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Biomedical subjects

J Zentner

Publications and source records attributed to J Zentner.

At least 91 records · Page 5Linked to original sources
PubMed1994

SEP and MEP in comatose patients.

Somatosensory and motor evoked potentials (SEP and MEP) were examined in a total of 254 comatose patients in the acute phase (n = 254) and during the course of the disease (n = 67). It was the aim of this study to define the prognostic value as well as the correlation of potentials with the development of the neurological condition. Our results clearly show that in terms of prognostic value, SEP are superior to MEP, with normal findings indicating favourable outcome and absent responses an unfavourable outcome. Regarding follow-up examinations, we found that both modalities are sensitive for assessment of clinical deterioration, while improvement of the neurological status usually was not followed by improved potentials. In conclusion, SEP are a valuable parameter for predicting the outcome of comatose patients. The value of electrophysiological follow-up examinations is limited, and the use of SEP and MEP in this context may only be convenient for early assessment of neurological deterioration.

Adolescent↗
PubMed1994

Anaplastic ganglioglioma: case report and review of the literature.

We present the case of a 13-year-old boy who had a 12 year history of complex partial seizures. Recent CT scan and Magnetic Resonance Imaging (MRI) showed a contrast-enhancing lesion of the left temporal lobe, while CT performed 6 years ago was unconspicuous. Extended lesionectomy was performed according to the results of presurgical epileptological evaluation. Histological examination of the specimen showed an anaplastic ganglioglioma (WHO grade III). The clinical, neuroradiological, and histopathological findings of our patient are presented with respect to the literature on malignant gangliogliomas.

Adolescent↗
PubMed1994

Gangliogliomas: clinical, radiological, and histopathological findings in 51 patients.

Clinical, radiological, and histopathological features of 51 surgically treated gangliogliomas were evaluated retrospectively. The most common presenting symptoms were epileptic seizures (47 patients (92%)). Focal neurological deficits occurred in 8% of the patients. The duration of symptoms at the time of operation ranged from three months to 45 years, mean 11 years. The temporal lobe was affected in 43 patients (84%), the frontal lobe in five patients (10%), and the occipital lobe in one patient (2%). Two of the tumours (4%) were localised infratentorially. On MRI, solid tumour parts usually showed a pronounced signal increase on proton density images and a less pronounced signal increase on T2 weighted images, whereas solid components were mainly isointense on T1 weighted images. Contrast enhancement was noted in 16 of 36 patients (44%). Cystic tumour parts were found in 23 of 40 patients (57%), all characterised by signal increase on T2 weighted images and decreased T1 signals. Signal deviation of cystic tumour parts on proton density images was variable. Computed tomography was performed in 17 patients and showed hypodense lesions in 10 (59%), and calcifications in seven (41%) cases. Surgery included complete tumour removal in 44 patients (86%) and partial resection in seven (14%). In six patients (12%) there were transient postoperative complications. One patient (2%) died postoperatively due to pulmonary embolism. Histopathological examination of the surgical specimens showed low grade gangliogliomas in 49 cases (96%) and anaplastic gangliogliomas in two (4%). Control MRI of 31 patients with a mean follow up period of 16 months was uneventful in all but one case of an anaplastic ganglioglioma. In all patients in whom the ganglioglioma was associated with medically intractable seizures the operation resulted in complete relief of seizures or a noticeable improvement of the epilepsy.

Adolescent↗
PubMed1994

[Morphological findings in temporal lobe epilepsy: experience with 216 consecutive surgical specimens].

We have examined 216 consecutive surgical specimens of patients with chronic pharmacoresistant temporal lobe epilepsy. Neoplasms were detected in 75 cases (34.7%). All but two of these tumors were of low histopathological grade (WHO-grade I or II). There were 34 gangliogliomas, 17 pilocytic astrocytomas, 9 oligodendrogliomas, 6 fibrillary astrocytomas, and 6 dysembryoplastic neuroepithelial tumors. Fifty-one specimens contained non-neoplastic focal lesions and an additional 13 cases had both tumors and non-neoplastic focal lesions within the same specimen. The most frequent non-neoplastic focal lesions were microscopic glioneuronal hamartias (32 cases), glioneuronal hamartomas (7 cases) and vascular malformations (13 cases). The hippocampal formation was structurally well preserved in 71 specimens and in 51 of these (71.8%) there was Ammon's horn sclerosis. The findings document that intractable temporal lobe epilepsy is associated with significant structural alterations in the great majority of patients.

Brain Neoplasms↗
PubMed1993

Effect of propranolol on portal vein hemodynamics: assessment by duplex sonography and indocyanine green clearance in healthy volunteers.

