Amyloidosis and the Carpal Tunnel Syndrome

Transcription

1 Amyloidosis and the Carpal Tunnel Syndrome FRANK O. BASTIAN, M.D. Department of Pathology, Duke University Medical Center, Durham, North Carolina ABSTRACT Bastian, Frank O.: Amyloidosis and the carpal tunnel syndrome. Am. J. Clin. Pathol. 61: , A histologic study was carried out on tissues from 87 patients who had undergone surgical decompression of the median nerve to determine the incidence and relationship of amyloid deposition to the carpal tunnel syndrome. Using histochemical and electron microscopic technics, amyloid was found in tissues from two male patients with the apparent idiopathic form of the disease. These data are significant, in that they show that screening of tissues from such patients is of value. This study is the first to demonstrate the submicroscopic pattern of amyloid deposits associated with the carpal tunnel syndrome. The focal deposits of the fibrils show pericollagenous distribution with separation of the individual collagen fibers, a morphologic pattern which contradicts recent reports based on light microscopy. (Key words: Amyloidosis; Amyloid; Carpal tunnel syndrome; Flexor retinaculum; Carpal ligament.) THE PATHOGENESIS of the carpal tunnel syndrome has remained relatively obscure, although the practice of sectioning the transverse carpal ligament has proved to be successful therapy in most instances. 1 There is a common association of this condition with rheumatoid arthritis and trauma, but the relationship to a number of systemic diseases, such as acromegaly, myxedema and amyloidosis, has been more difficult to define. 6 Recent morphologic studies of tissues from patients with the carpal tunnel syndrome associated with amyloidosis have shown amyloid deposits in the carpal ligament of patients with multiple myeloma, 13 in pa- Received October 23, 1973; received revised manuscript December 4, 1973; accepted for publication January 4, Supported in part by Training Grant NB from the United States Public Health Service, National Institutes of Health. Send reprint requests to: Department of Pathology, St. Luke's Episcopal Hospital, Houston, Texas dents with hereditary amyloidosis, 10 and in others without apparent systemic disease. 8 The fact that amyloidosis is considered a phenomenon of aging 12 has led to the premise that amyloidosis should be considered in all unexplained forms of carpal tunnel syndrome. A survey of idiopadiic carpal tunnel syndrome was necessary to determine the association widi amyloidosis. The feasibility of screening patients with "idiopathic" carpal tunnel syndrome is complicated by the lack of specificity of the routine histochemical tests used to characterize amyloid deposits. The Congo red stain, although considered by many to be the most reliable method currently in use, is not entirely specific, 5,15 and the standard thioflavin T procedure is unreliable. 2 Electron microscopy and die standardized toluidine blue procedure, considered to be the most accurate mediods, 4,15 were used in this study. 711

2 712 BASTIAN AJ.C.P. Vol. 61 7> FIG. 1. Electron micrograph of the carpal ligament from Case 1, showing an amyloid deposit (A) forming a fairly discrete mass distorting and displacing the adjacent collagen (C). There is no association with blood vessels. X Inset: Routinely stained section of the carpal ligament from Case 1, showing an indistinct homogenous pale eosinophilic area (A) which stained positively with all the histochemical methods used to characterize amyloid. Hematoxylin and eosin. x200. Formalin fixed. Materials and Methods The clinical records of 345 patients undergoing surgical decompression of the median nerve at Duke University Medical Center from 1960 through 1969 were reviewed. Tissue specimens from only 87 patients had been submitted for pathologic examination. Of these, 61 were female and 26 were male: 15 cases were posttraumatic; 11 patients had associated osteoarthritis; 14 had rheumatoid arthritis; 1 had myxedema; 1 had acromegaly; 1 had Buerger's disease; 5 had Dupuytren's contracture; 1 had "collagen" disease; in the largest group of 38 cases, mosdy women, the disorder was of the idiopathic variety. Clinically, none had associated amyloidosis. The available tissues from these 87 patients, along with a series of controls, were examined specifically for amyloid deposits, first using light microscopic methods. Sections 6 /un. thick were made from representative paraffin blocks and stained with hematoxylin and eosin. In addition, special histochemical methods, including the alkaline Congo red stain, the standardized toluidine blue procedure for examination by polarized light, and the thioflavin T method for examination by ultraviolet fluorescence microscopy, were employed.

