New criteria for sensory nerve conduction especially useful in diagnosing carpal tunnel syndrome

This article reports a technique for determining new standard values for median sensory nerve latencies, amplitudes, and durations. Use of these values should significantly improve the ability to diagnose carpal tunnel syndrome and to reduce the number of false negative results. Forty-five median sensory nerves of 30 neurologically healthy subjects were evaluated with rigid techniques and temperature control at stimulation and recording points. Latencies for antidromic and orthodromic conduction from wrist-to-thumb, wrist-to-index finger, wrist-to-middle finger, and wrist-to-ring finger (all 14 cm distances) are reported. Conduction time for nerve impulses through the transcarpal segment via ulnar and radial nerves was also measured for comparison with median nerve latencies. In addition to latency measurements, characteristics of electrical responses evoked by stimulation were described. These include amplitude of the recorded response measured from baseline to negative peak and from negative peak to positive peak, duration of the negative response wave (from baseline to return to baseline) and duration measured from onset of the negative wave to the positive peak. According to our data, a distal median nerve sensory latency of more than 3.3 ms (the mean of 2.9 ms plus two standard deviation values of 0.18 ms) when measured to the peak of the negative wave is indicative of abnormality.     

80例腕管综合征患者的神经电生理测定

目的：观察神经电生理检测对腕管综合征(CTS)的诊断敏感性。方法：80例临床提示为CTS或不能除外CTS的患者进行神经电生理测定并进行回顾性分析。结果：80例116侧正中神经复合肌肉动作电位末端运动潜伏期和波幅、肘至腕的运动传导速度、指至腕部的感觉传导速度及感觉神经动作电位波幅等5项指标检测异常率分别为75．0％、19．8％、9．5％、88．8％及37．9％；45例65侧拇指正中／桡浅神经潜伏期差(MRLD)及环指正中／尺神经潜伏期差(MULD)检测异常率95．4％。结论：正中神经拇指至腕段的感觉传导速度测定是诊断CTS的敏感指标，采用MRLD及MULD测定，诊断敏感性更高。     

Median and radial sensory latencies to digit I: normal values and usefulness in carpal tunnel syndrome

Median and radial sensory latencies were recorded from digit I at a distance of 10cm in 78 neurologically healthy people aged 20 to 79 years. The mean median latency was 2.5 +/- 0.3ms, and mean radial latency was 2.4 +/- 0.2ms. Both were measured to the negative peak. Twenty individuals with carpal tunnel syndrome determined by traditional electrodiagnostic techniques had at least 1ms longer latency in median nerve than the median latency for the healthy control group. This technique is useful in diagnosis of carpal tunnel syndrome.     

Ulnar nerve involvement in carpal tunnel syndrome

This is a retrospective study of the involvement of the ulnar nerve in patients with electrodiagnostic evidence of carpal tunnel syndrome as defined by median sensory nerve action potential (SNAP) greater than 3.6msec at the wrist and/or motor distal latency in excess of 4.3msec. The study included 248 patients, 63 (25%) with unilateral and 185 (75%) with bilateral carpal tunnel syndrome. The electrodiagnostic criteria for ulnar nerve involvement was a SNAP peak latency greater than 3.7msec and/or motor distal latency in excess of 4.2msec. One hundred fourteen patients (46%) had delayed ulnar SNAP peak at the wrist; of these, 100 cases had bilateral ulnar nerve involvement and 14 had unilateral abnormalities. Slowing of the motor nerve conduction velocity for the elbow-wrist segment was noted in 24% and 15% of the study group for the median and ulnar nerves, respectively. An incidental finding was the presence of "double crush syndrome" in 35 patients (14%). The results of this study suggest the frequent association of ulnar nerve involvement at the wrist for sensory fibers and carpal tunnel syndrome.     

