Cardiac Amyloidosis Screening at Trigger Finger Release Surgery

Cardiac amyloidosis is often preceded by orthopedic manifestations such as carpal tunnel syndrome, and 10% of patients who underwent idiopathic carpal tunnel release surgery will have biopsy-confirmed amyloid deposits in the tenosynovial sheath. Trigger finger is also commonly reported in patients with amyloidosis and involves the same tendon sheath as carpal tunnel syndrome, but the prevalence of amyloid deposition is unclear. This prospective cross-sectional study enrolled 100 patients aged ≥50 years at the time of surgery for idiopathic trigger finger. Patients underwent release surgery, and a sample of the tenosynovium of the affected finger was excised, stained with Congo red, and subtyped with mass spectrometry if amyloid was demonstrated. Further cardiac evaluation was performed in patients with amyloid deposition. Of the 100 patients (mean age 65.5 ± 8.1 years) enrolled, only 2 demonstrated amyloid deposits on Congo red staining. One patient with previous proteinuric kidney disease had fibrinogen A α-chain amyloidosis, and the other patient had untyped amyloidosis. Neither patient had cardiac involvement. A total of 13 of the 100 patients underwent concomitant carpal tunnel release surgery, and 2 of these patients had amyloid deposits in the carpal tunnel with "false-negative" samples from the trigger finger tenosynovium. In conclusion, biopsy during trigger finger release surgery demonstrated a 2% yield for amyloidosis, which is significantly lower than the previously published yield of 10% during carpal tunnel release surgery. This observation has important implications for the development of diagnostic algorithms to screen patients for amyloidosis during orthopedic operations.

Systemic Amyloidosis Caused by Monoclonal Immunoglobulins: Soft Tissue and Vascular Involvement

Clinical features of soft tissue amyloid light-chain (AL) amyloidosis include macroglossia, arthropathy, muscle pseudohypertrophy, skin plaques, and carpal tunnel syndrome. Vascular manifestations of AL amyloid include periorbital ecchymosis, jaw or limb claudication, and even myocardial infarction caused by occlusion of small vessel coronary arteries. Some of these features, such as macroglossia, periorbital ecchymosis, and the so-called shoulder-pad sign, are pathognomonic for AL amyloidosis. These findings may be the initial presenting features of the disease, and the recognition of these red flag symptoms is very important for the diagnosis and early intervention on the underlying plasma cell disease.

Muscle Fiber Type Changes in Lumbrical Muscles at Early Stages of Chronic Nerve Compression

Chronic nerve compression (CNC) neuropathy is a common disease in the clinic and provokes paraesthesia, or numbness at early stage. The changes in muscle fiber composition and motor nerve terminal morphology in distal muscles were studied in this study. A well-established CNC model was used to assess the changes in the muscles. Behaviors were measured by von Frey filament test. The myosin heavy chain isoforms and neuromuscular junctions (NMJs) were stained by immunofluorescence to show the muscle fiber types composition and motor nerve terminals morphologic changes in the flexor digitorum longus (FDL) and lumbrical muscle. The fiber cross-sectional areas of different muscle fiber types were measured. The small-fiber degeneration of cutaneous nerve fibers was examined by detecting the protein gene product 9.5 (PGP9.5) with immunofluorescence. At 2nd month after compression, the proportion of type I and type II B fibers was markedly decreased, and that of type II A fibers was increased in the lumbrical muscle. There was no significant change in composition of muscle fiber types in FDL and NMJ morphology of FDL and lumbrical muscles. Intra-epidermal nerve fibre density (IENFD) declined at 2nd month after the compression. Our study reveals the morphological changes of the FDL and lumbrical muscle at an early stage of CNC. These findings may be helpful to understand muscle damage and pathophysiological development of the nerve compression, and provide new evidence for early treatment of CNC.

Relaxin Modulates the Expression of MMPs and TIMPs in Fibroblasts of Patients with Carpal Tunnel Syndrome

PURPOSE

The aim of this study was to investigate the anti-fibrotic effect of relaxin in subsynovial fibroblasts activated by transforming growth factor beta (TGF-β).

MATERIALS AND METHODS

To test the anti-fibrotic effect of an adenovirus-relaxin construct (Ad-RLN) on subsynovial fibroblasts in vitro, cells from subsynovial connective tissue of patients with carpal tunnel syndrome were activated with TGF-β1 and exposed to Ad-RLN (as a therapeutic gene) or adenovirus-lacZ construct (as a marker gene) for four hours. Subsynovial fibroblast cultures without adenoviral exposure served as controls.

RESULTS

We observed induction of gene expressions of collagen I, III and IV, as well as the abatement of alpha-smooth muscle actin (a-SMA) synthesis, Smad2 phosphorylation, and fibronectin at the protein level, in comparison to controls. In addition, protein expressions of matrix metalloproteinase (MMP) I was significantly induced, whereas the protein expressions of tissue inhibitor of metalloproteinases (TIMP) I and IV were reduced due to relaxin expression.

CONCLUSION

RLN prevents excessive synthesis of extracellular matrix by reducing the expressions of its components, such as fibronectin, a-SMA, and phosphorylated Smad2, by increasing the expression of MMPs; and by decreasing the expression of TIMPs.

