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To establish the cutoff value of cross-sectional area (CSA) of the median nerve at the wrist, for determination of electrophysiologically moderate and severe carpal tunnel syndrome (CTS).
The prospective study was conducted among patients suspected of having CTS. A total of 106 patients (185 symptomatic wrists) received nerve conduction study (NCS) and ultrasonography. To establish a cutoff value, various diagnostic properties were calculated across a range of the CSA.
A mean±standard deviation of CSA of the median nerve of normal and mild, moderate and severe CTS was 9.4±2.1, 12.0±2.7, 13.8±4.7, and 15.4±4.1 mm2, respectively. The positive relationship between CTS severities and CSA was observed (rs=0.56). A 14 mm2 CSA had sufficient power to rule in moderate and severe CTS, with a specificity of 91.4% and sensitivity of 42.3%. In addition, it showed a post-test probability (positive predictive value) of 86.3% as against a pre-test probability of 56.2%.
Patients who had ≥14 mm2 of median nerve CSA had very high probability of moderate to severe CTS.
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To determine which ultrasonographic measurement can be used as an indicator reflecting the severity of carpal tunnel syndrome (CTS), by comparing electrodiagnostic results with ultrasonographic measurements in females. Many previous studies have tried to reveal that the ultrasonography (US) can possibility be used for diagnosis and severity of CTS. However, the criteria are different by gender. Thus far, there have been many efforts towards providing patients with a CTS diagnosis and severity prediction using US, but studies' results are still unclear due to lack of data on gender differences.
We collected data from 54 female patients. We classified the severity of CTS according to electrodiagnostic results. Ultrasonographic measurements included proximal and distal cross-sectional areas of the median nerve and carpal tunnel.
The severity by electrodiagnostic results statistically correlated to the proximal cross-sectional area (CSA) of the median nerve and carpal tunnel. However, there was no relationship between the proximal and distal nerve/tunnel indexes and the severity by electrodiagnostic results.
In female patients with CTS, the proximal CSAs of the median nerve and carpal tunnel increase. They correlate with the severity by electrodiagnostic findings. The CSA of the proximal median nerve could be particularly used as a predictor of the severity of CTS in female patients. However, the nerve/tunnel index is constant, irrespective of the severity of CTS.
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To investigate the relationship between electrodiagnosis and various ultrasonographic findings of carpal tunnel syndrome (CTS) and propose the ultrasonographic standard that has closest consistency with the electrodiagnosis.
Ultrasonography was performed on 50 female patients (65 cases) previously diagnosed with CTS and 20 normal female volunteers (40 cases). Ultrasonography parameters were as follows: cross-sectional area (CSA) and flattening ratio (FR) of the median nerve at the levels of hamate bone, pisiform bone, and lunate bone; anteroposterior diameter (AP diameter) of the median nerve in the carpal tunnel; wrist to forearm ratio (WFR) of median nerve area at the distal wrist crease and 12 cm proximal to distal wrist crease; and compression ratio (CR) of the median nerve. Independent t-test was performed to compare the ultrasonographic findings between patient and control groups. Significant ultrasonographic findings were compared with the electrodiagnosis results and a kappa coefficient was used to determine the correlation.
CSA and FR of median nerve at the hamate bone level, CSA of median nerve at pisiform bone level, AP diameter of median nerve within the carpal tunnel, CSA of median nerve at the distal wrist crease and WFR showed significant differences between patient and control groups. WFR showed highest concordance with electrodiagnosis (κ=0.71, p<0.001).
These findings suggested the applicability of ultrasonography, especially WFR, as a useful adjunctive tool for diagnosis of CTS.
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To identify the anatomic characteristics of the pronator quadratus (PQ) muscle and the entry zone (EZ) of the anterior interosseous nerve (AIN) to this muscle by means of cadaver dissection.
