有這個妹妹還是很好的...
http://www.wretch.cc/blog/joyfullife&article_id=1732119
碼的...害我看到眼睛在流汗...
星期三, 3月 16, 2005
星期一, 3月 14, 2005
CUBITAL TUNNEL SYNDROME (ULNAR NERVE AT ELBOW: A SENSORYAND MOTOR SYNDROME)
AMERICAN JOURNAL OF INDUSTRIAL MEDICINE 37:75-93 (2000)
While focal entrapment of the ulnar nerve is an increasingly recognized cause of work-associated morbidity, the literature on these disorders in the occupational setting is sparse. Cubital tunnel syndrome is ulnar nerve entrapment at the medial aspect of the elbow. It is the second most common entrapment neuropathy of the upper extremity after carpal tunnel syndrome [AAEM, 1999; Idler, 1996].
Epidemiology
Two recent comprehensive reviews of the epidemiology of WMSDs [Hagberg et al., 1995; Bernard, 1997] did not assess studies of nerve entrapments in the upper extremity aside from carpal tunnel syndrome. While Hagberg and Silverstein [1995] stated that ulnar nerve entrapment in the elbow region (cubital tunnel syndrome) was the second most frequent upper extremity entrapment neuropathy, they did not review this disorder, stating that studies providing evidence of its work-relatedness are currently lacking. However, earlier and subsequent articles and texts provide some evidence of the work-relatedness. Specifc work related risk factors common to the cubital tunnel syndrome appear to be aggravating motions consisting of repetitive and sudden elbow flexion, and repeated trauma or pressure to the elbow at the ulnar groove [Feldman et al., 1983; Herrington and Morse, 1995; Gordon, 1995]. Job tasks associated with cubital tunnel syndrome include shoveling, hammering, lifting, manipulating handles of boring and punching machines, leaning on the elbow at a desk or work bench, working in tight places, digging, and use of hand saws or large power machinery [Feldman et al., 1983; Gordon, 1995; Blair, 1995].
Anatomy and Pathology
The ulnar nerve originates from the inferior roots of the brachial plexus (C8-T1). Compressions of the nerve at given points along its course through the upper extremity give rise to the various nerve entrapment syndromes. While cubital tunnel is a general term used to describe localized entrapment of the ulnar nerve at the elbow, the site of entrapment of the ulnar nerve in the region of the elbow can occur in several locations including proximal to the elbow by the medial head of the triceps' "arcade of Struther's,'' at the elbow by the arcuate ligament, or in the mid-forearm by the flexor carpi ulnaris muscle. Precise localization of
entrapment is important if surgery is being contemplated [Hilburn, 1996].
Clinical Presentation
Depending upon the severity of the entrapment, typical symptoms of cubital tunnel syndrome include: (1) activityrelated numbness or paresthesias involving the 4th and 5th fingers; (2) pain in the medial aspect of the elbow and proximal forearm; (3) progressive inability to separate fingers, pick up small objects between the thumb and index finger; (4) loss of power grip and dexterity and, in severe cases, claw position of the ring and little fingers, hand fatigue and atrophy of the hypothenar and interosseous muscles [Idler, 1996; Feldman et al., 1983; Herrington and Morse, 1995; Blair, 1995]. As with carpal tunnel syndrome, symptoms of cubital tunnel syndrome are often associated with nocturnal awakening.
A variety of provocative tests have been suggested for use in diagnosing cubital tunnel syndrome. These include Tinel's sign (paresthesias in the fifth digit and medial half of the fourth digit when tapping over the ulnar nerve at the elbow), the elbow flexion test in which symptoms in digits 4 and/or 5 (paresthesias and/or numbness) develop following maximum flexion of the elbow with the forearm in supination and the wrist in neutral, and the pressure provocative test, in which pressure is applied proximal to the cubital tunnel with the elbow in 20 flexion and the forearm in supination [Novak et al., 1994].
Novak and colleagues [1994] evaluated the sensitivity and specificity of Tinel's sign over the cubital tunnel, the "pressure provocative test,'' and the elbow flexion test. The sensitivity and specificity of the Tinel's sign were 0.70 and 0.98, respectively. The sensitivity of the flexion test at 60 seconds was 0.75 and the specificity 0.99. The 60 second ressure test's sensitivity was 0.89, with a specificity of 0.98. A maneuver combining the elbow flexion test with maintaining local pressure over the cubital canal for 30 seconds, resulted in sensitivity=0.91, specificity=0.97, and ppv=0.93.
