1. ULTRASOUND EVALUATION FOR CARPAL TUNNEL SYNDROME
Yin-Ting Chen, MD1
Michael Fredericson, MD2
Eugene Y. Roh MD2
Andrew Gallo, DO
John Vasudevan, MD4
Sunghoon Lee, MD5
Michael Khadavi, MD6
1. Dept of Orthopaedic & Rehabilitation, Walter Reed National Military Medical Center, Bethesda, MD. 2. Department of Orthopedic Surgery, Stanford University Medical Center, Stanford, CA. 3. Department of Orthopedic & Rehabilitation, Ft. Belvoir Community Hospital, Ft. Bevoir, VA. 4. Department of Physical Medicine & Rehabilitation, University of Pennsylvania, Philadelphia, PA. 5. Department of Physical Medicine & Rehabilitation, Kwangju Christian General Hospital, Nam-Gu, Gwangju, Korea. 6. Carondelet Orthopaedic Surgeons and Sports Medicine, Leadwood, KS.

2. Objective Background Literature appraisal US vs EMG
Ultrasound protocol
Summary

3. Objective Background Literature appraisal US vs EMG
Ultrasound protocol
Summary

4. Disclosure
Michael Fredericson has no conflicting interests to disclose

5. Background CTS is the most common compressive neuropathy
Accounts for 90% of all compressive neuropathies
3.8% of all general population
9.2% in women and 6% in men
Electrodiagnostic examination (EDX) considered gold standard
Most common referral to EDX laboratory for evaluation
Ibrahim, I, W S Khan, N Goddard, and P Smitham. “Carpal Tunnel Syndrome: a Review of the Recent Literature.” The Open Orthopaedics Journal 6 (2012): 69–76. doi: /
Atroshi I, Gummesson C. “PRevalence of Carpal Tunnel Syndrome in a General Population.” JAMA 282, no. 2 (July 14, 1999): 153–158. doi: /jama

6. Advantages of US for CTS
Patient comfort
Non-invasive
Timely evaluation
Real time, office-based exam
Less time-consuming
Dynamic exam
Relatively inexpensive
High resolution anatomical evaluation (mass lesions, bifid median nerve, tenosynovitis, lipoma, ganglion cyst, lumbrical incursion… etc)

7. Disadvantages of US for CTS
Learning curve
Operator dependent
Not yet universally recognized
…..To be overcome with training, training, training

8. CTS Sonographic Characteristics
Increased cross sectional area (CSA) within the carpal tunnel due to swelling
Flexor retinaculum bowing
Increased flattening ratio of the median nerve
Median nerve notching
Hypervascularity of the median nerve
Increased Delta CSA (compared to forearm segments)