3 May 1974 AMYLOIDOSIS AND CARPAL TUNNEL SYNDROME 713 FIG. 2. The submicroscopic pattern of the amyloid deposit (A) in this synovial biopsy from Case 2 is similar to that seen in the carpal ligament in Case 1. The tissue is very well preserved considering that the specimen was recovered from paraffin. X Inset: Similar pale eosinophilic areas (A) seen in heavily stained sections from Case 2. These showed the characteristic red polarization color when stained with the standardized toluidine blue procedure. Iri these Zenke,r's-fixed tissues, the deposits could not be distinguished from the adjacent collagen (C) using other histochemical methods, i.e., the Congo red and thionavin T technics. Hematoxylin and eosin. X200. Zenker's fixation. Polarization microscopy of stained and unstained sections was carried out with a Leitz Ortholux research microscope with a revolving stage and fixed analyzer. Illumination was provided by a 6 volt, 5 amp., tungsten lamp. Examination with polar screens in full crossed position was essential. 16 Fluorescence microscopy was carried out also with the Leitz microscope, fitted with an HBO 2fJ0 -w, mercury lamp and darkfield condenser. Ultraviolet light (exciter filter 2 mm AGI; barrier filter K430) was used to examine the specially prepared thioflavin T sections. 2 Electron microscopy was used to confirm the presence of amyloid deposits. Tissues from two of the 87 patients, in which amyloid was demonstrated by histochemical methods, were processed for electron microscopy. The clinical data are as follows. Report of Two Cases Case 1. A 53-year-old man who had experienced numbness and paresthesias of his right hand for a year had recently noted similar difficulties with his left hand. The Tinel sign was positive over

4 714 BASTIAN A.J.C.P. Vol. 61 both wrists, and thenar atrophy with decreased median nerve conduction was noted in the right wrist. The patient had chronic asthma, but no other manifestation of systemic disease except degenerative arthritis and a peptic ulcer. No evidence of hereditary amyloidosis was found. At surgery, gross thickening of the carpal ligament was noted and a representative tissue specimen was obtained and fixed at room temperature for 24 hr. in 4% glutaraldehyde with M. sodium cacodylate buffer (ph 7.4), then postfixed at room temperature for 1 hr. with 1% osmium tetroxide in 0.05 M. veronal buffer (ph 7.4). The remainder of the specimen was fixed in 10% buffered formalin (ph 7.4) and embedded in paraffin for light microscopy. Case 2. A 69-year-old man with bilateral symptoms of the carpal tunnel syndrome for an 8-month period also had noted no evidence of systemic disease other than degenerative arthritis and peptic ulcer. The patient is well 8 years following the initial operation, with no evidence of hereditary amyloidosis or multiple myeloma but with recurrence of carpal tunnel symptoms. The gross appearance of the transverse carpal ligament at surgery was not altered pathologically, but the synovium of the flexor tendons were fibrosed and thickened. The tissues available for this case had been fixed in Zenker's solution and embedded in paraffin. Preparation for electron microscopy was accomplished by removing selected portions, 1 to 2 mm. in diameter, from the paraffin block and deparaffinizing them with xylol. They were then hydrated with graded alcohols and postfixed at room temperature for 1 hr. in 1% osmium tetroxide in 0.05 M. veronal buffer (ph 7.4). All tissues for electron microscopy after fixation were dehydrated in graded alcohols and embedded in Epon. Thin sections were cut with a Sorvall Porter Blum microtome, mounted on 300 mesh copper grids, doubly stained for 6 min. at room temperature in 4% uranyl magnesium acetate and then for 4 min. in lead citrate at ph 12. Examinations were made with an RCA EMU3G electron microscope operated at 50 Kv. The control material was obtained both to check the adequacy of the histochemical stains and to examine carpal tunnel tissues at random. The control amyloidmaterials were tissues from autopsies of four patients with generalized amyloidosis and one surgical biopsy from a tongue mass from a patient with multiple myeloma in which amyloid fibrils were clearly demonstrated by electron microscopy. The control carpal tunnel tissues were obtained from six randomly chosen autopsies and at operation from one patient who had the carpal tunnel sydrome. Results In reviewing tissue sections from the 87 cases in this study, routinely stained wim hematoxylin and eosin, we were unable initially to recognize amyloid deposits. Retrospective examination of the tissues from the two patients in this series later proven to have amyloid deposits showed indistinct foci of homogeneous pale eosinophilic deposits interspersed between collagen bundles on the sections (Fig. 1, inset; Fig. 2, inset). The tissues from this series varied between dense collagen and synovium, depending on whether the specimen was obtained from the flexor retinaculum or the synovium of the flexor tendons. Variable inflammation was present in all specimens, but was most marked in those from rheumatoid ardiritis patients. Special histochemical methods routinely used for the detection of amyloid provided satisfactory results when applied to formalin-fixed tissues from Case 1. In this specimen, the Congo red stain gave a

