A probabilistic atlas of the cerebellar white matter.

Imaging of the cerebellar cortex, deep cerebellar nuclei and their connectivity are gaining attraction, due to the important role the cerebellum plays in cognition and motor control. Atlases of the cerebellar cortex and nuclei are used to locate regions of interest in clinical and neuroscience studies. However, the white matter that connects these relay stations is of at least similar functional importance. Damage to these cerebellar white matter tracts may lead to serious language, cognitive and emotional disturbances, although the pathophysiological mechanism behind it is still debated. Differences in white matter integrity between patients and controls might shed light on structure-function correlations. A probabilistic parcellation atlas of the cerebellar white matter would help these studies by facilitating automatic segmentation of the cerebellar peduncles, the localization of lesions and the comparison of white matter integrity between patients and controls. In this work a digital three-dimensional probabilistic atlas of the cerebellar white matter is presented, based on high quality 3T, 1.25mm resolution diffusion MRI data from 90 subjects participating in the Human Connectome Project. The white matter tracts were estimated using probabilistic tractography. Results over 90 subjects were symmetrical and trajectories of superior, middle and inferior cerebellar peduncles resembled the anatomy as known from anatomical studies. This atlas will contribute to a better understanding of cerebellar white matter architecture. It may eventually aid in defining structure-function correlations in patients with cerebellar disorders.

Syringomyelia: a practical, clinical concept for classification.

BACKGROUND: The term syringomyelia describes many pathogenetically different disorders, and a variety of attempts to group these based on different criteria have been proposed in the literature. As a consequence a lack of consensus regarding classification and terminology exists. This inconsistency extends to the ICD-10 classification of diseases in regards to syringomyelia (G95.0) and hydromyelia (Q06.4). We propose a new unifying concept for classification that also incorporates diagnostics and treatment. METHODS: The PubMed online database was used to gain a general overview of the existing pathogenetic theories in relation to syringomyelia. Illustrative cases at our department were included and similar cases of the literature were found using the PubMed database. All material was reviewed with main focus on the classification and terminology used. RESULTS: Despite syringomyelia (G95.0) and hydromyelia (Q06.4) existing as independent ICD-10 entities, we have shown that the use of classifying terminology for fluid-filled cavities in the spinal cord is indiscriminate and inconsistent. Even though a general agreement on the believed pathogenetic mechanism exists, and the general treatment methods are used in accordance with this mechanism, the terminology fails to function as a simple and universal link between theory and treatment. CONCLUSIONS: We propose a new causal concept for an ICD classification with syringomyelia (G95.0) as the only describing terminology, thus abandoning the use of hydromyelia (Q06.4). Syringomyelia is divided into five subgroups according to the associated pathologies. The classification is based on applied diagnostics and serves as a clinical guidance for treatment.

Repeated transsphenoidal pituitary surgery (TS) via the endoscopic technique: a good therapeutic option for recurrent or persistent Cushing's disease (CD).

BACKGROUND: No data on results of repeated transsphenoidal surgery via the endoscopic technique for patients with persistent or recurrent Cushing's disease are available. DESIGN AND PATIENTS: We retrospectively evaluated the remission rates and complications of repeated transsphenoidal surgery via the endoscopic technique in 14 patients with persistent (N = 6) or recurrent (N = 8) Cushing's disease treated in our centre between 1999 and 2007. MAIN OUTCOMES: Remission was defined as the disappearance of symptoms of hypercortisolism with basal plasma cortisol level < or = 50 nmol/l 24-48 h after glucocorticoid withdrawal and/or suppression of plasma cortisol level < or = 50 nmol/l after 1 mg dexamethasone overnight within the first 3 months after transsphenoidal surgery. RESULTS: With repeated endoscopic transsphenoidal surgery a remission rate of 10/14 (71%) was achieved. No patient had a relapse during a median follow-up of 24 months. Cerebrospinal fluid leakage was the most frequent complication (6 patients) and 11 patients required hormonal substitution after surgery. The success of repeated transsphenoidal surgery could not be predicted by visualization of an adenoma on MRI before first or second surgery, histopathological confirmation of an ACTH secreting adenoma after first or second surgery, treatment with cortisol lowering agents before first or second surgery, the operation technique used during the first surgery, persistent vs. recurrent disease after the first surgery, age, gender and interval between the two surgeries. CONCLUSION: Repeated transsphenoidal surgery via the endoscopic technique is a good treatment option for selected patients with recurrent or persistent Cushing's disease following primary pituitary surgery.

