Abstract
Objective
To study mild to moderate carpal tunnel syndrome (CTS), compare median nerve entrapment
sites detected by electrophysiological inching studies with ultrasonographic abnormalities
of cross-sectional area (CSA), and correlate focal points of conduction delays detected
by sensory and motor inching recorded from the third digit and second lumbrical muscle.
Design
Analytic cross-sectional study.
Setting
Department of Rehabilitation Medicine, King Chulalongkorn Memorial Hospital, Bangkok,
Thailand.
Participants
Hands from 10 participants without CTS (n=15) and hands with mild to moderate CTS
from 29 participants (n=40) were selected by convenience sampling (N=55).
Interventions
Not applicable.
Main Outcome Measures
Correlation of electrophysiological entrapment site localization by inching study
with anatomic entrapment site detected by ultrasound (US).
Results
In all 40 hands tested, a sharply localized latency was found to increase across a
1-cm segment, most commonly 2-3 cm distal to the distal wrist crease for both sensory
and motor studies, showing a good match between the 2 with Pearson correlation coefficient
value (r=0.72). US revealed a narrowing CSA of the median nerve at 1-2 cm distal to the distal
wrist crease.
Conclusions
This study showed a high correlation for focal point conduction delay detected by
sensory and motor nerve conduction study. Recording from the second lumbricalis facilitated
motor inching along the straight course of the nerve instead of the arcuate recurrent
branch innervating the abductor pollicis brevis, the muscle traditionally used. US
examination also revealed a localized narrowing of the median nerve CSA at 1-2 cm
distal to the distal wrist crease, a possible site for anatomic entrapment. The most
enlarged CSA was seen at the distal wrist crease, a level corresponding to the inlet
of the carpal tunnel.
Keywords
List of abbreviations:
AANEM (American Association of Neuromuscular and Electrodiagnostic Medicine), CMAP (compound muscle action potential), CSA (cross-sectional area), CTS (carpal tunnel syndrome), US (ultrasound)To read this article in full you will need to make a payment
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References
- Carpal tunnel syndrome: a review of literature.Cureus. 2020; 12: e7333
- Diagnosis of carpal tunnel syndrome.J Am Acad Orthop Surg. 2009; 17: 389-396
- Quality measures in electrodiagnosis: carpal tunnel syndrome: an AANEM quality measure set.Muscle Nerve. 2020; 61: 460-465
- Practice parameter for electrodiagnostic studies in carpal tunnel syndrome: summary statement.Muscle Nerve. 2002; 25: 918-922
- Evidence-based guideline: neuromuscular ultrasound for the diagnosis of carpal tunnel syndrome.Muscle Nerve. 2012; 46: 287-293
- Ultrasonographic median nerve cross-section areas measured by 8-point “inching test” for idiopathic carpal tunnel syndrome: a correlation of nerve conduction study severity and duration of clinical symptoms.BMC Med Imaging. 2011; 11: 22
- Comparison of inching electrodiagnosis method and ultrasonographic findings in the determination of median nerve entrapment site in carpal tunnel syndrome.Am J Phys Med Rehabil. 2017; 96: 869-873
- The carpal tunnel syndrome: localization of conduction abnormalities within the distal segment of the median nerve.Brain. 1979; 102: 619-635
- Electrodiagnosis in diseases of nerve and muscle: principles and practice.4th ed. Oxford University Press, Oxford, UK2013
- Diagnostic value of the second lumbrical-interosseous distal motor latency comparison test in severe carpal tunnel syndrome.Ann Rehabil Med. 2016; 40: 50-55
- Lumbrical-interosseous recording technique versus routine electrodiagnostic methods in the diagnosis of carpal tunnel syndrome.Turk J Phys Med Rehabil. 2017; 63: 230-238
- Electrodiagnostic evaluation of carpal tunnel syndrome.Muscle Nerve. 2011; 44: 597-607
- Accuracy of ultrasonography for the diagnosis of carpal tunnel syndrome: a systematic review and meta-analysis.Arch Phys Med Rehabil. 2018; 99 (e10): 758-765
- Examination of the wrist—surface anatomy of the carpal bones.Curr Orthop. 2005; 19: 171-179
- Anatomy of the flexor retinaculum.J Hand Surg. 1993; 18: 91-99
- Correlating median nerve cross-sectional area with nerve conduction studies.J Hand Surg Am. 2016; 41: 958-962
- Accuracy of high-resolution ultrasonography in establishing the diagnosis of carpal tunnel syndrome.ANZ J Surg. 2020; 90: 1057-1061
- The role of ultrasound in the diagnosis and management of carpal tunnel syndrome: a new paradigm.Rheumatology. 2015; 54: 9-19
- Morphometric studies of the muscular branch of the median nerve.J Anat. 1996; 189: 445-449
- Sub-clinical entrapment neuropathy in man.J Neurol Sci. 1975; 24: 283-298
- Review of ultrasonography in the diagnosis of carpal tunnel syndrome and a proposed scanning protocol.J Ultrasound Med. 2016; 35: 2311-2324
- The significance of ultrasonographic carpal tunnel outlet measurements in the diagnosis of carpal tunnel syndrome.Clin Neurophysiol. 2016; 127: 3516-3523
- Does measuring the median nerve at the carpal tunnel outlet improve ultrasound CTS diagnosis?.J Neurol Sci. 2014; 339: 47-51
- Diagnosis of carpal tunnel syndrome assessed using high-frequency ultrasonography: cross-section areas of 8-site median nerve.Clin Rheumatol. 2016; 35: 2557-2564
- Anatomical changes in peripheral nerves compressed by a pneumatic tourniquet.J Anat. 1972; 113: 433-455
- The location of conduction abnormalities in human entrapment neuropathies.Can J Neurol Sci. 1976; 3: 111-122
- Anomalous course of the recurrent motor branch of the median nerve in a patient with carpal tunnel syndrome.J Neurosurg. 1977; 47: 113-114
Article info
Publication history
Published online: August 11, 2021
Accepted:
August 4,
2021
Received in revised form:
July 30,
2021
Received:
June 12,
2021
Footnotes
This work was supported by the Ratchadapisek Sompoch Endowment Fund, Chulalongkorn University (grant no. RA62/093).
Clinical Trial Register No. (Thai Clinical Trials Registry): TCTR20190605001.
Disclosures: none.
Identification
Copyright
© 2021 The American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.