5 May 1974 AMYLOIDOSIS AND CARPAL TUNNEL SYNDROME 715 FIG. 3. High magnifications of the amyloid deposits from Case 1, showing the haphazardly arranged paired amyloid fibrils (A), forming apparent helices with an average length of 2500 A, a variable width of 60 to 120 A, and a periodicity of about 30 A. Two collagen fibers (C) are present at the upper left corner of the photograph and pass from the plane of section as they course through the amyloid deposit. This close association with collagen was a constant feature in all the tissues examined, x 131,000.

6 716 BASTIAN A.J.C.P. Vol. 61 characteristic yellow-green polarization color to the amyloid deposits against the gray-white background of the collagen. Sections stained with thioflavin T technic gave a bright yellow-green fluorescence to the amyloid material, although the specificity was equivocal even when special care was taken to prepare the sections at a low ph, as well as to examine them with ultraviolet light. 2 The usually reliable Congo red stain, when performed on Zenker's-fixed tissues, gave a false green polarization color to normal collagen. The recendy described toluidine blue procedure was unaffected by this mode of fixation and gave to the amyloid deposits a distinct red polarization color that contrasted sharply with the gray-blue of the collagen. 15 Electron microscopy confirmed the presence of amyloid material in the two cases of amyloidosis found by the histochemical methods. The amyloid fibrils were arranged in fairly discrete masses closely associated with, and distorting, the adjacent collagen bundles (Figs. 1 and 2). No tissue destruction was observed, but simply separadon and displacement of the individual collagen fibrils. Higher magnifications of the amyloid deposits (Fig. 3) showed the individual fibrils to be haphazardly arranged, morphologically identical to those demonstrated by Cohen 3 and by Gueft and associates. 9 The measured spacing seems to be in accordance with their findings, forming an apparent twisted helix with a length of approximately 2,500A, and a variable width of 60 to 120 A. A few fibrils appeared to have a periodicity of approximately 30 A. Discussion The carpal tunnel or canal is an important anatomically defined space between the flexor retinaculum or transverse carpal ligament and the carpal bones. This structure is made up of two compartments, the long flexor tendons of the fingers and the thumb. The median nerve courses through the larger compartment. The smaller compartment accommodates only the tendon of the flexor carpi radialis. Compression of the median nerve at the wrist, which produces the classic symptoms of the carpal tunnel syndrome, is caused either by reduction in the capacity of this bony canal or by an increase in the volume of the contents of the larger compartment. 6 Specific factors involved in this compression phenomenon initiate the carpal tunnel syndrome. These factors are varied and often obscure. 13 Bony deformity following trauma, or mass lesions within the canal (e.g., hemangiomas, lipomas, or ganglion cysts), are easily explained. By contrast, the apparent tightness of the flexor retinaculum or fibrosis of the synovium of the flexor tendons (e.g., rheumatoid arthritis) is a more mysterious phenomenon. Fibrosis of the flexor synovialis is commonly found at operation in most patients with idiopathic carpal tunnel syndrome, and usually there is no gross pathologic change in the flexor retinaculum. 13 Since it has been suggested that screening all unexplained cases of carpal tunnel syndrome would uncover significant number of patients widi unsuspected systemic amyloidosis, 10 the question whether there is a recognizable pattern of distribution of amyloid deposits in such patients arises. Some variation in distribution of amyloid deposits in different forms of amyloidosis appears to exist, since in the hereditary type of disease the deposits are limited to the transverse carpal ligament, whereas in patients with multiple myeloma both this structure and the synovial tissue are involved. 13 Amyloid was found in tissue specimens from two of 87 patients in this series, both of whom were male. The deposits were present in both synovial and transverse carpal ligaments in what appeared to be