We examined the PQ muscle and AIN in 20 forearms from 10 fresh cadavers. After identifying the PQ muscle and the EZ of the AIN, we measured the distances from the midpoint (MidP) of the PQ muscle and EZ to the vertical line passing the tip of the ulnar styloid process (MidP_X and EZ_X, respectively) and to the medial border of the ulna (MidP_Y and EZ_Y, respectively). Forearm length (FL) and wrist width (WW) were also measured, and the ratios of MidP and EZ to FL and of MidP and EZ to WW were calculated.
The MidP was found to be 3.0 cm proximal to the ulnar styloid process or distal 13% of the FL and 2.0 cm lateral to the medial border of the ulna or ulnar 40% side of the WW, which was similar to the location of EZ. The results reveal a more distal site than was reported in previous studies.
We suggest that the proper site for needle insertion and motor point block of the PQ muscle is 3 cm proximal to the ulnar styloid process or distal 13% of the FL and 2 cm lateral to the medial border of the ulna or ulnar 40% side of the WW.
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To evaluate each digital branch of the median sensory nerve and motor nerves to abductor pollicis brevis (APB) and 2nd lumbrical (2L) according to the severity of carpal tunnel syndrome (CTS).
A prospective study was performed in 67 hands of 41 patients with CTS consisting of mild, 23; moderate, 27; and severe cases, 17. Compound muscle action potentials (CMAPs) were obtained from APB and 2L, and median sensory nerve action potentials (SNAPs) were recorded from the thumb to the 4th digit. Parameters analyzed were latency of the median CMAP, latency difference of 2L and first palmar interosseous (PI), as well as latency and baseline to peak amplitude of the median SNAPs.
The onset and peak latencies of the median SNAPs revealed significant differences only in the 2nd digit, according to the severity of CTS, and abnormal rates of the latencies were significantly lower in the 2nd digit to a mild degree. The amplitude of SNAP and sensory nerve conduction velocities were more preserved in the 2nd digit in mild CTS and more affected in the 4th digit in severe CTS. CMAPs were not evoked with APB recording in 4 patients with severe CTS, but obtained in all patients with 2L recording. 2L-PI showed statistical significance according to the severity of CTS.
The branch to the 4th digit was mostly involved and the branch to the 2nd digit and 2L were less affected in the progress of CTS. The second digit recorded SNAPs and 2L recorded CMAPs would be valuable in the evaluation of severe CTS.
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Method: Eighteen wheelchair ambulators with spinal cord injury who had neurological level below T2 were studied. Patients with peripheral or central neuropathies were excluded. Patients were assigned to either the electrodiagnostic CTS (group CTS, 7) or electrodiagnostically negative (group non- CTS, 11), and healthy volunteers (15) were classified as control group. The cross sectional area of the median nerve (MN-CSA) at carpal pisiform level was ultrasonographically measured. The degree of painful restriction to execute ADL by hands (TR-ADL), the pain grade (visual analog scale, VAS) of upper extremities and revised version of Korean spinal cord independence measure (KSCIM-R) for functional level were measured and analyzed. Results: Nine hands (14.3%) of 7 patients out of 34 hands had CTS in electrodiagnostic study. There were significant difference among groups in TR-ADL hours (CTS group; 5.0 vs non-CTS group; 10.2, p＜0.05), VAS (4.1 vs 2.0, respectively, p＜0.05), and no statistical difference in KSCIM-R (68.4 vs 52.1, p＞0.05), MN-CSA (12.3 mm2 vs 7.9 mm2 vs control group; 8.0 mm2, p＜0.05). Using the ROC curve, the cut-off value of MN-CSA produced 8.5 mm2 providing a diagnostic sensitivity of 77.8% and specificity of 59.6%. Conclusion: The ultrasonographic measurement of the median nerve may be a useful non-invasive screening test for the diagnosis of CTS in paraplegic patients with wrist pain. (J Korean Acad Rehab Med 2008; 32: 216-221)
Objective: To assess the median nerve compression with ultrasonography before and after the carpal tunnel release and to assess the correlation between electrophysiologic findings and ultrasonographic findings of the median nerve.
