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Biomedical subjects

J Schramm

Publications and source records attributed to J Schramm.

At least 199 records · Page 11Linked to original sources
PubMed1993

[The surgical treatment of epilepsy].

Twenty percent of the approximately 800,000 epileptic patients in Germany cannot be treated adequately by pharmacotherapy alone. According to conservative estimates, epilepsy surgery could be of fundamental therapeutic benefit to at least 10-25% of these patients. A complex presurgical diagnostic program is the basis for any epilepsy surgery. Numerous methods are used to create a hypothesis about the location and size of the epileptogenic area. In addition, before surgery is performed, it must be established that no additional serious neurological or neuropsychological deficits will result from the planned resection. For this purpose, electrostimulation of the cortex and temporary anaesthesia of brain areas by amobarbital tests are performed. In intractable epilepsy originating in the temporal lobe about 60% of patients become seizure free after surgery. Another 15-20% benefit from surgery by a significant improvement in their seizure situation. Resections of the dominant temporal lobe result in further impairment of memory functions in about 20-30% of patients.

Adult↗
PubMed1993

[Neuroradiologic methods and findings prior to the surgical treatment of epilepsy in children].

Epilepsy in childhood is often caused by morphological abnormalities and is frequently pharmacoresistant. Therefore it represents a challenge to the neuroradiologist because early and accurate diagnosis of abnormal morphology is the basis for planning surgical intervention with a high chance of controlling seizures and a low risk of complications. Both morphological (radiography, CT, MRI and angiography) and functional examinations [intracarotid amobarbital test (IAT)] are essential parts of the presurgical evaluation. In most cases MRI has proved to be most sensitive in detecting lesions except for some calcifications. Routine protocols for brain examinations are not sufficient, missing about 22% of lesions. Therefore a refined MRI and CT protocol is proposed. Even in very young children IAT can be performed at very low risk; these tests contribute highly valuable information about actual hemispheric dominance and other functions in more than 80% of procedures that is indispensable if postoperative neurological and neuropsychological deficits are to be avoided.

Adolescent↗
PubMed1992

German-Austrian Space Occupying Cerebellar Infarction Study (GASCIS): study design, methods, patient characteristics. The Steering and Protocol Commission.

An open prospective multicentric therapeutic trial to determine the timing and type of therapeutic intervention in patients presenting with secondary deterioration following cerebellar stroke is described. According to the results of retrospective studies a controlled approach comparing different therapies is ethically not feasible. Participants use the same scores and protocol for patient data collection but many choose different therapeutic procedures.

Austria↗
PubMed1992

Pre- and post-operative hydrocephalus in supratentorial intraventricular tumours.

Post-operative problems of hydrocephalus which occur in a high percentage of intraventricular tumours are infrequently discussed. Our experience, however, showed many problems in the treatment of hydrocephalus associated with supratentorial intraventricular tumours. In a series of 40 supratentorial intraventricular tumours different types of management were used and reviewed retrospectively. It is concluded that certain types of management are disadvantageous, like primary shunt insertion. As a result the recommended form of treatment is: primary temporary external CSF-drainage followed by tumour surgery. Post-operative assessment of ventricular compartments and tolerance of drainage withdrawal. Shunt insertion only if compartmentilization or drainage dependency were manifest.

Cerebral Ventricle Neoplasms↗
PubMed1992

Correlations between verbal memory performance and electrocorticographically determined suppression of electrical brain activity in intracarotid amobarbital tests.

As a part of presurgical evaluation, bilateral intracarotid amobarbital procedures (IAPs) were performed in 42 patients (84 tests) with long-standing, medically intractable complex-partial seizures. During the IAPs, electrocorticographic (ECoG) recording was carried out via bilaterally implanted subdural electrodes. Five distinct patterns of suppression of electrical brain activity were observed: (1) an isoelectric line; (2) a burst-suppression pattern; (3) polyphasic waves; (4) high-voltage beta; and (5) low-voltage beta activity. Further, two types of specific reactions of the epileptic focus were detectable: (1) spike-burst-suppression patterns (SBS; 11 left; 7 right; 6 in both IAPs) and amobarbital-induced spikes (7 left; 4 right). ECoG suppression patterns as well as SBS and spike induction showed great variability in duration and overall occurrence. To determine the influence of these amobarbital-induced ECoG changes on results of IAP memory testing, performance in a verbal learning task was analyzed according to the ECoG patterns predominant during encoding. In left IAPs, it was found that SBS at the beginning of or during encoding had a significant negative effect on verbal memory. In right IAPs, verbal memory performance improved significantly with the decline of ECoG suppression. Hence, verbal memory performance in IAPs is significantly affected by specific ECoG suppression patterns and activation of the epileptic focus.

