Helmut Wiedemayer

Surgical treatment of intramedullary spinal cord metastases of systemic cancer: functional outcome and prognosis

Objective: Intramedullary spinal cord metastases (ISCM) of systemic cancer are rare. To date, patients with ISCM tend to benefit only to a limited extend from surgery and adjuvant therapy. Subject of this investigation is to assess predictive factors for surgical outcome and survival and to evaluate the value of surgical radicality in the treatment of ISCM. Patients and methods: Between 1990 and 2004, a series of 146 patients with intramedullary tumors underwent surgical treatment in our institution. Among these, 13 patients with intramedullary cancer metastases (7 adenocarcinomas, 3 poorly differentiated carcinomas, 3 sarcomas) were identified. Standard microsurgical removal of the ISCM was performed. Functional outcome was graded according to a standardized scale and factors influencing outcome and survival were statistically analyzed. Results: Median progression-free survival was 13 weeks and median overall survival was 31 weeks. In 5 patients (38) the intramedullary lesion was the initial manifestation of the malignant disease. All poorly differentiated carcinomas and all sarcomas were resected incompletely. Surgical radicality presented a negative predictive factor for functional outcome, increasing radicality leading to functional deterioration. Age, sex, tumor localization, surgical radicality and the presence of neoplastic meningeosis did not affect survival. Conclusion: Surgery of ISCM can be performed with an acceptable operative morbidity. Radicality depended on tumor histology. However, radical tumor removal did not affect survival and was correlated with a poor functional outcome. Therefore, complete surgical removal of ISCM should only be intended in patients in whom an unproblematic excision is feasible.

Visual evoked potentials for intraoperative neurophysiologic monitoring using total intravenous anesthesia.

Conflicting reports on the usefulness of intraoperative monitoring of visual function by means of visual evoked potentials (VEPs) initiated this study. In 32 patients without visual problems, VEPs were recorded to evaluate the reliability for intraoperative monitoring with total intravenous anesthesia. All patients underwent noncranial surgery. Using a standard technique, VEPs were recorded preoperatively in the awake patients and after induction of anesthesia during surgery. A total of 1436 intraoperative traces were recorded and analyzed. A minor prolongation of the P100 latency of 8% and a more pronounced attenuation of the P100-N145 amplitude of 60% were observed in the anesthetized patients. In most of the anesthetized patients, a stable recording of VEPs was not obtainable. In 4 patients (12.5%), clearly identifiable VEP peaks were detected in more than 90% of the traces recorded intraoperatively. In 88% of the patients, reproducible VEPs were obtained in less than 75% of the intraoperative traces only. We concluded that with standard recording techniques and total intravenous anesthesia, intraoperative VEP monitoring in surgically anesthetized patients is not reliable.

Early seizures following non-penetrating traumatic brain injury in adults: risk factors and clinical significance.

Background : In the literature dissenting data are obtained about risk factors for early post-traumatic seizures and their impact on outcome. This study was conducted to obtain more information about the clinical significance of early seizures and their possible impact on the treatment of traumatic brain injury. Methods and results : A consecutive series of 1868 adult patients with head injury were analysed retrospectively. Demographic data of the patients, characteristics of the injury, and findings on CT scan were recorded. Risk factors for early post-traumatic seizures were identified using univariate statistics. A multivariate logistic regression was performed to look for interaction of different variables. The impact of early post-traumatic seizures on outcome was examined in an analogous way. Chronic alcohol abuse, subdural haematoma and brain contusion were identified as independent risk factors for early post-traumatic seizures. A significant association of early post-traumatic seizures with an unfavourable outcome was observed, but this effect was small compared to other variables. Conclusions : Early post-traumatic seizures appear to be an acute reaction of the brain to cortical damage with little independent impact on the management of head injury.

Brain Perfusion Following Single Seizures

Summary:  Purpose: The aim of this study was to assess the regional relative interictal and postictal perfusion changes in temporal and parietal lobe epilepsy.

