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J Schramm

Publications and source records attributed to J Schramm.

At least 145 records · Page 8Linked to original sources
PubMed1997

Petroclival meningiomas: is radical resection always the best option?

BACKGROUND: The surgical management of petroclival meningiomas is, despite the invaluable technical achievements in the past decade, still burdened by a high operative morbidity. It seems doubtful whether radical surgical removal should always be the primary goal in those lesions as advocated until very recently. METHODS: A series was critically analysed and the literature discussed to elucidate criteria for a different attitude. Between 1990 and 1995 a total of 19 patients harbouring petroclival meningiomas were operated on. The following approaches were used: petrosal (n = 13), retrosigmoidal (n = 5), and subtemporal (n = 1). Thirteen lesions were removed completely and six incompletely as assessed by postoperative MRI. RESULTS: No recurrence or regrowth could be detected on MRI after a mean follow up of 18 months. Surgical mortality occurred in one patient (5%) and there was early postoperative dysfunction in 56%. At the time of follow up major permanent operative morbidity was present in two patients (11%). CONCLUSIONS: In accord with recent literature subtotal resection of petroclival meningiomas should be contemplated in a subset of patients (with invasion of brain stem or cavernous sinus) to reduce the incidence of disabling deficits. Surgery should not be delayed in younger patients because surgical morbidity relates positively with tumour size.

Adult↗
PubMed1997

Can neuronavigation contribute to standardization of selective amygdalohippocampectomy?

Tailored selective amygdalohippocampal resections seem to be an interesting application for neuronavigation. The accuracy of freehand frameless neuronavigation was assessed in 28 patients for its ability to determine the hippocampal resection length, as compared to postoperative MRI. Brain collapse due to CSF displacement caused an expected error of navigation at the brain surface, but almost no error at the tentorial notch. Yet, the hippocampal resection length was overestimated by navigation to an extent of 3 +/- 2 mm. The discrepancy is explained by an anterior-posterior component of brain collapse in a tilted head. Horizontal positioning of the head or navigational marking prior to the occurrence of brain collapse may overcome the problem.

Adult↗
PubMed1997

Intravascular papillary endothelial hyperplasia of the sellar region. Report of three cases and review of the literature.

Intravascular papillary endothelial hyperplasia (IPEH) is considered a reactive proliferation of endothelium associated with thrombosis. The occurrence of IPEH in the cranial cavity is exceedingly rare. In this article, the authors report three cases of IPEH that originated from the cavernous sinus and extended into the sellar contents. The lesions were resected incompletely in two cases and completely in one case. The IPEH in one of the patients was incompletely resected and exhibited further growth on magnetic resonance imaging 3 months postoperatively; local radiation therapy was instituted. This led to shrinkage of the lesion over an additional follow-up period of 3.5 years. In a review of the literature, the authors located seven other cases of intracranial IPEH. The authors conclude that clinically symptomatic intracranial IPEH should be completely resected whenever possible, because it can cause considerable morbidity and mortality and because it is prone to progression or recurrence.

Adult↗
PubMed1997

Clonality of multiple meningiomas.

A significant number of patients with meningiomas develop multiple tumors without anatomical bridges. To understand the mechanism by which multiple meningiomas arise, the authors analyzed DNA from 39 multiple meningiomas in 12 patients to locate alterations in the neurofibromatosis type 2 (NF2) gene. This gene has been shown to be inactivated in meningiomas. No patient in our series had a family history of meningiomas or NF2. All tumors were investigated by single-strand conformation polymorphism analysis of the entire coding region of the NF2 gene and by direct DNA sequencing of altered fragments. The DNA from meningiomas in 10 patients carried NF2 gene mutations. In six of the 10 patients with NF2 mutations, all tumors in the respective individual exhibited the identical DNA alteration in the NF2 gene, thus indicating clonal origin. All four patients with more than two lesions had clonal meningiomas and four patients with two meningiomas each carried different mutations in their tumors. Analysis of constitutional DNA revealed a wild-type NF2 sequence in all 12 patients, thus excluding a forme fruste of NF2 in these cases. Our data demonstrate that the majority of multiple meningiomas with NF2 gene mutations are of somatic and clonal origin. Spread of tumor cells via the cerebrospinal fluid is the most likely mechanism to account for the development of these multiple meningiomas.