Carpal tunnel syndrome in patients on long-term hemodialysis

Sixteen cases with carpal tunnel syndrome (CTS) were reported out of 412 patients on long-term hemodialysis due to chronic renal failure. Clinical symptoms included numbness in the area innervated by the median nerve in 100% of symptomatic hands and pain in the wrist and hand in 81%. This pain usually became severer at night and during hemodialysis. Muscle atrophy was noted in 41% of the hands. Nerve conduction studies revealed prolonged distal sensory latency, slowed sensory nerve conduction velocity across the wrist and normal distal motor latency in 18%, prolonged distal motor latency in 51% and no response in motor or sensory stimulation in 31%. Evidence of denervation on electromyography was seen in 36% of the hands. Patients were conservatively treated avoiding daily activities precipitating the condition with volar wrist splint only at night in 18% and in 90% with steroid hormone injection in the carpal tunnel. Median nerve release was performed in 18% of the hands. Amyloid deposit was demonstrated in 3 of 4 operated hands. Although the relation between long-term hemodialysis and the occurrence of the amyloid deposition in the carpal tunnel has not been established, the present data along with other recent reports strongly indicate that amyloid deposit in the carpal tunnel on hemodialysis patients could be one of the most possible cause of CTS.     

Sensory palmar stimulation in the diagnosis of carpal tunnel syndrome

The measurement of motor and sensory latencies of the median and ulnar nerves using conventional techniques in able-bodied subjects and patients with a history compatible with carpal tunnel syndrome (CTS) is described. The results obtained by conventional techniques are compared with measurement of median nerve sensory latency obtained by palmar stimulation and the difference of median-ulnar nerve distal sensory latencies. It is concluded that the use of measurement of median palmar sensory latency under the flexor retinaculum adds to the sensitivity of the nerve conduction studies in the diagnosis of CTS. It is suggested that, in patients with suspected CTS in whom conventional nerve conduction studies are normal, other techniques such as the measurement of palmar sensory latency, difference between median and ulnar nerve distal sensory latency and examination of all the digits should be carried out.     

Residual latency: new applications of an old technique

Median and ulnar nerve conduction velocity was studied using residual latency techniques in a control population and in a population with neuropathy. Midpalmar stimulation sites were used to determine the residual latency of the distal short segment. The residual latency index (RLI) was the short segment residual latency divided by the residual latency for the entire terminal nerve segment. While it was 0.61 in the control population, it increased to 0.69 in the patients with ulnar neuropathy distal to the wrist and decreased to 0.36 in patients with neuropathy of the median nerve at the carpal tunnel. In five cases of median neuropathy at the carpal tunnel, muscle biopsy specimens revealed evidence consistent with neuropathic processes. The RLI is an accurate and relevant method of evaluating the sensory and motor conduction of very small nerve segments.     

Slowed conduction velocity of the median sensory nerve across the carpal tunnel in normal adults

OBJECTIVE: To examine the difference of using onset or peak latency in the segmental conduction study of the median nerve in normal adults without carpal tunnel syndrome. DESIGN: We investigated 60 hands of 30 young healthy adults (15 men and 15 women; mean age, 27.1 yrs; range, 18-36 yrs). We performed the mid-palm segmental conduction study using antidromic and orthodromic techniques in the median sensory nerves of the second and third digits and the onset and peak latencies of the proximal (wrist-palm) and distal (palm-digit) segments were measured. The distoproximal latency ratios were compared between onset and peak latencies and were compared with the ratios of the superficial radial sensory nerve. RESULTS: Distoproximal peak latency ratios in the median and superficial radial sensory nerves were always >1.0 in both the antidromic and orthodromic conduction studies. However, distoproximal onset latency ratios in the median sensory nerve were >1.0 in only 35% and 21.7% of second digits and in only 25% and 11.7% of third digits in orthodromic and antidromic studies, respectively (P < 0.05). The results of distoproximal onset latency ratios in the superficial radial sensory nerve were 93.3% in the orthodromic study and 86.7% in the antidromic study (P < 0.05). CONCLUSION: Prolongation of onset latency across the carpal tunnel during segmental conduction study of the median sensory nerve was common in healthy adults. When comparing proximal and distal segments for diagnosis of carpal tunnel syndrome, using onset latency as a diagnostic variable may cause greater reporting of false positives.     