9. CSA

12. Palmar Displacement

13. Bowing Ratio

14. Flattening Ratio

15. Median Nerve Notching
Median nerve notching

16. Doppler Signal

17. Conclusion
CSA is mostly studied and validated measurement for CTS

18. Objective Background Literature appraisal US vs EMG
Ultrasound protocol
Summary

19. Disclosure
Yin-Ting Chen has no relevant financial disclosures.

20. Buchberger, 1992 Duncan, 1999 Keberle, 2000 Sarria, 2000 Swen, 2001
Author, Year
Reference Methods
US measurement
Sensitivity (%)
Specificity (%)
Accuracy (%)
CSA (mm2)
Comment
Buchberger, 1992
Clinical symptoms + NCS abnormalities (undefined), MRI
DRUJ, pisiform, hamate; flattening ratio, swelling ratio, retinaculum bowing
14.5 (pisiform), 10.5 (hamate)
Duncan, 1999
Median/ulnar SNC, MNC (not specified)
Inlet 82 97 NA 9
Keberle, 2000
Median SNC, MNC (< 5 mV CMAP, DML < 4.6 msec, SNAP digit II > 0.01 mV, SNAP CV < 42 m/s)
Wrist, inlet, outlet, flattening ratio
100
Swelling ratio 1.3
Sarria, 2000
Clinical + median SNC, MNC (SNAP CV < 50 m/s or a DML > 4.2 ms.)
Wrist, inlet, outlet, flattening ratio, bowing
81.3 (bowing) 73.4 (wrist) 73.4 (inlet) 75 (outlet) 53.1 (all signs) 95.3 (one of signs)
64.3 (bowing) 57.1 (wrist) 57.1 (inlet) 57.1 (outlet) 78.5 (all signs) 40.4 (one of signs)
11 (all levels) 2.5 (bowing)
Swen, 2001
(1) The median nerve DSL > 3.6 msec. (2) Ring-diff > 0.4 msec, (3) DML-1 over the thenar > 4.3 msec. (4) The median MNC CV < 49 m/s. (5) The median sensory CV < 49 m/s. (6) The ulnar motor and sensory nerve CV Measurements 4, 5, and 6 were performed for the forearm. 70 63 68 10
US PPV 85, NPV 42 NCS sensitivity 98, specificity 19, PPV 78, NPV 75, accuracy Less sensitive than NCS but more specific.
Nakamichi, 2002
Median ulnar SNC, MNC
Forearm NAP (not specified)
Wrist, inlet, outlet, distal 1/3 forearm
67.0
96.4
93.9
12 (mean area without forearm)
NCS coefficient of variation < 5%, US < 10% Mean CSA at wrist, inlet, and outlet provides improved sensitivity without reducing specificity

21. Leonard, 2003 Altinok, 2004 Kotevoglu, 2004 El Miedany, 2004
Author, Year
Reference Methods
US measurement
Sensitivity (%)
Specificity (%)
Accuracy (%)
CSA (mm2)
Comment
Leonard, 2003
Clinical (characteristic history of paresthesia in the median nerve distribution with a positive Phalen’s test and no other co-existent neurological disease)
Inlet, outlet, flattening ratio 72 90 NA
Altinok, 2004
Median SNC, MNC
Median-ulnar midpalm-wrist DL dif > 0.4ms
Wrist, inlet, outlet
65.0
92.5
78.9
9 (inlet)
Swelling ratio > 1.3
Kotevoglu, 2004
Median SNC, MNC (not specified)
Wrist, inlet, out, flattening ratio, flex ret bowing 89
100
Abnormal US finding is correlated with clinical exam (Phalen, Tinnel)
El Miedany, 2004
(1) Median nerve distal sensory latency, upper limit of normal 3.6ms. (2) Difference between the median and ulnar nerve distal sensory latencies, upper limit of normal 0.4 ms. (3) Distal motor latency over the thenar, upper limit of normal 4.3 ms. (4) Median motor nerve conduction velocity, lower limit of normal 49m/s.
Inlet, outlet
97.9 10
Algorithm for CTS evaluation suggested
CTS severity by US: Mild: CSA Mod: CSA Severe: > 15
Wong, 2004
Median/ulnar SNC, MNC (8-cm transcarpal orthodromic median and ulnar SNAP peak latencies, median forearm CV, 8-cm median CMAP, and distal motor latencies)
Wrist, inlet, tunnel, outlet 94
Combine: 86 74
Wrist 8.8, inlet 9.8, outlet 85
Inter-rater reliability coefficient 0.87.
Keles, 2005
1. Median SNAP CV of digits I, II, and III of palm-to-wrist segments
2. Median nerve DML prolonged. 3. Ulnar SNC, MNC
Tunnel CSA, flex ret bowing, flattening of median nerve
80 (CSA) 71.4 (Flex ret bowing)
77.5 (CSA) 55 (Flex ret bowing)
9.3 (Tunnel CSA), 8.5 (inlet), 9.5 (oulet)
Lee, 2005
CSA inlet best correlates with EDX finding and questionnaires