Tests of function in muscles innervated by the ulnar nerve may not always be impaired because of cross supply to these muscles by the median nerve. Clinical methods described to test the ulnar innervated intrinsic muscles of the hand include: abduction of the digits (with the IP joints in extension) against resistance; flexion of the fifth digit DIP joint against resistance; difficulty in adducting the fifth digit while it is in extension (Wartenberg's sign); inability to properly cross the index and middle fingers (Scott Earle test); and inability to pinch index and thumb tips together firmly without sharp flexion of the DIP joint (positive Froment's sign) [Idler, 1996]. The "late'' signs include wasting of the intrinsic muscle mass of the first dorsal interosseous (FDI) muscle, one of the intrinsic muscles best viewed in the space between the thumb and the second metacarpal bone.
Sensory testing over the ulnar nerve distribution should include the palmar and dorsal aspects of the fourth and fifth digit, comparing the affected and non-affected sides. Such testing can be accomplished using standardized (Semmes-Weinstein) monofilaments or vibratory testing, since light touch and vibration sense are the first affected in early stages of nerve entrapment [Idler, 1996].
A classification of causes of cubital tunnel syndrome is described by Tetro and Pichora [1996]. Of the classification systems devised for describing the severity of cubital tunnel syndrome, that of Dellon [1989] is the most comprehensive, incorporating progression of symptoms and clinical tests of motor and sensory ulnar nerve function.
Electrodiagnostic Testing
Electrodiagnostic testing including nerve conduction velocity and electromyography should be performed whenever an entrapment neuropathy is suspected, but the severity of the clinical findings may not always correlate with the results of such testing. In addition, the proper technique and interpretation by the specialists performing these tests is of paramount importance for the evaluating physician who must decide when to refer a patient for surgery. Blair [1995] writes "the definition of cubital syndrome on the basis of absolute electrophysiologic values is of limited merit, as normal and abnormal values are technique and laboratory dependent".
The reader is referred to a recent comprehensive review, the American Association of Electrodiagnostic Medicine's "Practice Parameter for Electrodiagnostic Studies in Ulnar Neuropathy at the Elbow" [AAEM, 1999]. This document attempts to standardize the methodology and technique for performing electrodiagnostic testing of the ulnar nerve at the elbow. Its four-page summary is a useful guide in assessing the quality of electrodiagnostic testing for the clinician who refers a patient. Two of the three AAEM practice standards listed are: limb temperatures should be maintained and noted within a reference range (34 C is most commonly used), and, elbow position should be the same during electrodiagnostic stimulation and measurement of the nerve and also when comparing the patient's results with the normal values adopted by the testing laboratory. The AAEM suggests moderate elbow flexion of 70-90 from horizontal but recognizes that studies have used different elbow flexion/extension angles [AAEM, 1999]. The information provided by electrodiagnostic testing
of the ulnar nerve can help:
1. confirm injury to the nerve;
2. gauge the severity of nerve injury;
3. locate the site(s) of injury along the course of the nerve.
Electrodiagnostic studies are useful in documenting mild to marked entrapment of the ulnar nerve in the cubital tunnel. However, the values of electrodiagnostic tests must be interpreted in the clinical context, for 65% of the population may have 10±20 m/second slowing across the elbow [Blair, 1995]. Very mild cubital tunnel syndrome is a clinical diagnosis based on practitioner experience [Blair, 1995]. Comparison of the affected and unaffected limbs (if the condition is not bilateral) could also prove useful for reaching an accurate diagnosis. A review paper by Hilburn [1996] provides an excellent overview of the use of electrodiagnostic studies in the diagnosis of cubital tunnel syndrome as does a textbook by Preston and Shapiro [1998]. Once it is clear that the ulnar nerve is probably involved in the injury process, referral to an experienced specialist in electrophysiologic testing is warranted for the reasons listed above. In addition, the specialist can select, from among the various nerve conduction testing parameters available, those appropriate for the patient.
Treatment
The treatment of cubital tunnel syndrome is generally based on assessment of (1) the severity of symptoms and sensory or motor impairment upon presentation of the patient and (2) the duration of symptoms and nerve function impairment. In mild or moderate cubital tunnel syndrome a minimum of six months of non-surgical, conservative (medical) management is suggested before considering surgery [Idler, 1996]. Surgical intervention is generally recommended for severe sensory or motor impairment [Idler, 1996; Tetro and Pichora, 1996]. However, there is less agreement in the literature on the best method of initial treatment for moderate cubital tunnel syndrome, based on less successful outcomes compared to mild neuropathy. Medical monitoring of patients at 1±3 month intervals is warranted, which should include assessment of symptoms, signs of nerve impairment and compliance with treatment recommendations. If no improvement is seen or the clinical condition deteriorates, electrodiagnostic retesting is recommended by most authors and operative intervention should be considered [Tetro and Pichora, 1996].
