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Biomedical subjects

G Lundborg

Publications and source records attributed to G Lundborg.

At least 163 records · Page 9Linked to original sources
PubMed1988

Intraneural microcirculation.

Peripheral nerve trunks are well-vascularized structures where a well-developed collateral system may compensate for local vascular damage. Interference with intraneural blood flow is reflected rapidly in disturbances in nerve function. In compression lesions and nerve entrapments, the microvascular factor plays an important pathophysiologic role for development of symptoms. Although endoneurial capillaries normally constitute a BNB helping to optimize endoneurial environment, damage to the vessels may induce a miniature closed compartment syndrome by increasing the permeability, thereby contributing to increased endoneurial fluid pressure and development of an intrafascicular edema. Surgeons, performing intraneural dissections, should be aware of the potential risks associated with intraneural bleedings, edema, and intraneural fibrosis.

Arteriovenous Anastomosis↗
PubMed1988

Carpal tunnel syndrome. A scientific basis for clinical care.

The series of experimental studies reviewed in this article supports a classification of median nerve compression at the wrist into early, intermediate, advanced, and acute nerve compression. The findings correlate well with experimental studies on the pathophysiology of nerve compression. A patient-specific management approach is recommended based upon the clinical and electrophysiologic findings which can be correlated with previously demonstrated intraneural pathologic changes.

Carpal Tunnel Syndrome↗
PubMed1987

Morphologic changes in nerve cell bodies induced by experimental graded nerve compression.

The effects of experimental nerve fiber compression on the morphology of nerve cell bodies were studied. Rabbit cervical vagus nerves were crushed or subjected to compression at 0 (sham compression), 30, 200, or 400 mm Hg for 2 h. Morphometric measurements and light microscopical evaluation of the nerve cell bodies in the nodose ganglion were carried out 7 days after the injury on the injured and control sides. Crush and compression at 30, 200, or 400 mm Hg induced a slight decrease in total cell profile area compared with the control side, but it was not related to degree of injury. There was a marked decrease in the ratio between nuclear and total cell profile area (nuclear volume density) after compression at 200 and 400 mm Hg, as well as after crush, and to a lesser extent after compression at 30 mm Hg. Compression at 30, 200, or 400 mm Hg as well as crush of the vagus nerve induced migration of the nucleus to the periphery and dispersion of Nissl substance in the cytoplasm of the nerve cell bodies. Sham compression induced no obvious changes in total cell profile area, nuclear volume density, or migration of nucleus. There was a somewhat increased percentage of cells showing dispersion of Nissl substance in sham-compressed animals than in controls. The results show that nerve fiber compression induced pronounced reactive changes in nerve cell bodies, even at low pressures, corresponding to those found in human carpal tunnel syndrome. Such pressures are known to induce reversible inhibition of fast axonal transport as well as inhibition of retrograde axonal transport. The nerve cell body changes in the nodose ganglion may thus be a reaction to disturbances in axonal transport.

Animals↗
PubMed1987

Chronic compartment syndrome in the first dorsal interosseous muscle.

Fifteen patients with clinical signs that could indicate a chronic compartment syndrome of the first dorsal interosseous muscle of the hand were investigated by pressure recording at rest and during exercise. Objective data, verifying such a syndrome, were found in four of the patients. Increased muscle relaxation pressure during exercise and intramuscular pressure at rest after exercise compared with normal pressure were well correlated to the development of the symptoms of chronic compartment syndrome. Fasciotomy of the first dorsal interosseous muscle relieved the symptoms and normalized the pressure.

Adult↗
PubMed1987

A case of phalangeal lengthening.

A severely shortened and deformed index finger--due to osteomyelitis of the middle phalanx--of a 12-year-old boy was lengthened by using a Kessler distraction device. Distraction for 2 weeks followed by interposition of a 15-mm bone graft resulted in a stable painless finger of normal length.

Bone Lengthening↗
PubMed1987

Lateral elbow pain caused by anconeus compartment syndrome. A case report.

A carpenter presented with lateral elbow pain and bulging tenderness and impaired function of the anconeus muscle. Computed tomography showed enlargement of the muscle. The intracompartmental pressure was increased at rest, during and after exercise, and had a prolonged recovery time. The patient recovered immediately after fasciotomy of the anconeus muscle, and 6 months later he was still free from pain and intracompartmental pressures were normal.

Compartment Syndromes↗
PubMed1987

A new principle for assessing vibrotactile sense in vibration-induced neuropathy.

The vibrotactile perception threshold has been evaluated in 20 manual workers not exposed to occupational vibration and in 27 workers using hand-held vibrating tools. Threshold values were evaluated with a Békesy type of vibrometer at frequencies ranging from 8 to 500 Hz. The earliest sign of vibration lesion was a reduction of sensation at frequencies of 125 to 250 Hz, indicating dysfunction in receptors of the fast adapting type II (stage 1 curve), followed in more severe cases by a prominent loss of sensation at all frequencies higher than 65 Hz (stage 2 curve). The stage 3 curve indicated the most severe loss of sensation in which the function of slowly adapting type I receptors, as well as fast adapting type I receptors, was deteriorated; consequently the vibrotactile thresholds at low-, median-, and high-frequency ranges were impaired. The vibrotactile changes corresponded well to numbness and the presence of vibration-induced white finger.