22. Ziswiler, 2005 Wiesler, 2006 Hammer, 2006 Mallouhi, 2006 Bayrak, 2007
Author, Year
Reference Methods
US measurement
Sensitivity (%)
Specificity (%)
Accuracy (%)
CSA (mm2)
Comment
Ziswiler, 2005
Median/ulnar SNC, MNC (SNAP CV > 41–53 m/s, DML > 3.9–4.1 msec, and CMAP > 5 mV)
Wrist, inlet
86 (9 mm2),
82 (10mm2),
54 (11 mm2)
70 (9 mm2),
87 (10 mm2),
96 (11 mm2)
83.4
10 tunnel
CSA < 8mm to rule out CTS, > 12mm to rule in CTS
Wiesler, 2006
Median SNC, MNC (DSL > 3.5 ms, or DML latency > 4.5 ms)
Inlet, tunnel, outlet 91 84
11 at inlet
Hammer, 2006
Clincial + median NCS (palm-to-wrist median SNAP onset latency >2.0 msec at 7 cm, or absence of SNAP, and median DML >4.9 msec)
Inlet
The CSA was significantly higher in arthritic patients with CTS than in healthy controls and in RA patients without symptoms of CTS.
Healthy controls and RA patients without symptoms of CTS had no significant differences in their CSA CSA by continuous tracing better than ellipsoid calculation
Mallouhi, 2006
Clinical + NCS (median DSL> 6.2 msec and DML > 3.9 msec)
Wrist, inlet, outlet, Flex ret bowing, color Doppler
91 (CSA) 95 (color Doppler)
47 (CSA) 71 (color Doppler)
91(CSA) 91 (color Doppler) 11
Hypervascularization detected by color Doppler useful for CTS evaluation
Bayrak, 2007
Median/ulnar SNC, MNC (median–ulnar sensory latency difference >0.5 ms and a median–ulnar DML difference >1.2 ms); MUNE APB
Wrist, inlet, outlet
CSA tunnel correlate with MUNE and severity of CTS
Visser, 2008
Median DSL digit IV > 3.2 msec, Median ulnar ring-diff > 0.4 msec, median DML > 3.8 msec,
Distal 2/3 forearm, inlet 78
10 (inlet)
US CSA of 10 at inlet has equivalent sensitivity and specificity of ring-diff
Kaymak, 2008
Median SNC, MNC (cut off unspecified)
88 (Wrist) 68 (inlet)
66 (wrist) 62 (inlet)
11.2 (wrist), 11.9 (inlet)
Median DSL most predictative of severity; DML most predictative of functional status
Klauser, 2008
Clinical + NCS (not specified)
Wrist, inlet, tunnel, outlet, proximal third of PQ 99
100
Delta 2 mm
Delta CSA useful in both mild and severe CTS
Hoboson-Webb, 2008
NCS (Motor DML ≥ 4.4 at 6.5cm, mixed latency ≥ 2.2, or > 0.3 ms compared to ulnar)
Wrist-forearm ratio ≥ 1.4
10 inlet
Mhoon, 2012
99 (CSA 9)
97 (WFR 1.4)

