Michael T. Andary

Practice parameter: Electrodiagnostic studies in carpal tunnel syndrome Report of the American Association of Electrodiagnostic Medicine, American Academy of Neurology, and the American Academy of Physical Medicine and Rehabilitation

Carpal tunnel syndrome (CTS) is a common clinical problem and frequently requires surgical therapy. The results of electrodiagnostic (EDX) studies have been found to be highly sensitive and specific for the diagnosis of CTS. This document defines the standards, guidelines, and options for EDX studies of CTS based on a critical review of the literature published in 19931 and recently updated by a review of the literature through the year 2000.2 The reader is referred to the updated review2 for a detailed discussion of the literature and the EDX techniques for the assessment of CTS that are summarized here. Both reviews addressed the following key clinical questions: 1. In patients clinically suspected of having CTS, what are the best EDX studies to confirm the diagnosis? 2. How can future clinical research studies be improved to evaluate the usefulness of laboratory studies, including EDX studies, to confirm the diagnosis of CTS? The source of the articles for the first CTS Literature Review1 published in 1993 was a Medline search for literature in English from January 1, 1986 through May 1991. The Medical Subject Headings searched were 1) wrist injuries or wrist joint, 2) nerve compression syndrome, and 3) carpal tunnel syndrome. The search identified 488 articles. Based on a review of the abstracts, 81 articles describing EDX studies were chosen for this review. An additional 78 reports were identified from the bibliographies of these 81 articles and American Academy of Electrodiagnostic Medicine (AAEM) consultants recommended six others. Of the total of 165 articles reviewed, 20 were classified as background references. The source of the articles for the second CTS Literature Review2 was a Medline search for literature in English through December 2000. The Medical Subject Headings (MeSH) searched were 1) carpal tunnel syndrome and diagnosis or 2) carpal …

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

Carpal tunnel syndrome: pathophysiology and clinical neurophysiology

Carpal tunnel syndrome (CTS) is a constellation of symptoms associated with compression of the median nerve at the wrist. The pathophysiology of CTS is not fully understood but mechanical aspects of injury within the carpal tunnel are most likely. The issues of ischemia, mechanical trauma, ectopic impulse generation, demyelination, tendonitis, elevated carpal tunnel pressure, mechanical factors, small and large fiber involvement and the variability of symptoms are presented. Documentation of neurophysiologic abnormalities in the median nerve is helpful to establish the diagnosis for CTS. There are several types of clinical neurophysiologic evaluations of the median nerve across the wrist. Sensory and motor nerve conduction studies (NCS) of the median nerve segment across the wrist compared to another nerve segment that does not go through the carpal tunnel (i.e. median, radial, or ulnar) are the most sensitive and accurate techniques. Other neurophysiologic techniques used to document CTS include vibrometry threshold testing, current perception testing, Semmes-Weinstein monofilament testing and two-point discrimination. These techniques have considerable subjective components and have not been found to be as sensitive as traditional NCS.

Electrodiagnostic evaluation of carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common nerve entrapment. Electrodiagnostic (EDX) studies are a valid and reliable means of confirming the diagnosis. This monograph addresses the various EDX techniques used to evaluate the median nerve at the wrist. It also demonstrates the limitations of EDX studies with a focus on the sensitivity and specificity of EDX testing for CTS. The need to use reference values for populations such as diabetics and active workers, where normative values differ from conventional cutoffs used to confirm suspected CTS, is presented. The value of needle electromyography (EMG) is examined. Muscle Nerve, 2011

Treatment of carpal tunnel syndrome.

&NA; In September 2008, the Board of Directors of the American Academy of Orthopaedic Surgeons approved a clinical practice guideline on the treatment of carpal tunnel syndrome. This guideline was subsequently endorsed by the American Association of Neurological Surgeons and the Congress of Neurological Surgeons. The guideline makes nine specific recommendations: A course of nonsurgical treatment is an option in patients diagnosed with carpal tunnel syndrome. Early surgery is an option with clinical evidence of median nerve denervation or when the patient so elects. Another nonsurgical treatment or surgery is suggested when the current treatment fails to resolve symptoms within 2 to 7 weeks. Sufficient evidence is not available to provide specific treatment recommendations for carpal tunnel syndrome associated with such conditions as diabetes mellitus and coexistent cervical radiculopathy. Local steroid injection or splinting is suggested before considering surgery. Oral steroids or ultrasound are options. Carpal tunnel release is recommended as treatment. Heat therapy is not among the options to be used. Surgical treatment of carpal tunnel syndrome by complete division of the flexor retinaculum is recommended. Routine use of skin nerve preservation and epineurotomy is not suggested when carpal tunnel release is performed. Prescribing preoperative antibiotics for carpal tunnel surgery is an option. It is suggested that the wrist not be immobilized postoperatively after routine carpal tunnel surgery. It is suggested that instruments such as the Boston Carpal Tunnel Questionnaire and the Disabilities of the Arm, Shoulder, and Hand questionnaire be used to assess patient responses to carpal tunnel syndrome treatment for research.

