodgkin lymphoma of the L1 vertebra in whom surgical treatment (two operations and double approach) was followed by radiotherapy and chemotherapy. The diagnosis is often made at a late stage, when neurological deficits produced by epidural compression become evident. The surgical treatment is only palliative but has several goals: obtaining a biopsy, improving the neurological symptoms through decompression, stabilizing and "rebuilding" the spinal column; it is performed using posterior, anterior or combined approaches which are discussed. The combined surgical, radiotherapeutic and polychemotherapeutic treatment is associated with a 5-year survival rate of 60-80%. Such a prognosis justifies the risk of surgery which will lead to a stable and lasting reconstruction.

Anterior fontanelle pressure recording with the Rotterdam transducer: variation of normal parameters with age

Using a reliable non-invasive technique for ICP monitoring, we realized 93 continuous anterior fontanelle pressure (AFP) recordings in 86 healthy infants aged from 29 to 85 post-conceptional (PC) weeks. For each recording, we calculated the mean and extremes values of AFP, cerebral pulse amplitude, and pressure waves rate and amplitude. We observed the occurrence of plateau-waves of relatively low amplitude and duration in most infants aged of more than 49 PC weeks. We postulate that PW represents a physiological phenomenon which is amplified under pathological conditions. All AFP parameters are correlated to PC age and vary during early infancy according to an ascending sigmoidal relation (this variation may be explained by a connection between several cranio-cerebral characteristics of the young infant). We conclude that the interpretation of AFP recordings must take into account [1] PC age rather than postnatal age, [2] variation of AFP parameters with age, and [3] occurrence of physiological plateau-waves.

Monstrous skull osteomas in a probable Gardner's syndrome: case report

BACKGROUND

Gardner's syndrome includes a clinical triad of familial polyposis coli, osteomas, and soft tissue tumors.

METHODS

We present a very unusual case of probable isolated Gardner's syndrome characterized by extremely voluminous osteomas in the occipital and frontal areas associated with diffuse subcutaneous lipomas and without colic abnormality.

RESULTS

The neurosurgical management included resection of the osteomas for cosmetic reasons. After a follow-up period of 5 years, the patient remains free of digestive complaints and the resected osteomas did not recur.

CONCLUSIONS

The special clinical presentation of our case of possible Gardner's syndrome is discussed.

Ectopic prolactinoma in the clivus

BACKGROUND

Ectopic pituitary adenomas are rare. Only 29 cases are reported in the literature. The clivus was involved in some cases but sella turcica was occasionally involved.

CLINICAL PRESENTATION

Headache was the first symptom of a 47-year-old woman. Radiological examination diagnosed a clivus tumour. No connection with the pituitary gland was observed. Pre-operative diagnosis was metastasis of an unknown cancer.

INTERVENTION

By a transphenoidal approach, we removed a haemorrhagic tumour. No connection between the normal pituitary gland and the tumour was observed. Neuropathological analysis showed a prolactinoma.

CONCLUSION

We report a rare case of an ectopic prolactinoma in the clivus unrelated to the pituitary gland. Only one other case has been reported in the literature.

Prospective analysis by computed tomography and long-term outcome of 23 adult patients with chronic idiopathic hydrocephalus

From 1986 to 1989, 23 adult patients (average age, 70 yr) with idiopathic chronic hydrocephalus received shunts with medium-pressure Pudenz-Schulte valves for suspected normal pressure hydrocephalus. Prospective clinical and computed tomographic monitoring was continued for at least 5 years. We observed the formation of a hypodense subdural collection in each of 10 patients (43%). Those collections that occurred early, i.e., within the first 9 postoperative days, evolved differently from those that occurred late; only early hypodense collections became subdural hematomas (three cases). In one case, a subdural hematoma was already present 9 days after surgery, so that four patients (17%) presented a subdural hematoma within the first 2 postoperative months. Our long-term follow-up revealed three patients (13%) with hypodense subdural collections, which appeared more than 2 months after surgery. None of the collection evolved into a subdural hematoma. Thirteen patients (57%) died between 9 and 68 months (average, 20 mo) after surgery, most often of an ischemic stroke. During the 1st postoperative year, there was improvement in the condition of 22 patients (96%) who had received a ventricular shunt; 21 of these patients (91%) remained improved until death or for at least 5 years.

Anterior fontanelle pressure monitoring for the evaluation of asymptomatic infants with increased head growth rate

We studied non-invasive intracranial pressure monitoring in 20 asymptomatic infants with increased head growth rate. Both basal anterior fontanelle pressure (AFP) traces and occurrence of pressure waves were analysed and compared with normal range values previously established. Eight recordings were classified as pathological; cerebral imaging showed subdural collections or ventricular dilatation in all cases. Five out of these eight infants further developed neurological deficits and/or increase of the ventricular size, and required neurosurgical procedures. Twelve infants had normal AFP traces; six of these had normal cerebral imaging and six showed enlargement of subarachnoid spaces with normal ventricles. All of these 12 patients normalised their head growth rate and remained asymptomatic. This observation suggests that AFP monitoring may be helpful in asymptomatic infants with increased head growth rate to identify a progressive intracranial process and the potential need for a neurosurgical procedure.

Anterior fontanelle pressure variations during sleep in healthy infants

Our aim was to study the intracranial pressure (ICP) variations during sleep normal infants. Using a noninvasive method, ICP was measured continuously during polysomnography in 12 healthy infants aged from 1 to 11 months (median 3.5 months). We analyzed the variations of mean basal ICP, mean basal pulse pressure amplitude and maximal amplitude of both plateau and B-like waves between transient sleep, quiet sleep and rapid eye movement (REM) sleep. Mean ICP, mean pulse pressure amplitude and B-like wave amplitude increased significantly during transient sleep and REM sleep. Plateau waves occurred during transient sleep and especially REM sleep. By contrast, noninvasive ICP recordings were relatively flat during quiet sleep stages 2 and 3. ICP variations and pressure waves seem to be related to cerebrovascular changes associated with sleep. The physiological ICP variations during sleep must be known in order to allow correct interpretation of continuous ICP measurements in infants.