23. Areas of Measurement Data
Author
Areas of Measurement
Data
Distal PQ
DRUJ
Radiocarpal Joint
Prox Flex Retin.
Wrist Crease
Pisiform
Scaphoid-Pisiform (Navicular)
Scaph. tubercle
Inlet (Non-specific)
Tunnel (Non-specific)
Hook of Hamate
Trapezium-hook of Hamate
Distal Edge Flex Retin.
Outlet (Non-specific)
CSA (mm^2)
Sens, spec.
Duncan, 1999 X 9
82, 97
Lee, 1999 15
88, 96
Keberle, 2000
Swelling Ratio 1.3
100, 100
Sarria, 2000 11
73, 57
Swen, 2001 10
70, 63
Nakamichi, 2002 14
43, 96
Leonard, 2003
None, mean 11.6
72, 90
Altinok, 2004
65, 93
Kotevoglu, 2004
None, mean 15.3
89, 100
El Miedany, 2004
98, 100
Wong, 2004
prox 9 & outlet 12
94, 65
Yesildag, 2004
10.5
90, 95
Bachmann, 2005
Largest CSA, None
None
Kovuncuoglu, 2005
Keles, 2005
9.3
80, 78
Lee, 2005
Ziswiler, 2005
82, 87
Wiesler, 2006
91, 84
Hammer, 2006
None, Mean 15.7
Mallouhi, 2006
Largest CSA 11
91, 47
Bayrak, 2007
None, Mean 13.5
Visser, 2008
78, 91
Kaymak, 2008
11.9
88, 66
Klauser, 2008 12
94, 95
Mondelli, 2008
12.3
57, None
Pinilla, 2008
6.5
90, 93
Kwon, 2008
10.7
66, 63
Sernik, 2008
85, 92
Moran, 2009
62, 95
Mohammadi, 2010
8.5
97, 98
Deniz, 2011
84, 79
Klauser, 2011
93, 39
Roll, 2011
10.3
80, 91
Hunderfund, 2011
84, 84
Mohammadi, 2012
None, Mean 11.1
Ulasli, 2012
9.5
95, 71

24. Literature Appraisal Diagnostic value uncertain EMG US
CSA 6.5 mm2 to 13 mm2
Sensitivity 62% - 98%
Specificity 63% - 100%
Accuracy 68% %
EMG
Various EDX protocols used, differ across studies
Standard EDX protocol 80-90% accuracy, up to 20% false-positive rate
Combined sensory index (CSI) not used in any studies US
Various protocols (measurement method, location, study design, tracing algorithm... etc)
Technique and technician dependent

25. Literature Review
”…it is not evident how it compares to electrodiagnostic studies” (Beekman 2003)
“Determining the diagnostic utility of sonography has been confounded by a lack of standardization among research methodologies/designs and variability in evaluation and measurement protocols.” (Roll, 2011)
Beekman, Roy, and Leo H Visser. “Sonography in the Diagnosis of Carpal Tunnel Syndrome: a Critical Review of the Literature.” Muscle & Nerve 27, no. 1 (January 2003): 26–33. doi: /mus
Roll, Shawn C, Kevin D Evans, Xiaobai Li, Miriam Freimer, and Carolyn M Sommerich. “Screening for Carpal Tunnel Syndrome Using Sonography.” Journal of Ultrasound in Medicine: Official Journal of the American Institute of Ultrasound in Medicine 30, no. 12 (December 2011): 1657–1667.

26. Systematic Review Fowler et al 2011
Reviewed 323 papers; 19 entered analysis
Heterogenous set of reference standards
Pooled US sensitivity/specificity using different reference standards
Clinical 77.3 (62.1–84.6) 92.8 (81.3–100)
EDX 80.2 (71.3–89.0) 78.7 (66.4–91.1)
Composite 77.6 (71.6–83.6) 86.8 (78.9–94.8)
Compares favorably against EDX (69, 97%)
Limitation:
Variable reference methodologies
No clear cut-off value for CSA
Consider as first-line screening tool when there is high pre-test probability
Fowler, John R, John P Gaughan, and Asif M Ilyas. “The Sensitivity and Specificity of Ultrasound for the Diagnosis of Carpal Tunnel Syndrome: a Meta-analysis.” Clinical Orthopaedics and Related Research 469, no. 4 (April 2011): 1089–1094. doi: /s

