Björn-Ove Ljung

In vivo investigation of ECRB tendons with microdialysis technique--no signs of inflammation but high amounts of glutamate in tennis elbow

We used the microdialysis technique to study concentrations of substances in the extensor carpi radialis brevis (ECRB) tendon in patients with tennis elbow. In 4 patients (mean age 41 years, 3 men) with a long duration of localized pain at the ECRB muscle origin, and in 4 controls (mean age 36 years, 2 men) with no history of elbow pain, a standard microdialysis catheter was inserted into the ECRB tendon under local anesthesia. The local concentrations of the neurotransmitter glutamate and prostaglandin E 2 (PGE 2 ) were recorded under resting conditions. Samplings were done every 15 minutes during a 2-hour period. We found higher mean concentrations of glutamate in ECRB tendons from patients with tennis elbow than in w tendons from controls (215 vs. 69 _6;moL/L, p < 0.001). There were no significant differences in the mean concentrations of PGE 2 (74 vs. 86 pg/mL). In conclusion, in situ microdialysis can be used to study certain metabolic events in the ECRB tendon of the elbow. Our findings indicate involvement of the excitatory neurotransmitter glutamate, but no biochemical signs of inflammation (normal PGE 2 levels) in ECRB tendons from patients with tennis elbow.

Neurokinin 1-receptors and sensory neuropeptides in tendon insertions at the medial and lateral epicondyles of the humerus. Studies on tennis elbow and medial epicondylalgia

There is no information on the sensory innervation at the flexor muscle origin at the medial epicondyle of the humerus and it is not known if substance P receptors (Neurokinin 1‐receptors, NK1‐R) are present in tendon insertions in general. In the present investigation, we have studied the muscle origin in patients suffering from medial epicondylalgia and tennis elbow. Immunohistochemistry and antibodies to substance P (SP) and CGRP as well as the general nerve marker PGP 9.5 were used. Specific immunoreactions were observed in nerve bundles and as free nerve fibers. The immunoreactive structures were partly seen in association with some of the blood vessels. The observations constitute a morphological correlate for the occurrence of nerve mediated effects in this region. By using immunohistochemistry and antibodies to NK1‐R, the distribution of this receptor was studied at the insertion of the proximal tendon of the extensor carpi radialis brevis muscle at the lateral epicondyle. Specific immunoreactions were seen as varicose fibers occurring as single fibers or grouped into bundles, indicating that SP has effects in the nerves in this region. The results give further evidence for a possible neurogenic involvement in the pathophysiology of tennis elbow and in medial epicondylalgia.

Evidence of Wrist Proprioceptive Reflexes Elicited After Stimulation of the Scapholunate Interosseous Ligament

PURPOSE Recent publications on the sensory innervation of wrist ligaments have challenged our understanding of ligaments as mere passive restraints in wrist stability. Mechanoreceptors in ligaments have a role in signaling joint perturbations, in which the afferent information is believed to influence periarticular muscles. The scapholunate interosseous ligament is one of the most richly innervated ligaments in the wrist. The purpose of our study was to investigate the possible existence of a wrist proprioceptive reflex, by which afferent information elicited in the scapholunate interosseous ligament was hypothesized to influence the muscles moving the wrist joint. METHODS Nine volunteers (4 women and 5 men; mean age, 26 years; range, 21-28 years) participated in this study. Using ultrasound guidance, a fine-wire electrode was inserted into the dorsal scapholunate interosseous ligament and stimulated with four 1-ms pulses at 200 Hz. Electromyographic activities in extensor carpi radialis brevis, extensor carpi ulnaris, flexor carpi radialis, and flexor carpi ulnaris muscles were recorded using surface electrodes with the wrist actively positioned in isometric extension, flexion, and radial and ulnar deviation. The average EMGs from 30 consecutive stimulations were rectified and analyzed using the Students t-test to compare the prestimulus (t(1)) and poststimulus (t(2)) EMG activities. RESULTS Statistically significant changes in poststimulus EMG activity (t(1)- t(2)) were observed at various time intervals. Within 20 ms, an excitation was seen in the flexor carpi radialis and flexor carpi ulnaris in extension, radial and ulnar deviation, and in extensor carpi radialis brevis in flexion. Co-contractions between agonist and antagonist muscles were observed, with peaks around 150 ms after stimulus. CONCLUSIONS We present evidence of wrist ligamento-muscular reactions. The early-onset reactions may serve in a joint-protective manner, and later co-contractions indicate a supraspinal control of wrist neuromuscular stability. These findings contribute new information to the physiologic functions of the wrist joint, which may further our understanding of dynamic wrist stability and serve as a foundation for future studies on proprioceptive dysfunctions after wrist ligament injuries.