Adult↗
PubMed1997

Image guided microsurgery with a semifreehand neuronavigational device.

There is only limited experience with neuronavigators among the neurosurgical community so far. We evaluated such a prototype system in order to define indications for its succinct future use and to adjust it to daily clinical practice. We have employed an infrared light-linked computerized system (SPOCS; Aesculap/ISG) for preoperative planning and intraoperative navigation according to digitized images. A wired, penlike sensor-located "pointer" is used for navigation. Forty-eight patients (22 females, 26 males; aged 7-74 years) with a total of 53 intracranial lesions are included in the study. Fourteen lesions were smaller than 2 cm (26.4%), 33 were 2-4 cm (62.3%), and 6 were greater than 4 cm (11.3%). The documented accuracy was in the range of 3 mm or better in 33 patients throughout the whole operation and in an additional 7 through the most important surgical steps, with satisfactory results in all types of patient positioning except for the sitting position. In one patient the accuracy level decreased too early to perform useful intraoperative navigation. Technical dropouts early in the series led to abortion of the navigation in 7 instances but would currently no longer lead to abortion. There was no additional surgical morbidity associated with the use of the system. With more convenience in instrument design and development of techniques for real-time intraoperative reregistration, this kind of navigational device will play an increasingly important role for assistance during intracranial surgery. It proved to be helpful for planning of the craniotomy, intraoperative guidance on occasions of limited exposure and narrow visual field, localization and resection of small lesions in critical areas, and border definition of large lesions and for pure image guided resection of previously marked regions.

Adolescent↗
PubMed1997

Quantitative analysis of neurofibromatosis type 2 gene transcripts in meningiomas supports the concept of distinct molecular variants.

Meningiomas frequently show mutational inactivation of the neurofibromatosis type 2 tumor suppressor gene (NF2 gene). In a previous study, mutations were preferentially observed in the fibroblastic and transitional subtypes (75%), whereas the meningothelial variant was significantly less affected (25%). To study a potential role of the NF2 gene on the transcriptional level, we have analyzed NF2 transcripts in 67 meningiomas of different subtypes. A competitive reverse transcriptase-PCR assay with an external NF2 gene standard was used for quantitative mRNA analysis. Fibroblastic and transitional meningiomas exhibited significantly lower levels of NF2 mRNA compared with meningothelial variants (p = 0.001, unpaired t test). These data support the concept of a distinct molecular pathway in the formation of meningothelial meningiomas independent from the NF2 gene or its gene product merlin/schwannomin. In addition, in these tumors, NF2 expression was reduced by a factor of 10 (p < 0.001, unpaired t test) in those meningiomas with NF2 gene mutations suggesting decreased stability or impaired transcription of mutated NF2 mRNA. In conclusion, our data provide further evidence for molecular differences between subtypes of meningiomas and support an NF2-independent pathogenesis of meningothelial meningiomas.

Genes, Neurofibromatosis 2↗
PubMed1997

Efficacy of conservative treatment of lumbar disc herniation.

MATERIALS AND METHODS: This study comprises a total of 322 patients who were seen in our neurosurgical department as inpatients (N = 241) or outpatients (N = 81) for lumbar disk herniation. Patients presenting with major neurological deficits and/or symptoms reflecting lumbar stenosis were excluded. All patients were scheduled for conservative treatment which was based on bedrest for a minimum of two weeks. Thereafter, patients were assigned for further nonoperative or operative treatment. RESULTS: According to our results only 49% of conservatively treated patients had to be operated on. At long-term follow-up with a mean observation time of 2 years as available in 125 patients, 93% of patients who did not undergo surgery were improved with respect to pain. Motor function had recovered in 60%, and sensory deficits in 58% of these cases. CONCLUSIONS: In conclusion, conservative treatment is effective and in our opinion mandatory in the setting of sciatica caused by lumbar disc herniation except for patients presenting with severe, or progressive neurological deficits.