27. AANEM Evidence-Based Guideline, 2012 (Carwright et al 2012)
121 manuscripts reviewed
Class I: 4 (prospective cohort, blinded, appropriate reference, include measures of diagnostic accuracy)
Class II: 6 (retrospective, blinded, free of spectrum bias, include measures of diagnostic accuracy)
Class II with added value: (draw from a statistical and non-referral clinic-based sample of patients, evaluate all CTS patients prior to surgery, and conduct neuromuscular ultrasound on all study participants)
Cartwright, Michael S, Lisa D Hobson-Webb, Andrea J Boon, Katharine E Alter, Christopher H Hunt, Victor H Flores, Robert A Werner, et al. “Evidence-based Guideline: Neuromuscular Ultrasound for the Diagnosis of Carpal Tunnel Syndrome.” Muscle & Nerve 46, no. 2 (August 2012): 287–293. doi: /mus

28. AANEM Guideline, cont Class I finding: 8.5 to 10 mm2
Sensitivity 65% - 97%, specificity 72.7% - 98%, accuracy 79% - 97%
Class II finding:
Sensitivity %, specificity %, accuracy % at CSA 12 mm2
Delta CSA 4 mm2 shows sensitivity 92%, specificity 96%, accuracy 94%

29. Delta CSA, WFR, Swelling Ratio
Comparison of forearm (PQ or proximal) to tunnel, inlet
Indicative of swelling
Delta CSA 2 mm2 (99% sensitivity, 100% specificity) (Klauser 2008)
Delta CSA 4 mm2 for bifid median nerve (92.5% sensitivity, 94.6% specificity) (Klauser 2011)
WFR 1.4 (sensitivity 97-99%) (Hobson-Webb 2008, Mhoon 2012)
Klauser, Andrea S, Ethan J Halpern, Ralph Faschingbauer, Florian Guerra, Carlo Martinoli, Markus F Gabl, Rohit Arora, et al. “Bifid Median Nerve in Carpal Tunnel Syndrome: Assessment with US Cross-sectional Area Measurement.” Radiology 259, no. 3 (June 2011): 808–815. doi: /radiol
Mhoon, Justin T, Vern C Juel, and Lisa D Hobson-Webb. “Median Nerve Ultrasound as a Screening Tool in Carpal Tunnel Syndrome: Correlation of Cross-sectional Area Measures with Electrodiagnostic Abnormality.” Muscle & Nerve 46, no. 6 (December 2012): 871–878. doi: /mus

30. AANEM Guideline, cont. Class II with added value:
Significant anatomical abnormalities noted
25% occult ganglion cyst (Nakamichi 1993)
2 - 25% bifid median nerve (Iannicelli 2000)
6 - 9% persistent median nerve (Bayrak 2008, Padua 2011)
9% tenosynovitis (Padua 2011)
3% accessory muscles (Padua 2011)

31. Literature Review Conclusion
Pisiform is the most commonly measured location
No studies definitively demonstrates correlation to severity
CSA greater than 14 mm2 rules-in CTS
CSA less than 8 mm2 rules-out CTS
Delta CSA
Non-bifid median nerve: 2 mm2
Bifid median nerve: 4 mm2
WFR ratio > 1.4

32. Literature Review Conclusion, Cont.
US should be considered as first line screening tool in patients with high pre-test probability; EDX may not be needed
US should be considered in atypical CTS (unilateral, sudden onset, in setting of trauma) due to high prevalence of structural abnormalities

33. Objective Background Literature appraisal US vs EMG
Ultrasound protocol
Summary

34. Disclosure John Vasudevan, MD has no relevant financial disclosures.
Andrew Gallo, DO has no relevant financial disclosures

35. Comparing US and EMG
EMG and clinical examination both considered as competing “gold standards” for CTS diagnosis
EMG, however, offers objective data
Severity
Prognosis
Rule out co-existing conditions
EMG mostly used as validating standard in US CTS studies
El Miedany YM, Aty SA, Ashour S (2004) Ultrasonography versus nerve conduction study in patients with carpal tunnel syndrome: substantive or complementary tests? Rheumatology (Oxford) 43(7):887–895 .