Non-surgical management of the cubital tunnel syndrome should include modification of inciting exposures and activities at work and at home. Extreme elbow flexion should be avoided at home and at work. Patients frequently benefit from use of an elbow splint. The elbow should be splinted in elbow extension which limits flexion to no greater than 45 but does not apply direct pressure to the nerve [Sailer, 1996]. Splints should be used at night even in the absence of nighttime paresthesias noted upon awakening. During the day, elbow pads may be used to protect the ulnar nerve within the ulnar groove from direct pressure or trauma. Use of elbow padding and night splinting is suggested for a trial of at least three months. In severe cases, daytime splinting may be tried [Idler, 1996]. Additionally, for more chronic and severe cases of cubital tunnel syndrome, physical or occupational hand therapy should be performed.
Authors differ over the time from the onset of symptoms for which adequate conservative measures are to be tried before surgery should be considered in patients who present with mild or moderate cubital tunnel syndrome, but it ranges from six months [Idler, 1996] to one year [Tetro and Pichora, 1996]. Dellon et al. [1993] have found that a high percentage (89%) of patients with "mild, intermittent disease were successfully treated nonoperatively, whereas only 38% of those with moderate disease(persistent paresthesias, muscle weakness, abnormal two-point discrimination [less than 10 mm] were successfully managed conservatively." Urbaniak [1991] recommends a trial of conservative measures in patients with the following findings: "(1) early symptoms, intermittent episodes; (2) mild paresthesias without significant pain; (3) minimal physical findings (slight numbness), with normal motor examination.'' He suggests operative exploration without a trial of conservative treatment in those with "severe findings of weakness, decreased two-point discrimination, and electromyographic evidence of denervation potentials..."[Tetro and Pichora, 1996].
The medical literature varies on the most appropriate operative procedure for the different subtypes of cubital tunnel syndrome. Basically, releasing constrictions at all affected sites along the nerve in the elbow region is one surgical option (simple decompression), and changing the position of the nerve to the front of the elbow (anterior transposition) is the second major category of operation, with variations used within each category. Needless to say, there is debate over the best operative procedure to be used, and the reader can refer to the reference article by Tetro and Pichora for a discussion of the different operative procedures.
It is important to modify ergonomic risk factors associated with ulnar nerve entrapment flexion (greater than 45), repetitive elbow flexion, and forceful exertions of the wrist, forearm or elbow.
AMERICAN JOURNAL OF INDUSTRIAL MEDICINE 37:75-93 (2000)
While focal entrapment of the ulnar nerve is an increasingly recognized cause of work-associated morbidity, the literature on these disorders in the occupational setting is sparse. Cubital tunnel syndrome is ulnar nerve entrapment at the medial aspect of the elbow. It is the second most common entrapment neuropathy of the upper extremity after carpal tunnel syndrome [AAEM, 1999; Idler, 1996].
Epidemiology
Two recent comprehensive reviews of the epidemiology of WMSDs [Hagberg et al., 1995; Bernard, 1997] did not assess studies of nerve entrapments in the upper extremity aside from carpal tunnel syndrome. While Hagberg and Silverstein [1995] stated that ulnar nerve entrapment in the elbow region (cubital tunnel syndrome) was the second most frequent upper extremity entrapment neuropathy, they did not review this disorder, stating that studies providing evidence of its work-relatedness are currently lacking. However, earlier and subsequent articles and texts provide some evidence of the work-relatedness. Specifc work related risk factors common to the cubital tunnel syndrome appear to be aggravating motions consisting of repetitive and sudden elbow flexion, and repeated trauma or pressure to the elbow at the ulnar groove [Feldman et al., 1983; Herrington and Morse, 1995; Gordon, 1995]. Job tasks associated with cubital tunnel syndrome include shoveling, hammering, lifting, manipulating handles of boring and punching machines, leaning on the elbow at a desk or work bench, working in tight places, digging, and use of hand saws or large power machinery [Feldman et al., 1983; Gordon, 1995; Blair, 1995].
Anatomy and Pathology
The ulnar nerve originates from the inferior roots of the brachial plexus (C8-T1). Compressions of the nerve at given points along its course through the upper extremity give rise to the various nerve entrapment syndromes. While cubital tunnel is a general term used to describe localized entrapment of the ulnar nerve at the elbow, the site of entrapment of the ulnar nerve in the region of the elbow can occur in several locations including proximal to the elbow by the medial head of the triceps' "arcade of Struther's,'' at the elbow by the arcuate ligament, or in the mid-forearm by the flexor carpi ulnaris muscle. Precise localization of
entrapment is important if surgery is being contemplated [Hilburn, 1996].