Adult↗
PubMed1996

Evidence for a novel tumor suppressor gene on chromosome 15 associated with progression to a metastatic stage in breast cancer.

Loss of heterozygosity (LOH) studies have emerged as a valuable indicator for tumor suppressor genes involved in the formation or progression of carcinomas. We here present data indicating that human chromosome 15 harbours a novel putative tumor suppressor gene which appears to play a role during later stages of carcinogenesis and which may be associated with metastasis in breast cancer. In this study, 153 primary and metastatic carcinomas from 101 patients have been analysed for LOH with 13 polymorphic microsatellite markers on chromosome 15. The tumors included carcinoma of the lung in 49 patients, breast carcinoma in 29, colorectal carcinoma in nine, renal carcinoma in five, pancreatic carcinoma in five, urinary bladder carcinoma in two and prostate carcinoma and ovarial carcinoma in one patient each. LOH15 was seen in 42/99 (42%) informative patients. In metastatic tumors, LOH15 was observed in 37/68 (54%). High incidences of allelic losses were detected in metastases from lung (56%), breast (70%) and colorectal (67%) carcinomas. In carcinomas of the breast, there was a significant difference (P<0.01) in LOH15 frequencies between non-metastatic tumors (11%) and brain metastases (70%). Such a difference was not observed on the chromosomal arm 17p which yielded high proportions of LOH in both non metastatic breast tumor (73%) and breast carcinoma metastases (90%). In 16 patients, interstitial deletions could be detected. The common region of overlap extended from D15S231 to D15S641, thus mapping this putative tumor suppressor gene to chromosome 15q14. Our data indicate that a gene on chromosome 15 contributes to the pathogenesis of metastatic carcinoma.

Brain Neoplasms↗
PubMed1996

[Differential therapy of cerebral arteriovenous malformations. An analysis with reference to personal microsurgery experiences].

A total of 126 patients (63 female, 63 male) underwent microsurgical removal of their cerebral arteriovenous malformations (AVMs) by the same surgeon. The mean age at surgery was 34.7 (6-72) years. The symptoms were intracerebral hemorrhage (37.3%), seizure disorder (34.9%) or focal neurological deficits and minor symptoms. According to the Spetzler/Martin scale, 20.6% of the AVMs were grade I, 28.6% grade II, 32.5% grade III, 14.3% grade IV and 4% grade V. In all, 78 AVMs (61.9%) were located in functionally important brain regions. The series was split into three different groups: small AVMs under 3 cm in diameter (n = 62/49.2%), medium-sized AVMs (n = 58/46%) and large AVMs (n = 6/4.8%). Seventeen patients had preoperative embolization of their AVM. All patients had postoperative angiographic control and 3- and 6-month follow-up. One patient died (0.8%), and another one (0.8%), in whom the AVM was incompletely resected, suffered a secondary hemorrhage. Seventeen (27.4%) of the patients with small AVMs developed transient neurological worsening post-operatively, which remained permanently significant in 3.2%. The respective numbers for the patients with medium-sized AVMs were 48.3% and 10.3% and for the large AVMs 83.3% and 33.3%. The results of microsurgical removal of cerebral AVMs can still be considered superior to the results of stereotactic radiosurgical treatment available from the literature-even for small AVMs. This is due to immediate exclusion of the AVM under direct local control of the angioarchitecture and thereby a reduced risk of secondary hemorrhaging and a decreasing morbidity rate with increasing time after the operation. Radiosurgical treatment requires a 2-year latency period for obliteration and carries a mortality rate of up to 12.5% and a rate of unexpected side effects of up to 20%. This treatment should be reserved for small, deep, surgically inaccessible AVMs or used as part of a multimodality treatment regimen consisting of partial embolization, partial excision and consecutive radiation of the residual nidus in initially very large AVMs. Embolization therapy-such as radiosurgery-carries a significant risk of morbidity (8%) and a mortality rate of up to 6%. It should only be considered for AVMs that are expected to be fully obliterated afterwards, or for primary inoperable AVMs that are to be changed into operable ones by embolization. Size reduction of otherwise operable AVMs does not justify the additional risk of embolization. Close collaboration of the specialties involved is desirable.