36. Literature Overview Literature correlating severity El Mietany 2004
Pauda 2008
Karadag 2009
Literature not correlating severity
Kaymak 2008
Mondelli 2009
Mhoon 2012
Visser 2008
El Miedany YM, Aty SA, Ashour S (2004) Ultrasonography versus nerve conduction study in patients with carpal tunnel syndrome: substantive or complementary tests? Rheumatology (Oxford) 43(7):887–895 .

37. El Miedany et al, 2004
Cross-sectional, age-group-matched case–control study
n=78, control n=78
Boston Carpal Tunnel Questionnaire (BCTQ)
EMG severity scale
US: flattening ratio, CSA (inlet, mid-tunnel)
Result
Diagnostic CSA mm2, flattening ratio 0.3
Mild: mm2
Moderate: mm2
Severe: > 15 mm2
Highly positive correlation between EMG and CSA, as well as both symptom and functional severity scales
“…In addition to being of high diagnostic accuracy it is able to define the cause of nerve compression and aids treatment planning; US also provides a reliable method for following the response to therapy.”
El Miedany YM, Aty SA, Ashour S (2004) Ultrasonography versus nerve conduction study in patients with carpal tunnel syndrome: substantive or complementary tests? Rheumatology (Oxford) 43(7):887–895 .

38. Pauda et al, 2008
Prospective study examining correlation between CSA, clinical, neurophysiological, patient-oriented measures (BCTQ), EMG findings, and clinical findings (n=54)
CSA at inlet (10 mm2)
EMG
Clinical exam
Conclusion
Statistically significant linear correlation between CSA and clinical scales
“…when neurophysiological tests are negative – US may be useful because it may show abnormal findings that are not revealed even using sophisticated neurophysiological tests.”
Padua L, Pazzaglia C, Caliandro P, Granata G, Foschini M, Briani C, Martinoli C. Carpal tunnel syndrome: ultrasound, neurophysiology, clinical and patient-oriented assessment. Clin Neurophysiol Sep;119(9): doi: /j.clinph Epub 2008 Jul 11.

39. r: 0.51, p: <
r: 0.51, p: <
r: 0.35, p: = 0.01

40. r: 0.80, p: <
p: 0.017

41. Karadag et al, 2009
Prospective study examining correlation between CSA, patient symptoms and functions (BCTQ), EMG, and clinical findings
BQTQ assigned severity scale
Mild: 1.1 – 2
Moderate: 2.1 – 3
Severe: 3.1 – 4
Extreme: 4.1 – 5
US CTS severity score based on El Miedany
Mild: mm2
Moderate: mm2
Severe: > 15 mm2
EMG CTS severity based on Pauda
Karadağ YS, Karadağ O, Ciçekli E, Oztürk S, Kiraz S, Ozbakir S, Filippucci E, Grassi W. Severity of Carpal tunnel syndrome assessed with high frequency ultrasonography. Rheumatol Int Apr;30(6): doi: /s x. Epub 2009 Jul 11.

42. Karadag, cont.
Result:
Substantial agreement for CTS severity (Cohen’s k coefficient = 0.619) between CSA and NCS
Based on US CTS severity classification, groups were significantly different in VAS (P = 0.017) and BQ-sympt (P = )
Conclusion: “CSA reflects in itself
the degree of nerve damage as
expressed by the clinical picture”
Karadağ YS, Karadağ O, Ciçekli E, Oztürk S, Kiraz S, Ozbakir S, Filippucci E, Grassi W. Severity of Carpal tunnel syndrome assessed with high frequency ultrasonography. Rheumatol Int Apr;30(6): doi: /s x. Epub 2009 Jul 11.