Method: We studied 50 hands of 29 patients diagnosed as carpal tunnel syndrome electrophysiologically and 20 hands of 19 asymptomatic controls. We evaluated the flattening ratio and compression ratio through the short axis and long axis of the median nerve by ultrasonography before carpal tunnel release, 2 weeks and 3 months after release. The correlation of the
improvement between the eletrophysiologic findings and compression ratio was analyzed.
Results: The compression ratio of the median nerve was decreased significantly after carpal tunnel release, compared with that before release. The decrease of the compression ratio correlated with the improvement of the electrophysiologic findings significantly.
Conclusion: The ultrasonography is useful to follow up the median nerve after carpal tunnel release. (J Korean Acad Rehab Med 2002; 26: 172-176)
Objective: Nerve conduction study of palmar cutaneous branch of median nerve is infrequently evaluated in spite of its importance because of perceived technical difficulties. This study reports the different nerve conduction responses of palmar cutaneous branch of median nerve by change of stimulation site.
Method: Conduction study of palmar cutaneous branch of median nerve was performed in 42 normal individuals stimulated at the site of 7 cm proximal to the recording electrode. Results were compared to those of stimulated at the site of 10 cm proximal to the recording electrode with t-test by SPSS 7.5.
Results: Values of conduction study stimulated at the site of 10 cm proximal to the recording electrode were 2.37⁑0.48 msec (mean⁑SD) for peak latency, 15.67⁑8.31μV for amplitude and 34.52⁑5.97 mA for supramaximal intensity.
Those values stimulated at 7 cm proximal were 1.72⁑0.33 msec for peak latency, 24.48⁑11.41μV for amplitude and 12.82⁑2.18 mA for supramaximal intensity. Amplitude stimulated at the site of 7 cm was significantly larger than that stimulated at the site of 10 cm (p＜0.01). Supramaximal intensity stimulated at the site of 7 cm was significantly smaller than that stimulated at 10 cm (p＜0.01).
Conclusion: The different stimulation site influences on the nerve conduction study of the palmar cutaneous branch of median nerve. Conduction study of palmar cutaneous branch of median nerve with stimulation at 7 cm proximal is a more reliable and convenient method compared to 10 cm proximal in respect of larger amplitude and smaller supramaximal intensity. (J Korean Acad Rehab Med 2002; 26: 46-49)
Objective: To acknowledge whether flexion or extension of wrist joint produces any changes in median nerve conduction of the diabetes with or without polyneuropathy.
Method: With thirty healthy adults selected as control, 33 diabetes with polyneuropathy (Group I) and 21 diabetes without polyneuropathy (Group II) were studied. Before the study, the wrist joint was positioned in flexion or extension for 5 minutes. The variables used for the statistic analysis were mean changes of latencies and amplitudes in the median motor and sensory responses in neutral, flexed, and extended position.
Results: After wrist flexion or extension, there was no significant difference in the mean change of latencies and trans-carpal conduction velocities between Group I and Group II in the median motor and sensory nerve conduction studies, and in the mean change of amplitudes between the two groups in the median motor nerve study. But, there was significant difference in the mean change of amplitude between Group I and Group II in the median sensory nerve study after wrist extension.
Conclusion: We conclude that the change of amplitude in median nerve conduction study in different wrist position may be helpful to detect carpal tunnel syndrome with diabetic polyneuropathy in its early stage.
Objective: To evaluate the usefulness of the diagnostic ultrasound (US) to diagnose carpal tunnel syndrome (CTS) and the correlation between electrodiagnosis and US findings.
