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Biomedical subjects

A Prescher

Publications and source records attributed to A Prescher.

At least 55 records · Page 3Linked to original sources
PubMed1999

Extra- and intracellular accumulation of ultrasmall superparamagnetic iron oxides (USPIO) in experimentally induced abscesses of the peripheral soft tissues and their effects on magnetic resonance imaging.

UNLABELLED: The effects of ultrasmall superparamagnetic iron oxide (USPIO) particles on magnetic resonance imaging (MRI) were studied in an animal abscess model and the findings compared with microscopic sections of the abscesses. Staphylogenic abscesses of the right hind leg were induced in six Sprague-Dawley rats. The USPIO particles consisted of polyethylene-glycol-coated Fe3O4 with a mean size of 26 nm and were injected intravenously (i.v.), with three animals receiving a dose of 50 micromol/kg and three animals a dose of 150 micromol/kg. Before and immediately after i.v. administration of the particles, MR data were acquired with fast gradient-echo technique FLASH sequences applied over a period of 60 min. The Fe3O4-induced signal changes were registered in regions of interest (ROIs) placed over the margin and center of the abscess, over the perifocal granulation tissue and over corresponding sites of the contralateral healthy muscle. Microscopic sections were prepared using the conventional paraffin technique and, in part, a kryohistologic method before staining of the specimen with hematoxylin and Berlin-blue reaction. In addition to the mostly perfusion dependent loss of signal intensity within 8 s after injection, a signal reduction, which could be rather pronounced, was observed in the abscess margin and perifocal granulation tissue, with the underlying mechanism mainly attributed to extravasation and predominantly extracellular deposition of Fe3O4. CONCLUSION: The USPIO particles used in this study lead to a prolonged demarcation of abscesses in the peripheral soft tissues due to particle extravasation and accumulation in the periphery of the abscesses. Besides the known accumulation of already characterized USPIO in the RES of liver, spleen and lymph nodes the study could demonstrate ultrasmall iron oxide deposition (BY 818) in abscesses of the peripheral soft tissue.

Abscess↗
PubMed1999

An unusual cavity within the styloid process.

A rare case of an unusual sinus within the styloid process is described. The radiological appearance of this malformation is presented with CT-scans and a hypothesis for its development is presented. The malformation is designated as "Recessus processus styloidei" and this entity is considered to be a dysgenesis of the second branchial arch.

Branchial Region↗
PubMed1998

MR-guided interstitial cryotherapy of the liver with a novel, nitrogen-cooled cryoprobe.

The purpose of the study was to test a newly developed, MR-compatible, liquid nitrogen-cooled cryoprobe. The probe has an outer diameter of 3.5 mm and was specifically developed for percutaneous, MR-guided, interstitial cryotherapy. The probe was inserted percutaneously into the livers of 10 rabbits. The cryotherapy procedure was monitored with a surface coil in a 1.5 Tesla magnet using a gradient echo sequence. Follow-up examinations were performed 3 and 7 days after the freezing procedure using T1- and T2-weighted spin echo sequences. At 7 days the animals were sacrificed and the cryolesions were examined histologically. The cryoprobe enabled artifact-free MR imaging of the "iceball" formation during freezing of the rabbit liver. After 1 min of freezing, the iceball at the tip of the probe showed an average maximum diameter of 10.8 mm. No bleeding complications were observed during or after the freezing procedure. Histologic examination 7 days after cryotherapy confirmed that the liver lesions were the same size as had been predicted by the images of the acute iceball. This new, percutaneously inserted, MR-compatible, liquid-nitrogen cooled cryoprobe allows accurate, artifact-free MR imaging of interstitial cryotherapy.

Animals↗
PubMed1998

Stability of different wiring techniques in segmental spinal instrumentation. An experimental study.

The pullout force of sublaminar and transspinous wires for segmental instrumentation which had been inserted into different segments of human cadaver spines were compared. Four different types of wiring were tested: single and double sublaminar wires, button-wires according to Drummond's technique and button-wires with the additional use of two crimps for each spinous process. A total of 50 tests were performed. In all attempts the bone proved to be the limiting factor. None of the 300 fixed wires failed. Typical types of fractures appeared with different wiring techniques. There was no statistically significant difference between the sublaminar wiring techniques tested. However, there were significant differences between sublaminar and transspinous wiring. The transspinous techniques achieved between 30% and 45% of the pull-out strength of sublaminar techniques. The forces decreased with increasing cranialisation. In all techniques the values in the upper segment (D5-D3) were almost half those of the lower segment (L5-L3). The differences of the transspinous techniques increased cranially, in favour of the technique with additional crimps. Thus, the crimps have the strongest effect on weak spinous processes. This study demonstrates that in non-dynamic testing, the stability of the bone and not the type of wiring is the limiting parameter in segmental spinal stabilisation. As the wires are inserted in different areas, the transspinous technique shows significantly lower tension forces in comparison with sublaminar wiring.