Adolescent↗
PubMed1996

Altered distribution of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor subunit GluR2(4) and the N-methyl-D-aspartate receptor subunit NMDAR1 in the hippocampus of patients with temporal lobe epilepsy.

In patients with therapy-refractory temporal lobe epilepsy (TLE), alterations of glutamate receptors have been proposed as a mechanism for enhanced excitability. Using commercially available monoclonal antibodies specific for the N-methyl-D-aspartate (NMDA) receptor subunit NMDAR1 and for the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor subunit GluR2(4), we have examined the distribution of these polypeptides in human hippocampal tissue that was surgically removed from patients with intractable TLE. Surgical specimens were classified according to the presence of Ammon's horn sclerosis (AHS) or a focal lesion in the temporal lobe. Cell counts and a densitometric analysis of the immunoreactivity patterns were carried out for all hippocampal subfields. NMDAR1 and GluR2(4) levels were markedly reduced in patients with AHS, primarily in those subfields with substantial neuronal cell loss (in particular CA1, CA4 and CA3), compared to those seen in patients with focal lesions and in control specimens obtained at autopsy. In contrast, the molecular layer of the dentate gyrus (DG-ML) showed significantly higher levels of GluR2(4) immunoreactivity in AHS compared to control tissue, while NMDAR1 showed no significant up-regulation in this sublayer. When the receptor staining intensity was normalized for alterations in neuronal density, no significant alterations could be detected except for an increase in GluR2(4) in the DG-ML of patients with AHS. These changes may reflect synaptic reorganization observed in the DG-ML of specimens from patients with chronic intractable TLE.

Adolescent↗
PubMed1996

Preservation of calretinin-immunoreactive neurons in the hippocampus of epilepsy patients with Ammon's horn sclerosis.

Selective neuronal vulnerability and aberrant axonal reorganization in the hippocampus may play an important role for the pathogenesis of pharmaco-resistant temporal lobe epilepsy (TLE). Interneurons containing calcium-binding proteins (CaBPs) are candidates for pathogenetically relevant neurons in the hippocampus of patients with TLE. Here we have examined the cellular localization and distribution of calretinin (CR), a recently discovered CaBP, in the hippocampus of 35 patients with TLE. There was a striking preservation of CR-immunoreactive neurons in TLE patients with Ammon's horn sclerosis (AHS). No significant differences in the distribution of CR-immunoreactive neurons were observed between patients with lesion-associated TLE and control patients without epilepsy. However, a subpopulation of CR-immunoreactive interneurons with morphological features of Cajal-Retzius-like cells, which are only transiently detectable in the normally developing hippocampus, was markedly increased in epilepsy patients with AHS. This increase did not correlate with the duration of the epileptic disorder. Another significant finding was a striking increase and reorganization of CR-immunoreactive neuropil throughout the entire molecular layer of the dentate gyrus (DG-ML) in patients with AHS as compared to patients with focal lesions and control specimens. Ultrastructural analysis identified the CR-immunoreactive axonal profiles as components of an inhibitory, intrinsic neuronal system. The presence of a CR-positive, aberrant cell population, in combination with sprouting of CR-positive axonal processes may significantly alter the gating function of the dentate gyrus and thereby increase hippocampal epileptogenicity in epilepsy patients with AHS.