Adolescent↗
PubMed1987

Intraneural edema following exposure to vibration.

Peripheral neuropathy represents a well-known complication from long-term exposure to vibration. In the present study an experimental model is presented with the purpose of analyzing the formation of intraneural edema following vibration exposure. Vibration (82 Hz, peak-to-peak amplitude 0.21 mm) was induced in the hind limb of rats by the use of vibrating electric motors during 4 h/d for 5 d. Tracer techniques (with albumin Evans blue and horseradish peroxidase) were used to study the permeability of intraneural microvessels after the vibration exposure on day 5. It was found that the vibration trauma in this model induced epineurial edema in the sciatic nerve. It is hypothesized that the formation of intraneural edema may be an important pathophysiological factor in the occurrence of vibration-induced neuropathy.

Animals↗
PubMed1987

Sensorineural stages of the hand-arm vibration syndrome.

Recent work has shown that the vascular signs and neurological symptoms commonly associated with exposure of the hand to vibration may develop independently. A classification for the neurological component of the hand-arm vibration syndrome has been developed for those symptoms dominated by sensory afferent involvement, based on the results of objective tests on 634 hands. The first symptomatic stage (1SN) consists essentially of episodic finger numbness with or without tingling, the second involves, in addition, reduced sensory perception (2SN), while the most severe stage (3SN) focuses on reduced tactile discrimination and/or manipulative dexterity. Consistent implementation of this classification by means of objective tests requires one, or more, precise, quantitative measure of peripheral somatosensory dysfunction, in addition to the traditional neurological tests (fine touch, pain, and temperature). Measurements of tactile function by means of esthesiometry or vibrotactile perception appear suited to this purpose. A procedure for staging individual hands may then be based on combining numerical scores assigned to the results of the traditional neurological tests and, additionally, esthesiometer and/or vibrotactile perception thresholds.

Hand↗
PubMed1986

Nerve repair and axonal transport: outgrowth delay and regeneration rate after transection and repair of rabbit hypoglossal nerve.

The axonal transport and distribution of the fast phase of [3H]leucine-labeled proteins were used to monitor the outgrowth delay and regeneration rate in rabbit hypoglossal nerves 5-21 days after crush or transection. The transected nerves were repaired with mesothelial chambers or epineurial sutures. Radiolabeled proteins were transported into regenerating axons in the distal nerve segment after an initial delay of 2.5 days for crushed nerves and after a delay (initial and scar delays) of 4.8 and 5.7 days for sutured and mesothelial chamber-reconnected nerves, respectively. Regeneration rate was 3.5 mm/day after a crush and 2 mm/day after a transection with either type of repair. Total radioactivity was greater in both crushed and repaired nerves than in their contralateral controls. Transported radioactivity accumulated at the site of the lesions. This accumulation was greater and persisted longer in repaired nerves than in crushed ones. The difference in regenerative response after different types of trauma with respect to changes in axonal transport is emphasized.

Animals↗
PubMed1986

Flexor tendon repair.

Healing canine flexor tendons treated with either total immobilization, delayed protected mobilization, or early protected mobilization was studied by biomechanical, microangiographic, biochemical, and histologic techniques at intervals through 12 weeks. The healing characteristics of the early mobilization tendons showed higher tensile strengths and improved gliding function than the delayed mobilization and immobilization tendons. Protected passive motion brought about accelerated changes in peritendinous vessel density and configuration, as well as increased repair site total DNA content. While adhesions obliterated the space between the tendon surface and the tendon sheath of the immobilized repairs, the mobilized tendons demonstrated coverage of the repair site by cells from the epitenon by 10 days, and a smooth, gliding surface that was maintained free of adhesions through 42 days. A series of in vitro studies demonstrated the cellular processes involved in the repair: phagocytosis of cellular debris and collagenous fragments by cells from the epitenon, and collagen synthesis primarily by endotenon cells.

Animals↗
PubMed1986

Experimental hyperthyroidism stimulates axonal growth in mesothelial chambers.

An experimental model is presented for studying axonal growth after experimental hyperthyroidism and hypothyroidism. The left sciatic nerve of the rat was transected and transposed to the back. The proximal nerve stump was inserted into a 50-mm-long mesothelial chamber leaving the distal end of the chamber open. Different groups of young adult rats were given daily injections of thyroxine (10 micrograms/100 g body weight) or the goitrogen, thiamazol, in the drinking water (0.125 g/liter) for 12 weeks. Thyroxine treatment increased significantly the extent of axonal outgrowth from the proximal nerve stump compared with untreated rats. Experimental hypothyroidism (thiamazol treatment), evidenced by a retarded body growth, did not affect the extent of axonal outgrowth. In other experiments the left proximal nerve stump was cross-anastomosed with the right distal nerve stump. The two nerve stumps were bridged with a mesothelial chamber leaving a 15-mm gap. This gap distance is known from our previous studies to inhibit axonal overgrowth to the distal nerve stump. As evidenced by histological evaluation, in three of six thyroxine-treated rats, axons had bridged the 15-mm gap. We conclude that experimentally induced hyperthyroidism enhances axonal growth in mesothelial chambers.