Effects of Neuromobilization Maneuver on Clinical and Electrophysiological Measures of Patients with Carpal Tunnel Syndrome

[Purpose] The aim of this study was to investigate the efficacy of neuromobilization combined with routine physiotherapy in patients with carpal tunnel syndrome through subjective, physical, and electrophysiological studies. [Subjects and Methods] Twenty patients with carpal tunnel syndrome (totally 32 hands) were assigned two groups: treatment and control groups. In both groups, patients received the routine physiotherapy. In addition to the routine physiotherapy, patients in the treatment group received neuromobilization. The symptoms severity scale, visual analogue scale, functional status scale, Phalen’s sign, median nerve tension test, and median nerve distal sensory and motor latency were assessed. [Results] There were significant improvements in the symptoms severity scale, visual analogue scale, median nerve tension test, and Phalen’s sign in both groups. However, the functional status scale and median nerve distal motor latency were significantly improved only in the treatment group. [Conclusion] Neuromobilization in combination with routine physiotherapy improves some clinical findings more effectively than routine physiotherapy. Therefore, this combination can be used as an alternative effective non-invasive treatment for patients with carpal tunnel syndrome.Key words: Carpal tunnel syndrome, Neuromobilization, Electrophysiological measures     

Sensory and mixed nerve action potential temporal dispersion in median neuropathy at the wrist.

This retrospective pilot study was undertaken to help determine the usefulness of measuring sensory nerve action potential and mixed nerve action potential temporal dispersion in median neuropathy at the wrist (MNW; i.e., carpal tunnel syndrome). The records were reviewed for 34 patients who were referred to an electrodiagnostic medicine laboratory with normal antidromic median sensory nerve action potential (recording from the index finger), median transcarpal mixed nerve action potential, and ulnar transcarpal mixed nerve action potential peak distal latencies (NO group) and 29 patients with prolongation (>2.2 ms) of the left median transcarpal mixed nerve action potential peak distal latency or relative prolongation of this response (>0.4 ms) compared with the ipsilateral normal ulnar transcarpal mixed nerve action potential peak distal latency (MNW group). By using the time difference between onset and negative peak as a measure of waveform temporal dispersion, mean +/- standard deviation of the median transcarpal mixed nerve action potential time difference for the MNW group (0.57 +/- 0.15 ms) was found to be greater than the NO group (0.44 +/- 0.09 ms; P < 0.01). No statistically significant differences were found for the median sensory nerve action potential time difference between the two groups or between the subgroup of MNW patients with concurrent prolongation of the median sensory nerve action potential peak distal latency and the NO group. These findings suggest that increased median transcarpal mixed nerve action potential temporal dispersion may occur in association with median transcarpal mixed nerve action potential peak distal latency prolongation in MNW. The small magnitude of this increase, however, makes the clinical usefulness of this observation unclear.     

Sensitivity of median sensory nerve conduction tests in digital branches for the diagnosis of carpal tunnel syndrome

OBJECTIVE: To compare the sensitivity of median sensory nerve conduction tests performed by stimulating digital branches in patients with carpal tunnel syndrome. DESIGN: A prospective study in 506 hands of patients with carpal tunnel syndrome diagnosed electrophysiologically. RESULTS: The sensitivity of median sensory nerve conduction tests across the first three digit-to-wrist segments and palm-to-wrist segment was determined. The most common abnormal electrophysiologic finding was the slowing of sensory nerve conduction velocity over the palm-to-wrist segment, which was detected in 98.5% of the hands. Slowing of sensory nerve conduction velocity over the digit 1-, 2-, and 3-to-wrist segments of the median nerve was found in 95.4%, 88%, and 82% of the hands, respectively. CONCLUSION: The sensory nerve conduction velocity test of the digit 1-to-wrist segment has the most sensitivity among the three digital branches of the median sensory nerve, and it may be used more widely in the electrodiagnosis of carpal tunnel syndrome.     

The pronator syndrome. An evaluation of dynamic maneuvers for improving electrodiagnostic sensitivity

The role of three test maneuvers (elbow flexion, forearm pronation and finger flexion against resistance) in improving sensitivity of conventional nerve conduction studies used in cases of suspected pronator teres syndrome were evaluated in 11 healthy control subjects and 10 patients with the clinical diagnosis of pronator teres syndrome. Stimulation of the median nerve was performed above and below the elbow before exercise and immediately after the test maneuvers; the resultant median motor and sensory responses were recorded. Before and after exercise, median motor and sensory responses (e.g., amplitude, latency, velocity) did not differ significantly between the two groups; only one patient with suspected pronator teres syndrome developed sensory amplitude changes after exercise. We concluded that these test maneuvers did not significantly improve the sensitivity of conventional nerve conduction studies in the diagnosis of pronator teres syndrome.     