Method: Forty hands of 30 patients diagnosed with CTS by electrodiagnosis and 28 hands of 19 controls were examined with US. The 7.5 MHz probe of the US was used to view the median nerve in the carpal tunnel. The short and the long axis and the area at the two points, 2 cm proximal and 1 cm distal to the distal wrist crease were measured. The flattening and compression ratio and the ratio of the area in both groups were analysed. The correlation between the eletrodiagnostic severity and compression ratio were analyzed.
Results: The compression ratio of CTS was significantly increased comparing with that of control group. The compression ratio of severe CTS was significantly increased comparing with that of mild and moderate CTS.
Conclusion: These results suggest that US is useful in diagnosis of CTS.
Objective: Intraoperative somatosensory evoked potentials (SEPs) are widely used for the early detections of cerebral ischemia during temporary occlusive procedures of the parent vessels in aneurysm surgery. This study intended to evaluate the usefulness of median nerve SEPs during intracranial aneurysm surgery.
Method: Between September 1995 and June 1997, we monitored 42 aneurysm patients in Uijongbu St. Mary's hospital. Median nerve SEPs were detected on scalp and cervical spine during surgery. We measured latencies, amplitudes of N20 and N13 waveforms and central conduction time (CCT, N20-N13). We analyzed pre- and post-surgical radiologic findings and changes of neurologic signs.
Results: The delayed latencies, CCT, and reduced amplitudes of median nerve SEPs during intraoperative monitoring were closely related to neurological deficits after surgery.
Conclusion: Intraoperative SEPs are useful in preventing clinical neurological injury during surgery of intracranial aneurysm and in predicting which patients will have unfavourable outcomes.
Objective: To determine whether flexion and extension of the wrist joint produce the change in the conduction study of the median nerve in the normal and diabetic patients, and to compare the susceptibility of median nerve compression injury in two groups.
Method: Thirty healthy adults as control and thirty diabetic patients without carpal tunnel syndrome were studied. The wrist joint was maintained in flexion or extension position for 5 minutes before performing conduction study. The variables used for statistical analysis included the mean difference of amplitude and latency in median motor and sensory responses in neutral, flexion, and extension positions.
Results: The results showed that significant differences in the latency and amplitude of median motor and sensory responses between neutral, extension, and flexion of wrist within each group (p＜0.01). The differences in the median sensory latency (p＜0.01), amplitude (p＜0.05) and the change of wrist-palm segmental conduction velocity (p＜0.01) were statistically significant between the diabetes and the normal control.
Conclusion: The results of this study suggest that median nerves are susceptible to compression pressure in diabetic patients. Therefore, the position of the wrist joint should be considered in the median nerve conduction study.
Objective: The purpose of this study was to find out diagnostic clue for the carpal tunnel syndrome. So we investigated the postional relationships between the structures, the degree of entrance of the muscle bellies in the carpal tunnel, the location of flexor retinaculum (FR) and the cross sectional area to the tunnel of the tendons, the median nerve and the soft tissues occupied with the wrist.
Method: Seventy-seven wrists of Korean adults's cadavers were dissected. Fifty-three wrists were examined by posteroanterior view of X-ray. The area of each structure was measured by image analyzer (Optimas Co. WA). The upper and lower borders the FR were confirmed at the sagittal plane after sagittal section.
Results: Frequency of the bellies of FDS, FDP and lumbricalis observed in each finger, the length of these bellies entering into the carpal tunnel were obtained. The cases that the third and fourth FDS were located side by side, the second FDS tendon under the third FDS tendon and the fifth tendon under the fourth FDS tendon were most common. The cases that the median nerve was bordered on the third FDS and the second FDS deep inside of the median nerve were most common. Mean length of the FR was 32.1 mm. The cases that the location of the upper margin of the FR was 10 mm and 15 mm from the end of radius were most common (44%). The cases that the margin of FR was 5 mm and 10 mm from the base of the 3rd metacarpal bone were most common (52%). The cross sectional area ratios to the carpal tunnel of the tendon, median nerve and connective tissues were 30%, 4%, 66% at the level of the pisiform bone, 36%, 4%, 60% at the level of the hook of hamate and 28%, 3%, 67% at the level of the lower margin of the FR, respectively.