Osteoplastic laminotomy using titanium microplates for reconstruction of the laminar roof: A technical note

A technique to reconstruct the posterior elements of the spinal canal in osteoplastic laminotomy is described. The use of titanium microplates allows a stable fixation of the laminar arch with optimal realignment of the lamina cut ends. The titanium implants are fully compatible with magnetic resonance imaging. The autors experience with thirty patients is reported. The method proved to be simple and effective with distinct advantages over conventional techniques.

Intramedullary pilocytic astrocytomas — a clinical and morphological study after combined surgical and photon or neutron therapy

Ten patients suffering from intramedullary pilocytic astrocytomas (WHO-classification: astrocytoma grade I) were investigated catamnesticly. Combined surgery and radiotherapy was performed. Seven patients received neutron irradiation postoperatively. In four cases the neurological symptoms were improved after follow-up periods ranging from 33 to 89 months. The three other patients died after 6 to 21 months. The autopsy findings of a 14 year old child are presented. Our results are compared with reports in the literature. In addition, long-term problems of the spinal column are discussed. It seems that the combined surgical and neutron therapy improves the prognosis of pencil gliomas.

Functional magnetic resonance imaging in anesthetized patients: a relevant step toward real-time intraoperative functional neuroimaging.

OBJECTIVE: The introduction of intraoperative 1.5-T magnetic resonance imaging may provide up-to-date functional information in the surgical environment. However, feasible passive paradigms that allow the examination of anesthetized patients will be a precondition for intraoperative functional magnetic resonance imaging (fMRI). The aim of this study is to evaluate the feasibility of a recently developed passive fMRI paradigm for functional neuroimaging in anesthetized patients. METHODS: We investigated four anesthetized patients with intracranial pathological conditions not related to the sensorimotor cortex. All patients had been anesthetized with standard total intravenous anesthesia for more than 24 hours before the fMRI scan. Anesthesia and monitoring were sustained during the scanning procedure. A simultaneous electrical stimulation of the median and tibial nerves was applied to elicit a cortical activation using a custom-designed magnetoelectrically shielded conductor. Statistical evaluation using Statistical Parametric Mapping software (Wellcome Department of Imaging Neuroscience, University College, London, England) and the Talairach Daemon Client (Version 1.1; Research Imaging Center, University of Texas Health Science Center, San Antonio, TX) followed. RESULTS: Three of four patients showed a good activation of the sensorimotor cortex under anesthesia. In one patient, no significant activation was observed, presumably as a result of increased body impedance because of severe edema. Standard dosages of the narcotics did not influence the cortical response; however, stimulation intensity had to be increased compared with awake patients. We did not detect relevant interferences with magnetic resonance imaging arising from the technical setup. CONCLUSION: The method presented proved to be a feasible paradigm for fMRI evaluation of the sensorimotor cortex in anesthetized patients and thus forms a relevant step toward real intraoperative functional neuroimaging.

Operative treatment and prognosis of syringomyelia

Twenty-two patients suffering from syringomyelia were treated operatively. Different shunt procedures were performed. Most often syringo-subarachnoid shunt (seven cases) and syringopleural shunt (eight cases) were used. Operative findings and complications were discussed. Postoperative improvement was observed in five patients, twelve were stable-unchanged, four showed further deterioration and one died. Operative treatment should be performed before gross neurological deficit is established.

Fusion of the cerebellar hemispheres ventral to the brainstem: a rare hindbrain-related malformation

IntroductionNew variations of cerebellar malformations are being increasingly recognized using modern neuroimaging techniques. Until now only dorsal cerebellar fusion syndromes, such as the rhombencephalosynapsis and its variations have been recognized.Case reportWe report on a 17-month-old male infant presenting with an exceptional hindbrain related malformation characterized by midline fusion of the cerebellar hemispheres ventral to the brainstem and causing symptoms due to brainstem compression.Discussion and conclusionA more detailed understanding of the cerebellar embryogenesis is required to unravel the underlying mechanisms leading to this type of cerebellar malformation, which cannot easily be integrated into the common classification systems. Both the morphological features and the clinical presentation are different from those of other cerebellar structural abnormalities. If this type of congenital malformation is detected more frequently in the future, it seems reasonable that it should be added to the list of cerebellar malformations as a distinct type.