Biomechanical Phenomena↗
PubMed1998

Anatomic and functional aspects of the kinetics of the shoulder joint capsule and the subacromial bursa.

This anatomic study was devoted to the kinetics of the shoulder joint and especially the subacromial region. Following dissection of the shoulder joint capsule and subacromial region of 80 unpreserved shoulder joints, the anatomic relationships of the subacromial space in the neutral position and in continuous abduction (30 degrees, 60 degrees and 90 degrees with fixed scapulae) were examined. These investigations were supplemented by histologic preparations. In the course of our examinations we discovered a gliding mechanism of the subacromial bursa. Moreover, we found a subcoracoid attachment of the shoulder joint capsule and a precoracoid ligamentous connection running between the short head of the biceps brachii m. and the coracoacromial ligament. We termed this the coracoid aponeurosis, which facilitates gliding behaviour of the shoulder joint capsule beneath the coracoid process. In view of this gliding mechanism of the subacromial bursa and the coracoid aponeurosis, discovered in the course of our investigations, we have to reassess the kinetics of the sub-acromial and subcoracoid space. Further, we should reconsider our operative technique in cases of the subacromial or subcoracoid impingement syndrome.

Bursa, Synovial↗
PubMed1998

Detection of an occult transclival cerebrospinal fluid fistula by CT and MRI.

We describe an unusual occult transclival cerebrospinal fluid (CSF) fistula to the sphenoid sinus demonstrated by MRI. CT was performed because of a posterior cerebral infarct caused by cardiac arrhythmia. Axial sections showed fluid in the sphenoid sinus. High-resolution scans revealed a bony defect 3 mm in diameter of the posterior wall of the sphenoid sinus, and MRI showed a transclival CSF fistula. This occult lesion was confirmed by surgery and duraplasty was successfully performed via an endonasal approach.

Arachnoid Cysts↗
PubMed1998

Femoral nerve lesion in total hip replacement: an experimental study.

A total of 20 hip joints of 10 non-fixed corpses were examined within 48 h of death to measure the pressure below the inguinal ligament simulating the surgical conditions during total hip arthroplasty. The purpose of this study was to assess the influence of various leg positions and insertion techniques of retractors during the surgical procedure for total hip replacement in order to detect supposed causes for indirect pressure injuries of the femoral nerve. The obtained results verified no increase of pressure in the inguinal canal which could explain an indirect injury of the femoral nerve. If the retractor is inserted correctly at the anterior acetabular rim, the pressure in the lacuna musculorum can even be reduced, and furthermore, the femoral nerve is protected by the iliopsoas muscle. Femoral nerve lesions which have been published so far can only be explained by an incorrect use of instruments or implants (e.g., screws, cement, acetabular cup) or an extreme postoperative leg length discrepancy.

Arthroplasty, Replacement, Hip↗
PubMed1998

Unusual sinus of the styloid process.

The case of a 50-year-old man with an unusual sinus of the styloid process is presented. This anomaly caused recurrent otorrhea and repeated neck inflammation. The sinus was identified in the upper part of the styloid process and was resected completely as definitive treatment. Since the styloid process is formed by mesenchymal tissue of the second branchial arch, lack of chondrification and ossification was presumed to be the cause of the sinus found in the patient. In case of direct communication between the styloid process cavity and the middle ear space the term "styloid process recess" is suggested. This recess can act as a possible source for recurrent middle ear infections and neck inflammations.

Branchial Region↗
PubMed1998

Anatomy and pathology of the aging spine.

The vertebral column is a complicated anatomical structure which is composed of the intervertebral discs and the vertebrae. Both components develop special degenerative changes and morphologic features during life. This paper first reviews the anatomical fundamentals and then describes the morphological features of the aging intervertebral disc and the subsequent osseous changes of the vertebral bodies and the zygapophyseal joints. The aging intervertebral disc is characterised by processes which are labeled as intervertebral chondrosis and intervertebral osteochondrosis. Often these processes are combined with typical dislocations of intervertebral disc tissue in an anterior or dorsolateral direction. The well known Schmorl's nodules must also be mentioned in this context. Furthermore calcification and ossification of the intervertebral disc tissue can take place. More severe processes lead to osseous changes of the vertebral bodies. In particular, an osteophytosis of the vertebral bodies can be established. These sturdy osteophytes are able to stiffen the vertebral column. Furthermore the arthrotic changes of the zygapophyseal joints are delineated in this paper. The special appearances of these changes are discussed according to the different and specialised regions of the vertebral column. The advanced degenerative changes of the zygapophyseal and uncovertebral joints of the cervical spine are of essential clinical interest because the compression of the vertebral artery or the narrowing of the intervertebral foramina by these processes may cause severe neurological symptoms. The arthrotic changes of the medial atlantoaxial joint, which lead to the crowned odontoid, and the pseudospondylolisthesis (so called M. Junghanns) of the lumbar spine must also be mentioned. It is the aim of this paper, not only to explain and review the degenerative changes, but to illustrate the anatomy and pathology of the aging spine on the basis of macerated osseous specimens in order to make radiological investigations and pictures more understandable and clear.