Conclusion: These results could help to understand the etiology of the carpal tunnel syndrome and would be a helpful information to the diagnostic imaging of the carpal tunnel.
Objective: To establish the reference values of the sensory conduction for all the digits in the hand, conduction studies were performed using the standard technique.
Method: One hundred hands of fifty neurologically healthy adults with mean age of 45 years (range, 23∼69) were tested. Depending on ages, the 50 adults were devided into three groups: group 1, 20∼45 years old; group 2, 46∼60 years old; group 3, 61∼ years old. Antidromic sensory nerve conduction techniques using a fixed distance were performed. The onset latency and baseline to peak amplitude of the sensory nerve action potentials (SNAPs) were measured. During the test, the skin temperature of the hand was maintained at 34oC or above. These variables from SNAPs were compared according to age, gender, side, and recording digits.
Results: Comparison of the median and ulnar SNAPs between age groups revealed longer onset latency and smaller amplitude in the elderly group. The amplitude of SNAPs was larger in females than in males and the left side than the right side. Comparison of the latencies and amplitudes between the second and third digits showed no significant difference statistically. Also, the latencies and amplitudes of the median and ulnar nerves recorded from the fourth digits showed no significant difference statistically.
Conclusion: Based on these results, the reference values for sensory conductions from all the digits were obtained. These values would be helpful in evaluation of CTS or unspecified finger pain or upper extremity neuropathy.
Objective: To determine the prevalence, location, and risk factors for the peripheral nerve entrapments of upper extremity among the crutch or cane users.
Method: We performed the clinical and electrodiagnostic assessments of both upper extremities in 43 crutch or cane users and 49 able-bodied controls.
Results: The prevalence for the nerve entrapment of upper extremity among the crutch or cane users was 27.9% by the clinical criteria and 86.0% by the electrodiagnostic criteria. Electrodiagnostically, the median nerve entrapment was 76.7%, and the ulnar nerve entrapment was 72.1% among the crutch or cane users. The carpal tunnel was the most common site for the entrapment. Body weight, duration of disability, and duration of crutch or cane use were found to be significantly correlated with the emtrapments of median nerve, whereas duration of crutch or cane use alone was significantly correlated with the entrapments of ulnar nerve.
Conclusion: The peripheral nerve entrapments of upper extremity is associated with the chronic crutch or cane use and the preventive strategies need to be developed for the patients with risks.
For the diagnosis of carpal tunnel syndrome (CTS), a sensory conduction study of median nerve is the most sensitive parameter, by either antidromic or orthodromic recording. Many different sensory recordings have been developed to detect the mild or early cases of carpal tunnel syndrome. A comparison of the median and ulnar sensory responses using the 4th digit either orthodromically or antidromically has been one of the methods. However, a simultaneous comparison of both antidromic and orthodromic methods on the 4th digit has not been documented. For the comparison between the median and the ulnar sensory nerve conduction of the 4th digit recorded antidromically or orthodromically, conduction studies of the median and ulnar sensory nerves were performed using standard methods in normal populations as well as in patients with carpal tunnel syndrome. We studied 31 CTS patients (46 hands) with mean age of 54 years old (range, 25∼70). Also, 51 subjects (102 hands) with mean age of 48 years old were studied as control. The difference of antidromic latencies between the median and the ulnar nerves was less than or equal to 0.4 msec in the control subjects and greater than or equal to 0.5 msec in the patients with carpal tunnel syndrome. The difference of orthodromic latencies was less than or equal to 0.5 msec in the control subjects and greater than or equal to 0.5 msec in the patients with carpal tunnel syndrome. By the antidromic and orthodromic methods, the mean difference between latencies of the median or ulnar nerve was not statistically significant. However the amplitude of median or ulnar nerve was 2 times larger by the antidromic method than by the orthodromic. We concluded that the latency difference of 0.5 msec or greater between the median and ulnar nerve sensory conductions from the 4th digit would be valuable for the diagnosis of CTS. The antidromic methods with larger amplitude may be more technically convenient to determine CTS than the orthodromic methods.