43. Kaymak et al 2008
EMG vs US as predictor of symptom severity (n=34, control=38)
Symptoms: measured by BCTQ
US: median nerve at level of DRUJ vs pisiform
CSA and flattening ratio
EMG: standard studies
Result:
Symptom BCTQ significantly correlated w/sens peak latency
Function BCTQ significantly correlated w/motor distal latency
No US correlation with BCTQ
Kaymak B1, Ozçakar L, Cetin A, Candan Cetin M, Akinci A, Hasçelik Z. A comparison of the benefits of sonography and electrophysiologic measurements as predictors of symptom severity and functional status in patients with carpal tunnel syndrome. Arch Phys Med Rehabil Apr;89(4): doi: /j.apmr

44. Mondelli et al, 2008
Prospective study of US vs NCS (n=85)
Symptom: BCTQ
NCS (AAEM standard)
Median SNAP, Ulnar SNAP, Median CMAP, median-ulnar transpalmar
US: CSA at inlet, outlet, mid-tunnel using manual tracing method
Result:
NCS (57/85): 67%
US (55/85): 64.7%
NCS + US: 76.5%
Mondelli, Mauro, Georgios Filippou, Adriana Gallo, and Bruno Frediani. “Diagnostic Utility of Ultrasonography Versus Nerve Conduction Studies in Mild Carpal Tunnel Syndrome.” Arthritis and Rheumatism 59, no. 3 (March 15, 2008): 357–366. doi: /art

45. Mhoon et al 2012
Prospective, blinded study comparing CSA and WFR to EDX and clinical symptoms (n=100, n=25 control)
EDX: standard studies
US: Inlet, 12 cm proximal to inlet
WRF > 1.4 considered positive
Result:
CSA 9 mm2 sens 99%, WRF 1.4 sens 97%
US parameters not related to CTS severity
Consider EMG only if CSA ≤8 mm2
Mhoon, Justin T, Vern C Juel, and Lisa D Hobson-Webb. “Median Nerve Ultrasound as a Screening Tool in Carpal Tunnel Syndrome: Correlation of Cross-sectional Area Measures with Electrodiagnostic Abnormality.” Muscle & Nerve 46, no. 6 (December 2012): 871–878. doi: /mus

46. Visser et al, 2008 n= 168 CTS, 137 control
NCS: Median DSL digit IV > 3.2 msec, Median ulnar ring-diff > 0.4 msec, median DML > 3.8 msec
US: distal forearm vs. inlet
Patient survey on preference (EMG vs. US)
Result:
US: sens 78 (70–84), spec 91 (86–95)
EMG: 82 (75–88) 88 (78–95)
CSA inlet differed significantly between control and subject (P < )
Patient survey indicates preference for US
Visser, L H, M H Smidt, and M L Lee. “High-resolution Sonography Versus EMG in the Diagnosis of Carpal Tunnel Syndrome.” Journal of Neurology, Neurosurgery, and Psychiatry 79, no. 1 (January 2008): 63–67. doi: /jnnp

47. US vs EDX Conclusion US has similar diagnostic value as NCS
Conflicting data on correlating CTS severity
Can consider US as the first diagnostic procedure in patients with typical CTS
EMG remains essential to detect other confounding diagnoses

48. Objective Background Literature appraisal US vs EMG
Ultrasound protocol
Summary

49. Disclosure
Michael Khadavi and Eugene Roh have no relevant financial disclosures.

50. Key Views Distal forearm transverse axis, for baseline CSA
Wrist inlet, transverse axis, CSA
Delta CSA = inlet – baseline
WRF = inlet / baseline
Tunnel to outlet, transverse axis, for mass lesions
Across carpal tunnel, long axis view
Baseline diameter
Notching
Tethering
Dynamic tests
FDS intrusion test
Lumbrical intrusion test
Thenar digital flexion stress test, LAX and SAX
Accessory structures
PCB MN

51. Ultrasound Protocol Patient comfortably seated across from examiner
Wrist on table at comfortable height, in slight extension (10-20 degrees)
Generous gel, throughout distal arm to wrist
Staying perpendicular to structure
Maintaining proper echotexture
Areas examined
Distal forearm (pronator quadratus)
Carpal tunnel (inlet, tunnel, outlet)

