Friedrich K. Albert

Intraoperative diagnostic and interventional magnetic resonance imaging in neurosurgery

OBJECTIVE The benefits of intraoperative magnetic resonance (MR) imaging for diagnostic and therapeutic measures are as follows: 1) intraoperative update of data sets for navigational systems, 2) intraoperative resection control of brain tumors, and 3) frameless and frame-based on-line MR-guided interventions. The concept of an intraoperative MR scanner in the sterile environment of operating theater is presented, and its advantages, disadvantages, and limitations are discussed. METHODS A 0.2-tesla magnet (Magnetom Open; Siemens AG, Erlangen, Germany) inside a radiofrequency cabin with a radiofrequency-shielded sliding door was installed adjacent to one of the operating theaters. A specially designed patient transport system carried the patient in a fixed position on an air cushion to the scanner and back to the surgeon. RESULTS In a series of 27 patients, intraoperative resection control was performed in 13 cases, with intraoperative reregistration in 4 cases. Biopsies, cyst aspirations, and catheter placements (mainly frameless) were performed under direct MR visualization with fast image sequences. The MR-compatible equipment and the patient transport system are safe and reliable. CONCLUSION Intraoperative MR imaging is a safe and successful tool for surgical resection control and is clearly superior to computed tomography. Intraoperative acquisition of data sets eliminates the problem of brain shift in conventional navigational systems. Finally, on-line MR-guided interventional procedures can be performed easily with this setting. As with all MR systems, individual testing with phantoms, application of correction programs, and determination of the optimal amount of contrast media are absolute prerequisites to guarantee patient safety and surgical success.

Image-guided neurosurgery with intraoperative MRI : update of frameless stereotaxy and radicality control

Intraoperative shifts and resulting inaccuracies have been a concern in frame based and frameless stereotactically guided interventions, particularly in open microsurgical procedures. Trying to solve this problem, we developed a method to perform intraoperative MRI (0.2 tesla, Magnetom Open) and use intraoperatively acquired data sets to update neuronavigation. In 21 patients, intraoperative images could be used to reference navigation (mean accuracy of 0.83 +/- 0.31 mm). The operation was continued in 10 cases to resect detected tumor remnants using navigation, leaving 4 patients (19%) with residual tumor postoperatively. We showed that update of frameless stereotaxy to compensate for brain shift is feasible and might increase the number of cases where radiologically complete resection can be achieved.

Pure motor hemiparesis with stable somatosensory evoked potential monitoring during aneurysm surgery: case report.

We report a patient who sought treatment for an acute subarachnoid hemorrhage as a result of an intracranial aneurysm. Management included early surgical repair and intraoperative monitoring of evoked potentials. Pan-angiography revealed berry aneurysms of the communicating anterior artery and right middle cerebral artery. Surgery was uneventful, and the somatosensory evoked potential monitoring did not show any abnormalities. Nevertheless, the patient showed a neurological deficit due to a clip-related infarct in the right middle cerebral artery territory characterized by a right hemiparesis with no sensory deficit. This case report supports the possibility of false-negative results in single-mode intraoperative monitoring during aneurysm surgery.

Coil placement after clipping: endovascular treatment of incompletely clipped cerebral aneurysms

✓ In up to 4% of patients whose aneurysms are microsurgically clipped, there is an expected or unexpected aneurysm residuum. The authors describe two patients in whom surgical clipping did not result in complete obliteration of the aneurysm sac and in whom a second operation was not believed to be the solution to the problem. In both patients complete occlusion of the aneurysm residuum was achieved via an endovascular approach. Using the Guglielmi detachable coil system, it was possible to place two platinum coils selectively into the aneurysms. The endovascular approach may be a good treatment option for all patients in whom surgical clipping does not result in complete obliteration of the aneurysm sac and reoperation is contraindicated or unacceptable to the patient.

Intraoperative Computer-Assisted Neuronavigation in Functional Neurosurgery

The clinical experience with a frameless computer-assisted neuronavigational system (ISG. Canada) used in functional neurosurgery is described. The advantage of image-guided surgery is stressed for functional procedures of the cortex with delineation of the gyral pattern, e.g. motor cortex stimulation and procedures at the base of the skull with triplanar and three-dimensional reconstruction of the bony landmarks. A general use of the device for aiming at subcortical targets cannot be recommended. Limitations are the accuracy (< or = 2.2 mm) and software deficiencies and the lack of a reliable fixation of the position sensing arm (wand).

