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Biomedical subjects

O Diedrich

Publications and source records attributed to O Diedrich.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Event related potentials and emotional pictures:effect of stimulus presentation time].

The perception of the emotional content of a stimulus is a preattentive automatic process which causes an emotional reaction. As the ongoing stream of behavior might be disturbed by the emotional reaction, a controlled process is initialited at the same time, which normally leads to an inhibition of the emotional response. By means of event related potentials it should be possible to observe these controlled processes. In a first study using photographs from the International Affective Picture System, Diedrich et al. (1997) reported enhanded P300 amplitudes for emotional stimuli, even when the task distracted from the emotional content of the stimuli. This was interpreted as an index of the additional, controlled information processing elicited by the emotional content of the stimuli. Additionally, Diedrich et al. observed a frontel slow positivity, which might indicate the inhibition of the emotional response. However, this frontal slow wave might also be explained by the stimulus presentation time, which lasted 500 ms. This study is a conceptual replication of the experiment of Diedrich et al. Stimulus presentation time of neutral and emotional slides was varied in three steps (250 ms, 500 ms and 2000 ms). Subjects either performed a structural or an emotion-focused task on the stimuli. The results for the P300 component were exactly replicated. However, the variation of slow frontal positivity differed from that in the first study. Differences in the intensity of the emotional stimuli are discussed as a reason für this result.

Adult↗
PubMed1992

The scalp topography of P300 in the visual and auditory modalities: a comparison of three normalization methods and the control of statistical type II error.

This study was designed to replicate recent findings suggesting that the P3 component of the event-related potential is dependent on the modality of the eliciting stimulus. When assessing this research hypothesis two methodological problems are of special interest: first, the amplitudes have to be normalized, due to problems with the model of the analysis of variance; second, special care has to be taken regarding the beta error, which is the probability of falsely accepting the null hypothesis of a statistical test. A possible modality independence is associated with the acceptance of a null hypothesis. The first problem was assessed by using different normalization procedures and comparing their results. The second was solved by controlling the beta error. Results for P3 amplitudes from two sessions in which 61 subjects performed in each session an auditory and a visual oddball task (EEG measured at 11 locations) showed no influence of modality on the P3 elicited by the rare, task relevant, stimulus. Influences of modality were observed for the P3 elicited by the frequent stimulus. As it is quite unlikely that P3 generating sources are strongly active during the processing of the frequent stimulus, this effect is possibly due to a component overlap from the vertex potential.

Adult↗
PubMedDate not supplied

Implications of orthopedic fretting corrosion particles on skeletal muscle microcirculation.

Particulate corrosion and wear products of metal implants are increasingly becoming topics of interest, due to the cascade of biological and biomechanical events they induce. The impairment of skeletal muscle microcirculation by fretting corrosion particles may have profound consequences. We therefore studied in vivo leukocyte-endothelial cell interaction in skeletal muscle after confrontation with characterized titanium and stainless steel fretting corrosion particles, and compared these results with those of the bulk materials. Using the hamster dorsal skinfold chamber preparation and intravital microscopy, we could demonstrate that stainless steel induces a more pronounced inflammatory answer in contrast to the implant material titanium. However, we were not able to show a general benefit of bulk vs. debris. Overall, the study suggests that not only the bulk properties of orthopaedic implants, but also the microcirculatory implications of inevitable wear debris, may play a role in determining biocompatibility and ultimately longevity of an implant. The skinfold chamber is a feasible and versatile model for observation of the dynamic process of microvascular response after foreign-body implantation, and offers much perspective.

Journal Article↗
PubMedDate not supplied

[Differential diagnostic considerations in microcephalic dwarfism].