Adolescent↗
PubMed1996

Somatosensory evoked potential phase reversal and direct motor cortex stimulation during surgery in and around the central region.

In 99 patients with mass lesions in and around the central region, the central sulcus was intraoperatively localized with the use of somatosensory evoked potential (SEP) phase reversal. In 33 of these patients, the motor cortex was directly stimulated and electromyographic responses were recorded from the forearm flexor, thenar, and hypothenar muscles. An additional 25 patients, with subcortical lesions or lesions directly located at the pyramidal tract, were continuously monitored during surgery by motor evoked potentials (MEPs). An exact determination of the central sulcus and tumor localization was possible in all patients; a phase reversal was obtained in 90.8% of the patients, and localization was possible as a result of anatomic structures and the loss of N20 or P20 of SEPs in the other 9.2%. MEPs were obtained in 32 of 33 patients and also in all 25 patients who underwent MEP monitoring at the beginning of tumor removal. From this study, it can be concluded that the combination of SEP phase reversal and modified electrical cortex stimulation is compatible with general anesthesia, although anesthesia was not systematically controlled according to a protocol. Although this study demonstrates that the combined SEP/MEP technique was feasible, it is not yet possible to demonstrate benefit in improving the outcome of patients. Concerning the safety of stimulation, the exact localization of the central sulcus by the noninvasive SEP method, compared with direct electrical stimulation, offered more safety for the patient. The modified technique of direct motor cortex stimulation needed much less charge density than did the common technique. The recording of electromyographic responses instead of movements made objective documentation possible, and the analysis of amplitudes and latencies will supply quantitative information about the motor system.

Adolescent↗
PubMed1996

Transcranial high-frequency repetitive electrical stimulation for recording myogenic motor evoked potentials with the patient under general anesthesia.

OBJECTIVE: To demonstrate the feasibility of transcranial high-frequency electrical stimulation with the patient under general anesthesia with propofol and alfentanil. This method may be a useful tool for intraoperative monitoring of the motor pathways during cerebral and spinal operations. METHODS: A short train from one to eight monopolar anodal electrical pulses was applied transcranially to the motor cortex with a frequency from 100 to 500 Hz in 10 patients. Myogenic motor evoked potentials (MEPs) were recorded from forearm flexor muscles, thenar, and hypothenar. Amplitude and latency of MEPs were evaluated after different stimulation parameters. This combination of anesthetic and transcranial stimulation technique allows recording of myogenic MEPs during general anesthesia, which was found not to be possible with single pulse transcranial stimulation. RESULTS: To elicit myogenic MEPs from the target muscles, stimulation had to be applied within the following parameters: minimum threshold intensity was 60 mA for forearm flexor and thenar and 80 mA for hypothenar; minimum number of pulses was two for forearm flexor muscles and thenar and three for hypothenar; minimum stimulation frequency was 200 Hz for thenar and hypothenar and 100 Hz for forearm flexor muscles. CONCLUSION: Transcranial high-frequency repetitive electrical stimulation seems to be a new method for monitoring the motor tract. With this method, it is possible to monitor the motor function without interfering with the surgical team or with the surgical treatment of infratentorial and spinal lesions. Monitoring of relaxation is necessary to compare the amplitude of MEPs.

Adolescent↗
PubMed1996

Properties of a delayed rectifier potassium current in dentate granule cells isolated from the hippocampus of patients with chronic temporal lobe epilepsy.