Association of a high normalized protein catabolic rate and low serum albumin level with carpal tunnel syndrome in hemodialysis patients

Carpal tunnel syndrome (CTS) is the most common mononeuropathy in patients with end-stage renal disease (ESRD). The association between chronic inflammation and CTS in hemodialysis (HD) patients has rarely been investigated. HD patients with a high normalized protein catabolic rate (nPCR) and low serum albumin level likely have adequate nutrition and inflammation. In this study, we assume that a low serum albumin level and high nPCR is associated with CTS in HD patients. We recruited 866 maintenance hemodialysis (MHD) patients and divided them into 4 groups according to their nPCR and serum albumin levels: (1) nPCR <1.2 g/kg/d and serum albumin level <4 g/dL; (2) nPCR ≥1.2 g/kg/d and serum albumin level <4 g/dL; (3) nPCR <1.2 g/kg/d and serum albumin level ≥4 g/dL; and (4) nPCR ≥1.2 g/kg/d and serum albumin level ≥4 g/dL. After adjustment for related variables, HD duration and nPCR ≥1.2 g/kg/d and serum albumin level <4 g/dL were positively correlated with CTS. By calculating the area under the receiver-operating characteristic curve, we calculated that the nPCR and HD duration cut-off points for obtaining the most favorable Youden index were 1.29 g/kg/d and 7.5 years, respectively. Advance multivariate logistic regression analysis revealed that in MHD patients, nPCR ≥1.29 g/kg/d and serum albumin <4 g/dL, and also HD duration >7.5 years were associated with CTS. A high nPCR and low serum albumin level, which likely reflect adequate nutrition and inflammation, were associated with CTS in MHD patients.

Transforming growth factor-β (TGF-β) expression is increased in the subsynovial connective tissue in a rabbit model of carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is an idiopathic disease that results from increased fibrosis of the subsynovial connective tissue (SSCT). A recent study found overexpression of both transforming growth factor-β (TGF-β) and connective tissue growth factor (CTGF) in the SSCT of CTS patients. This study investigated TGF-β and CTGF expression in a rabbit model of CTS, in which SSCT fibrosis is induced by a surgical injury. Levels of TGF-β1 and CTGF at 6, 12, 24 weeks after injury were determined by immunohistochemistry A significant increase in TGF-β1 and a concomitant significant increase in CTGF were found at 6 weeks, in addition to higher cell density compared to normal (all p<0.05), Interestingly, CTGF expression was reduced at 12 and 24 weeks, suggesting that an initial insult results in a time limited response. We conclude that this rabbit model mimics the fibrosis found in human CTS, and may be useful to study pathogenetic mechanisms of CTS in vivo.

Molecular and pathological studies in the posterior interosseous nerve of diabetic and non-diabetic patients with carpal tunnel syndrome

AIMS/HYPOTHESIS

We sought to establish the molecular and pathological changes predisposing diabetic and non-diabetic patients to the development of carpal tunnel syndrome (CTS).

METHODS

The posterior interosseous nerve (PIN) was biopsied in 25 diabetic and 19 non-diabetic patients undergoing carpal tunnel decompression for CTS. Detailed morphometric and immunohistological analyses were performed in the nerve biopsy.

RESULTS

In diabetic patients median nerve distal motor latency was prolonged (p < 0.05 vs non-diabetic patients), PIN myelinated fibre density (p < 0.05), fibre area (p < 0.0001) and axon area (p < 0.0001) were reduced, the percentage of unassociated Schwann cell profiles (p < 0.0001) and unmyelinated axon density (p < 0.0001) were increased and the axon diameter was reduced (p < 0.0001). Endoneurial capillary basement membrane area was increased (p < 0.0001) in diabetic patients, but endothelial cell number was increased (p < 0.01) and luminal area was reduced (p < 0.05) in non-diabetic patients with CTS. There was no difference in the expression of hypoxia-inducible factor 1α between diabetic and non-diabetic patients with CTS. However, the expression of vascular endothelial growth factor A (VEGF) (p < 0.05) and its receptors VEGFR-1 (p < 0.01) and VEGFR-2 (p < 0.05) was significantly increased in diabetic patients, particularly those with type 1 diabetes, and related to the severity of nerve fibre pathology.

CONCLUSIONS/INTERPRETATION

This study demonstrates increased nerve fibre and microvascular pathology in relation to enhanced expression of VEGF and its receptors in a non-compressed nerve in diabetic compared with non-diabetic patients with CTS. It therefore provides a potential molecular and pathological basis for the predisposition of diabetic patients to the development of CTS.

Reversal of TGF-β1 stimulation of α-smooth muscle actin and extracellular matrix components by cyclic AMP in Dupuytren's-derived fibroblasts

BACKGROUND

Myofibroblasts, a derived subset of fibroblasts especially important in scar formation and wound contraction, have been found at elevated levels in affected Dupuytren's tissues. Transformation of fibroblasts to myofibroblasts is characterized by expression of alpha- smooth muscle actin (α-SMA) and increased production of extracellular matrix (ECM) components, both events of relevance to connective tissue remodeling. We propose that increasing the activation of the cyclic AMP (cAMP)/protein kinase A signaling pathway will inhibit transforming growth factor-beta1 (TGF-β1)-induced ECM synthesis and myofibroblast formation and may provide a means to blunt fibrosis.

METHODS

Fibroblasts derived from areas of Dupuytren's contracture cord (DC), from adjacent and phenotypically normal palmar fascia (PF), and from palmar fascia from patients undergoing carpal tunnel release (CTR; CT) were treated with TGF-β1 (2 ng/ml) and/or forskolin (10 μM) (a known stimulator of cAMP). Total RNA and protein extracted was subjected to real time RT-PCR and Western blot analysis.

RESULTS

The basal mRNA expression levels of fibronectin- extra domain A (FN1-EDA), type I (COL1A2) and type III collagen (COL3A1), and connective tissue growth factor (CTGF) were all significantly increased in DC- and in PF-derived cells compared to CT-derived fibroblasts. The TGF-β1 stimulation of α-SMA, CTGF, COL1A2 and COL3A1 was greatly inhibited by concomitant treatment with forskolin, especially in DC-derived cells. In contrast, TGF-β1 stimulation of FN1-EDA showed similar levels of reduction with the addition of forskolin in all three cell types.

CONCLUSION

In sum, increasing cAMP levels show potential to inhibit the formation of myofibroblasts and accumulation of ECM components. Molecular agents that increase cAMP may therefore prove useful in mitigating DC progression or recurrence.