In the past decade several randomized trials have shown a beneficial effect of propranolol in cirrhotic patients. The effect of propranolol has been attributed to a reduction in portal vein pressure. So far the monitoring of portal vein hemodynamics following propranolol administration has been achieved mainly by hepatic vein catheterization. We studied the effect of propranolol on portal vein hemodynamics noninvasively in five healthy volunteers using duplex sonography and indocyanine green clearance. Measured by duplex sonography, blood flow was reduced by 28.6% in the portal vein (P < 0.05) and by 8.7% in the hepatic artery (NS) 60 min after oral administration of 80 mg propranolol. During this time total hepatic blood flow, measured by indocyanine green clearance, was reduced by 19.5% (P < 0.05). We conclude that both methods are useful for the study of portal vein hemodynamics during propranolol therapy, duplex sonography being more easily practicable.

Adult↗
PubMed1993

Surgical pathology of chronic epileptic seizure disorders: experience with 63 specimens from extratemporal corticectomies, lobectomies and functional hemispherectomies.

The surgical treatment of chronic pharmacoresistant epilepsies is increasing rapidly. Although several studies have reported on histopathological findings in temporal lobe epilepsy, little is known about the surgical pathology of other seizure disorders. Here we report the histopathological findings in 63 consecutive surgical specimens of patients who were operated for chronic pharmacoresistant epileptic seizures other than temporal lobe epilepsy (37 corticectomies, 19 functional hemispherectomies, 5 lobectomies, 1 multilobectomy, and 1 frontal lobe deafferentiation combined with a temporal lobectomy). There were structural lesions in 85.7% of the specimens. In 16 cases (25.4%) the predominant lesions were malformative (focal glioneuronal hamartias and hamartomas, vascular malformations, abundant ectopic neurons in the white matter, microgyria, and arachnoid cyst). Lesions indicating pre- or perinatal necrosis such as porencephaly, ulegyria, and congenital hemiatrophy were present in 7 cases (11.1%). Twelve specimens (19.0%) contained low-grade neoplasms (7 gangliogliomas, 3 astrocytomas, 1 oligodendroglioma and 1 oligoastrocytoma). There were 3 cases of Rasmussen encephalitis, 1 specimen with atrophy and gliosis due to previous herpetic encephalitis and 1 case with an old abscess wall. Posttraumatic or postoperative changes were the predominant finding in 7 specimens (11.1%). In 7 patients there were only nonspecific changes such as cortical atrophy and gliosis or old hemorrhage. No structural alterations were identified in 9 specimens (14.3%). The findings suggest that the structural lesions observed in the great majority of the specimens were closely related to the pathogenesis of intractable seizures.

Adolescent↗
PubMed1993

Surgical pathology of temporal lobe epilepsy. Experience with 216 cases.

The surgical treatment of chronic epilepsies is increasing rapidly. Here we report the histopathologic findings in 216 consecutive surgical specimens of patients with chronic pharmacoresistant temporal lobe epilepsy. In 75 cases (34.7%) there were tumors, all but two of which were of low histopathological grade (WHO grade I or II). The most common tumors were gangliogliomas (34 cases), pilocytic astrocytomas (17 cases), oligodendrogliomas (9 cases), fibrillary astrocytomas (6 cases), and dysembryoplastic neuroepithelial tumors (6 cases). There were 51 cases with non-neoplastic focal lesions and an additional 13 cases with tumors and non-neoplastic focal lesions within the same specimen. The most frequent non-neoplastic focal lesions were microscopic glioneuronal hamartias (32 cases), glioneuronal hamartomas (7 cases), and vascular malformations (13 cases). The hippocampal formation was structurally well preserved in 71 specimens. In 51 of these (71.8%) there was Ammon's horn sclerosis. Presurgical placement of depth electrodes was invariably associated with circumscribed defects of the brain parenchyma. The implantation of subdural electrodes was sometimes followed by chronic inflammatory changes of the leptomeninges. Our findings indicate that in the majority of patients with medically intractable temporal lobe epilepsy there are significant histopathologic findings, many of which are only rarely encountered otherwise.

Adolescent↗
PubMed1992

Do motor evoked potentials allow quantitative assessment of motor function in patients with spinal cord lesions?