CME for neurosurgeons in the Netherlands: the "quality" conferences.

In 1993 the Netherlands Society for Neurosurgery started a yearly event, a "Quality Conference", specifically devoted to continuous medical education (CME). These conferences differ from "normal" scientific meetings, in the choice for specific topics, in the preparation with inquiries among all the Dutch neurosurgical centres, and in the way the results of these inquiries are discussed, preceded by lectures concerning the chosen topic by guest faculty and Dutch neurosurgeons. Each year's principal guest delivers the "Beks Lecture", named after the former professor in Neurosurgery in Groningen, Jan Beks. On several occasions, the foreign guests suggested to present this format for a larger neurosurgical forum. Therefore, it was decided to describe the various aspects of this format for CME in the Netherlands in a paper for Acta Neurochirugica. Examples of topics are given, a summary of two recent inquiries are presented and discussed, and the way of organizing such a conference including finance and the obligatory character are described.

The combined supraorbital keyhole-endoscopic endonasal transsphenoidal approach to sellar, perisellar and frontal skull base tumors: surgical technique.

INTRODUCTION: Extended endoscopic endonasal transsphenoidal approaches (extended EETA) are increasingly being explored for lesions around the sella and the frontal skull base. These approaches, however, require significant surgical expertise and training that can only be obtained in high-volume centers and therefore these approaches are not generalizable to the whole neurosurgical community. Also, these approaches require significant skull base destruction and reconstruction, which comes with a high risk of CSF fistulas. The aim of this article is to describe a combined supraorbital keyhole-endoscopic endonasal transsphenoidal approach as an alternative surgical strategy to the extended EETA that is easier to perform and that leaves the skull base anatomy more intact. TECHNIQUE: Two fairly common neurosurgical approaches, the supraorbital keyhole approach and the endoscopic endonasal transsphenoidal approach, are combined into a single-stage or two-stage surgical procedure. The procedure can be performed as a single neurosurgeon-serial approach and as a two neurosurgeon-parallel simultaneous approach. The philosophy and technique of this combined approach will be described. CONCLUSION: The combined supraorbital keyhole-EETA approach can be used without extra surgical training or expertise and with preservation of skull base anatomy for sellar, perisellar and frontal skull base tumors.

Criteria for transcranial electrical motor evoked potential monitoring during spinal deformity surgery A review and discussion of the literature.

Transcranial electrical stimulated motor evoked potential monitoring (TES-MEP) has proven to be a successful and reliable neuromonitoring technique during spinal correction surgery. However, three criteria for TES-MEP monitoring have been described in the literature. This study aims at discussing and comparing the following criteria: (1) the "threshold level criterion" introduced by Calancie et al. (J Neurosurg 88 (1998) 457-70): a more than 100V over more than 1h increase of threshold level to get useful TES-MEP responses indicated neurological impairment; (2) the "amplitude criterion": for TES-MEP monitoring in corrective surgery of the spine, a more than 80% decrease of one or more response amplitudes was considered a valuable criterion for impending neurological deficits by Langeloo et al. (Spine 28 (2003) 1043-50); (3) "the morphology criterion": introduced in 2005 by Quinones et al. (Neurosurgery 56 (2005) 982-93), it is based on the morphology of the MEP-compound muscle action potentials (CMAP). The criterion was applied during TES-MEP monitoring during intramedullary spinal cord tumour resection. Neurological events are defined by a sharp decrease of response duration and/or waveform complexity and an increase in voltage threshold of 100V or greater. Although all methods have been reported to be successful during spinal surgery, the threshold criterion and the morphology change criterion carry several drawbacks. We consider the amplitude reduction method to be most useful during corrective spinal surgery. The sequences of observations and decisions during a TES-MEP monitoring that is based on this criterion are schematized in a flowchart.