Aged↗
PubMed1998

Mechanisms of accumulation of small particles of iron oxide in experimentally induced osteosarcomas of rats: a correlation of magnetic resonance imaging and histology. Preliminary results.

RATIONALE AND OBJECTIVES: This study was conducted to investigate the distribution and kinetics of small particles of iron oxide in osteosarcoma-like tumors. METHODS: Magnetic resonance (MR) imaging was performed in eight athymic nude rats with an experimentally induced osteosarcoma of the right hind leg immediately after intravenous injection of a superparamagnetic iron oxide preparation. Five animals received 150 mumol iron oxide/ kg and three received 50 mumol iron oxide/kg. The iron oxide preparation consisted of polythylenglycol-coated particles with a core diameter of 6 to 8 nm. The MR images were correlated with histologic slices of the tumors. RESULTS: The tumors accumulated iron oxide rapidly. A marked decrease in signal intensity, preferentially along the periphery of the tumor, was followed by a partial return of the signal intensity within the first minute. The maximum signal decrement throughout the entire tumor exceeded 41% and 21% with one dose each of 150 mumol iron/kg and 50 mumol iron/kg, respectively. The rate of return depended on the injected dose and tumor area, with the signal intensity approaching the initial value before the injection of iron oxide after 45 minutes. Histologic correlation only showed deposition of contrast medium in the proliferative areas of the tumors, mainly confined to the tumor margin. In addition to a predominantly extracellular deposition, intracellular storage could be detected. CONCLUSIONS: The findings help to advance the understanding of the distribution and kinetics of intravenous-injected small particles of iron oxide in osteosarcoma-like tumors. A first-pass accumulation of iron oxide could be documented by MR imaging in the periphery of osteosarcomas. Due to sieving of iron oxide particles by liver, spleen, and bone marrow, the signal intensity at 45 minutes after the injection of iron oxide returned to 89% (150 mumol iron oxide/kg) and 95% (50 mumol iron oxide/kg) of the preinjection intensity.

Animals↗
PubMed1998

[Sensory innervation of the hip joint capsule in dogs].

The innervation of the canine hip joint has become increasingly important in the treatment of hip dysplasia and hip arthrosis, since investigations proved that simple removal of periosteum around attachment of hip joint capsule, called denervation results in an instant analgesia and allows the dog to regain joyful freedom of movement. A macroscopic-anatomic examination of 16 canine hips furnished new findings and knowledge in the field of veterinary medicine on the sensitive innervation of the canine hip joint capsule. Accordingly, the craniolateral area of hip joint capsule is innervated by rami articulares of N. glutaeus cranialis, the caudolateral area by rami articulares of N. ischiadicus and the medial area by rami articulares of N. femoralis.

Animals↗
PubMed1997

Anatomic study of femoral vein occlusion during simulated hip arthroplasty.

An anatomic study was undertaken to establish whether positioning of the leg and surgical approaches for total hip replacement (THR) cause changes in the femoral v. which may contribute to the development of deep vein thrombosis (DVT). The patency of 32 femoral vv. of 18 cadavers was inspected at different levels during simulated THR. Before and after removal of the femoral head through a transgluteal or posterior approach, a wide-angle endoscope was inserted into the femoral v. via the external iliac v. Blood flow was simulated by proximal irrigation with saline through the popliteal v. After removal of the femoral head distinct changes were observed in both approaches. In the transgluteal approach the changes were dependent on the degree of adduction and the body build of the cadaver. Initially, an oval form was seen in a constricted lumen with an increasingly oblique oval deformation and a final facet-like closure, usually at about 5 to 7.5 cm below the inguinal ligament. In total adduction this stenosis occurred regardless of build. Using a posterior approach, the necessary internal rotation caused a closure of the vein in 50% of cases. In combination with flexion and adduction there was stenosis in all cadavers regardless of body build. Our results indicate that the duration of the adducted position of the thigh during THR via a transgluteal approach should be minimised, as there is a reduction in blood flow with even minor degrees of adduction. In the posterior approach the stenosis occurs earlier, and is independent of the build of the cadaver.