Motor evoked potentials (MEP) were recorded in a total of 110 patients with tumorous (n = 39) and non-tumorous (n = 71) lesions of the cervical (n = 59), thoracic (n = 37) and thoracolumbar (n = 14) spinal cord. In all cases MEP were elicited by electrical stimulations, and in 50 of them also by magnetoelectric stimulation, of the motor cortex. The peripheral conduction time was determined by electrical stimulation of the lumbar nerve roots. It was the aim of this study to determine whether 1. MEP are sensitive for detection of lesions along the spinal cord and 2. whether they allow quantitative assessment of motor function. To achieve this goal, we compared potential and clinical findings of our patients, each divided into seven categories. Our results clearly showed the high sensitivity of MEP for semi-quantitative evaluation of motor function, as there were no false negative results in our series. Moreover, unilaterally accentuated motor deficits correlated significantly with changes in MEP, which were affected more strongly on the corresponding side (Student's t-test, alpha = 0.05). However, clinical and electrophysiological findings did not correlate in the quantitative evaluation of the motor status as established by variance analysis (F = 0.52). There was no difference in results with respect to the electrical and magnetoelectric stimulation technique. Our results lead to the following conclusions. MEP are sensitive for semi-quantitative evaluation of spinal motor function; however, MEP do not allow quantification of the clinical motor status.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Periventricular neurocytoma: a pathological entity.

Three cases of periventricular neurocytomas are presented. All patients had a large but well-circumscribed, hyperdense tumor with insignificant contrast enhancement in the lateral and third ventricle, causing hydrocephalus. Calcification was present in one patient. Angiography revealed a blush tumor enhancement in two cases. Surgical removal was complete in two patients and incomplete in one. Light microscopy showed a cell pattern that resembled either ependymoma or oligodendroglioma. However, in all cases the tumor was confirmed to be a neurocytoma by immunocytochemical analysis that showed reactivity for synaptophysin and/or neuron-specific enolase in a high percentage of neoplastic cells. With respect to the literature it is concluded that neurocytomas represent an individual pathological entity of supratentorial midline tumors. Complete surgical removal without irradiation is the recommended treatment.

Adult↗
PubMed1992

Intracerebral chloroma complicating acute monocytic leukemia.

We present the case of a 21-year-old woman with an acute monocytic leukemia. When she was in complete hematological remission, she developed rapid progressive hemiparesis on the right caused by a left frontoparietal chloroma as confirmed by surgery and histological examination. Postoperatively, the patient recovered completely, and x-ray therapy followed. Since intracerebral myeloblastic tumors are extremely rare and since the neurosurgeon may be involved in treatment of these lesions, we are encouraged to present our findings.

Adult↗
PubMed1992

Influence of halothane, enflurane, and isoflurane on motor evoked potentials.

The influence of the inhalational anesthetics halothane, enflurane, and isoflurane on motor evoked potentials was studied in a total of 10 rabbits. Motor evoked potentials were recorded from the extremity muscles as well as from the epidural space of the spinal cord and cauda equina in response to electrical stimulation of the motor cortex at baseline conditions and equianesthetic concentrations (0.25 to 1.5 minimal alveolar concentration). Our results show a dose-dependent suppression of the electromyographic responses, which was similar with all anesthetics. Beyond 0.5 minimal alveolar concentration of any of the agents, electromyographic responses were absent. In contrast, spinal evoked responses representing neural activity were only slightly affected by the anesthetics. We hypothesize that the descending impulse elicited by the electrical stimulation of the motor cortex is mainly inhibited at the level of the spinal interneuronal or motoneuronal systems, because 1) electromyographic responses evoked by the stimulation of the cervical and lumbar nerve roots were only minimally affected by 1.5 minimal alveolar concentration halothane; and 2) spinal evoked responses were stable several minutes after cardiac arrest, indicating a subcortical action site of the electrical impulse. In conclusion, intraoperative monitoring of descending pathways by means of motor evoked potentials during anesthesia with the inhalational agents halothane, enflurane and isoflurane is only feasible when neural activity is evaluated.

Afferent Pathways↗
PubMed1992

The prognostic value of somatosensory and motor evoked potentials in comatose patients.

Somatosensory and motor evoked potentials (SEP and MEP) were examined in a total of 213 patients in traumatic (n = 140) and nontraumatic (n = 73) coma. It was the aim of this study to compare the prognostic value of MEP elicited by both electrical and magnetoelectric transcranial stimulation with the use of SEP alone. According to the presence or absence of responses and the duration of central conduction time, SEP and MEP obtained during Days 1 through 3 after the onset of coma were divided into four categories and correlated with the outcome of the patients, as assessed by the Glasgow Outcome Scale. Our results clearly show that in terms of prognostic value, SEP are superior to MEP, with normal findings indicating a favorable outcome and absent responses an unfavorable outcome. On the other hand, patients with normal electromyographic responses after both electrical and magnetoelectric stimulation had favorable and unfavorable outcomes about equally. Thus, unlike SEP, normal MEP do not allow any prognostic conclusions. Only the bilateral absence of MEP in response to electrical stimulation was a definitely unfavorable prognostic sign because all of these patients died. In contrast, with magnetoelectric stimulation, neither normal nor absent responses allowed any prognostic conclusions. Therefore, the prognostic value of electrically evoked motor responses is limited, and magnetoelectric stimulation cannot be recommended in this context.

