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Biomedical subjects

B Rydevik

Publications and source records attributed to B Rydevik.

80 records · Page 5Linked to original sources
PubMed1977

The vascularization of human flexor tendons within the digital synovial sheath region--structureal and functional aspects.

The intrinsic vascularization of human flexor tendons within the digital sheath region was studied on fresh amputation specimens with the aid of angiographic and histochemical techniques. In the flexor digitorum profundus tendon, three separate vascular systems of various origin and with no or very little communication could be verified. In the flexor digitorum superficialis tendon, two such systems were observed. The volar surface of both tendons is more or less devoid of vessels. Moreover, at the proximal interphalangeal joint level, the flexor digitorum profundus tendon has a volar avascular zone, constituting about 1 mm, i.e., about one-third to one-fourth of the thickness of the tendon. It is assumed that the synovial fluid is of importance for the nutrition of the tendons and that therefore the synovial sheath should be preserved as much as possible.

Adult↗
PubMed1977

Permeability of intraneural microvessels and perineurium following acute, graded experimental nerve compression.

Experimental compression lesions of peripheral nerves were induced by applying pressure direct to exposed rabbit nerve trunks. A specifically designed compression chamber was used, enabling application of graded pressures (50--600 mmHg) to the nerves for various periods of time (15 min to 6 hours). After releasing the pressure, analyses were performed concerning the intraneural microvascular permeability and the barrier function of the perineurium. The method used was fluorescence microscopic tracing of intravenously injected or locally applied albumin labelled with Evans blue. The results indicate that a slight trauma to a nerve (e.g. 50 mmHg during 2 hours) induced an epineurial oedema by increasing the permeability of the epineurial vessels, which were more susceptible to compression trauma than the endoneurial vessels. Compression at higher pressure levels or of prolonged duration caused injury also to the endoneurial vessels, leading to intrafascicular oedema formation, which generally was most prominent at the edges of the compressed nerve segment. The perineurial barrier was remarkably resistant to compression trauma. Possible pathophysiological effects of various degrees of post-traumatic intraneural oedema formation are discussed.

Animals↗
PubMed1976

Intraneural tissue reactions induced by internal neurolysis. An experimental study on the blood-nerve barrier, connective tissues and nerve fibres of rabbit tibial nerve.

Surgical treatment of peripheral nerve lesions associated with intraneural fibrosis is sometimes extended to include internal neurolysis. This procedure is performed in order to release the individual nerve fascicles from interfascicular scar tissue which is believed to constrict nerve fibres and thereby interfere with their function and regenerative capacity. However, an internal neurolysis per se implies a significant trauma to the nerve and may induce microvascular damage and formation of new intraneural scar tissue. Considering this, such a procedure appears justified only when the preoperative intraneural fibrosis is more severe than the scarring which might be induced by the surgical procedure as such. In order to evaluate the tissue reactions following internal neurolysis an experimental investigation was carried out: internal neurolysis was performed on normal rabbit tibial nerve. After varying postoperative periods up to 6 months specimens of nerves were analysed. Reactive changes of connective tissue and myelin sheath lesions, indicating nerve fibre damage, were investigated in histological sections studied by light microscopy. Barrier function of perineurial membrane and endoneurial vessels was investigated by fluorescent microscopic tracing of locally applied or intravenously injected albumin labelled with Evans' blue. The results indicate that an experimental internal neurolysis per se may induce fibrosis in all layers of the nerve and may cause some nerve fibre damage. However, the barrier function of the perineurium and the endoneurial vessels seems to be generally well preserved. The findings are discussed in relation to indications for internal neurolysis.

Animals↗
PubMedDate not supplied

Pathoanatomy and pathophysiology of nerve root compression.

The anatomy and physiology of the nerve root complex in the lumbar spine are reviewed, with special reference to the effects of mechanical deformation of nerve roots in association with intervertebral disc herniation and spinal stenosis. Biomechanical aspects of nerve root deformation induced by compression are discussed. The functional changes induced by compression can be caused by mechanical nerve fiber deformation but also may be a consequence of changes in nerve root microcirculation, leading to ischemia and formation of intraneural edema. Nerve root compression can, by different neurophysiologic mechanisms, induce motor weakness and altered sensibility or pain. Intraneural edema and demyelination seem to be critical factors for the production of pain in association with nerve root compression.

Capillary Permeability↗
PubMedDate not supplied

Effects of collagenase on nerve tissue. An experimental study on acute and long-term effects in rabbits.

Intradiscal injection of proteolytic enzymes implies a potential risk for exposure of nervous tissue to the enzyme solution. In the present study, the effects on peripheral nerve tissue of application of a solution containing a clinically recommended concentration of collagenase have been evaluated. Acute experiments showed that the enzyme induces transient swelling at the site of application and edema in the epineurium. There were, however, no detectable effects on the permeability of the perineurium or the endoneurial microvascular bed. Four and 8 weeks later, there was a slight fibrosis in the epineurium, but neurophysiologic tests did not reveal any impairment of the nerve function. The results are discussed in terms of the clinical use of collagenase for dissolution of herniated intervertebral discs.

Animals↗