PURPOSE: While the rare Seckel-Syndrome is defined by clear criteria, clinical and radiologic findings for microcephalic osteodysplastic primordial dwarfism (MOPD) make an exact diagnosis and classification difficult. By comparing our patients to previously described cases of MOPD we evaluate the hypothesis that this disorder has a greater heterogeneity than has been believed up until now. Furthermore the differential diagnosis of the MOPD-complex is discussed. RESULTS: Two cases that show typical growth retardation, microcephalus and facial anomalies as well as osteodysplastic deformities including hip dysplasia are presented. The parents of both children are consanguineous and of Arabic race. In one of the children growth hormone levels were noticeably decreased. In discrepancy to the Seckel-syndrome both children showed no signs of mental retardation, therefore the classification into the heterogeneous group of microcephalic osteodysplastic primordial dwarfism (MOPD) is the most likely diagnosis. CONCLUSION: It is suggested that microcephalic osteodysplastic primordial dwarfism (MOPD) has a greater clinical and radiological expression than has been assumed up until now. Whether our results are merely a variant or suggest a new subtype of the MOPD can only be resolved by further cases. The exact pathogenesis of the disease currently remains unknown but the most probable cause is an autosomal recessive inheritance.

Abnormalities, Multiple↗
PubMedDate not supplied

[Dorsal lumbar interbody implantation of cages for stabilizing segmental spinal instabilities].

PURPOSE: The technique of posterior lumbar interbody fusion (PLIF) has been critically discussed due to a high degree of complications, including the development of pseudarthrosis. With the recent establishment of intercorporeal implants new aspects have to be contemplated in surgical techniques, especially concerning the posterior approach. In this study we present our first results after intercorporeal stabilisation of segmental spinal instabilities utilising carbon and titanium cages. METHOD: 45 spinal instabilities were surgically stabilised in 42 patients who were evaluated on average for 2.8 years post-operatively. 12 patients had isthmic and 19 patients degenerative instabilities while 11 patients suffered from instabilities resulting from prior spinal surgery. RESULTS: Assessed according to the Hambly-score, 69% of the patients had an excellent or good result; 2 (4.8%) patients were subjectively worse off than before surgical treatment. After implantation of cages precise radiological evaluation of bony ingrowth is frequently impaired by artefacts. We found that three months after implantation of a titanium cage, which had to be removed after incorrect placement, no bony consolidation was visible. Persisting or recurrent instabilities in fused segments were not recorded. CONCLUSION: By means of PLIF and implantation of cages the interbody space is reconstructed and jeopardized neural structures are decompressed. In addition to this, the frequently osteochondrotically degenerated segment is immobilized. The posterior approach allows decompression of neural structures and, with comparable results concerning stability, the considerable risks of the ventral approach are avoided.

Adult↗
PubMedDate not supplied

[Surgical outcome of single segment ventral fusion with plate osteosynthesis in therapy refractory chronic cervico-brachialgia].

INTRODUCTION: In anterior cervical stabilization, collapses of the grafted bone with resulting localized kyphosis and graft dislocation has been reported. It was the aim of this clinical trial to evaluate the benefit of additional plating while taking specific implant-related complications into account. METHODS: The results of single level anterior cervical spinal fusion were evaluated. In 44 patients suffering from chronic cervical radicular pain with degenerative changes, arthrodesis with iliac-crest bone and plate fixation was performed. Apart from clinical parameters, the pre- and postoperative segmental kyphosis and cervical lordosis were evaluated. RESULTS: The total cervical alignment increased from 15.4 degrees to 18.5 degrees while the alignment of the fused segment increased from 2.6 degrees to 7.7 degrees. Postoperative decrease of correction did not occur. Bony fusion was confirmed in 95% after 12 months and 100% aller 36 months. Our results show that patients had more relief from radicular pain (80%) than from unspecific neck pain (66%). DISCUSSION: In single level anterior cervical fusion, additional plating successfully prevents dislocation of the bone graft and postoperative kyphosis. The clinical results and pseudarthrosis rate do not differ from studies without plating. Long. term follow-up studies are necessary to show the benefit of the reduced postoperative kyphosis.

Bone Plates↗
PubMedDate not supplied

[Sacral osteoid osteoma--a rare cause of back pain in childhood and adolescence].

Osteoid-osteoma should be included in the differential diagnosis of any young patient with pain in the back. The tumor is the most common cause of painful scoliosis in adolescents. In spite of typical symptoms the diagnosis is often delayed. The osteoid-osteoma is seldom located in the sacrum and it can be difficult to diagnose the lesion by plain radiography there. At best, the radiographs may show an area of perifocal sclerosis. Scintigraphy and computed tomography can establish the diagnosis. Therapeutic procedures are medical treatment, operative excision or percutaneous radiofrequency coagulation. We report the case of a thirteen year old boy who suffered from an osteoid-osteoma in the sacrum.