Upper limb musculoskeletal abnormalities and poor metabolic control in diabetes

INTRODUCTION

An increased prevalence of musculoskeletal disease is recognised in diabetes and is a common source of disability. It is known to predominantly affect the upper limbs especially the hand and shoulder. The relationship with other complications of diabetes and glycaemic control is uncertain. We designed this study to clarify these relationships, and to assess differences between types 1 and 2 diabetes.

METHODS

We identified a group of 96 people with established diabetes and examined them for the presence of locomotor disease focussing on the upper limbs. We recorded the mean HbA1c and the presence of diabetic complications, together with the health assessment questionnaire (HAQ) score. We explored correlations between locomotor disease and these variables using logistic regression. We compared data between type 1 and type 2 diabetics and contrasted the amalgamated data with that of a matched control population of medical out patients using Students t tests.

RESULTS

Locomotor disease was present in 75% of diabetics with the upper limb the commonest site for abnormalities. This prevalence was significantly higher than that seen in the controls (53%) [p=0.02]. Shoulder capsulitis (25%), carpal tunnel syndrome (20%), tenosynovitis (29%), limited joint mobility (28%) and Dupuytrens contracture (13%) were the most frequent findings and were much commoner than in controls. Capsulitis usually coexisted with other upper limb abnormalities and best predicted the presence of retinopathy and/or neuropathy. The mean HbA1c was significantly higher in patients with combined shoulder and hand problems (9.1%) than in those with no upper limb problems (8.0%) [p=0.018]. The pattern of results was similar in type 1 and type 2 diabetes, although the prevalence of abnormalities and mean HAQ were significantly greater in type 2 patients, which may be in part a function of their greater mean age.

CONCLUSION

Upper limb locomotor abnormalities are very common in diabetes and are associated with worse glycaemic control and more diabetic complications. Assessment of upper limb locomotor disease in diabetes should include an estimate of glycaemic control and a search for other complications.

Involvement of tenascin-C and PG-M/versican in flexor tenosynovial pathology of idiopathic carpal tunnel syndrome

Increased intra-carpal-tunnel pressure due to swelling of the flexor tenosynovium is the most probable pathological mechanism of idiopathic carpal tunnel syndrome (CTS). To clarify the role of tenascin-C and PG-M/versican, which have often been found to be involved in tissue remodeling and vascular stenosis in the pathogenesis of CTS, we histologically and biochemically examined the production of extracellular matrix in the flexor tenosynovium from 40 idiopathic CTS patients. Tenascin-C was temporarily expressed in the vessel wall, synovial lining and fibrous tissue, with expression regulated differently in each tissue. Tenascin-C expression by vessels correlated with disease duration and appeared to be involved in vascular lesion pathology. Morphometric analysis showed that tenascin-C expression by small arteries is correlated with PG-M/versican expression in surrounding connective tissue. PG-M/versican was also present at the neointima of severely narrowed vessels. Although tenascin-C expression by synovial lining and connective tissue shows marked regional variation and seems inconsistent, in vitro examination suggested that tenascin-C production by these tissues is regulated in response to mechanical strain on the flexor tenosynovium.

Immunolocalization of collagen types in the subsynovial connective tissue within the carpal tunnel in humans

The tenosynovium within the carpal tunnel consists of a single layer of synovial cells, which lines the bursae within the carpal tunnel, and the subsynovial connective tissue (SSCT), which contains the tendon vasculature and other structural elements. In this study, we used immunogold labeling to localize collagen types within the SSCT in three cadaver specimens and three patients with carpal tunnel syndrome. Positive labeling for collagen types I, III and VI was found with immunoelectron microscopy. Collagen types I and III were codistributed within the SSCT. Type VI was primarily located in microfibrillar structures between collagen bundles, between elastin and collagen bundles and between collagen bundles and cells. There was no difference in the distribution of collagen types when comparing cadaver specimens and carpal tunnel patients.

Biochemistry of carpal tunnel syndrome

Although carpal tunnel syndrome (CTS) occurs due to intrinsic or extrinsic causes, the idiopathic group outnumbers the rest by far. Compression of the median nerve may be due to mechanical or ischemic causation. The cause of idiopathic CTS is thought to be intermittent compression of the median nerve in predisposed people, especially working females, producing ischemia of the nerve. Reperfusion injury may occur during periods of recovery. Intermittent perfusion of the cellular tissue following ischemia releases free oxygen radicals. With continued oxidative stress, the normal antioxidant system is overwhelmed and cellular injury ensues, affecting both nerve and synovial cells. This is confirmed by changes seen locally in nerve and synovial tissue both serologically and histologically. These changes are reverted or checked by the use of antioxidants in vitro. Simulated compression of the nerve in laboratory animals also confirms these findings, further corroborating the pathophysiology and suggesting means of preventing idiopathic CTS.

The relationship of VEGF and PGE2 expression to extracellular matrix remodelling of the tenosynovium in the carpal tunnel syndrome

Tenosynovial thickening within the confined space of the carpal tunnel is thought to be the cause of the carpal tunnel syndrome (CTS). However, little is known about the pathological mechanism of tenosynovial thickening. In this study, the role of prostaglandin E(2) (PGE(2)) and vascular endothelial growth factor (VEGF) (two representative molecules that can induce oedema by increasing vascular permeability) was analysed in CTS by using immunohistochemistry and enzyme-linked immunosorptive assay (ELISA). Expression of these molecules was compared with the patients' clinical histories and a temporary increase in production of these molecules was found in cells within the vessels and synovial lining during the intermediate phase of the syndrome when the histology of the tenosynovium changes from oedematous to fibrotic. Statistical analysis clearly demonstrated that there is a close correlation between the expression of PGE(2) and VEGF. Furthermore, immunohistochemical analysis with anti-proliferating cell nuclear antigen (PCNA) revealed that the area with distinct VEGF expression closely matched the area where endothelial cells, vascular smooth muscle cells, and synovial lining cells proliferate. In contrast, despite marked alteration in the extracellular matrix (ECM) component of the tenosynovium, the fibroblasts responsible for most ECM framework production do not proliferate during any phase of CTS. Histological analysis demonstrated that angiogenesis takes place only during the intermediate phase. Since clusters of capillaries and arterioles are often surrounded by type III collagen-rich, disorganized, degenerate connective tissue, which contains fewer fibroblasts than normal, angiogenesis appears to take place as a part of a regenerative reaction that results in fibrosis. These findings strongly indicate that both PGE(2) and VEGF are expressed in the tenosynovium in CTS during the intermediate phase and induce the histological changes seen in the tenosynovium.

