Practice parameter for electrodiagnostic studies in carpal tunnel syndrome: Summary statement

Orthodromic SNAPs were recorded over the median nerve using needle electrodes at the wrist and elbow after stimulation of the thumb and middle fingers. CMAPs were recorded with concentric needle electrodes placed in the endplate zone of the APB after stimulation at the wrist and elbow. NCVs were determined for 28 male and 20 female normal subjects aged 16 to 62 years. There was no significant difference in NCV between male and female subjects. There was a decrease in NCV with increasing age. No CTS patients were studied. 186. Occupational Disease Surveillance. Carpal tunnel syndrome. MMWR Morb Mortal Wkly Rep 1989;38:485-489. Background Reference Source: Baker, 1990. 187. *Osborn JB, Newell KJ, Rudney JD, Stoltenberg JL. Carpal tunnel syndrome among Minnesota dental hygienists. J Dent Hyg 1990;64(2):79-85. Criteria Met (2/6: 1,2) Source: Medline Search. 188. Padua L, Lo Monaco M, Valente EM, Tonali PA. A useful electrophysiologic parameter for diagnosis of carpal tunnel syndrome. Muscle Nerve 1996;19:48-53. Criteria Met (6/6: 1,2,3,4,5,6). Source: Medline Search. Abstract: In 43 patients (50 hands) with clinical manifestations of mild-moderate CTS and 36 healthy volunteers (40 hands), orthodromic sensory nerve conduction velocity (SNCV) was measured with surface electrodes in the median nerve between the third digit and palm and between the palm and wrist. These figures were used to calculate the ratio of distal to proximal conduction (distoproximal ratio). All 90 hands were also subjected to other nerve conduction studies used for diagnosis of CTS. All control hands presented distoproximal ratios less than 1.0 reflecting higher conduction rates in the proximal segment. In contrast, 49 of 50 CTS hands (98%) presented reversed ratios (>1.0) indicating compromised proximal conduction. The sensitivity of this test was significantly greater than that of other methods evaluated, including comparative studies and segmental study of the palm-wrist portion of the median nerve. Segmental study of median SNCV with calculation of the distoproximal ratio is a sensitive technique for diagnosis of CTS in patients with normal findings in standard nerve conduction studies. Note: The author indicated by correspondence that the mean ± SD for the Control DML in Table 1 should read 3.2 ± 0.4 and not 3.2 ± 0.8 as published. 189. Padua L, LoMonaco M, Gregori B, Valente EM, Padua R, Tonali P. Neurophysiological classification and sensitivity in 500 carpal tunnel syndrome hands. Acta Neurol Scand 1997;96:211-217. Criteria Med (6/6: 1,2,3,4,5,6) Source: Medline Search. Abstract: Prospective study of 500 hands (379 patients) with clinical diagnosis of CTS symptoms. Normal values from the same laboratory previously published (Padua, 1996). In the 500 CTS patients, DML was prolonged (55%), median orthodromic sensory latency was prolonged (D2, 74%; D3, 67%). Of the remaining 117 patients with normal DML and median orthodromic sensory studies over 14 cm, the median sensory palmwrist NCV over 8 cm was abnormal in 21% and the distoproximo ratio of the median palm and digit segments was abnormal in 87%. 190. Palliyath SK, Holden L. Refractory studies in early detection of carpal tunnel syndrome. Electromyogr Clin Neurophysiol 1990;30:307-309. Criteria Met (5/6: 1,3,4,5,6) Source: Medline Search. Abstract: Using paired stimuli and varying the inter-stimulus interval, the absolute refractory period (ARP) and relative refractory period (RRP), were determined in 10 patients with mild electrophysiologic changes suggestive of CTS. They found that the sensory RRP was sensitive in diagnosing early CTS. 191. *Pavesi G, Olivieri MF, Misk A, Mancia D. Clinicalelectrophysiological correlations in the carpal tunnel syndrome. Ital J Neurol Sci 1986;7:93-96. Criteria Met (3/6: 2,3,5) Source: Medline Search. 192. Pease WS, Cannell CD, Johnson EW. Median to radial latency difference test in mild carpal tunnel syndrome. Muscle Nerve 1989;12:905-909. Criteria Met (4/6: 1,3,5,6) Source: Medline Search. Abstract: The following techniques were studied: (a) antidromic DSL median radial differences to the thumb, (b) antidromic DSL after stimulation at the wrist and recording from the third digit, (c) median mid-palmar DSL compared as a ratio of the wrist to middle finger DSL, (d) median ulnar DSL latency difference between the ulnar Practice Parameter: Carpal Tunnel Syndrome Muscle & Nerve Supplement X 2002 S971 SNAP recorded from the little finger after stimulation at the wrist and the median DSL after stimulation at the wrist and recording from the middle finger, and (e) median motor DML after recording from the APB after stimulation at the wrist. Three hundred thirty-three symptomatic hands in 262 patients were initially evaluated with subgroups of patients with CTS evaluated with different tests. The median radial DSL difference and median ulnar DSL difference were most likely to be abnormal followed by median