Coil placement after clipping: endovascular treatment of incompletely clipped cerebral aneurysms: Report of two cases

In up to 4% of patients whose aneurysms are microsurgically clipped, there is an expected or unexpected aneurysm residuum. The authors describe two patients in whom surgical clipping did not result in complete obliteration of the aneurysm sac and in whom a second operation was not believed to be the solution to the problem. In both patients complete occlusion of the aneurysm residuum was achieved via an endovascular approach. Using the Guglielmi detachable coil system, it was possible to place two platinum coils selectively into the aneurysms. The endovascular approach may be a good treatment option for all patients in whom surgical clipping does not result in complete obliteration of the aneurysm sac and reoperation is contraindicated or unacceptable to the patient.

Epidurale Hirndruckmessung und Hirndrucktherapie bei „malignem“ Mediainfarkt

ZusammenfassungObwohl die kontinuierliche intrakranielle Hirndruckmessung (ICP-Monitoring) bei der intensivmedizinischen Behandlung zerebraler Ischämien immer häufiger angewandt wird, ist der Nutzen des Verfahrens bei diesem Krankheitsbild noch nicht etabliert. Der klinische Verlauf bei 48 Patienten mit den Zeichen erhöhten intrakraniellen Druckes aufgrund eines großen raumfordernden Hemisphären- oder Mediaterritorialinfarktes, im kranialen Computertomogramm (CCT) gesichert, wurde prospektiv ausgewertet. Epidurale Drucksonden wurden ipsilateral oder sagittal zu der Seite der primären zerebralen Läsion bei allen und zusätzlich bei 7 Patienten kontralateral eingebracht. Alle Patienten wurden mit einem standardisierten Protokoll zur Behandlung erhöhten intrakraniellen Druckes therapiert. Druckwerte wurden mit dem klinischen Befund zum Zeitpunkt einer Verschlechterung, mit dem Endzustand und mit computertomographischen Befunden korreliert. Verschiedene Therapiemodalitäten zur Hirndrucksenkung wurden bezüglich ihrer Effektivität analysiert. Nur 9 der 48 Patienten (19 %) überlebten den ischämischen Hemisphäreninfarkt (19 %). Die Todesursache war bei allen 39 Patienten die transtentorielle Herniation mit konsekutivem Hirntod. Der durchschnittliche Punktwert der SSS bei Aufnahme betrug 20,6 (Überlebende 21,5 ± 5,6 vs. Verstorbene 19,8 ± 6,5). Bei allen Patienten gingen die klinischen Zeichen der Herniation dem Anstieg des intrakraniellen Druckes voraus. Hirndruckwerte über 35 mm Hg wurden nicht überlebt. Das Ausmaß der Mittellinienverlagerung korrelierte nicht eindeutig mit den absolut gemessenen Hirndruckwerten. Die kontinuierliche Hirndruckmessung bei großen hemisphärischen Infarkten ermöglicht eine Aussage über die weitere Prognose des Patienten. Zur Steuerung der antiödematösen Therapie nach ausgedehntem Mediainfarkt ist die kontinuierliche epidurale Hirndruckmessung nur wenig hilfreich. Ob die kontinuierliche Hirndruckmessung einen positiven Einfluß auf den intensivmedizinisch-klinischen Verlauf nach zerebraler Ischämie hat, bleibt fraglich.SummaryBackground and purpose: A permanent elevation of ICP after severe brain injury for instance in subarachnoid or intracerebral hemorrhage or neurotrauma is associated with a poor clinical outcome. Although increasingly being used in the intensive care of patients with elevated ICP, continous epidural ICP monitoring in ischemic stroke has not been firmly established yet. Patients and methods: We prospectively evaluated the clinical course and outcome of patients with raised ICP due to space occupying ischemic middle cerebral artery (MCA) infarction as seen in CT, who underwent continous ICP monitoring. Epidural ICPprobes were inserted ipsilaterally (all patients) and contralaterally (additional in 7 patients) to the side of infarctation. Glasgow Coma and Scandinavian Stroke Scales (GCS and SSS) were obtained initially and in the further clinical course. All patients were subjected to a standardized treatment protocol for raised ICP. ICP values were correlated with clinical presentation at the time point of deterioration, with outcome and CT findings. Effectiveness of different treatment modalities to lower ICP were analyzed and discussed. Results: 9 of 48 patients survived the MCA infarct (19 %), with the cause of death being transtentorial herniation with subsequent brain death in all 39 patients. Mean SSS at admission was 20.6 (survivors 21.5 ± 5.6, nonsurvivers 19.8 ± 6.5). All patients showed clinical signs of herniation before the increase of ICP. All 39 patients who died developed ICP values higher than 35 mm Hg and no patient with ICP values of more than 35 mm Hg survived. CCT changes dit not necessarily reflect the absolute measured ICP values. All treatment modalities for raised ICP including osmotherapy, controlled hyperventilation, tromethamol and barbiturates were initially effective, but only in a minority of patients ICP control could be sustained. Conclusions: We conclude that ICP monitoring in large hemispheric infarction may predict clinical outcome. ICP monitoring was not helpful in guiding long term treatment of ICP. It remains doubtful, whether ICP monitoring has a positive influence on clinical outcome of acute severe ischemic stroke.

