The role of ultrasound in the diagnosis of carpal tunnel syndrome

Transcription

1 Muthanna Medical Journal 2016; 3(2): The role of ultrasound in the diagnosis of carpal tunnel syndrome Ali Taha Hassan Al-Azzawi 1* Abstract The aim of this study is to confirm the accuracy of sonography in the diagnosis of the carpal tunnel syndrome by measuring the cross-section area of the median nerve. A prospective study of 80 patients suspected of having carpal tunnel syndrome was underwent sonography at Al-Hussein Teaching Hospital in Samawa city from 1/1/2015 to 1/1/2016. The cross sectional area of the median nerve was measured at three levels, immediately proximal to carpal tunnel inlet, at carpal tunnel inlet and carpal tunnel outlet. The average value was measured. The flexor retinaculum was used as a landmark to margin of the carpal tunnel. Sensitivity and specificity of sonography were revealed as (89%) and (90%) respectively. All patients were sent for electro-diagnosis as standard reference test to compare with the values of sonography. The study proved that the sonography is sensitive but in compared with the electrodiagnosis has lower specificity. Demographic information including age, sex, side of the limb affected, and duration of the symptoms and grading of severity of the cases of the carpal tunnel syndrome were revealed. The study revealed associated disorders with the carpal tunnel syndrome such as diabetes mellitus (7 patients), pregnancy (5 patients), trauma (3 patients), hypothyroidism (1 patient), rheumatoid arthritis (1 patient), dorsal wrist ganglia (2 patients), and history of Colles fracture (2 patients), obese patient (12 patients), workers at manufacturing industries (3 patients) and two writers. The study proved that the sonography is easily performed, painless, rapid and available for the diagnosis of the carpal tunnel syndrome as adjuvant to electro-diagnosis but is not as substitute to it. Keywords: Ultrasound; Carpal tunnel syndrome; Median nerve *1 Department of Anatomy, College of Medicine, Muthanna University Received 11 September 2016, Accepted 09 December 2016, Available online 16 December This is article distributed under the terms of the Creative Commons Attribution License ( which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright 2016 AA. Introduction Carpal Tunnel Syndrome (tardy median palsy), is the result of compression and irritation of the median nerve as it passes under the transverse carpal ligament within 107

2 the carpal tunnel. Carpal tunnel syndrome may affect 1% to 10% of the population it occurs most often in patients 30 to 60 years old and is two to three times more common in women than in men; it forms about 9 % in women and about 6 % in men. Anatomy of carpal tunnel A cylindrical, inelastic cavity connecting the volar forearm with the palm, the carpal tunnel is bounded by the transverse arch of the carpal bones dorsally; the hook of the hamate, triquetrum, and pisiform medially; and the scaphoid, trapezium, and fibroosseous flexor carpi radialis sheath laterally. The ventral (palmar) aspect, or roof, of the carpal tunnel is formed by the flexor retinaculum, consisting of the deep forearm fascia proximally, the transverse carpal ligament over the wrist, and the aponeurosis between the thenar and hypothenar muscles distally. The most ventral (palmar) structure in the carpal tunnel is the median nerve. Lying dorsal (deep) to the median nerve in the carpal tunnel are the nine flexor tendons to the fingers and thumb, including the four tendons of the flexor digitorum superficialis, the four tendons of the flexor digitorum profundus, and the flexor pollicis longus tendon. Etiology Decrease in Size of Carpal Tunnel Bony abnormalities of the carpal bones, Acromegaly and Flexion or extension of wrist. Increase in Contents of Canal Forearm and wrist fractures (Colles fracture, scaphoid fracture), Dislocations and subluxations (scaphoid rotary subluxation, lunate volar dislocation), Posttraumatic arthritis (osteophytes), Musculotendinous variants, Aberrant muscles (lumbrical, palmaris longus, palmaris profundus), Local tumors (neuroma, lipoma, multiple myeloma, ganglion cysts), Persistent medial artery (thrombosed or patent), Hypertrophic synovium and Hematoma (hemophilia, anticoagulation therapy, trauma). Neuropathic Conditions Diabetes mellitus, Alcoholism, Doublecrush syndrome and Exposure to industrial solvents. Inflammatory Conditions Rheumatoid arthritis, Gout, Nonspecific tenosynovitis and Infection. Alterations of Fluid Balance Pregnancy, Menopause, Eclampsia, Thyroid disorders (especially hypothyroidism), Renal failure, Longterm hemodialysis, Raynaud disease, Obesity, Lupus erythematosus, Scleroderma, Amyloidosis and Paget disease. External Forces 108