52. Distal Forearm

53. Inlet Sc: scaphoid i: flexor retinaculum Ps: pisiform q: median nerve
S: FDS
s: ulnar nerve
P: FDP
U a/v: ulnar a/v
PL: palmaris longus

54. Palmar Cutaneous Branch

55. Outlet

56. Longitudinal View

57. Dynamic Testing FDS intrusion
Sucher BM, Schreiber AL. Carpal tunnel syndrome diagnosis. Phys Med Rehabil Clin N Am May;25(2): doi: /j.pmr

58. Dynamic Testing Lumbrical intrusion test
Sucher BM, Schreiber AL. Carpal tunnel syndrome diagnosis. Phys Med Rehabil Clin N Am May;25(2): doi: /j.pmr

59. Dynamic Testing Thenar digital flexion stress test, LAX
Detect intracanal, where most compression occurs
Improves visualization of notching, at 3rd CMC
Sucher BM, Schreiber AL. Carpal tunnel syndrome diagnosis. Phys Med Rehabil Clin N Am May;25(2): doi: /j.pmr
Sucher BM. Carpal tunnel syndrome: ultrasonographic imaging and pathologic mechanisms of median nerve compression. J Am Osteopath Assoc 2009;109: 641–7.

60. Dynamic Testing Thenar digital flexion stress test, SAX
“open mouth view”
Sucher BM, Schreiber AL. Carpal tunnel syndrome diagnosis. Phys Med Rehabil Clin N Am May;25(2): doi: /j.pmr
Sucher BM. Carpal tunnel syndrome: ultrasonographic imaging and pathologic mechanisms of median nerve compression. J Am Osteopath Assoc 2009;109: 641–7.

61. Key Views Distal forearm transverse axis, for baseline CSA
Wrist inlet, transverse axis, CSA
Delta CSA = inlet – baseline
WRF = inlet / baseline
Tunnel to outlet, transverse axis, for mass lesions
Across carpal tunnel, long axis view
Baseline diameter
Notching
Tethering
Dynamic tests
FDS intrusion test
Lumbrical intrusion test
Thenar digital flexion stress test, LAX and SAX
Accessory structures
PCB MN

62. Objective Background Literature appraisal US vs EMG
Ultrasound protocol
Summary

63. Disclosure
Andrew Gallo has no relevant financial disclosures.

64. Future Research Direction
Large, population-based perspective study
Assess prevalence of structural abnormalities to define the expected benefit for delineating anatomical detail
Standardized research protocol, with defined measuring method, location
Evaluate efficacy outcome compared between EDX, US or clinically defined CTS
Utilize improved reference standard (CSI)

65. Summary Limitation of literature; interpret result with caution
No conclusive diagnostic CSA
Rule in > 14 mm2, rule out < 8 mm2
Delta CSA 2 mm2, 4 mm2 (bifid), WFR ratio > 1.4
Conflicting literature on correlating to severity; data support correlation to subjective symptom and function
Complementary to EDX
Consider for atypical cases for dynamic lesions, first- line for classic CTS, combine with EDX for improved sensitivity and specificity
CTS examination can be performed quickly, and well- preferred by patients
Prospective research with standardized protocol

66. Questions?

67. Thank You!

68. Reference, Cont.
Ibrahim, I, W S Khan, N Goddard, and P Smitham. “Carpal Tunnel Syndrome: a Review of the Recent Literature.” The Open Orthopaedics Journal 6 (2012): 69–76. doi: /
Atroshi I, Gummesson C. “PRevalence of Carpal Tunnel Syndrome in a General Population.” JAMA 282, no. 2 (July 14, 1999): 153–158. doi: /jama
Beekman, Roy, and Leo H Visser. “Sonography in the Diagnosis of Carpal Tunnel Syndrome: a Critical Review of the Literature.” Muscle & Nerve 27, no. 1 (January 2003): 26–33. doi: /mus
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