MGMT promoter methylation status in anaplastic meningiomas

Anaplastic meningioma [World Health Organization (WHO) grade III] is characterized by aggressive biological behavior and recurrent tumor growth [1]. Radiation therapy is commonly employed after both total and subtotal resection, but effective chemotherapeutic regimens are lacking [2]. Hypermethylation of the O-methylguanine-DNA methyltransferase (MGMT) promoter is an important prognostic marker and also predicts response to therapy with alkylating agents (e.g., temozolomide) in patients with malignant gliomas [3]. While in benign meningiomas (WHO grade I) MGMT promoter methylation is rare or absent [4, 5] and temozolomide lacked efficiency in a small series of grade I meningiomas refractory to treatment [6], in anaplastic meningiomas, i.e., those neoplasms most likely to be considered for adjuvant treatment, MGMT methylation status has only been assessed in one and three cases, respectively [4, 5] and the role of temozolomide remains unclear. We thus aimed to examine MGMT methylation status in a large series of anaplastic meningiomas. Formalin-fixed paraffin-embedded tissue samples from all anaplastic meningiomas diagnosed from 1989 to 2009 were retrieved from the archives of the Institute of Neuropathology, Münster. In addition, available samples of formerly grade II or recurrent grade III tumors of these patients were also retrieved. All samples were reviewed neuropathologically according to WHO criteria [1]. After isolation and bisulfite conversion (EZ DNA Methylation-Gold Kit; Zymo Research, Orange, CA), DNA from representative tumor material was subjected to methylation-specific polymerase chain reaction (PCR) as described previously [7]. Controls included clones representing methylated and unmethylated bisulfite converted DNA [8] as well as enzymatically methylated human genomic DNA (Zymo Research). Using the above approach, a total of 55 samples from 30 patients could be examined. The median age of the 17 females and 13 males was 66 years (range 33–92 years). Eighty-five percent of the tumors were of supratentorial location. As shown in Fig. 1, MGMT promoter methylation status was negative in all cases except for a single specimen. This 57-year-old male suffered from recurrent grade III meningioma, showing hypermethylation of the MGMT promoter region on repeated analyses. Using the same methodology, MGMT promoter methylation status was positive in 90 out of 194 malignant astrocytic tumors (46%, data not shown). B. Brokinkel S. Peetz-Dienhart W. Paulus M. Hasselblatt (&) Institute of Neuropathology, University Hospital Münster, Domagkstraße 19, 48149 Münster, Germany e-mail: hasselblatt@uni-muenster.de

Inadvertent intrathecal use of ionic contrast agents: Treatment with immediate ventriculolumbar lavage

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Histopathological analysis of intracerebral hemorrhage: implications for clinical management

BackgroundThe clinical impact of routine neuropathologic examination of samples from patients with intracerebral hemorrhage (ICH) is unclear.MethodsTherefore, we evaluated a consecutive series of 378 surgical specimens from patients with ICH concerning demographic data, localization of hemorrhage, preoperative clinical diagnosis and neuropathological diagnosis.ResultsHistological examination revealed the putative origin of ICH in 143 cases (37.8%). Vascular pathologies were detected in 127 patients (33.6%), while tumors were identified in 9 patients (2.4%), infarction in 6 patients (1.6%) and abscess in 1 patient (0.3%). Preoperatively, tumor was considered in 65 patients (17.2%), while vascular malformations were supposed in 94 patients (24.9%), infarction in 18 cases (4.8%) and abscess in 3 cases (0.8%). In 198 patients (52.4%) no specific assumption was made.ConclusionsComparing preoperative assumptions and histological diagnoses, tumor, vascular malformations and infarctions were clinically overestimated, while arteriolosclerosis and amyloid angiopathy were underestimated. In conclusion, we found that histological findings potentially affecting clinical management and prognosis were obtained in 37.8% of cases. Our data suggest that histopathological examination of intracerebral hemorrhage provides important information for patient management and should be routinely performed.