Transsphenoidal pituitary surgery via the endoscopic technique: results in 35 consecutive patients with Cushing's disease.

OBJECTIVE AND DESIGN: The endoscopic technique has been recently introduced in the field of transsphenoidal pituitary surgery. This technique allows inspection of sellar, supra- and parasellar structures and removal of the tumor under direct visualization, is minimally traumatic and permits easier reoperations. This is the first report on the results of endoscopic surgery for patients with Cushing's disease. Our aim was to retrospectively analyze the results of pituitary surgery in 35 consecutive patients with Cushing's disease operated in our hospital after the introduction of the endoscopic technique (1998-2004). METHODS: Remission was defined as suppression of plasma cortisol (< or =50 nmol/L) after 1 mg dexamethasone overnight determined in the first 3 months after surgery and disappearance of clinical signs and symptoms of hypercortisolism. The patients were followed for an average of 27 months (range 4 to 81 months, median 20 months). RESULTS: Pituitary MRI showed a macroadenoma in 6 patients, a microadenoma in 17 patients and no adenoma in 12 patients. After the initial surgery 27 patients (77%) were in remission. None of the patients had a relapse during follow-up. In the remaining 8 patients hypercortisolemia persisted after surgery. Three of them had a second endoscopic pituitary surgery resulting in remission in two patients. In one patient a second endoscopic pituitary surgery will soon follow. The remaining four patients were treated with radiotherapy postoperatively. Two of them were at the time of data collection in remission. One patient from the remission group had a serious epistaxis and three patients had cerebrospinal fluid leakage, one requiring an external lumbar drain, shortly after surgery. No complications were recorded in the failure group. Postoperatively 34% of all patients required substitution with levothyroxine, 40% required substitution with glucocorticoids, 17% received estrogens or testosterone and 6% still required desmopressin. CONCLUSIONS: Endoscopic transsphenoidal pituitary surgery resulted in our series of patients with Cushings disease in an excellent postoperative remission rate. A randomized clinical trial, comparing endoscopic and conventional pituitary surgery in patients with Cushings disease, is needed to determine the pros and cons of both techniques.

Cerebrospinal fluid leakage as complication of treatment with cabergoline for macroprolactinomas.

Treatment of patients with prolactinomas consists primarily of dopamine agonists (DA). Cerebrospinal fluid (CSF) leakage has sporadically been reported in patients with macroprolactinomas treated with short-acting DA such as bromocriptine. Little is known on the incidence of this complication in patients treated with the long-acting D2 specific DA cabergoline. We report three patients with CSF leakage shortly after initiation of cabergoline treatment for macroprolactinoma. All three patients responded rapidly to cabergoline (CAB) by shrinkage of the tumor and release of the optic chiasm compression. The CSF leakage occurred within 10 days after initiation of treatment. CAB treatment was not discontinued. In one patient the CSF leakage ceased spontaneously, with no additional therapy. The second patient had a surgical repair of the CSF fistula, permitting cabergoline to be continued without a recurrence of the CSF leakage. The third patient refused surgical repair of the sellar defect. In this patient the cabergoline dosage was temporarily decreased with no effect on the CSF leakage. Four years later, the CSF leakage is unchanged in this patient, whilst no other complications occurred during the follow-up. No infectious complications occurred in these three patients. In conclusion, patients with large, invasive macroprolactinomas are at risk of CSF leakage during medical treatment with CAB. It is advisable to warn these patients for occurrence of this complication and to monitor them closely especially during the first months of treatment.

Dentatorubrothalamic tract localization with postmortem MR diffusion tractography compared to histological 3D reconstruction.