Studies on unfolded β2-microglobulin at C-terminal in dialysis-related amyloidosis

BACKGROUND

In 1997, Stoppini et al reported that monoclonal antibody specific to the C-terminal 92-99 of beta(2)-microglobulin (beta(2)m) had been capable of inhibiting fibrillogenesis of beta(2)m in vitro. Meanwhile, recent studies have indicated that an acidifying procedure can unfold conformation of the precursor protein, leading to fibril formation of beta(2)m as well as a transthyretin.

METHODS

We thus prepared monoclonal antibody specific to the C-terminal 92-99 (mAb 92-99), and investigated its reactivity in plasma ultrafiltrate and amyloid tissues from 18 hemodialysis patients with dialysis-related amyloidosis (DRA).

RESULTS

beta(2)m extracted from ultrafiltrate showed no reaction for mAb 92-99, whereas acidified beta(2)m from ultrafiltrate showed a reaction for mAb 92-99. Similarly, a homogenate of carpal amyloid tissues showed a strong reaction for mAb 92-99 on immunoblotting. Immunohistochemical study showed also a distinct staining for mAb 92-99 in 7 Congophilic specimens from DRA patients. More interestingly, staining for mAb 92-99 could be found in most, though not all, non-Congophilic tissues.

CONCLUSION

This study demonstrates that the monoclonal antibody specific to the C-terminal 92-99 of beta(2)m can detect the conformational intermediate in amyloidogenesis of beta(2)m ex vivo, and demonstrates that an unfolded beta(2)m at C-terminal could be found not only in Congophilic area but even in non-Congophilic area as well.

The role of proteoglycans in idiopathic carpal tunnel syndrome

Decompression of the carpal canal is the most common hand surgery performed in the United States. Hand surgeons perform 460,000 carpal tunnel releases (CTR) each year, which cost the medical industry in excess of two billion dollars per year. The focus of this investigation was to identify the changes, which occur in the flexor tenosynovium of patients undergoing CTR at the connective tissue level. The connective tissues determine the amount and arrangement of macromolecules (fibers, proteoglycans, and glycoproteins) in the extracellular matrix. The proteoglycans are soluble macromolecules that have both structural and metabolic roles. Glycoproteins help to form the interstitial space, basement membrane and function as cell surface receptors. The mechanical function of the proteoglycans includes stabilization of the collagen fibers as well as function in the hydration of the tissues. It has been previous shown that changes in the oxygen concentration at the tissue level can alter the proteoglycans profile of the tissue. During periods of hypoxia, such as those obtained during repetitive motion CTS; the glycolytic pathway acts as the energy source for the tissue. Productions of chondroitin sulfates are a process consumes NAD and would be potentially toxic to the cells under anaerobic conditions. Production of keratan sulfate is NAD sparing product, and may act as a survival pathway for cells under adverse conditions. The disruption in the proteoglycan balance will allow for alterations in the ECM and changes in hydration status of the tissues may have serious implication in CTS because the carpal canal is anatomically very narrow and increases in volume within the canal can result in further compression of the nerve. Flexor tenosyioum was obtained from patients undergoing CTR and compared with control tissue for dermatan, keratan and chondroitin sulfate. The results show a greater density of keratan reactivity in CTS tissues identified by immunostaining. In addition to changes in proteoglycan content there was also an increase in new vessel formation in the CTS tissues. The data obtained suggests that the shifts in the proteoglycan ratios may render the tissues less able to withstand the compressive forces and therefore allow for more force to be placed on the median nerve within the carpal canal.

Biochemical evaluation of serum and flexor tenosynovium in carpal tunnel syndrome

In total, 41 consecutive patients with "idiopathic carpal tunnel syndrome" and abnormal electrophysiologic findings who underwent carpal tunnel release were studied prospectively. The focus of this investigation was the evaluation of the levels of specific chemical mediators within the serum and flexor tenosynovium of these patients. Blood was collected from these patients within 1 week prior to carpal tunnel release, and flexor tenosynovium was obtained at time of surgery. Specimens were then analyzed to determine the levels of interleukins 1 and 6, prostaglandin E(2) (PGE(2)), and malondialdehyde bis diethyl acetal. These values were compared to those of controls who had no evidence of carpal tunnel syndrome. A significant increase was noted in the serum malondialdehyde and tenosynovial levels of malondialdehyde, interleukin 6, and prostaglandin PGE(2) compared to controls. The elevated levels of these biologic factors and the absence of interleukin 1 elevation support a noninflammatory ischemia-reperfusion etiology for so-called "idiopathic carpal tunnel syndrome" that causes progressive edema and fibrosis of the tissues within the carpal canal. These findings correlate with previous histopathology reports. We believe that "idiopathic carpal tunnel syndrome" is an "-osis" not an "-itis."