Comparative diagnostic sensitivities of orthodromic or antidromic sensory inching test in mild carpal tunnel syndrome

OBJECTIVES: To compare the reliability, sensitivity, and specificity of the "inching test" (IT) or "centimetric test," performed orthodromically (OIT) and antidromically (AIT). METHODS: Incremental palmar study of the sensory fibers of the median nerve was evaluated over 10cm across the wrist in 20 patients with mild carpal tunnel syndrome (CTS) and in 20 controls. Mild CTS was defined as clinical features of CTS with normal electrophysiologic findings by standard methods. The CTS patients were preselected with abnormal orthodromic median-ulnar latency difference of the fourth digit (mean .66+/-.21ms; nl < .40ms). RESULTS: In controls, the mean conduction delay per centimeter (CD/cm) was .192ms for OIT and .191ms for AIT; the mean maximum conduction delay per centimeter (MCD/cm) was .250+/-.032ms for OIT and .344+/-.10ms for AIT. MCD/cm was located inside the carpal tunnel in 85% of patients (OIT) versus 80% for AIT. No MCD/cm was greater than .32ms (OIT) or .60ms (AIT). With corresponding pathologic thresholds of .36ms (mean + 3.4 standard deviation [SD]) for OIT and .64ms (mean + 2.6 SD) for AIT, IT was abnormal in 20 patients (100%) with OIT compared with only 4 patients (20%) with AIT. CONCLUSIONS: The orthodromic method was superior to the antidromic method in controls and in patients (chi2 = 23; p = 1.8 x 10(-6)). These findings suggest that orthodromic IT should be used when standard electrodiagnostic tests fail to reveal median nerve sensory abnormality in persons with mild CTS.     

Second lumbrical muscle recordings improve localization in severe carpal tunnel syndrome

OBJECTIVE: To determine how often the second lumbrical motor potential is present when the abductor pollicis brevis (APB) motor potential is absent in severe carpal tunnel syndrome (CTS). DESIGN: Prospective study of consecutive patients with severe CTS and an absent motor potential from the APB. SETTING: Single-center public hospital-based electromyography lab. PARTICIPANTS: Patients with a clinical diagnosis of CTS who had an absent median sensory response and an absent median motor response to APB on routine nerve conduction testing. Twenty-two hands of 19 patients were examined. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Presence and distal latency of motor potential to the second lumbrical. RESULTS: The second lumbrical potential was present in 17 hands (77%). The distal motor latency to the second lumbrical was prolonged in all (mean, 9.1ms; normative value, <4.1ms). CONCLUSIONS: Second lumbrical recordings improve localization in many patients with severe CTS when routine median sensory and motor conduction studies produce no potentials.     

感觉神经传导检查比较法在诊断轻度腕管综合征中的应用

目的寻找诊断轻度腕管综合征（CTS）敏感的神经电生理指标。方法回顾性分析经吉林大学第一医院手外科医生临床诊断,并经手术治疗疗效确实,但常规电生理检查提示拇短展肌复合肌肉动作电位的潜伏期（CAMP）及示、中指感觉神经传导检查正常的患者80人,共92例手的腕管综合征患者进行神经电生理分析,采用顺向法记录掌腕正中、尺神经混合神经电位潜伏期时差和环指腕正中、尺神经感觉神经电位潜伏期时差,以潜伏期时差差值≥0．4ms为阳性指标,计算其阳性符合率,并进行统计学分析。结果掌腕正中、尺神经混合神经电位潜伏期时差≥0．4ms为64例,阳性率为69．56％;环指腕正中、尺神经感觉神经电位潜伏期时差≥0．4ms为83例,阳性率为90．21％。其中两种方法均为阳性的62例,均为阴性的7例。结论环指腕正中、尺神经感觉神经电位潜伏期时差在诊断轻度腕管综合征时具有较高的诊断价值。     

Compound nerve action potentials from the median and ulnar nerves

The compound nerve action potentials from mixed motor/sensory (MNAP) and sensory (SNAP) nerve stimulation in the median and ulnar nerves were recorded in both arms of 20 able-bodied subjects. Intranerve and internerve peak-to-peak amplitudes were compared. An SNAP/MNAP amplitude ratio greater than 0.25 exceeded the mean by 2SD. The fastest, intermediate, and slowest conduction velocities were calculated from chosen points on the biphasic waveform. An intermediate MNAP conduction velocity for the median and ulnar nerves of less than 49.5m/sec exceeded more than 2SD below the mean. Likewise, an intermediate SNAP conduction velocity of less than 45.5m/sec exceeded 2SD below the mean. Median MNAP latency across the carpal tunnel was 1.0 +/- 0.3 and ulnar MNAP conduction velocity across the elbow was 59.7 +/- 3.8m/sec. This technique may supplement traditional electrodiagnostic studies in evaluating upper extremity neuropathies.     