7 May 1974 AMYLOIDOSIS AND CARPAL TUNNEL SYNDROME 717 idiopathic forms of the syndrome. This electron microscopic study is also the first reported submicroscopic observation of amyloid deposits associated with the carpal tunnel syndrome, with the focal deposits showing a pericollagenous distribution with separation of the individual collagen fibers by closely associated amyloid fibrils and no destruction of collagen. This contradicts recent reports based on light microscopy that amyloid replaced collagen in unit-by-unit fashion. 10 Patients with the carpal tunnel syndrome associated with systemic hereditary amyloidosis have some characteristic clinical presentations that differ from those of these two cases. 10 The disorder in male patients is usually associated with peripheral polyneuropathy, although the carpal tunnel syndrome may be the only manifestation in female patients. Hereditary amyloidosis is transmitted as an autosomal dominant; the patients in Cases 1 and 2 had no family history of this condition. Amyloid is found characteristically deposited in connective tissue throughout the body. A previous skin biopsy from the patient in Case 1 had showed no amyloid in the subcutaneous tissues. Sufficient studies have not been done to completely rule out systemic disease in these two cases, but the data available suggest that they represent focal deposition of amyloid in the carpal tunnel tissues. This warrants careful searching for amyloid deposits in all male patients who have idiopauiic carpal tunnel syndrome. References 1. Brain WR, Wright AD, Wilkinson M: Spontaneous compression of both median nerves in the carpal tunnel: Six cases treated surgically. Lancet 1:277, Burns J, Pennock CA, Steward PJ: The specificity of the staining of amyloid deposits with thioflavin T. J Pathol Bacterid 94: , Cohen AS: Amyloidosis. N Engl J Med 277: , Cooper JH: An evaluation of current methods for the diagnostic histochemistry of amyloid. J Clin Pathor22: , De Lellis RA, Glenner GG, Sriram J: Histoqhemical observations on amyloid with reference to polarization microscopy. J Histochem Cytochem 16: , Entin MA: Carpal tunnel syndrome and its variants, Practical Surgery of the Hand. Edited by MA Entin. Surg Clin North Am 48: , Glenner GG, Cuatrecasas P, Isersky C, et al: Physical and chemical properties of amyloid fibers. J Histochem Cytochem 17: , Grokoest AW, Demartini FE: Systemic disease and the carpal tunnel syndrome. JAMA 155: , Gueft B, Kikkawa Y, Hirschl S: An electron microscopic study of amyloidosis from different species, Amyloidosis. Edited by E Mandema, L Ruenen, JH Scholten, et al. Amsterdam, Excerpta Medica Foundation, 1968, pp Lambird PA, Hartmann WH: Hereditary amyloidosis, the flexor retinaculum and the carpal tunnel syndrome. Am J Clin Pathol 52: , Missmahl H: Reticulin and collagen as important factors for the localization of amyloid. The use of polarization microscopy as a tool in the detection of the composition of amyloid, Amyloidosis. Edited by E Mandema, L Ruenen, JH Scholten, et al. Amsterdam, Excerpta Medica Foundation, 1968, pp Ozdemir A, Wright JR, Calkins E: Influence of rheumatoid arthritis on amyloidosis of aging. N Engl J Med 285: , Phalen GS: The carpal-tunnel syndrome: Seventeen years' experience in diagnosis and treatment of six hundred, fifty-four hands. J Bone Joint Surg (Am) 48: , Reissenweber NJ, Decaro J: Dichroism with Congo red. A specific test for amyloid? Virchows Arch [Pathol Anat] 347: , Wolman M: Amyloid, its nature and molecular structure: Comparison of a new toluidine blue polarized light method with traditional procedures. Lab Invest 25: , Wolman M: On the use of polarized light in pathology, Pathology Annual. Edited by SC Sommers. New York, Appleton-Century- Crofts, 1970, pp