Adolescent↗
PubMedDate not supplied

[Non-cerebrovascular complication in chirotherapy manipulation of the cervical vertebrae].

PURPOSE: Chirotherapy is a popular and successful management option for reversible functional disorders of the cervical spine. Though rarely observed, complications do occur, mainly involving the cerebrovascular system. By means of the here described case and a literature survey, we aim to highlight non-cerebrovascular complications of chirotherapeutic cervical spine manipulation. RESULTS: A 43-year-old male initially consulted an ENT specialist, suffering from tinnitus aurium and loss of hearing ability. His hearing significantly increased after intravenous drug therapy, but the tinnitus remained. During chiropractic manipulation of the cervical spine by an orthopaedic surgeon for the tinnitus, the patient described severe neck pain following a clearly audible clicking sound. Scans of the cervical spine prior to and after manipulation showed an intracapsular/intraosseus oedema of the facet joints C2/C3 with lesion of the nerve root C3, most probably induced by chirotherapy. CONCLUSION: Although complications after chiropractic manipulation are extremely rare, treatment of the spine, especially the cervical spine, is not wholly harmless. An adequate history taking followed by clinical and radiographic patient evaluation is necessary to keep the risk of iatrogenic trauma at a minimum. Above all, the chiropractic manipulation of the cervical spine belongs in the hands of a qualified and experienced medical practitioner.

Adult↗
PubMedDate not supplied

[Extracorporal shock wave treatment of the achilles tendinitis: Experimental and preliminary clinical results].

OBJECTIVE: Various studies have shown the benefit of extracorporal shock wave therapy (ESWT) in the treatment of soft tissue pathologies. The aim of this prospective study was to compare the results of ESWT with the operative treatment for achilleus tendopathy. Furthermore mechanical effects of the shock waves on the achilleus tendon were analysed by an in-vitro model. METHOD: The achilleus tendons of common pigs treated with 1500 impulses twice using an energy varying from 0.23 - 0.54 mJ/mm (2) were histologically examined. The clinical results of two patient groups of which the first (n = 28) was treated with 2000 impulses (0.23 mJ/mm (2)) once and the second (n = 26) underwent surgery for achilleus tendopathy were compared. RESULTS: The in-vitro model demonstrated that an EFD of 0.42 and 0.54 mJ/mm (2) can lead to tendon lesions. One year follow-up showed good and excellent results in 69 % and satisfactory results in 15 % of the operated group and good and excellent results in 29 % and satisfactory results in 43 % of the ESWT group. We could show a time-dependent effect of the shock wave treatment on the clinical outcome. CONCLUSIONS: Follow-ups show acceptable results with little side effects when an energy flow density (EFD) under 0.23 mJ/mm (2) is used. ESWT offers a non-invasive therapeutic concept that can seriously be contemplated before operative treatment, but lower success rates in comparison to the operative results can be expected.

Achilles Tendon↗
PubMedDate not supplied

[Striated muscle microvascular response to implants with sol-gel calcium phosphate coating. A comparative in vivo study].

AIM: Local microvascular perfusion plays an important role in reparative processes and the pathogenesis of infection. The impairment of skeletal muscle microcirculation by a biomaterial may therefore have profound consequences. The aim of our study was to determine whether the biological acceptance of the widely utilised implant material stainless steel can be improved by a coating of sol-gel calcium phosphate. METHODS: Using the hamster dorsal skinfold chamber preparation and intravital microscopy, we quantified nutritive perfusion and leukocyte-endothelium interaction in skeletal muscle after implantation of sol-gel calcium phosphate-coated stainless steel- and commercial pure titanium implants, and compared these results to those obtained with uncoated stainless steel and titanium. RESULTS: Within the first 24 h after implantation, animals with calcium phosphate coated stainless steel showed a significantly lower inflammatory response than did those with an uncoated stainless steel implant. After 24 h the quantified microcirculatory parameters deteriorated for animals with a calcium phosphate-coated stainless steel plate, indicating that, for as yet unknown reasons, the shielding mechanism of the calcium phosphate seems to deteriorate. Although not as inert as pure titanium, we found a relatively low inflammatory response for calcium phosphate coated titanium over the whole observation period, suggesting that the coating as such is well tolerated by the skeletal muscle microcirculation. CONCLUSIONS: Our in vivo results suggest that the biological acceptance of a conventional stainless steel implant can be improved over a short term by a sol-gel coating of calcium phosphate. Concerning tolerance by the local vascular system, commercially pure titanium currently remains unsurpassed.