Animals↗
PubMed1986

Nerve repair and axonal transport. Distribution of axonally transported proteins during maturation period in regenerating rabbit hypoglossal nerve.

The distribution of fast migrating [3H]leucine-labelled proteins was studied in transected and repaired rabbit hypoglossal nerves. The nerves were repaired 90 days earlier with mesothelial chamber or epineurial suture technique. Fast migrating radiolabelled proteins were transported into the distal nerve segment and neurophysiological recordings from the tongue as well as the presence of myelinated axons in the distal nerve segment verified successful regeneration. The total amount of radioactivity was increased in repaired nerves as compared to contralateral nerves. In both groups there was a significant accumulation of radiolabelled proteins at the site of lesion. Nerves repaired with mesothelial chambers showed significantly more radioactivity in the distal nerve segment as compared to sutured nerves. The present study indicates long-standing effects on axonal transport system after both types of nerve repair. It is our opinion that axonal transport studies are a valuable complement when evaluating experimental nerve repair.

Animals↗
PubMed1986

Absence of ongoing activity in fibres arising from proximal nerve ends regenerating into mesothelial chambers.

Morphological studies have indicated that proximal nerve ends of transected rat sciatic nerves regenerating into preformed mesothelial chambers show a different organization as compared to neuromas developed in contact with a muscle fascia. We have studied the physiological properties of nerve fibres arising from these types of preparations with reference to ongoing activity, response to mechanical stimulation and noradrenaline sensitivity. The study included also fibres arising from ligated and encapsulated neuromas. Fibres with ongoing activity arising from the neuroma could be found from neuromas in contact with a muscle fascia and also from ligated and encapsulated neuromas. This ongoing activity was enhanced by mechanical stimulation and i.v. infusion of noradrenaline. In contrast, fibres arising from proximal nerve ends in mesothelial chambers did not show ongoing activity. These silent fibres responded dynamically to light mechanical stimulation. Noradrenaline did not induce ongoing activity in these fibres.

Animals↗
PubMed1986

Digital vibrogram: a new diagnostic tool for sensory testing in compression neuropathy.

A Békésy audiometer was modified for use in analysis of vibrotactile sensibility of the hand at frequencies ranging from 8 to 500 Hz. In control subjects the "digital vibrogram" has a typical shape, which differs characteristically in patients with carpal tunnel syndrome (CTS). Changes in digital vibrogram usually parallel or precede abnormalities in neurophysiologic tests, and appear long before changes in two-point discrimination (2PD). One-hundred-thirty-two hands of 76 patients diagnosed as having CTS were tested with a vibrometer. Of 113 hands with normal 2PD, the digital vibrogram showed abnormal in 86 cases. Of 19 hands with abnormal 2PD, the digital vibrogram showed abnormal in all but three cases. Twenty-six hands with neurophysiologically normal appearance had abnormal digital vibrogram in 14 cases, while 53 hands neurophysiologically classified as CTS showed abnormal digital vibrogram in 44 cases. It is concluded that the digital vibrogram is a useful tool for early diagnosis of CTS.

Carpal Tunnel Syndrome↗
PubMed1986

A study of neurotrophism in a primate model.

This study investigated the existence of neurotrophism in a primate model. In eight adult cynomolgus monkeys the sensory component of the femoral nerve was sectioned and introduced into the proximal channel of a silicone Y chamber. The proximal stump was given distal choices of various tissues inserted into the remaining arms of the silicone Y chamber. The targets presented were combinations of tendon, muscle, intact distal nerve, distal nerve graft, or an empty silicone channel. After 6 weeks, ultrastructural analysis confirmed axonal growth toward distal nerve tissue, while minimal or no nerve regeneration was directed toward tendon, muscle, or the empty silicone channel. The results showed that either a distal nerve stump or a nerve graft will act as a specific target to the regenerating primate proximal nerve stump.

Animals↗
PubMed1986

Visualization of regenerating sciatic nerve fibres by neurofilament immunohistochemistry.

Regeneration of injured sciatic nerve in rats was studied with an immunohistochemical technique visualizing neurofilaments in nerve fibres as well as S-100 protein in Schwann cells. Outgrowing axons with delicate sprouts could be demonstrated along pathways formed by Schwann cells. In contrast, axons which had stopped growing or were degenerating showed bulb-like swellings in their terminal parts. The use of immunohistochemical techniques offers advantages over conventional neurohistochemical staining methods, enabling more detailed observations of nerve regeneration mechanisms in animals.

Animals↗