Beta2-microglobulin and amyloidosis

Dialysis-associated amyloidosis is a serious complication in chronic dialysis patients. Its clinical expression in terms of arthralgias, destructive arthopathies and carpal tunnel syndrome is often associated with amyloid deposits, which are mainly composed of beta2-microglobulin (beta2-M) fibrils, but in addition contain a number of other compounds. It is probable that beta2-M-amyloid deposition is related, at least in part, to the elevated plasma beta2-M that is characteristic of chronic renal failure. The latter can decrease with high-performance dialysis techniques but cannot be reduced to the normal range. Almost certainly, several other systemic and local factors are involved, including beta2-M transformed by advanced glycation end products and advanced oxidation protein products, serum P component, ubiquitin, calcium crystals, cytokines, immunoglobulin light chains, proteases and antiproteases, as well as modified collagen and glucosaminoglycans. It is also possible that the beta2-M protein, in its native or modified form, exerts noxious effects on bone and joint tissues, in addition to its mere 'passive' presence as amyloid fibrils. Several retrospective studies and one prospective study suggest that dialysis strategies with highly permeable, synthetic membranes and/or ultrapure dialysate may be partially protective or at least delay the onset of dialysis amyloidosis. Successful kidney transplantation generally halts the disease process and leads to rapid relief of osteoarticular pain although regression of beta2-M-amyloid deposits probably does not occur.

Effect of ascorbic acid and growth factors on collagen metabolism of flexor retinaculum cells from individuals with and without carpal tunnel syndrome

The effects of ascorbic acid and various growth factors on the proliferation rate and collagen metabolism were studied in cells from the flexor retinaculum of individuals with carpal tunnel syndrome (FR-CTS) and without carpal tunnel syndrome (FR control) and in human dermal fibroblasts. Ascorbic acid and four growth factors, including basic fibroblast growth factor, transforming growth factor, platelet-derived growth factor, and epidermal growth factors, were used. Ascorbic acid stimulates type I collagen production more in FR control than in FR-CTS. Growth factor treatment resulted in the following responses by the cells: (1) a higher mitogenic response than in the control cells; (2) a higher stimulation of type III collagen production and a lower stimulation of type I collagen production in CTS cells as compared with control cells; and (3) more alpha 2 (I) than alpha 1 (I) collagen production in CTS cells, unlike in control cells. We concluded that cells of the FR from individuals with CTS are physiologically altered.

Beta2-microglobulin and renal bone disease

Dialysis-related amyloidosis (DRA) is characterized by amyloid deposition mainly in bone and joint structures, presenting as carpal tunnel syndrome, destructive arthropathy, and subchondral bone erosions and cysts. Beta2-microglobulin has been demonstrated to be a major constituent of amyloid fibrils. DRA occurs not only in patients undergoing long-term hemodialysis, but also in patients undergoing continuous ambulatory peritoneal dialysis. The incidence of this complication increases with the duration of dialytic therapy and the age of the patient. While a definitive diagnosis of DRA can be made only by histological findings, various imaging techniques often support diagnosis. The molecular pathogenesis of this complication remains unknown. Recent studies have, however, suggested a pathogenic role of a new modification of beta2-microglobulin in amyloid fibrils--that is, the advanced glycation end-products (AGEs) formed with carbonyl compounds derived from autoxidation of both carbohydrates and lipids ("carbonyl stress"). Therapy for DRA is limited to symptomatic approaches and surgical removal of amyloid deposits. High-flux biocompatible dialysis membranes could be used to delay DRA development.

The advanced glycation endproduct, pentosidine, in the carpal ligament in patients with carpal tunnel syndrome undergoing hemodialysis: comparison with idiopathic carpal tunnel syndrome

BACKGROUND/AIMS

Carpal tunnel syndrome (CTS) is a major complication that occurs in the musculoskeletal system in patients on long-term hemodialysis (HD). Pentosidine is an advanced glycation endproduct (AGE) and there is evidence that shows AGEs contribute to the pathogenesis of the complications in patients undergoing HD. The aim of this study is to investigate whether pentosidine accumulates in the carpal ligament in patients undergoing HD with CTS in comparison with idiopathic CTS.

METHODS

Carpal ligaments and skin were obtained during surgery from 28 patients with CTS undergoing HD and 13 patients with idiopathic CTS (ID CTS). Pentosidine was measured by HPLC after hydrolysis of the samples, and amyloid deposits in the samples of HD CTS were examined histologically.

RESULTS

Pentosidine levels in ligament and skin were significantly higher in HD CTS than ID CTS. On the other hand, there was no difference in pyridinoline which is a physical cross-link between HD and ID CTS. Amyloid deposits were observed in 14 ligament samples, whereas there was none in 14 other samples. There was no significant difference in pentosidine and pyridinoline in ligament, pentosidine in skin, duration of HD and serum beta2-microglobulin between the amyloid+ group and the amyloid- group.

CONCLUSION

A greater concentration of pentosidine in the carpal ligament in HD patients compared with idiopathic patients suggests that an accumulation of AGEs contributes to one of the pathologies of occurrence of CTS in patients undergoing HD.

Biochemical and histological analysis of the flexor tenosynovium in patients with carpal tunnel syndrome

Carpal tunnel release is the most common hand operation performed in this country. In the absence of specific systemic diseases, the etiology and persistence of pain and dysfunction even after surgical decompression is poorly understood. The focus of this investigation was to investigate the biological factors present within the patients serum that may lead to increased sensitivity to pain. Tissue was collected from patients during surgery. The tissue was homogenized and the homogenate analyzed for the presence of IL-1, IL-6, prostaglandin E series (PGE2). The levels were compared with volunteers that had no evidence of carpal tunnel syndrome or pain. The results showed similar levels of IL-1 (range 42-26 ng/ml) in tissue homogenates, and a significant increase in levels of IL-6 and malionaldehyde bis-(diethyl acetal) in CTS patients in comparison to control tissues. This increase may be associated with oxidative changes occurring as a result of ischemia and reperfusion. Tissue homogenates were also evaluated for PGE2. The CTS tissues showed a five fold elevation in PGE2 compared to control tissues. Levels of PGE2 in CTS tissues were statistically different using a two-tailed student T-test. Increased levels of PGE2 can enhance vascular permeability at the site of injury, and can play an important role in activating adenylate cyclase which increases intracellular cyclic adenosine monophosphate (cAMP). This increase in cAMP levels can inhibit functional responses to other inflammatory stimuli. Increases in PGE2 can also cause sensitization of the nerve endings so that a normal stimulus that would not necessarily cause pain will now be experienced as painful. The results of this study demonstrate that arachidonic acid metabolites PGE2 may be responsible for both the pathological changes and clinical symptomatology in carpal tunnel syndrome.