Adolescent↗
PubMed1992

Interhemispheric dissociation of expressive and receptive language functions in patients with complex-partial seizures: an amobarbital study.

Bilateral intracarotid amobarbital procedures (IAP) were performed in 144 patients with medically intractable complex-partial seizures. As a result of language testing, 29 patients (20.1%) were found to have bilateral language representation to different degrees. In four (2.8%) of these patients--all right-handers with early onset of epilepsy and/or evidence of early brain damage--there was strong evidence of an interhemispheric dissociation of expressive and receptive language functions. Two of these patients had circumscribed temporal foci (one left, one right), and receptive language functions were represented in the hemisphere contralateral to the focus. One patient with a right frontal focus showed left-hemisphere dominance for expressive functions, while the fourth patient exhibited left-hemisphere dominance for receptive functions associated with a right temporo-parietal focus. It is argued that in these four cases the circumscribed functional and/or structural impairments have led to a shift of the anatomically associated language functions to the opposite hemisphere (rather than to neighboring regions of the same hemisphere). These findings substantiate the hypothesis that in special circumstances the anterior (expressive) language area can be located in one hemisphere and the posterior (receptive) area in the other.

Adolescent↗
PubMed1992

Linguistic perseveration in dominant-side intracarotid amobarbital tests.

148 patients with medically intractable complex-partial seizures received bilateral intracarotid amobarbital tests. In 21 patients (14.2%), there were inappropriate responses (intrusions: N = 10; perseverations: N = 11) to a series repetition task (counting backwards) given immediately before amobarbital injection. Five cases from the perseveration subgroup are discussed in detail. In these patients, linguistic perseveration occurred with left-sided amobarbital injection, although they were all found to have left hemispheric speech dominance according to language testing during the amobarbital procedure. It is argued that these perseverations are best explained as a right hemispheric continuation of a speech motor program previously initiated by the left hemisphere.

Adolescent↗
PubMed1992

Recent developments in neurosurgical spinal cord monitoring.

In a review 8 years ago, the then current status of intraoperative spinal cord monitoring (SCM) was discussed. Concerning future developments, that article concluded that the major challenge lay in (a) the improvement of the reliability and clinical relevance of somatosensory evoked potential (SEP) monitoring, where the incidence of false-negative and false-positive results had to be reduced, and (b) the application of new techniques like motor evoked potential (MEP) monitoring, which might turn out to be a method complementary to the SEP approach. Since that time, there has been a considerable amount of newly published results from intraoperative SCM, although clinical articles on exclusively neurosurgical SCM are rare (Table I). A selective literature search for the present review (primarily for the time from 1988 to 1992) yielded more than 200 citations. Eighty-one studies entered into the final evaluation; among these were 3 conference proceedings, 6 book chapters, and 10 review articles. Further, 40 clinical articles, and 22 articles on experimental work were counted. In particular, experimental studies in animals have given support to clinical monitoring by exploring the usefulness of new stimulation and recording techniques. This reappraisal only considers recent work on SEP and MEP in neurosurgical SCM with some experimental studies relevant to clinical SCM. Spinal cord monitoring in orthopaedic surgery is not evaluated in this review for reasons detailed in the article.

Evoked Potentials↗
PubMed1992

Dose changes in long- and medium-term intrathecal morphine therapy of cancer pain.

Intrathecal morphine analgesia for the treatment of cancer pain was administered using implanted ports and drug delivery systems (DDS) in 79 patients. Effective control of the pain was achieved in nearly all patients; in only two patients was the use of the DDS discarded because of relative ineffectiveness. Fifty-three manual drug release systems (41 lumbar, 12 ventricular) and 26 lumbar ports were used. Forty patients survived more than 2 months; the maximum survival time was 560 days (mean survival time, 80 days with a port system, 100 days with a manual DDS). Patients still alive at the time of this study, i.e., with unknown survival time, were excluded. The initial mean daily dose was 8.5 mg in lumbar ports, 2.75 mg in lumbar DDS, and 0.2 mg with intraventricular application. Dose change patterns disclosed no alteration of the initial dose in 18 of 26 port patients, an initial increase in 4, a preterminal increase in 3, and a single intermittent increase in 1 patient. Of 40 lumbar DDS patients, 13 showed a constant dose, 9 an initial, 3 a preterminal, and 5 an intermittent increase. Three patients with less than 2 months' survival time had a rather continuous increase. All long-time survivors (i.e., with more than 2 months' survival time) reached a plateau and remained there until a preterminal if any increase occurred. These findings suggest the morphine dosage to be indicative of the progress of the disease rather than of a drug tolerance.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesia, Epidural↗
PubMed1992

Total intravenous anesthesia for improvement of intraoperative monitoring of somatosensory evoked potentials during aneurysm surgery.