Identifying lumbosacral radiculopathies: An optimal electromyographic screen

ObjectiveThe objective of this study was to determine prospectively the optimal electromyographic screening examination of the lower limb that ensures identification of those lumbosacral radiculopathies that can be electrodiagnostically confirmed, yet minimizes the number of muscles studied. DesignA prospective multicenter study was conducted from May 1996 to September 1997. Patients with suspected lumbosacral radiculopathy referred to participating electrodiagnostic laboratories were recruited and examined by needle electromyography using a standard set of muscles. Patients with electrodiagnostically confirmed lumbosacral radiculopathies were selected for analysis. Various muscle screens were tested against this group of patients with radiculopathies to determine the frequency with which each screen identified the patient with radiculopathy. ResultsThere were 102 patients identified. When paraspinal muscles were one of the screening muscles, four-muscle screens identified 88–97% of the radiculopathies, five-muscle screens identified 94–98%, and six-muscle screens 98–100%. When paraspinal muscles were not part of the screen, identification rates were lower for all screens, and eight distal muscles were necessary to identify about 90% of the radiculopathies. ConclusionsSix-muscle screens with paraspinal muscles yielded consistently high identification rates. Studying additional muscles produced no improvements in identification.

Diagnosis of carpal tunnel syndrome.

AbstractThis clinical practice guideline was created to improve patient care by outlining the appropriate information-gathering and decisionmaking processes involved in managing the diagnosis of carpal tunnel syndrome. The methods used to develop this clinical practice guideline were designed to com

Neurogenic atrophy of suboccipital muscles after a cervical injury: a case study.

This case report describes abnormalities in bilateral rectus capitis posterior minor muscles in one individual with persistent head and neck pain. These findings are muscle atrophy, fatty infiltration on magnetic resonance imaging, and electromyographic abnormalities compatible with denervated muscle. The objective of the study contained herein was to determine if fatty infiltration on magnetic resonance imaging of the rectus capitis posterior minor muscle is the result of disuse or denervation. Electromyography and magnetic resonance imaging data were collected from normal and atrophied muscles. Electromyography and magnetic resonance imaging abnormalities compatible with denervation atrophy were detected. Although we cannot rule out aging or other unknown causes, we suspect that denervation is caused by nerve damage from trauma to the C1 dorsal ramus as a consequence of entrapment within the rectus capitis posterior major muscle.

Motor unit number estimation: A technology and literature review

Introduction: Numerous methods for motor unit number estimation (MUNE) have been developed. The objective of this article is to summarize and compare the major methods and the available data regarding their reproducibility, validity, application, refinement, and utility. Methods: Using specified search criteria, a systematic review of the literature was performed. Reproducibility, normative data, application to specific diseases and conditions, technical refinements, and practicality were compiled into a comprehensive database and analyzed. Results: The most commonly reported MUNE methods are the incremental, multiple‐point stimulation, spike‐triggered averaging, and statistical methods. All have established normative data sets and high reproducibility. MUNE provides quantitative assessments of motor neuron loss and has been applied successfully to the study of many clinical conditions, including amyotrophic lateral sclerosis and normal aging. Conclusions: MUNE is an important research technique in human subjects, providing important data regarding motor unit populations and motor unit loss over time. Muscle Nerve 50: 884–893, 2014

American Academy of Orthopaedic Surgeons Clinical Practice Guideline on The Treatment of Carpal Tunnel Syndrome

Summary of Recommendations The following is a summary of the recommendations in the AAOS’ clinical practice guideline, The Treatment of Carpal Tunnel Syndrome. This summary does not contain rationales that explain how and why these recommendations were developed nor does it contain the evidence supporting these recommendations. All readers of this summary are strongly urged to consult the full guideline and evidence report for this information. We are confident that those who read the full guideline and evidence report will also see that the recommendations were developed using systematic evidence-based processes designed to combat bias, enhance transparency, and promote reproducibility. This summary of recommendations is not intended to stand alone. The American Association of Neurological Surgeons and the Congress of Neurological Surgeons have endorsed this guideline.