Clinical Presentation
Depending upon the severity of the entrapment, typical symptoms of cubital tunnel syndrome include: (1) activityrelated numbness or paresthesias involving the 4th and 5th fingers; (2) pain in the medial aspect of the elbow and proximal forearm; (3) progressive inability to separate fingers, pick up small objects between the thumb and index finger; (4) loss of power grip and dexterity and, in severe cases, claw position of the ring and little fingers, hand fatigue and atrophy of the hypothenar and interosseous muscles [Idler, 1996; Feldman et al., 1983; Herrington and Morse, 1995; Blair, 1995]. As with carpal tunnel syndrome, symptoms of cubital tunnel syndrome are often associated with nocturnal awakening.
A variety of provocative tests have been suggested for use in diagnosing cubital tunnel syndrome. These include Tinel's sign (paresthesias in the fifth digit and medial half of the fourth digit when tapping over the ulnar nerve at the elbow), the elbow flexion test in which symptoms in digits 4 and/or 5 (paresthesias and/or numbness) develop following maximum flexion of the elbow with the forearm in supination and the wrist in neutral, and the pressure provocative test, in which pressure is applied proximal to the cubital tunnel with the elbow in 20 flexion and the forearm in supination [Novak et al., 1994].
Novak and colleagues [1994] evaluated the sensitivity and specificity of Tinel's sign over the cubital tunnel, the "pressure provocative test,'' and the elbow flexion test. The sensitivity and specificity of the Tinel's sign were 0.70 and 0.98, respectively. The sensitivity of the flexion test at 60 seconds was 0.75 and the specificity 0.99. The 60 second ressure test's sensitivity was 0.89, with a specificity of 0.98. A maneuver combining the elbow flexion test with maintaining local pressure over the cubital canal for 30 seconds, resulted in sensitivity=0.91, specificity=0.97, and ppv=0.93.
Tests of function in muscles innervated by the ulnar nerve may not always be impaired because of cross supply to these muscles by the median nerve. Clinical methods described to test the ulnar innervated intrinsic muscles of the hand include: abduction of the digits (with the IP joints in extension) against resistance; flexion of the fifth digit DIP joint against resistance; difficulty in adducting the fifth digit while it is in extension (Wartenberg's sign); inability to properly cross the index and middle fingers (Scott Earle test); and inability to pinch index and thumb tips together firmly without sharp flexion of the DIP joint (positive Froment's sign) [Idler, 1996]. The "late'' signs include wasting of the intrinsic muscle mass of the first dorsal interosseous (FDI) muscle, one of the intrinsic muscles best viewed in the space between the thumb and the second metacarpal bone.
Sensory testing over the ulnar nerve distribution should include the palmar and dorsal aspects of the fourth and fifth digit, comparing the affected and non-affected sides. Such testing can be accomplished using standardized (Semmes-Weinstein) monofilaments or vibratory testing, since light touch and vibration sense are the first affected in early stages of nerve entrapment [Idler, 1996].
A classification of causes of cubital tunnel syndrome is described by Tetro and Pichora [1996]. Of the classification systems devised for describing the severity of cubital tunnel syndrome, that of Dellon [1989] is the most comprehensive, incorporating progression of symptoms and clinical tests of motor and sensory ulnar nerve function.
Electrodiagnostic Testing
Electrodiagnostic testing including nerve conduction velocity and electromyography should be performed whenever an entrapment neuropathy is suspected, but the severity of the clinical findings may not always correlate with the results of such testing. In addition, the proper technique and interpretation by the specialists performing these tests is of paramount importance for the evaluating physician who must decide when to refer a patient for surgery. Blair [1995] writes "the definition of cubital syndrome on the basis of absolute electrophysiologic values is of limited merit, as normal and abnormal values are technique and laboratory dependent".
The reader is referred to a recent comprehensive review, the American Association of Electrodiagnostic Medicine's "Practice Parameter for Electrodiagnostic Studies in Ulnar Neuropathy at the Elbow" [AAEM, 1999]. This document attempts to standardize the methodology and technique for performing electrodiagnostic testing of the ulnar nerve at the elbow. Its four-page summary is a useful guide in assessing the quality of electrodiagnostic testing for the clinician who refers a patient. Two of the three AAEM practice standards listed are: limb temperatures should be maintained and noted within a reference range (34 C is most commonly used), and, elbow position should be the same during electrodiagnostic stimulation and measurement of the nerve and also when comparing the patient's results with the normal values adopted by the testing laboratory. The AAEM suggests moderate elbow flexion of 70-90 from horizontal but recognizes that studies have used different elbow flexion/extension angles [AAEM, 1999]. The information provided by electrodiagnostic testing
of the ulnar nerve can help:
1. confirm injury to the nerve;
2. gauge the severity of nerve injury;
3. locate the site(s) of injury along the course of the nerve.