Two anesthetic regimens for monitoring somatosensory evoked potentials (SEPs) during intracranial aneurysm surgery were compared. Eighty-four sequential cases of intracranial aneurysms were operated on employing SEP monitoring. The first group of 22 cases was anesthetized with "balanced anesthesia" and the second group of 62 cases received total intravenous anesthesia (TIVA) consisting of propofol and alfentanil. In the TIVA group, the amplitude of early cortical SEP responses (N20-P25, or P40-N50) was significantly higher than that of responses in the balanced anesthesia group. In median nerve SEPs, the averaged amplitude of N20-P25 was 3.22 microV with TIVA and 1.69 microV with balanced anesthesia (P = 0.006). Similarly, posterior tibial nerve SEPs showed a P40-N50 response of 1.85 microV and 1.00 microV, respectively (P = 0.017). The superior signal-to-noise ratio obtained with TIVA allowed more frequent and reliable intraoperative SEP recordings than was possible with balanced anesthesia, resulting in rapid and reliable feedback for the surgeon. In 19% of median nerve SEPs recorded with TIVA, the cortical responses were over 5 microV in amplitude, so that reproducible N20-P25 responses were obtainable by averaging only 10 to 50 serial responses, that is, two to three recordings per minute. The higher amplitude of posterior tibial nerve SEPs recorded with TIVA made monitoring during surgery for anterior communicating artery aneurysms possible in all cases. This was not always the case with balanced anesthesia. The late deflection of median nerve SEPs (N30) was more frequently observed with TIVA.(ABSTRACT TRUNCATED AT 250 WORDS)

Alfentanil↗
PubMed1992

[Intraoperative monitoring of early auditory evoked potentials in hearing acoustic neuroma patients complemented by cochlear nerve action potentials].

Hearing preservation was attempted in eight cases of acoustic neurinomas with good preoperative hearing. This was successful in 3 cases. Brain-stem auditory evoked potentials (BAEP0 were monitored in all cases, and compound nerve action potentials (CNAP) were recorded from the cochlear nerve in the last 3 cases. The BAEP was extremely sensitive to intraoperative manipulation. Intraoperative loss of wave V in BAEP was observed not only in all 5 cases with postoperative hearing loss, but also in 2 out of 3 cases with successful hearing preservation. CNAP correlated better with the hearing outcome than BAEP. In the cases where hearing was preserved, intact CNAP responses were demonstrated at the end of the operation. Conversely, deterioration of CNAP was seen in a case of postoperative hearing loss. CNAP was 10-15 times larger in amplitude than BAEP, so that the new responses were obtainable in shorter intervals. This capability of frequent examination seemed to increase the possibility of avoiding irreversible damage to the hearing by changing surgical tactics. The addition of CNAP monitoring is a good supplement to conventional BAEP monitoring in acoustic neurinoma surgery.

Adult↗
PubMed1991

Motor versus somatosensory evoked potential changes after acute experimental spinal cord injury in rats.

In this study, averaged cortical somatosensory evoked potentials (SEP) after sciatic nerve stimulation, and lower extremity muscle responses after motor cortex stimulation (MEP) were compared in rats. 10 animals served as light (25 g-cm) and 10 animals as severe (80 g-cm) acute spinal cord injury group after weight dropping trauma. After the initial loss of components, both SEP and MEP recovered in most cases in the light injury group. In the severe injury group, however, no recovery was observed in cortical SEPs, while the muscle MEP recovered in some animals. Light spinal cord injury had little effect on muscle MEPs and caused a paradoxical amplitude increase in some MEP recordings. Latency values of muscle MEPs did not show great changes after either kind of injury, while cortical SEP latency was considerably delayed. In this model cortical SEPs were more sensitive to light spinal cord injury than muscle MEPs after single electrical cortical stimuli. Severe spinal cord injury caused amplitude changes or loss of waves from both SEP and MEP.