Effect of Hand Warming on Electrodiagnostic Testing Results and Diagnosis in Patients With Suspected Carpal Tunnel Syndrome

Burnham RS, Burnham TR. Effect of hand warming on electrodiagnostic testing results and diagnosis in patients with suspected carpal tunnel syndrome.

Objectives

To evaluate the effects of hand warming on electrodiagnostic (EDX) parameters of carpal tunnel syndrome (CTS). Specifically, to evaluate the type and magnitude of change in EDX values; to determine whether warming can change the EDX diagnosis of CTS and, if so, to determine whether specific EDX tests are more vulnerable to the effects of warming.

Design

Interventional before-after trial.

Setting

Community EDX laboratory.

Participants

Consecutive patients (N=33) referred for EDX evaluation of suspected CTS.

Intervention

Each upper limb was tested at room temperature (average hand temperature, 31.9°C) and retested after 20 minutes of heating pad warming (average hand temperature, 33.5°C).

Main Outcome Measures

Median and ulnar nerve motor and sensory latency, conduction velocity, and amplitude.

Results

Warming resulted in significantly faster transcarpal tunnel sensory and motor conduction (6%–10%), reduced median: ulnar sensory latency to digit 4 difference (23%), and reduced sensory nerve and compound motor action potential amplitude (10% and 13%, respectively). The changes resulted in 15% fewer limbs meeting the EDX conduction velocity criteria of CTS and 9% fewer by median: ulnar sensory latency to digit 4 difference. Waveform amplitudes became abnormally low after warming in 12% of limbs.

Conclusions

Hand warming using a heating pad for 20 minutes increases median nerve transcarpal tunnel conduction velocity and reduces amplitude. These phenomena introduce potential sources of diagnostic error, particularly in borderline cases. Generally, within hand, between nerve, and within nerve comparison techniques are less susceptible to the conduction velocity effects of warming.     

腕管综合征46例临床与神经电生理分析

目的：探讨腕管综合征的临床特点和神经电生理检测的诊断价值。方法：回顾性分析46例腕管综合征的临床特征和神经电生理检测结果。结果：46例腕管综合征中76．1％为女性，共有病变71侧，单侧病变21例，双侧病变25例。以桡侧3个半手指为主29侧，5个手指均有症状42侧。临床表现为手指麻木、疼痛，可向肘部和肩部放射。电生理检查正中感觉神经传导速度异常占95．8％，正中运动神经潜伏期延长占67．6％，运动传导速度异常53．5％，拇展短肌呈神经源性损害占31％。结论：腕管综合征以中年女性多见，临床上以手指麻木、疼痛为主要特点，活动和甩手可使症状减轻。神经电生理检测对腕管综合征的诊断与鉴别诊断具有重要价值。     

"Tethered" median nerve stress test in chronic carpal tunnel syndrome

Tension of the median nerve produced by simultaneous extension of the supinated wrist and distal interphalangeal joint of the index finger was noted to result in proximal volar forearm pain radiation in patients with chronic carpal tunnel syndrome. This sign was less frequent in patients with a more acute syndrome. Adhesions between the median nerve and the overlying transverse carpal ligament and the development of a pseudoneuroma can individually or together occur in the chronic carpal tunnel syndrome limiting distal nerve excursion of the tethered nerve during simultaneous wrist and index finger extension.     

腕管综合征和肘管综合征的超声影像学研究

目的探讨超声在腕管综合征和肘管综合征中的诊断价值。方法80例健康者为对照组,临床疑诊27例腕管综合征和32例肘管综合征患者,超声测量其正中神经、尺神经的前后径、左右径及横截面积,同时测定神经传导速度。结果腕管综合征和肘管综合征组正中神经、尺神经的前后径、左右径及横截面积均大于对照组（P〈0．01）,腕管综合征和肘管综合征组的病变神经横截面积均与运动传导速度呈负相关（r分别为-0．76、-0．80）。结论超声可为腕管综合征和肘管综合征的诊断提供影像学依据,并对其治疗及疗效评价有重要价值。