Arthroplasty, Replacement, Hip↗
PubMed1997

The sensory innervation of the hip joint--an anatomical study.

Typically obturator nerve blockade is used to relieve hip pain. It sometimes only has a minor effect in resolving symptoms. This clinical observation led us to examine comprehensively the sensory nerve innervation of formalin-fixed hip joint capsules. Following macroscopic preparation, the area of the hip joint capsule was inspected with the aid of an operating microscope. We discovered a separation between the anterior and posterior sensory innervation of the hip joint capsule. The anteromedial innervation was determined by the articular branches of the obturator n. Additionally, the anterior hip joint capsule was innervated by sensory articular branches from the femoral n. In the posterior part we found articular branches from the sciatic n., which in addition to the articular branches from the nerves to the quadratus femoris m., innervate the postero-medial section of the hip joint capsule. Moreover, articular branches of the superior gluteal n. were found, which innervate the posterolateral section of the hip joint capsule. This anatomical study demonstrates that the obturator n. block is insufficient for the treatment of hip pain. Further investigations will determine if these nn. can be reached percutaneously. Effective neural blockade of the hip joint must include the femoral n., the sciatic n. and the superior gluteal n.

Femoral Nerve↗
PubMed1997

[Development and pathophysiology of abdominal wall defects].

Repair of abdominal wall hernias is the most frequently performed operation in surgery. Primary hernias arise at anatomical weak points; incisional hernias result from laparotomies. As the fascia heals slowly, the suture should be strong enough to withstand the intraabdominal pressure. Complications in wound healing may lead to a hernia, especially when absorbable sutures have been used. The rate of incisional hernias is technically influenced by the type of incision, the suture technique, and the suture material. To achieve adequate repair it is often necessary to change the principles of abdominal wall closure, for example by using alloplastic material. The meshes reinforce the architecture of the abdominal wall both by pure mechanical means and by induction of a stable scar formation (polypropylene, polyester).

Abdominal Muscles↗
PubMed1997

Some remarks on, and a new case of the rare os intercuneiforme (Dwight).

A new case of the rare os intercuneiforme (Dwight) is presented and compared with the two cases reported by the anatomist first describing this bone. Taking a large series of anatomical investigations into account, the frequency of occurrence for this supernumerary tarsal bone can be given as 0.026%. Furthermore, it is supposed that the os intercuneiforme belongs rather to the medial than to the intermediate cuneiform.

Aged↗
PubMed1997

The glenoid notch and its relation to the shape of the glenoid cavity of the scapula.

The prevalence of a notch in the anterior margin of the glenoid cavity of 236 scapulae (118 female, 118 male) was investigated. The notch was found in 129 scapulae (55%) and gave rise to a pear-shaped cavity. In 107 scapulae (45%) the notch was absent, the shape of the cavity being oval. No sex difference was found in the prevalence of the notch. If a distinct notch exists, the glenoid labrum is not attached to bone at the notch and is therefore liable to be sheared off (Bankart lesion).

Female↗
PubMed1997

[A comparison between GE and SE sequences in MRT after the i.v. application of superparamagnetic iron particles in the assessment of experimentally induced soft-tissue osteosarcomas].

PURPOSE: An MRI study on experimentally induced osteosarcomas of the peripheral soft-tissues in nude rats was conducted, comparing SE and GE sequences after i.v. application of superparamagnetic iron oxides with regard to contrast and image quality. MATERIAL AND METHODS: 40 nude rats with an osteosarcoma in the right hind leg and 7 tumour-free animals were measured without, one and 48 hours after i.v.-injection of the contrast medium. 4 SE and 3 GE sequences with different parameters and slice orientation were applied. The contrast medium consisted of Fe3O4 particles with a core diameter of 6-8 nm and a coating material of polyethylene glycol (PEG). The laboratory animals were divided into 5 groups of 7-12 animals each. The rats of the first 4 groups were given a contrast-medium dosage of 100, 150, 200 and 250 mumol Fe/kg body weight, respectively. The animals of the fifth group were tumour-free and served as controls. RESULTS: The minimum dosage for detection of Fe3O4-containing PEG magnetites, one hour after application, was established at 100-150 mumol Fe/kg body weight. The higher the dosage of the contrast medium, the more signal alterations could be measured. The GE sequences were more sensitive than SE sequences. One GE sequence with the parameters TR 90 ms, TE 13 ms, FL 8 degrees turned out to be highly sensitive. CONCLUSION: Superparamagnetic iron oxides induce signal alterations in tumours of the peripheral soft tissue. GE sequences proved to be more sensitive than SE sequences.

Animals↗