Diffusion-weighted imaging (DWI) tractography is a technique with great potential to characterize the in vivo anatomical position and integrity of white matter tracts. Tractography, however, remains an estimation of white matter tracts, and false-positive and false-negative rates are not available. The goal of the present study was to compare postmortem tractography of the dentatorubrothalamic tract (DRTT) by its 3D histological reconstruction, to estimate the reliability of the tractography algorithm in this specific tract. Recent studies have shown that the cerebellum is involved in cognitive, language and emotional functions besides its role in motor control. However, the exact working mechanism of the cerebellum is still to be elucidated. As the DRTT is the main output tract it is of special interest for the neuroscience and clinical community. A postmortem human brain specimen was scanned on a 7T MRI scanner using a diffusion-weighted steady-state free precession sequence. Tractography was performed with PROBTRACKX. The specimen was subsequently serially sectioned and stained for myelin using a modified Heidenhain-Woelke staining. Image registration permitted the 3D reconstruction of the histological sections and comparison with MRI. The spatial concordance between the two modalities was evaluated using ROC analysis and a similarity index (SI). ROC curves showed a high sensitivity and specificity in general. Highest measures were observed in the superior cerebellar peduncle with an SI of 0.72. Less overlap was found in the decussation of the DRTT at the level of the mesencephalon. The study demonstrates high spatial accuracy of postmortem probabilistic tractography of the DRTT when compared to a 3D histological reconstruction. This gives hopeful prospect for studying structure-function correlations in patients with cerebellar disorders using tractography of the DRTT.

Conventional radiotherapy combined with carbogen breathing and nicotinamide for malignant gliomas.

High grade malignant gliomas are among the most radioresistant human tumors and total doses up to 80 Gy are inadequate to achieve long-term local control in most of the patients. Hypoxia has been demonstrated in primary brain tumors and may be one of the reasons for their radioresistance. In experimental models carbogen breathing and nicotinamide have been shown to act against hypoxia by different mechanisms and both modalities were tested in 16 patients with supratentorial malignant gliomas in combination with a conventional radiotherapy scheme (50 Gy in 25 daily fractions). The present study was performed to determine the feasibility and toxicity of conventional radiotherapy combined with carbogen breathing and nicotinamide. The unexpectedly high incidence of acute liver toxicity, the possible increase of subacute and late CNS toxicity, and the absence of a higher effectivity led us to reconsider this new treatment modality for patients with malignant gliomas.

Familial congenital hydrocephalus and aqueduct stenosis with probably autosomal dominant inheritance and variable expression.

A kindred is reported on with suspected autosomal dominant congenital hydrocephalus and aqueduct stenosis. In contrast to patients with X-linked congenital hydrocephalus with stenosis of the aqueduct of Sylvius (HSAS) our patients were not mentally retarded and they did not show any pyramidal tract dysfunction or clasped thumbs; the pyramids were not affected either, as was confirmed by autopsy, CT or MRI. Molecular genetic studies in our patients have not revealed abnormalities of eight exons of the L1 neural adhesion molecule gene that is related to HSAS.

Intraoperative dislocation of the distal lens of a neuroendoscope: a very rare complication: technical case report.

OBJECTIVE AND IMPORTANCE: A very unusual complication of neuroendoscopy that was caused by equipment failure is described. CLINICAL PRESENTATION: Intraoperatively, the distal lens of a reusable rigid, lenscope-type neuroendoscope became dislodged. Fortunately, this did not have any adverse consequences for the patient. DISCUSSION: The cause remains obscure but probably relates to the repeated use of the scope. Perhaps the use of a disposable neuroendoscope could have prevented this, but reusable lenscopes are designed to be used many times. CONCLUSION: The risk of such equipment failure should be weighed against the distinct advantage of a much clearer image than is provided by fiberscopes.

Meningioma of the pituitary stalk without dural attachment: case report and review of the literature.