3 Vibration and direct pressure repetitive use. Clinical evaluation 1) Paraesthesia over the sensory distribution of the median nerve is the most frequent symptom; it occurs more often in women and frequently causes the patient to awaken several hours after falling asleep with burning and numbness of the hand that is relieved by exercise. 2) Tingling, numbness, Numbness is typically appreciated in the thumb, index, and middle fingers but has been reported to be present in all fingers. relief with hand shaking, and the dropping of objects are common complaints. 3) Pain mostly at night. Provocative tests must recreate 1) Phalen s sign / reverse Phalen s sign. 2) Tinel s sign over the carpal tunnel. 3) Weakness of the abductor pollicis brevis. 4) Thenar atrophy may be present, usually late in the course. 5) Sensory loss to pinprick, light touch, two-point discrimination or Semmes Weinstein monofilament test in a median nerve distribution. Diagnosis 1) Electrodiagnostic tests analyze the electric waves of nerves and muscles. These tests can help detect median nerve compression in the carpal tunnel Electrodiagnostic tests are the best methods for confirming a diagnosis of CTS at this time.specific Electrodiagnostic tests, called nerve conduction studies and electromyography, are the most common ones performed 2) Sonography; High Frequency with Doppler Ultrasound provides high resolution, precise anatomical and physiological information of the median nerve in carpal tunnel, all the Sonographic criteria(presence of nerve edema, nerve swelling, nerve flattening, bowing of the flexor retinaculum, or intraneural hypervascularization) shows significant detectability of carpal tunnel syndrome.by Sonography it can measure the cross section area of the median nerve at three areas, the inlet. At the tunnel and at the outlet and then by measuring the average reading. 3) computerized tomography. 4) Magnetic Resonance Imaging (MRI). 109

4 Patients and Methods A prospective study of 80 patients suspected of having carpal tunnel syndrome were underwent examination with (5-13) MHz linear array transducer sonography at Al-Hussein Teaching Hospital at Samawa city at the period from 1/1/2015 to 1/1/2016 to evaluate the cross section area of the median nerve to confirm the diagnosis of carpal tunnel syndrome. This study focused on the cross section area of the median nerve which was measured at three levels, immediately proximal to the carpal tunnel inlet, at the inlet and the outlet, and the average value was measured. Flexor retinaculum use as landmark to the margin of the carpal tunnel figure 1 and figure 2. The value of cross sectional area ( 0.01 cm 2 ) was consider as a positive diagnosis for the carpal tunnel syndrome, while its value (< 0.01 cm 2 ) was consider as a negative diagnosis. Sensitivity and specificity of the sonography were calculated and compared with the results of the electro-diagnosis. All patients were referred for electro-diagnosis as a standard reference to compare with the sonography results. Demographic information regarding the age, sex, side of the affected limb, and duration of the symptoms were revealed. The associated disorder such as diabetes mellitus, rheumatoid arthritis, hypothyroidism, trauma, pregnancy and ganglia where revealed. The sensitivity and specificity of sonography were measured and statistically compared with the electrodiagnosis. Classification of the carpal tunnel syndrome depends on the cross section area of the median nerve into mild, moderate and severs. The false positive and false negative cases were proved. Results A prospective study of 80 patients suspected of having carpal tunnel syndrome were underwent examination with (5-13) MHz linear array transducer sonography at Al-Hussein Teaching Hospital in Samawa city from 1/1/2015 to 1/1/2016. The study focused on the cross section area of the median nerve which was measured at three levels, immediately proximal to the carpal tunnel inlet, at the inlet and the outlet, and the average value was measured. All patients were sent for electrodiagnosis as a standard reference. The study revealed associated disorders with the carpal tunnel syndrome such as diabetes mellitus (7 patients), pregnancy (5 patients), trauma (3 patients), hypothyroidism (1 patient), rheumatoid arthritis (1 patient), dorsal wrist ganglia (2 patients), and history of Colles fracture (2 patients), obese patient (12 patients), workers at manufacturing industries (3 patients) and two writers. 110

5 Table 1. Ali Taha Hassan Al-Azzawi /Muthanna Medical Journal 2016; 3(2): Frequency distribution of the side of affected wrist Side of affected wrist Bilateral Right Left Total Frequancy Percentage Table 2. Gender of patient's frequency distribution Gender male female Total Frequency Percent Table 3. Patient's age group's frequency distribution Age groups less than more than 60 Total Frequency Percent %

6 Table 4. Severity of the carpal tunnel syndrome according to cross section area Severity Cross section area (cm 2 ) No. of patients Percent % Mild Moderate Sever > Table 5. The incidence of duration of symptoms Duration No. of patients Percent % < 6 months months > 12 months Table 6. Validity and predictive rates regarding Ultra sound method for the diagnosis of carpal tunnel syndrome Sensitivity 89% Specificity 90% +ve predictive value 96% -ve predictive value 77% Table 7. Comparison between sensitivity and specificity of sonography and electro-diagnosis Sensitivity % Specificity % Sonography Electro-diagnosis