The purpose of this study was to investigate the maturation characteristics of neonates.
Ninety three neonates underwent a somatosensory evoked potentials(SEPs) testing. Twenty four point seven percent of them were neonates at risks including the neonatal asphyxia, low birth weight under 1500 g, or a suspicious CNS abnormality.
Seventy five point three percent of neonates showed normal median SEPs, and 24.7% of them showed abnormal or a flat response. The mean latency of the first cortical component(N1) was 25.3⁑5.4 msec, duration 16.3⁑5.5 msec and amplitude 1.00⁑1.27 ㄍV.
Thirty one point two percent of neonates showed normal posterior tibial SEPs, and 68.8% showed abnormal or a flat response. The mean latency of the first cortical component(P1) was 44.9⁑5.6 msec, duration 17.5⁑3.9 msec and amplitude 0.47⁑0.38 ㄍV.
This result suggests that the maturation of rostal nervous system develops earlier than the caudal system.
Linear decrease of the cortical latency with post-menstrual age reflects maturation of the central pathway and not merely maturation of the peripheral nerves. But our study showed much less frequency of recordings of the tibial nerve SEPs than the median nerve responses, which suggested that the maturation of spinal cord and lower-limb nerves would be slow, in addition to that the length of pathway was increasing. This result suggests that the maturation of the proximal shorter nervous pathway develops earlier than the distal longer pathway.
Many factors have been identified which to affect the rate of propagation of impulses along motor fibers. These include temperature changes around the nerve, diameter of the axon, degree of myelinization, age of infants, and local environment of the nerve. Motor nerve conduction velocity and Hoffman's reflex latency have been used to assess the degree of myelination and maturation of the nervous system. The conduction velocities in infants of a short gestational age are significantly lower than those of the fullterm infants. The extrauterine myelination and maturation might increase nerve conduction velocity. We measure the median motor nerve conduction velocity, compound muscle action potentials amplitude and H-reflex latency of premature infants to determine the neurological maturation after birth. The premature infants with gestational age above 37 weeks have a significantly higher conduction velocity and a shorter H-reflex latency than those of gestational age below 37 weeks. The premature infants with weight over 2.5 kg have a significantly higher conduction velocity, larger compound muscle action potentials amplitude and a shorter H-reflex latency than those of weight below 2.5 kg. And there is a statistically significant negative correlation of the H-reflex latency with the postmenstrual age. The determination of motor nerve conduction velocities and H-reflex latencies seem to be an additional method in assessing the degree of maturity in infants after birth.
Pain, numbness, and weakness in the upper extremity are the common problems among wheelchair users. The prevalence of nerve injury of the upper extremity in the wheelchair users has been reported variously by many authors in other nations. To determine the prevalence, location, and risk factors of upper extremity peripheral nerve entrapment among wheelchair users, we performed clinical and electrodiagnostic assessments on both upper extremities of wheelchair users (n=49) and able-bodied controls (n=49).
The prevalence of nerve entrapment of the upper extremity among the wheelchair users was 15.6% according to clinical criteria, and 46.9% according to electrodiagnostic criteria. Electrodiagnostically, median nerve entrapment was identified in 28.6% of tested cases, and ulnar nerve entrapment was identified in 22.4% of tested cases among wheelchair users. The carpal tunnel was the most common site of nerve entrapment. The duration of wheelchair use was found to be correlated negatively with median wrist to palm and wrist to digit sensory conduction velocity, whereas age correlated positively with distal median and ulnar motor latency.
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