OBJECTIVE AND IMPORTANCE: Tumors in the suprasellar region such as adenomas of the pituitary gland, craniopharyngiomas, nonneoplastic cystic lesions (especially Rathke's cleft cysts), and meningiomas are frequently encountered in neurosurgical practice. Meningiomas originate from the arachnoid layer connected to the dura of the anterior or posterior clinoidal process, or the tuberculum, dorsum, or diaphragma sellae. Tumors originating from the pituitary stalk are rare. Such lesions may include germinomas, astrocytomas, histiocytosis X, hamartomas, and sarcoidosis. We report a patient with a suprasellar meningioma originating from the pituitary stalk with no connection to the adjacent dura. CLINICAL PRESENTATION: A 50-year-old man was assessed for impotence and loss of libido. Physical examination revealed no abnormalities. Endocrinological investigations disclosed nearly complete hypopituitarism, and magnetic resonance imaging revealed a suprasellar homogeneously enhancing tumor. INTERVENTION: Complete surgical resection was performed in an endoscope-assisted right-sided supraorbital craniotomy. The tumor originated from the pituitary stalk with no connection to the surrounding dura. The histopathological diagnosis was meningioma. CONCLUSION: Although meningiomas frequently occur in the suprasellar region, this patient with a suprasellar meningioma is unique because the tumor originated from the pituitary stalk with no connection to the surrounding dura. The absence of dural attachment has been described in 43 extracerebral meningiomas, but a suprasellar location has been reported only once previously. Recognition of this phenomenon is important, because meningiomas require a different therapeutic strategy than most other tumors of the pituitary stalk.

Endoscope-assisted supraorbital craniotomy for lesions of the interpeduncular fossa.

OBJECTIVE: The supraorbital approach is well accepted for lesions in the anterior fossa, the sellar region, and the anterior circle of Willis. However, the usefulness of this approach has not yet been elucidated for lesions in the interpeduncular fossa. The technique of an endoscope-assisted, ipsi- and contralateral supraorbital approach to lesions within the interpeduncular fossa is described, and the initial results are reported. METHODS: A small supraorbital craniotomy, using an eyebrow incision, was performed in each of seven patients who were operated on for different types of lesions in the interpeduncular fossa, including a neuromuscular choristoma of the oculomotor nerve, a retrosellar epidermoid tumor, and five aneurysms (two of the basilar artery tip, two at the offspring of the superior cerebellar artery, and one fusiform arterial widening of the basilar artery apex). The surgical approach, its indications and limitations, and the additional value of an endoscope are outlined. RESULTS: All lesions could be easily reached and well visualized through this approach by using an endoscope as an adjunct to the operating microscope. The saccular aneurysms all could be clipped successfully, the fusiform widening was wrapped, the epidermoid tumor was removed completely, and the choristoma was removed only partially because of brain stem invasion. The patient with the neuromuscular choristoma had persistent diabetes insipidus postoperatively, most probably caused by stretching the pituitary stalk with the endoscope. The patient with the epidermoid tumor showed a postoperative transient partial oculomotor nerve paresis at the side of the approach. The cosmetic results of the eyebrow incisions for this approach were excellent in all patients. CONCLUSION: Lesions in the interpeduncular fossa can be effectively treated using a supraorbital approach, which can be ipsi- or contralateral to the side of the lesion, depending on the exact location of the lesion. The use of an endoscope is essential to visualize these lesions that lie in the shadow of the sellar and parasellar anatomic structures. The major advantage over other approaches are a nearly perpendicular surgical route (although the distance is longer, which is, on the other hand, not a disadvantage), a minimized amount of dissection and brain retraction by using an endoscope through anatomic gateways, and a small surgical incision with excellent cosmetic results.

Occipitotranstentorial approach for lesions of the superior cerebellar hemisphere: technical report.

OBJECTIVE: The occipitotranstentorial approach is well accepted for lesions of the pineal region, superior cerebellar vermis, or mesencephalon. Although evidently suitable, this approach has not, to our knowledge, been reported for lesions of the superior cerebellar hemisphere in adults. Experience with this approach is reported. METHODS: Four patients underwent surgery between August 1995 and March 1997. The findings obtained are evaluated. RESULTS: All lesions were situated in the quadrangular lobules (one extending into the vermis), and all were completely removed. Postoperative deficits, especially visual field deficits, did not occur. CONCLUSION: Lesions of the superior cerebellar hemispheres are easily approached by an occipitotranstentorial route. The major advantages over a supracerebellar approach are that the surgical route is nearly perpendicular to the lesion and to the tentorium instead of parallel, and wide exposure is thereby possible.

Protective coating of cranial nerves with fibrin glue (Tissucol) during cranial base surgery: technical note.