Adolescent↗
PubMed1991

Motor evoked potential monitoring during neurosurgical operations on the spinal cord.

In order to monitor descending pathways during neurosurgical operations on the spinal cord, motor evoked potentials (MEP) were recorded from the epidural space of the spinal cord and the cauda equina following transcranial electrical cortex stimulation in a total of 40 patients. It was the aim of our study to test this invasive recording technique with regard to recordability of potentials as well as correlation to post-operative neurological conditions. In 15 of 23 patients (65.2%) intraoperative potentials were obtained from the spinal cord and in 33 of 40 patients (82.5%) they were obtained from the cauda equina. On the basis of acceptable changes in amplitudes of up to 50% at the end of the operation, 13 of 15 (86.7%) recordings from the spinal cord and 28 of 33 (84.8%) from the cauda equina correlated correctly with the post-operative motor status. At the same time, there were false positive results in 2 (13.3%) and 5 (15.2%) recordings, respectively. False negative results were not observed. Post-operative deterioration of the motor status as observed in 3 patients coincided in 2 patients with a permanent reduction in amplitudes of more than 50% of the baselines and in 1 patient with an intra-operative loss of potentials. Thus both spinal cord and cauda equina recording of MEP elicited by transcranial electrical stimulation were proven to be sensitive methods for detection of impending neurological complications. Cauda equina recording, however, seems to allow recording in more cases.

Adolescent↗
PubMed1991

A wooden foreign body penetrating the superior orbital fissure.

The case of a 12-year-old patient with a wooden foreign body which had penetrated the superior orbital fissure is presented. Using a transethmoidal approach, only some splinters lying in the periorbital soft tissue were removed. The patient became febrile, indicating an infectious complication due to a retained foreign body. This was confirmed by CT scan and MRI demonstrating a main splinter in the superior orbital fissure. Total removal of the wood was achieved via a pterional extradural approach. The difficulties of identifying wooden foreign bodies as well as the topographical problems involved with the approach to the superior orbital fissure are discussed.

Bicycling↗
PubMed1991

Prevention of an air embolism by moderate hypoventilation during surgery in the sitting position.

The effect of ventilation (normo-, hypo-, and hyperventilation) on transverse sinus pressure (TSP), central venous pressure (CVP), mean arterial blood pressure (mABP), and heart rate was studied in 15 patients undergoing neurosurgical treatment in the sitting position for tumors of the posterior fossa, and the findings were compared with the influence of positive end expiratory pressure (PEEP) on these parameters. TSP was not influenced significantly by PEEP ranging from 0 to 15 mbar, whereas CVP increased. At the same time, mABP decreased slightly. In contrast, TSP showed characteristic changes with varying ventilation: during normoventilation [end expiratory CO2 pressure (PECO2), 38 mm Hg], TSP was 3 mm Hg and increased to 7 mm Hg on average with hypoventilation (PECO2, 44 mm Hg), whereas hyperventilation (PECO2, 32 mm Hg) caused a reduction in TSP to the atmospheric range. At the same time, CVP remained unchanged, whereas mABP increased with hypoventilation. Presuming that the risk of venous air embolism is closely related to the level of TSP, our results allow the following conclusions. 1) PEEP does not seem to be effective in preventing venous air embolism. 2) Hyperventilation is dangerous in the sitting position, as TSP is reduced to the atmospheric and even subatmospheric range. 3) To prevent air embolism, moderate hypoventilation is recommended during the most critical period of exposing the posterior fossa followed by normoventilation when surgery of the actual lesion has begun.

Aged↗
PubMed1991

Surgical treatment of olfactory groove meningiomas using the pterional approach.

We present our experience with the surgical treatment of olfactory groove meningiomas using a pterional approach. This approach provides the advantages of previous techniques, such as preserving the frontal brain and superior sagittal sinus, early devascularization of the tumour, and late dessection of tumour borders. Moreover, it also compensates for the shortcomings of other techniques, e.g., compression of frontal bridging veins, late dissection of dorsal tumour aspects involving vessels and optic nerves as well as facultative infection and cerebrospinal fluid fistula-related complications caused by opening of frontal sinuses. To date, 11 patients were treated in this way. As we encountered no surgical complications in our series we are encouraged to present our procedure.

Adult↗