7 Figure 1. The perineurium become less apparent when the median nerve swells, probably as a result of the intrinsic compression synovial tissue that lines the tendons within Discussion Table (1) shows that the right side and bilateral sides of the extremities were the carpal tunnel, so the symptoms are exacerbated by forceful and repetitive use of the wrists. The repetitive mechanical dominant and this is because of repetitive stress inducing necrosis, edema, and use of the wrist. Normal pressure of the carpal tunnel has been defined as a range of (2 10) mm Hg, and wrist flexion increases the pressure (8-fold), while the extension increases it (10-fold). Repetitive fragmentation of collagen fibers. Table (2) shows increase the incidence of carpal tunnel syndrome in the females and this is due to: 1) Increase domestic activities of flexion and extension in the wrist the females in the house such as significantly increase the fluid pressure in the tunnel through thickening of the ringing of the clothes, sweeping, etc. 113

8 2) Hormonal effect: because luck of the estrogen, this lead to osteoporosis and this increase the liability for fracture especially Colles fracture which lead to compression on the median nerve. Some conditions which are dominant in the female such as rheumatoid arthritis and pregnancy in which there is hormonal changes (high progesterone levels) and water retention (which swells the synovium) and these increase the incidence of carpal tunnel syndrome during pregnancy. Table (3) shows increase the incidence of carpal tunnel syndrome at the age group from (30-49) years, and during this period of the life there is increase in the daily activities. Regarding Table (4) the median nerve swelling as detected by calculating the cross sectional area reflects the degree of nerve damage expressed by clinical picture. The cross sectional area of the median nerve has a diagnostic value for confirming or excluding carpal tunnel syndrome, and we can grade this disorder according to the cross sectional area into mild, moderate and sever. Regarding Table (5) the median nerve can usually move up to (9.6 mm) to allow the wrist to flex and to lesser extent during extension. Long term compression on the median nerve inhibits nerve gliding which may lead to injury and scarring. When scarring occurs, the nerve will adhere to the tissues around it and becomes locked into a fixed position, so that less movement is apparent, this will increase the severity of clinical symptoms of the median nerve. Chronic focal compression of the median nerve can lead to alteration in its morphology and cause demyelination by mechanical stress, deforming the myelin lamellae. Ischemia can account for the intermittent paraesthesia that can occur at night or with wrist flexion. And this explains why the patient with the carpal tunnel syndrome suffering from night wrist pain. Regarding Table (6) and Table (7) we used electrodiagnostic testing combined with clinical symptoms as the reference standard in our study. Electro-diagnostic studies have been widely used in the diagnosis of the carpal tunnel syndrome. These two tables show the sensitivity and specificity of the ultrasound, the ultrasound is sensitive but has lower specificity in compared with the Electro-diagnosis. From these results we proposed that ultrasound should be the first line investigation for the diagnosis of carpal tunnel syndrome unless there are clinical indications to use the Eletrodiagnosis. Measurements of the median nerve are probably best obtained within, rather than outside, the echogenic perineurium, for two reasons: First, the delineation between the hypoechoic nerve fascicles and the 114

9 hyperechoic perineurium is more clearly defined than is the delineation between the echogenic perineurium and the similarly echogenic perineural fat. Second, it is our impression that the nerve fascicles, rather than the perineurium, become swollen in CTS. The perineurium become less apparent when the median nerve swells, probably as a result of the intrinsic compression (Fig.3) Conclusion 1) The aim of this study was to prospectively evaluate the accuracy of Sonography for diagnosis of carpal tunnel syndrome in patients who were clinically suspected of having the disease in one or both hands. 2) High frequency ultrasound examination of the median nerve and measurement of its cross sectional area should be strongly considered as a new alternative diagnosis modality for the evaluation of carpal tunnel syndrome. In addition to being of high diagnostic accuracy it is able to define the cause of nerve compression and aids treatment planning, ultrasound also provides a reliable method for following the response to therapy. 3) Sonography is comparable to electro-diagnosis study in diagnosis of carpal tunnel syndrome and should be considered as initial test and used as an adjuvant method in the diagnosis of the disease but cannot substitute the electrodiagnosis. 4) Ultrasound will not replace electrodiagnosis in complicated or unclear cases. 5) Ultrasound is very useful in cases were clinical diagnosis of the carpal tunnel syndrome is confirmed and the physician want to know if there is any specific structural median nerve alteration including tumors or pseudotumor, besides diseases extrinsic to the nerve within the carpal tunnel when might increase the tissue pressure in the region. 6) In this study statistically significant linear correlation between cross sectional area and clinical scales. 7) We proved in this study that the ultrasound is sensitive but is compared to electro-diagnosis has lower specificity. 8) High frequency ultrasound is a safe, painless, rapid, inexpensive, available and easily performed test in the investigation of clinically suspected carpal tunnel syndrome. 115

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