Animals↗
PubMedDate not supplied

[Effect of posterior lumbar interbody fusion on the lumbar sagittal spinal profile].

AIM: To determine the effect of different cage geometries and posterior instrumentation on the sagittal spinal profile after monosegmental lumbar interbody fusion. METHOD: The study is based on a retrospective analysis of 119 patients with segmental instability, who were surgically managed by monosegmental PLIF with PEEK-Cages and dorsal instrumentation. RESULTS: At radiographic follow-up after surgery we found a significant improvement of the lumbar sagittal spinal profile, independent of the cage geometry utilised. A marked discrepancy between 0 degrees -standard and 4 degrees -trapezoid implants concerning the radiographic parameters lumbar lordosis, disc height, correction of spondylolisthesis and sacral inclination was not found. With the use of 4 degrees optimised cages in segment L4/5 slightly better results for segmental lordosis were obtained. Reliability of the radiographic evaluation, expressed as intra-observer error, was satisfactory. Cage geometry did not have an effect on the clinical result. By combining interbody fusion with pedicular instrumentation the reposition of slipped vertebra and distraction of the interbody space could more effectively be achieved. Patients without dorsal instrumentation had a higher rate of pseudarthrosis as well as a less satisfactory clinical outcome. CONCLUSION: These results show that normal sagittal alignment after single-level lumbar fusion can be achieved with rectangular and 4 degrees -wedged cages. Although results after utilization of 4 degrees -wedged cages do not significantly differ, these implants offer the surgeon one more sizing variation with which physiological lumbar lordosis may be attained. The combination of intersomatic implants with dorsal instrumentation achieves a more precise realignment and has a lower rate of cage-associated complications. It therefore seems prudent that an interbody fusion for the surgical management of lumbar segmental instability should be combined with pedicular instrumentation.

Equipment Failure Analysis↗
PubMedDate not supplied

[Comparison of dorso-lateral and dorso-ventral stabilization procedures in the treatment of vertebral fractures].

AIM: The radiological and clinical outcome of surgical treated thoracolumbal fractures were followed up after 6.7 years. METHOD: The study encompassed 97 patients. The degrees of the bony deformation and the local kyphosis were measured on the lateral view X-ray at 4 different time points: post trauma, after the operation, before implant removal and at the follow up examination. The clinical outcome was evaluated by the Oswestry score. RESULTS: 74 fractures were treated with a fixateur intern and a dorsal fusion by apposition of autologous bone postero-laterally. 23 fractures were fused in a combined dorso-ventral manner by intervertebral fusion with tricortical autologous bone. The lateral X-rays showed a loss of correction up to 48 % in the dorsal fused group and 10 % loss of correction in the combined group. The local kyphosis increased up to 84 % in the dorsal operated group due to degeneration of the injured disk. The clinical Oswestry score showed no significant difference in both groups. CONCLUSION: The additional ventral surgery should be evaluated carefully.

Adult↗
PubMedDate not supplied

[Coccygectomy in the treatment of coccygodynia].

AIM: Excision of the coccyx for the treatment of therapy-resistant coccygodynia is a disputable management option. Due to the low morbidity only few studies concerning the long-term follow-up after coccygectomy exist. The aim of this study is a retrospective analysis of our patients surgically managed for coccygodynia and a critical review of the results obtained in comparison to the literature. METHOD: 12 patients with complete radiographic and clinical data were included in the study. The average age of patients at the time of surgery was 43.3 years (11 - 75 years). The average follow-up was 9.8 years (2 - 16 years). As suggested by Hambly (1989) the clinical result was assessed according to postoperative pain status and subjective patient satisfaction. RESULTS: 9 of 12 patients regarded the surgical intervention as a success and claimed that they would repeat the procedure (75 %). Three patients did not show marked improvement after coccygectomy. All patients (n = 6) surgically managed for traumatically induced coccygodynia had a positive result, while only 3/6 patients treated for idiopathic coccygodynia reported that symptoms were postoperatively reduced. CONCLUSION: According to our results and review of those documented in the literature, excision of the coccyx for the treatment of coccygodynia, after all conservative treatment options have been exhausted, seems a justifiable alternative. Patients with a history suggestive of traumatically induced coccygodynia are more likely to benefit from coccygectomy.