Amyloid and non-amyloid carpal tunnel syndrome in patients receiving chronic renal dialysis

OBJECTIVE

To determine the prevalence of amyloid deposits among patients with carpal tunnel syndrome (CTS) receiving dialysis, and to investigate the factors associated with amyloid and non-amyloid CTS.

METHODS

Subjects for this prospective study were dialysis patients who underwent surgery for CTS in the same surgical unit between 1989 and 1997. CTS was diagnosed from clinical and electromyographic (EMG) findings. Systematic standard radiographs and laboratory data were also obtained. Surgical investigations included systematic macroscopic examination and biopsy of the epineurium, flexor retinaculum, synovium, and flexor tendon sheaths. Samples were stained for amyloid and examined by plain and polarized light microscopy, immunohistochemistry, and electron microscopy.

RESULTS

Forty-one samples from 30 patients (11 bilateral cases) were examined. Amyloid deposits were found in 26 samples from 18 patients (7 M, 11 F). Fifteen samples from 12 patients (3 M, 9 F) showed no amyloid deposits. Amyloid CTS was statistically significantly associated with arthralgia and longterm dialysis [mean 13.3 (range 5.5-23) vs 7.5 yrs (range 3 mo-14 yrs)] in non-amyloid CTS. Flexor tenosynovitis and carpal bone erosion occurred more frequently in amyloid CTS. There were no statistically significant differences between the 2 groups in clinical, laboratory or EMG findings, type of dialysis membrane, or frequency of ipsilateral fistula. Only amyloid CTS was recurrent.

CONCLUSION

Amyloid deposits were confirmed microscopically in 63.4% of patients. The relatively large number of cases of non-amyloid CTS without signs of dialysis associated arthropathy suggests that CTS is not a satisfactory criterion for diagnosis of dialysis arthropathy or beta2-microglobulin amyloidosis unless the presence of amyloid has been confirmed or duration of dialysis treatment has been at least 15 years.

Carpal tunnel syndrome induced by two types of calcium deposition

Two rare cases of carpal tunnel syndrome caused by calcification in the carpal tunnel are reported. One case involved a tumorous calcification consisting of basic calcium phosphate, and the other involved a diffuse calcification consisting of a mixture of calcium pyrophosphate dihydrate and basic calcium phosphate. These cases suggest that the shape of carpal tunnel calcifications is influenced by the nature of calcifying substance itself, i.e., whether it is heterogenous or homogenous.

Histopathology and clinical results of carpal tunnel syndrome in idiopathic cases and hemodialysis patients

The results of the histological examinations of specimens of the tenosynovium of the flexor tendon, the epineurium and the transverse carpal ligament from two groups of Japanese patients with carpal tunnel syndrome (idiopathic and hemodialysis) were compared. Amyloid deposits, positively identified as beta 2-microglobulin, appeared in all patients in the long-term hemodialysis group, but in no patients in the idiopathic group. Although the pathogenesis differed between the two groups, both resulted in nerve compression in the carpal tunnel. Therefore, surgical release is considered beneficial for both groups.

Expression of inflammatory cytokines and adhesion molecules in haemodialysis-associated amyloidosis

BACKGROUND

The occurrence of various arthropathies including carpal-tunnel syndrome (CTS) in dialysis-associated amyloidosis, a condition caused by the deposition of beta 2 microglobulin (beta 2MG), has been emphasized for several years. We attempted to analyse the pathogenesis of CTS in haemodialysis-associated amyloidosis (HA).

METHODS

The expression of cell adhesion molecules and inflammatory cytokines in tenosynovial tissues was determined by using both reverse-transcriptase polymerase chain reaction (RT-PCR) and immunostaining.

RESULTS

There was a marked expression of ICAM-1, VCAM-1, E-selectin mRNAs together with increased mRNA expression of inflammatory cytokines (IL-1 beta, TNF alpha, IL-6 and MCP-1) in proliferating synovial tissues. ICAM-1 was expressed not only on vascular endothelial cells, but also on synovial cells. In contrast, both VCAM-1 and E-selectin were exclusively expressed on endothelial cells. Mononuclear cells bearing CD13, CD14, CD33 and HLA-DR with macrophage-like morphology were accumulated in the perivascular area and expressed VLA-4, LFA-1 and Mac-1. Moreover, synovial lining cells, vascular endothelial cells and infiltrated mononuclear cells expressed chemokines such as MCP-1 and MIP-1 alpha.

CONCLUSIONS

These data suggest that upregulated expression of inflammatory cytokines and adhesion molecules promotes activation and infiltration of macrophages causing CTS in haemodialysis-associated amyloidosis patients.