Animals↗
PubMed1991

Ventricular late potentials in patients with and without inducible sustained ventricular tachycardia: a combined analysis in the time and frequency domain.

Time and frequency of signal-averaged electrocardiograms from 51 patients and 19 normal subjects were studied. A new filter device was designed to facilitate the analysis of the complete QRS complex, particularly the high-frequency components. All patients underwent electrical programmed stimulation (EPS) with up to three extra stimuli. In 29 patients, sustained ventricular tachycardia (VT) was inducible (group A), whereas in 22, sustained VT could not be elicited (group B). Between A and B, we compared several variables from the signal-averaged ECG as well as clinical data. The variables that differed between the two groups (P less than 0.01) were entered into a logistic regression model to determine which ones could most reliably predict the outcome of EPS. A combination of three variables (number of minima and maxima in the terminal QRS; third of four areas of equal length, divided by the total area below the QRS; maximum of the frequency spectre in the terminal QRS) could predict the inducibility of sustained VT with 82.8% sensitivity and 86.4% specificity.

Adult↗
PubMed1991

Delayed hearing loss after surgery for acoustic neurinomas: clinical and electrophysiological observations.

In a series of 26 patients with medium-sized and large acoustic neurinomas and documented hearing before surgery, 7 patients had preservation of hearing initially after the procedure but then developed delayed hearing loss. The most prominent intraoperative electrophysiological finding in these cases was a gradual deterioration of brain stem auditory evoked potentials (BAEP), especially of Wave V. Four additional patients with a similar gradual intraoperative loss of BAEP and severe postoperative hearing deterioration received vasoactive treatment after surgery (low-molecular weight dextran). In all 4 patients, including 1 patient with documented total deafness after surgery, hearing was preserved. Initial preservation of cochlear nerve function after the removal of an acoustic neurinoma does not guarantee postoperative hearing. Intraoperative BAEP help to identify patients at risk for delayed postoperative hearing loss. The pathophysiological mechanism can be attributed to disturbances of the microcirculation in endoneurial vasa nervorum caused by the mechanical manipulation of the cochlear nerve.

Adult↗
PubMed1991

Motor evoked potentials facilitated by an additional peripheral nerve stimulation.

In order to explore the use of intraoperative monitoring of motor systems under general anesthesia, the effect of transcutaneous electric brain stimulation was examined by non-invasive muscle activity recording. The mechanisms of anesthetic suppression of myogenic responses as well as different concepts to circumvent this suppression are reviewed. Facilitation of cortical stimulation effect at the spinal level was attempted by adding a well-timed peripheral nerve stimulation to it, similar to that for H-reflex from M. flexor carpi radialis. Eight comatose patients from the intensive care unit and 17 patients under general anesthesia were examined. Spinal motoneuron excitability changes caused by cortical stimulation in anesthetized patients showed a monophasic facilitation pattern with lower facilitation degree and shorter duration, compared to non-anesthetized patients. The latter showed a long-lasting, three-phase pattern of excitability change. Before there can be any clinical application of this facilitation technique, however, two problems remain to be solved: achieving a stable motoneuron conditioning level throughout anesthesia, and making the application of a compatible technique in more muscles possible.

Anesthesia↗
PubMed1991

[Neurologic findings before and after removal of cerebrovascular abnormalities].

In a retrospective serie the results of 72 cerebral vascular malformations, operated on consecutively were reviewed: 57 AV-malformations (in 55 patients), 1 dura AV-malformation, 9 cavernomas, 1 telangiectasia, 2 venous angiomas and 2 mixed malformations. The most frequent initial symptoms were headache, epileptic seizures and intracranial bleeding. In 5 cases the initial symptom was loss of consciousness with coma. A total resection could be proved angiographically in all cases. Mortality was 0%, neurological morbidity, i.e., new deficits or increase of existing deficits, was 8.6%. There were no recurrences of bleeding in the postoperative period. Quality of life, as assessed by the Karnofsky Index 6 months postoperatively, was satisfactory, approximately 80% of all patients being back at work. In this group of selectively operated patients it could be shown that localization of the malformation in or close to an eloquent brain area (n = 32) is rarely associated with significant persisting new deficits. Taking into consideration the natural history of AV malformations, with an 8% morbidity and 2% mortality each year, as compared to the surgical results, it is concluded that surgery may be more often indicated for AV malformations than was previously thought, even when they are near eloquent brain areas and relatively large in diameter.

Adult↗