General Innervation Pattern and Sensory Corpuscles in the Scapholunate Interosseous Ligament

The scapholunate interosseous ligament (SLIL) is biomechanically important in maintaining wrist motion and grip strength in the hand, but its possible sensory role in the dynamic muscular stability of the wrist joint has not been examined. The aim of this study was to use immunohistochemical methods to analyze the general innervation and the possible existence of sensory corpuscles in the SLIL. The ligament was excised in its entirety from 9 patients. Antibodies against the low-affinity p75 neurotrophic receptor (p75) were used to reveal sensory corpuscles as well as general innervation. Furthermore, antibodies against the general nerve marker protein gene product 9.5 (PGP 9.5) and the glial marker S-100 were used to additionally depict innervation and corpuscular structures. Blood vessels occurred in areas interspersed throughout the homogenous collagenous structure. In these vascularized areas, the SLIL was found to be supplied with nerve fascicles and sensory corpuscles of both the Ruffini and lamellated type. p75 immunoreactivity (IR) was detected in association with the nerve fascicles and the corpuscles, particularly in their capsule. S-100 IR was found in the Schwann cells in the central regions of the corpuscle, and PGP 9.5 IR marked the axonal structures in the corpuscles. New information on neurotrophin receptor distribution in ligaments has been obtained here. The presence of nerve fascicles and particularly sensory corpuscles in the SLIL suggests that the ligament has a proprioceptive role in the stability of the wrist. The marked p75 IR further indicates that neurotrophins play a part in a proprioceptive system in the ligament, given the importance of neurotrophins in maintaining sensory function.

Immunohistochemical evidence of local production of catecholamines in cells of the muscle origins at the lateral and medial humeral epicondyles: of importance for the development of tennis and golfer’s elbow?

Background: Tennis elbow (TE) is a painful condition affecting the common extensor origin at the lateral humeral epicondyle. Colour Doppler examination has shown increased blood flow at this site and the sensory, and sympathetic innervation patterns have been delineated. However, it is not known whether there is local production of catecholamines and/or acetylcholine in this tissue, which is the case in patellar and Achilles tendinopathies. Objective: To investigate the possible presence of local production of catecholamines and acetylcholine in non-neuronal cells (fibroblasts) in connective tissue at the muscle origin at the lateral humeral epicondyle in patients with TE. Design: Immunohistochemical studies were performed on biopsies taken from the extensor origin in patients with TE and in pain-free controls. For reference purpose, biopsies from the flexor origin in patients with golfer’s elbow (GE) were also studied. Patients: Seven patients with TE and four patients with GE. Six healthy asymptomatic individuals served as controls. Method: Immunohistochemistry, using antibodies detecting synthesising enzymes for catecholamines (tyrosine hydroxylase; TH) and acetylcholine (choline acetyltransferase; ChAT). Results: TH-like immunohistochemical reactions were seen in fibroblasts in four of the seven patients with TE and two of the four patients with GE. No such reactions were detected in controls (0/6). No ChAT reactions were seen in any of the investigated specimens. Conclusions: There is evidence of local, non-neuronal production of catecholamines, but not acetylcholine, in fibroblasts in the tissue at the muscle origin at the lateral and medial epicondyles in patients with TE and GE, respectively, which might have an influence on blood vessel regulation and pain mechanisms in these conditions.

Blood Flow to the Extensor Carpi Radialis Brevis Muscle Following Adrenaline Infusion in Patients With Lateral Epicondylitis

PURPOSE Based on previous evidence of muscle fiber injury and decreased blood flow in the extensor carpi radialis brevis (ECRB) muscle in lateral epicondylitis (LE), we hypothesized that there would also be an abnormal (vasoconstrictive) vascular response to adrenaline in the ECRB muscle in LE. METHODS In a case-control study, we measured skeletal muscle blood flow in 8 patients with LE and in 8 healthy controls in response to a 30-minute intravenous infusion of adrenaline. We used local clearance of technetium-99m in the main portion of the ECRB muscle to calculate muscle blood flow. RESULTS In support of the hypothesis, the blood flow response to the adrenaline infusion was markedly different in the 2 study groups. Whereas the continuous decrease in technetium-99m clearance rate over time was interrupted by the adrenaline-induced vasodilatory effect in the control group, we detected no such effect in the patient group. CONCLUSIONS In the ECRB muscle in LE, there is a shift in the balance of vasodilatory and vasoconstrictory influences of adrenaline, leading to vasoconstriction during low-dose adrenaline infusion. The adverse adrenaline effect is similar to what was previously observed after minor muscle injury. Whether the vasoregulatory change, by causing relative muscle ischemia, represents the primary etiology in LE or results from muscle injury cannot be determined, but it is likely to contribute to the development and continuation of chronic muscle pain in LE. New ways of thinking about the condition may be required, and pharmacological treatment might be an option to improve the blood supply and avoid further damage to the affected ECRB muscle-tendon unit.