An immunohistochemical study on cutaneous sensory receptors after chronic median nerve compression in man

Carpal tunnel syndrome represents the most frequent chronic compressive neuropathy in man and hence may be investigated as a spontaneous model of peripheral nerve damage and repair. In the present report the fate of nerve fibers in the digital skin after long-lasting median nerve compression has been investigated immunohistochemically in comparison to normal digital skin, with special consideration to sensory endings and encapsulated receptors. The presence has been documented of the neurospecific marker PGP 9.5, the glia-associated protein S-100, and the neuropeptides CGRP and CPON which are mainly associated with the sensory and sympathetic nerve fibers respectively. The morphology and distribution of nerve fibers and corpuscles appeared comparable to that of normal digital skin; a reduction in the density of sensory receptors has, however, been observed, although not to the degree that was expected to explain the clinical deficits. It has been also demonstrated that at least part of the CGRP-containing sensory and CPON-containing sympathetic axons may survive unaltered even in patients with a long clinical history of profound sensorial impairment. An apparent discrepancy between the maintenance of nerve fibers and the sensory disturbances and the frequent observation of prompt postoperative recovery even after years of compression results from this investigation. The correlation of immunohistochemical observations and functional scores may not be considered conclusive. It must, however, be discussed if the sensorial impairment in this syndrome might have, at least in some cases, not only an anatomical but also an electrophysiological basis.

Carpal tunnel syndrome in hemodialyzed patients

A total of 18 hemodialyzed patients submitted to surgery for the treatment of carpal tunnel syndrome are examined. In all of the cases pre- and postoperative EMG and biopsy were performed. Six months after surgery all of the patients showed improved pain symptoms, in 66% there was good recovery of sensitivity and of the function of the hand: these results were confirmed by EMG monitoring. In all of the biopsies amyloid deposits, particularly diffused in the tendinous and nervous sheaths, were observed. At 2-year follow-up 75% of the patients showed recurrence of pain symptoms. Thus, surgery does not seem to definitively resolve symptoms.

Aberrant cytokine production from tenosynovium in dialysis associated amyloidosis

Culture supernatants of tenosynovial tissues from patients with carpal tunnel syndrome undergoing chronic haemodialysis contained interleukin (IL) 1-like and IL6-like activity. These culture supernatants also induced active proliferation of rheumatoid synovial cells. Immunohistochemical analysis of teno-synovial tissues showed the accumulation of mononuclear cells bearing CD14 and HLA-DR antigens adjacent to the deposition of amyloid protein (beta 2 microglobulin). These cells also reacted with antibodies to IL1 and IL6 respectively. These data suggest that multiple cytokines, including IL1 and IL6, produced from tenosynovial tissues in patients with dialysis associated amyloidosis might induce the proliferation of synovial cells that, together with deposition of amyloid protein, might cause carpal tunnel syndrome.

Amyloid localized to tenosynovium at carpal tunnel release. Immunohistochemical identification of amyloid type

Thirty-five patients seen at the Mayo Clinic from 1968 to 1977 who had carpal tunnel syndrome and local deposition of amyloid without evidence of systemic amyloidosis were identified. The unlabeled immunoperoxidase method was used with antisera against purified amyloid proteins of the AA, A kappa, A lambda, AF/ASC1 (prealbumin) (transthyretin), and AB (beta 2-microglobulin) types. In 33 of the 35 patients, amyloid stained with antisera to transthyretin; in the remaining 2 patients, the amyloid did not stain with any antisera. Nine of the 35 patients had a monoclonal protein in the serum, and 2 had a monoclonal light chain in the urine. Systemic amyloidosis or multiple myeloma did not develop in any of these 11 patients. During follow-up, systemic amyloidosis developed in only 2 of the 35 patients: 1 had senile systemic amyloidosis and 1 had tissue that was inadequate for immunohistochemical staining. Amyloid localized to the tenosynovium consists of transthyretin, and systemic amyloidosis rarely develops.

[Carpal tunnel syndrome associated with long-term hemodialysis: case report]

Since Warren and Otieno reported carpal tunnel syndrome in patients on intermittent hemodialysis in 1975, a number of related reports have been published. However, there are few reports associated with neurosurgery about carpal tunnel syndrome in patients on long term hemodialysis. We reviewed this disease and reported our case. We treated a patient who complained of bilateral hand numbness and atrophy of the right thenar muscle. He had been suffering from chronic renal failure and had been treated with hemodialysis for ten years. We diagnosed carpal tunnel syndrome based on the findings concerning Tinel's sign, Phalen test, and the conduction velocity of the median nerve. We performed decompression surgery of the median nerve. However, although there was no recovery from thenar muscle atrophy, there was improvement of hand numbness. Histologically, amyloid deposits within the hypertrophic transverse carpal ligament on the right side, could be found but on the left side where the internal shunt had been made amyloid deposits were absent. The reason why patients receiving long term hemodialysis develop carpal tunnel syndrome is controversial, but it seems that beta 2 microglobulin may play an important role in developing carpal tunnel syndrome in hemodialysis patients. This was reported by Gejyo in 1985. There may be uremic and/or diabetic neuropathy in these patients, and these neuropathies may be responsible for the more rapid deterioration and poorer surgical results in carpal tunnel syndrome associated with hemodialysis than in idiopathic cases. It is most important that carpal tunnel syndrome has to be diagnosed early and that surgical decompression is performed while the disease is in its early stage.

Amyloid localized to tenosynovium at carpal tunnel release. Natural history of 124 cases

One hundred fifty-two patients with amyloid in the tenosynovium who had carpal tunnel release were identified. Twenty-eight patients were excluded because of systemic amyloidosis: primary systemic amyloidosis (AL) in 24, secondary amyloidosis (AA) in 3, and familial amyloidosis (AF) in 1. The remaining 124 patients (82%) had carpal tunnel syndrome with local deposition of amyloid and no evidence of systemic amyloidosis. Median survival of the 124 patients from diagnosis of amyloidosis was 12 years. Only two patients had systemic amyloidosis develop--9 and 10 years after recognition of tenosynovial amyloid. Of particular interest were 12 patients who had an M-protein in the serum or urine. None of the 12 patients have had evidence of systemic amyloidosis or multiple myeloma during the median follow-up of 14 years. The authors conclude that amyloid may be localized to the tenosynovium and that systemic amyloidosis rarely develops during long-term follow-up.