Adolescent↗
PubMedDate not supplied

[Effectiveness of interscalene plexus block for open subacromion decompression].

AIM: The aim of this study was to assess the influence of interscalene brachial plexus blocks on the functional outcome, subjective pain appraisal and patient satisfaction after open shoulder surgery. These results were compared with patients treated by conventional analgesic measures. METHOD: 23 patients with interscalene brachial plexus block (ISB) and 21 patients without ISB were evaluated preoperatively as well as 1, 7, 12 and 90 days after open surgery of the shoulder. By means of a visual analogue scale (VAS) subjective postoperative pain intensity was assessed. Using the Constant score preoperatively and 6 months after surgery the functional status of the treated shoulder was evaluated. At discharge from hospital patients were asked whether they were satisfied with the analgesic measures taken. RESULTS: The range of motion of the shoulder of patients treated with an ISB was significantly higher 1 and 7 days after surgery than those without ISB. 12 and 90 days postoperatively the range of motion in the ISB group was still higher, but no longer statistically significant. Assessment of the postoperative subjective pain status showed that patients with an ISB had significantly lower values and required less additional analgesia. In both groups the Constant score was significantly higher 6 months after surgery, compared to the preoperative condition. Compared to the control group, patients treated with ISB were clearly more satisfied with the postoperative pain management. CONCLUSION: By implementing ISB sufficient analgesia in the early postoperative period after open shoulder surgery is attained, allowing for early physiotherapy. This positively influences convalescence and the outcome of the surgical procedure. Furthermore, patients are visibly more satisfied with the postoperative pain management.

Acromion↗
PubMedDate not supplied

[Residual stability of different interbody fusion techniques after pedicle screw loosening].

INTRODUCTION: In spinal surgery, postoperative failure of pedicle screw instrumentation due to loosening of the implant at the bone-screw interface is a clinically relevant problem. While there are numerous biomechanical studies dealing with stability after internal fixation, little is known about the remaining segmental stability after pedicle screw loosening. We hypothesize that, in cases of implant loosening, the remaining stability is dependent on whether the segment received an isolated pedicle screw instrumentation or a 360 degrees instrumentation. METHODS: Motion analysis was performed under static, damage-free, sagittal strain (preload 100 N) on intact (controls) and posterior monosegmental L5/6 destabilized lumbar spines of sheep. Spine preparations underwent a flectional torque. Changes of spinal profile were radiographically documented, digitalized and then evaluated. Primary insertion of the conical pedicle screws was performed with a torque of 1.4 Nm. Pedicle screw loosening was simulated by turning the inserted screw back either 180 degrees or 540 degrees . Specimens instrumented with screws of differing diameters (5.5 mm and 6.7 mm) as well as non-instrumented pedicles were also compared. RESULTS: Independent of the type of instrumentation, we found that a loosening of pedicle screws increased remaining segmental motion. In maximal flexion (20 degrees ) and loosening of pedicle screws by 540 degrees, we found a statistically significant increase of remaining segmental motion with sole pedicle instrumentation (- 3.1 degrees ) in contrast to 360 degrees instrumentation (- 1.6 degrees ). For extension, a significant discrepancy between the two stabilization methods could not be shown. In cases where screws were firmly inserted, there was no advantage of using pedicle screws with an increased diameter of 6.7 mm. Independent of the type of fixation method, 5.5 mm screws that were inserted in widened pedicles showed a marked decrease of primary segmental stability. CONCLUSION: This study suggests that, concerning the remaining stability, 360 degrees instrumentation is superior in cases where pedicle screw loosening has occurred. The screw diameter plays an only subordinate role in primary segmental stability when the pedicle screws are inserted firmly.

Animals↗