Electrodiagnostic studies are useful in documenting mild to marked entrapment of the ulnar nerve in the cubital tunnel. However, the values of electrodiagnostic tests must be interpreted in the clinical context, for 65% of the population may have 10±20 m/second slowing across the elbow [Blair, 1995]. Very mild cubital tunnel syndrome is a clinical diagnosis based on practitioner experience [Blair, 1995]. Comparison of the affected and unaffected limbs (if the condition is not bilateral) could also prove useful for reaching an accurate diagnosis. A review paper by Hilburn [1996] provides an excellent overview of the use of electrodiagnostic studies in the diagnosis of cubital tunnel syndrome as does a textbook by Preston and Shapiro [1998]. Once it is clear that the ulnar nerve is probably involved in the injury process, referral to an experienced specialist in electrophysiologic testing is warranted for the reasons listed above. In addition, the specialist can select, from among the various nerve conduction testing parameters available, those appropriate for the patient.
Treatment
The treatment of cubital tunnel syndrome is generally based on assessment of (1) the severity of symptoms and sensory or motor impairment upon presentation of the patient and (2) the duration of symptoms and nerve function impairment. In mild or moderate cubital tunnel syndrome a minimum of six months of non-surgical, conservative (medical) management is suggested before considering surgery [Idler, 1996]. Surgical intervention is generally recommended for severe sensory or motor impairment [Idler, 1996; Tetro and Pichora, 1996]. However, there is less agreement in the literature on the best method of initial treatment for moderate cubital tunnel syndrome, based on less successful outcomes compared to mild neuropathy. Medical monitoring of patients at 1±3 month intervals is warranted, which should include assessment of symptoms, signs of nerve impairment and compliance with treatment recommendations. If no improvement is seen or the clinical condition deteriorates, electrodiagnostic retesting is recommended by most authors and operative intervention should be considered [Tetro and Pichora, 1996].
Non-surgical management of the cubital tunnel syndrome should include modification of inciting exposures and activities at work and at home. Extreme elbow flexion should be avoided at home and at work. Patients frequently benefit from use of an elbow splint. The elbow should be splinted in elbow extension which limits flexion to no greater than 45 but does not apply direct pressure to the nerve [Sailer, 1996]. Splints should be used at night even in the absence of nighttime paresthesias noted upon awakening. During the day, elbow pads may be used to protect the ulnar nerve within the ulnar groove from direct pressure or trauma. Use of elbow padding and night splinting is suggested for a trial of at least three months. In severe cases, daytime splinting may be tried [Idler, 1996]. Additionally, for more chronic and severe cases of cubital tunnel syndrome, physical or occupational hand therapy should be performed.
Authors differ over the time from the onset of symptoms for which adequate conservative measures are to be tried before surgery should be considered in patients who present with mild or moderate cubital tunnel syndrome, but it ranges from six months [Idler, 1996] to one year [Tetro and Pichora, 1996]. Dellon et al. [1993] have found that a high percentage (89%) of patients with "mild, intermittent disease were successfully treated nonoperatively, whereas only 38% of those with moderate disease(persistent paresthesias, muscle weakness, abnormal two-point discrimination [less than 10 mm] were successfully managed conservatively." Urbaniak [1991] recommends a trial of conservative measures in patients with the following findings: "(1) early symptoms, intermittent episodes; (2) mild paresthesias without significant pain; (3) minimal physical findings (slight numbness), with normal motor examination.'' He suggests operative exploration without a trial of conservative treatment in those with "severe findings of weakness, decreased two-point discrimination, and electromyographic evidence of denervation potentials..."[Tetro and Pichora, 1996].
The medical literature varies on the most appropriate operative procedure for the different subtypes of cubital tunnel syndrome. Basically, releasing constrictions at all affected sites along the nerve in the elbow region is one surgical option (simple decompression), and changing the position of the nerve to the front of the elbow (anterior transposition) is the second major category of operation, with variations used within each category. Needless to say, there is debate over the best operative procedure to be used, and the reader can refer to the reference article by Tetro and Pichora for a discussion of the different operative procedures.
It is important to modify ergonomic risk factors associated with ulnar nerve entrapment flexion (greater than 45), repetitive elbow flexion, and forceful exertions of the wrist, forearm or elbow.
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