Beta-2-microglobulin-associated amyloidosis in chronic hemodialysis patients with carpal tunnel syndrome

The clinical manifestations of beta-2-microglobulin (beta 2M)-associated amyloidosis in chronic hemodialysis patients with carpal tunnel syndrome from a medical center hospital are presented. The predominant morbidity of beta 2M-amyloid was musculoskeletal, with deposits identified in surgical or biopsy specimens from trigger fingers, carpal tunnels, fractures, and radiolucent bone lesions. Lucent bone lesions were the characteristic radiologic finding of beta 2M-amyloidosis and were most commonly found in carpal bones, humeral heads, and femoral heads. Carpal tunnel syndrome occurred in greater than 20% of our chronic hemodialysis patients. The longer the period of time on chronic hemodialysis the greater the morbidity from beta 2M-amyloid. Although significant amounts of beta 2M-amyloid were detected in the perivascular regions of viscera, clinical compromise of internal organs from this type of amyloid was not documented. In acute studies, beta 2M clearance during hemodialysis was markedly increased using the Fresenius polysulfone dialyzers compared to cuprophane dialyzers. In summary, beta 2M-amyloid is common and causes significant morbidity in chronic hemodialysis patients. Long-term dialysis with highly permeable membranes effects greater beta 2M clearance which may result in less tissue deposition of beta 2M-amyloid, and therefore, fewer clinical complications.

Beta 2-microglobulin amyloidosis (AB2M) in patients undergoing long-term hemodialysis. A new type of amyloid

Amyloidosis has been increasingly recognized in association with renal failure and chronic hemodialysis. This report describes three patients who had long-term hemodialysis (between 7-18 years), in whom deposits developed of a new type of amyloid of beta 2-microglobulin origin. Beta 2-microglobulin amyloid (AB2M) was found in multiple organs, i.e., bone, subendocardium, gastrointestinal blood vessels, tongue, and carpal tunnel connective tissue. AB2M displayed characteristic amyloid features on conventional light and polarized microscopic examination after congo red staining. However immunostaining with anti-amyloid A protein, kappa, and lambda antisera were negative. The studied material reacted positively with beta 2-microglobulin antisera, identifying AB2M in all three cases. Ultrastructural study revealed an unusual curvi-linear fibrillar configuration. AB2M appears to be a new subtype of systemic amyloidosis secondary to renal failure and long-term hemodialysis.

Chemical heterogeneity of amyloid in the carpal tunnel syndrome

140 biopsies from 108 patients afflicted with the carpal tunnel syndrome were studied, 27 of whom showed deposition of amyloid, in 6 of them to such an extent that the amyloid was considered significant in the pathogenesis of the carpal tunnel syndrome. Morphologically, vessels and ligaments were affected and especially the peritendinous structures. As it was always part of generalized amyloidosis, the amyloid in the carpal tunnel consisted immunohistologically of amyloid A in three cases (including one case with simultaneous amyloid deposition of the AA- and the AB-type), of amyloid A kappa in one case, of amyloid of prealbumin origin in seventeen cases and of AB-amyloid in eight cases. We also described for the first time the manifestation of generalized senile amyloidosis (ASs) in the carpal tunnel. Deposition of amyloid of beta-2-microglobulin type (AB) in the carpal tunnel was particularly frequent and massive.

Carpal tunnel syndrome caused by amyloid containing beta 2 microglobulin: a new amyloid and a complication of long term haemodialysis

Three patients receiving long term haemodialysis treatment for chronic renal failure due to non-amyloid nephropathy developed the carpal tunnel syndrome requiring decompression surgery. The excised material contained amyloid, which by immunocytochemical techniques was shown to contain beta 2 microglobulin. This is, therefore, a new chemical form of amyloid whose deposition is likely to be the cause of osteoarticular and connective tissue disorders, which are being recognised with increasing frequency in patients receiving long term haemodialysis. Raised beta 2 microglobulin levels are known to occur in chronic renal failure, and the molecule is unable to cross conventional dialysis membranes. The importance of beta 2 microglobulin amyloidosis lies in the threat which it poses to the success of long term haemodialysis.

Beta 2-microglobulin: a new form of amyloid protein associated with chronic hemodialysis

Carpal tunnel syndrome (CTS) has been associated with amyloid deposits and is now regarded as a major complication in chronic hemodialysis patients. While this new syndrome has been receiving increasing attention, its etiology has not been clarified. We have isolated amyloid fibrils from amyloid laden tissues inside the carpal tunnel in four different hemodialysis patients with CTS. After solubilization in guanidine HCl, a significant amount of the protein was located in a homogeneous, low molecular weight fraction. Each protein was found to be identical to beta 2-microglobulin with regard to its molecular weight of 11,000 on SDS-PAGE, amino acid composition and N-terminal amino acids: Ile-Gln-Arg-Thr-Pro-Lys-Ile-Gln-Val-Tyr-Ser-Arg-His-Pro-Ala-Glu. In direct immunofluorescent study, anti-beta 2-microglobulin did react positively with amyloid deposits. These results demonstrate that the amyloid associated with chronic hemodialysis contains as major component a new form of amyloid fibril protein that is homologous to beta 2-microglobulin. It is postulated that beta 2-microglobulin cannot be removed from the blood by conventional hemodialysis, and accumulates in tissues causing the formation of amyloid fibrils, which, having a relatively high affinity to the carpal tunnel area, thus causes CTS.

Amyloid deposits in the periarticular tissue

Periarticular and peritendinous tissue was investigated in cases of rheumatoid arthritis, osteoarthritis and carpal tunnel syndrome for the appearance of amyloid deposits. In rheumatoid arthritis no amyloid was present. In 7.8% of the cases with osteoarthritis and in 8% of the cases with carpal tunnel syndrome amyloid was present. These amyloid desposits were present essentially in old patients and since no further clinical symptoms of systemic amyloidosis were reported, these deposits are regarded as an age related phenomenon without clinical relevance.