DSL then the palmto-wrist DSL latency ratio and lastly the DML. 193. Pease WS, Cunningham ML, Walsh WE, Johnson EW. Determining neurapraxia in carpal tunnel syndrome. Am J Phys Med Rehabil 1988;67:117-119. Criteria Met (5/6: 1,3,4,5,6) Source: Medline Search. Abstract: With needle stimulation at the wrist and midpalm, CMAPs were recorded over the APB in 25 CTS patients and 23 healthy asymptomatic persons. They found a significant difference in the amplitude of the CMAP in the CTS group when compared to the control group. They propose that this is evidence for conduction block (neurapraxia) in CTS. 194. Pease WS, Lee HH, Johnson EW. Forearm median nerve conduction velocity in carpal tunnel syndrome. Electromyogr Clin Neurophysiol 1990;30:299-302. Criteria Met (4/6: 1,3,4,5) Source: Medline Search. Abstract: The NCV of the median nerve in the forearm was determined by 2 methods: (a) stimulation in the forearm and recording the nerve action potential at the wrist, and (b) stimulation at the wrist and elbow with recording over the APB, in 21 CTS patients and 16 control subjects. They found that the forearm NCV was slowed in the CTS group using either technique. The authors have proposed that this suggest that there is proximal nerve dysfunction as a result of median nerve compression in the carpal tunnel. 195. *Peterson GW, Will AD. Newer electrodiagnostic techniques in peripheral nerve injuries. Orthop Clin North Am 1988;19:13-25. Criteria Met (0/6) Source: Narkis, 1990. 196. *Phalen GS. The carpal tunnel syndrome: clinical evaluation of 598 hands. Clin Orthop 1972;83:29-40. Background Reference. Source: Katz 1990 (J Rheumatology). 197. *Phalen GS. The carpal tunnel syndrome: seventeen years’ experience in diagnosis and treatment of 654 hands. J Bone Joint Surg 1966;48:211-228. Criteria Met (1/6: 2) Source: Meyers, 1989. 198. Phalen GS, Gardner WJ, LaLonde AA. Neuropathy of the median nerve due to compression beneath the transverse carpal ligament. J Bone Joint Surg 1950;32-A:109-112. Background Reference. Source: Braun, 1989. 199. Plaja J. Comparative value of different electrodiagnostic methods in carpal tunnel syndrome. Scan J Rehabil Med 1971;3:101-108. Criteria Met (4/6: 1,3,5,6) Source: Joynt, 1989. Abstract: The following techniques were studied: (a) CMAP potentials were recorded after stimulation at the wrist and recording with coaxial needle electrodes, (b) orthodromic SNAPs with stimulation over the index finger and recording with surface electrodes at the wrist, (c) needle EMG using a coaxial needle, (d) strength/duration curves and chronaxy. Fifty-six cases of CTS and 20 normal subjects were evaluated. Sensory latencies were more likely to be abnormal than the other techniques measured. 200. Preston DC, Logigian EL. Lumbrical and interossei recording in carpal tunnel syndrome [see comments]. Muscle Nerve 1992; 15: 1253-1257. Criteria Met (5/6: 1,3,4,5,6) Source: Medline Search. Abstract: Median motor studies are commonly “normal” in mild carpal tunnel syndrome (CTS). This reflects either the sparing of motor compared to sensory fibers, or the inability of conventional studies to detect an abnormality. A novel approach to demonstrate early motor fiber involvement in CTS is the placement of the same active electrode lateral to the third metacarpal, allowing recording from the second lumbrical or the deeper interossei, when stimulating the median or ulnar nerves at the wrist, respectively. We compared the difference between these latencies in 51 normal control hands to 107 consecutive patient hands referred with symptoms and signs suggestive of CTS, who were subsequently proven to have electrophysiologic CTS by standard nerve conduction criteria. A prolonged lumbrical-interossei latency difference (>0.4 ms) was found to be a sensitive indicator of CTS in all patient groups. It was also helpful in patients with coexistent polyneuropathy, where localization of median nerve pathology at the wrist was otherwise difficult. 201. *Preston DC, Ross MH, Kothari MJ, Plotkin GM, Venkatesh S, Logigian EL. The median-ulnar latency difference studies are comparable in mild carpal tunnel syndrome. Muscle Nerve 1994; 17: 1469-1471. Criteria Met (2/6: 1,3). Source: Medline Search. Abstract: Compares sensitivity 159 patients of orthodromic palm-wrist mixed palmar median-ulnar peak latency difference with normal <0.4 ms, antidromic wrist-D4 sensory median-ulnar onset latency difference with normal <0.5 ms, and the second lumbrical/interossei motor with normal <0.5 ms. See discussion of benefits of techniques and diagrams of electrode placements and line drawings of electrode and stimulator placement. 202. Preswick G. The effect of stimulus intensity in motor latency in carpal tunnel syndrome. J Neurol Neurosurg Psychiatry 1963;26:398-401. Criteria Met (4/6: 1,3,5,6) Source: Loong, 1971. Abstract: With stimulation at the wrist and coaxial needle electrode recording from the APB, DMLs were recorded at super-maximal stimulation and threshold stimulation in 29 CTS hands f