PURPOSE: Properties of potassium outward currents were investigated in human hippocampal dentate gyrus granule cells from 11 hippocampal specimens obtained from patients with temporal lobe epilepsy (TLE) during resective surgery. METHODS: Dentate granule cells were isolated enzymatically and outward currents analyzed by using the whole-cell configuration of the patch-clamp method. Hippocampal specimens were classified neuropathologically with respect to severe segmental cell loss, gliosis, and axonal sprouting (Ammon's horn sclerosis, AHS), or the presence of a focal lesion in the adjacent temporal lobe. RESULTS: A delayed rectifier outward current (IK), but not an A-type potassium current (IA) or inwardly rectifying potassium currents, was observed in all cells. The average current density of IK, the time-dependent decay of IK, and the resting membrane characteristics were not significantly different between patients with and without AHS. The voltage of half-maximal activation V1/2(act) was 5.4 +/- 1.8 mV in AHS compared with -2.9 +/- 1.8 mV in lesion-associated epilepsy (NS). In contrast, V1/2(inact) was shifted in a hyperpolarizing direction in AHS (-67.7 +/- 0.6 mV) compared with that in hippocampi not showing AHS (-47.7 +/- 2.6 mV; p = 0.0017). CONCLUSIONS: The altered steady-state voltage-dependence of IK may result in abnormal excitability of dentate granule cells in AHS and exert a marked influence on input-output properties of the dentate gyrus.

Adult↗
PubMed1996

Surgical treatment of extratemporal epilepsy: clinical, radiologic, and histopathologic findings in 60 patients.

PURPOSE AND METHODS: The aim of this study was to analyze clinical, radiologic, and histopathologic findings in 60 consecutive patients with medically intractable extratemporal epilepsy who were operated on between November 1987 and May 1993. RESULTS: Histologically, there were distinct structural abnormalities in 50 (83%) of the surgical specimens. Signal abnormalities on magnetic resonance imaging (MRI) were present in all patients with neoplastic lesions (n = 17) and in 94% of patients with nonneoplastic focal lesions (n = 32). Overall, structural abnormalities were detected by MRI in 47 (96%) of 49 patients with focal lesions. During a mean follow-up of 4 years, 30 (54%) patients remained completely seizure free, 11 (20%) had < or = 2 seizures per year, seven (12%) showed a seizure reduction of > or = 75%, and eight (14%) had < 75% reduction in seizure frequency. The fraction of seizure-free patients was 12 (80%) of 15 in patients with neoplastic lesions, 16 (52%) of 31 in patients with nonneoplastic focal lesions, and two (20%) of 10 for those without histopathologic abnormalities. The differences in seizure outcome between patients with and without focal lesions were statistically significant (p < 0.05), if seizure-free outcome was compared with persistent seizures. CONCLUSIONS: Focal lesions and particularly neoplasms are associated with improved postoperative seizure control compared with patients without histopathologic abnormalities. We advise caution in considering surgery to treat extratemporal epilepsy in patients who have normal MRI scans, because the outcome with the approach described in this study is poor in such cases.

Adolescent↗
PubMed1996

Presence and removal of arteriovenous malformation: Impact of regional cerebral blood flow, as assessed with xenon/CT.

In 26 patients with supratentorial AVMs and 1 patient with a dural arteriovenous fistula, the regional cerebral blood flow (rCBF) was assessed by means of xenon-enhanced computed tomography (Xe/CT) before and after complete resective surgery. Each assessment comprised an acetazolamide challenge in order to check the cerebrovascular reserve capacity. While scanning through the AVM was purposely avoided, a single brain slice at the level of the basal ganglia was examined. Five regions of interest (ROIs) in gray matter of the AVM-bearing hemisphere were compared to the contralateral ROIs and categorized into 7 CBF groups. Interhemispherical differences exceeding 20% of the contralateral value in either direction were considered to the significant. AVM-related (AVM-R) and AVM-non-related (AVM-NR) ROIs were looked at separately. Before surgery, all possible rCBF patterns were found, including a normal rCBF as well as a reduced or an increased rCBF, either in AVM-R, AVM-NR, or both. After AVM removal, a rCBF increase in AVM-R is relatively rare, whereas a rCBF decrease is twice as frequent. A rCBF drop to a level of impaired reserve capacity correlates with the occurrence of post-operative neurological deficit.

Acetazolamide↗