OBJECTIVE: Cranial nerve deficit, either transient or permanent, is a common postoperative complication after cranial base surgery. Frequently, this occurs because intracranial nerves are directly involved in the cranial base lesion. However, any cranial nerve adjacent to the lesion can be damaged because of direct or indirect manipulation during surgery, leading to severe morbidity. We describe a new technique in which the adjacent intracranial nerves are protected from surgical trauma by coating the nerves with a biological two-component fibrin glue (Tissucol; Immuno A.G., Vienna, Austria). SURGICAL TECHNIQUE: The technique was performed in patients who underwent cranial base surgery for different types of lesions. After exposure of the operating field, the cranial nerves that were at risk of operative trauma were coated with a thin layer of fibrin glue using a double lumen catheter within a traditional suction device. RESULTS: With the application of fibrin glue, a protective layer of a rubbery consistency is formed around the nerve. No intraoperative complications or adverse effects of the application were noted. Moreover, no surgical injury of the nerves occurred and no or minimal postoperative cranial nerve deficit was noted in the coated nerves. CONCLUSION: Although it is difficult to compare the postoperative cranial nerve deficit in the coated nerves with a control group, we think that this technique is a valuable method to minimize or avoid intraoperative cranial nerve injury during cranial base surgery.

The use of Gore-Tex membrane for adhesion prevention in tethered spinal cord surgery: technical case reports.

OBJECTIVE: The incidence of retethering caused by postoperative adhesions at the repair site after initial tethered spinal cord surgery is not uncommon. To assess the effectiveness of a Gore-Tex membrane in preventing these adhesions, only clinical radiological and experimental animal evaluation has been reported. In this report, we describe two cases in which Gore-Tex membrane was implanted at the initial untethering surgery and in which we were able to confirm the real effectiveness of the Gore-Tex membrane during a second operation. METHODS: In the first patient, Gore-Tex membrane was used for dural repair in the untethering surgery of the split spinal cord malformation. Because of the suspicion of a thickened filum terminale, repeated surgery was indicated 10 months after the initial procedure. In the second patient, Gore-Tex membrane was implanted during the initial untethering surgery for a lipomyeloschisis and a dermal sinus. Because of a persistent fistula of the dermal sinus, a second operation was necessary 1 year after the first operation. RESULTS: During the repeated surgery, a thorough inspection of the implanted Gore-Tex membrane revealed no adhesions between the Gore-Tex membrane and the intradural content in both cases. CONCLUSION: We support the use of Gore-Tex membrane in the prevention of postoperative dural adhesions in the repair of spinal dysraphism.

Intracarotid slow bolus injection of nimodipine during angiography for treatment of cerebral vasospasm after SAH. A preliminary report.

Nimodipine was given as an intracarotid slow bolus injection in six patients with subarachnoid hemorrhage (SAH) due to rupture of a cerebral aneurysm, with angiographically demonstrated vasospasm. The patients were followed by serial angiograms for demonstration of the effect of nimodipine on vasospasm. After angiography, all patients were treated with a constant venous infusion of this new calcium antagonist. Although the therapeutic regimen was started only a few hours after onset of vasospasm, there was no change in cerebral vessel caliber detectable on angiograms following the intracarotid injection. Three patients died, two patients finally recovered with neurological deficits due to cerebral ischemia, and one patient with asymptomatic vasospasm remained symptom-free. Although nimodipine may act to prevent cerebral vasospasm after SAH, the authors believe that the intracarotid application is not effective after vasospasm has occurred.

Spinal subdural abscess. Case report.

Only 44 cases of spinal subdural abscess have been reported to date. The authors present another case and review the relevant literature. The findings of intraspinal gassification on computerized tomography scans and Escherichia coli as the causative organism have not previously been described in relation to spinal subdural abscess. Most frequently, Staphylococcus aureus is the responsible organism. Hematogenous spread of infection from a distant source often takes place. In a surprising number of incidences, iatrogenic causes are the primary foci of spinal subdural abscess. Spinal subdural abscess is an unpredictable disease, with an unfavorable outcome if left untreated. If there is suspicion of a spinal subdural abscess, urgent radiological examination followed by immediate surgical drainage and appropriate antibiotic therapy is warranted.