CTS-US AANEM Scottsdale 2015...‘Thickening and fibrosis of the SSCT (subsynovial connective tissue), Increased adhesions and decreased excursion of the median nerve and FDP tendons’

8/13/2015

1

Ultrasound Imaging of the Median Nerve

Carpal Tunnel Syndrome

Benjamin M. Sucher, D.O., FAOCPMR-D, FAAPMR

EMG LABs of [email protected]

North Phoenix, Mesa, Glendale, West Phoenix

Disclosure

Benjamin M. Sucher, D.O.

has no relevant financial disclosures.

Why Ultrasound and EDX?

1. Collaborative/Supplemental – provides anatomic info about the nerve;correlate with EDX and clinical exam

2. Provides dynamic physiologic information about the nerve during motion

3. Provides functional info about surrounding structures (mm, tendon, etc), and how they interact with the nerve during activity

4. Do the Ultrasound findings correlate (degree and location of swelling)?

5. EDX is still the ‘gold standard’; perform EDX first to plan US imaging

6. Use the Ultrasound findings to optimize management decisions

8/13/2015

2

DIAGNOSTIC TESTS FOR CTS

Anatomic v. Physiologic Vascular v. Neurologic

X-Ray

MRI Scan

EDX

Ultrasound Ultrasound

MRI Scan

EDX

Ultrasound Ultrasound

The Thumb

‘The human thumb emerges as a compromise at one point in evolutionary time, a locomotor organ that has been transformed into a manipulative organ

(by stone tool use).

Frank Wilson, The Hand, 1998

The Thumb‘…the modern human brain came into being after the hominid hand became “handier” with tools, …the human brain was the last

organ to evolve”.

Frank Wilson, The Hand, 1998

“….both the most delicate and the most dangerous of the primates”.

“Because of its unique capabilites…the thumb, if need be,

can carry on as a solo act”.

8/13/2015

3

The ThumbJust how important and powerful is it?

ETIOLOGY OF CTS• IDIOPATHIC

• INFLAMMATORY: Tendonitis/Rheumatoid

• ARTHRITIC: DJD/OA

• CARPAL CANAL STENOSIS / FIBROSIS

• WORK-RELATED: Trauma, Repetition,

Awkward Posturing, Vibration, Cold

• MISCELLANEOUS: Connective Tissue,

Endocrine, Amyloid, etc.

- is it really?

DIAGNOSTIC EVALUATION OF CTS

• HISTORY

• PHYSICAL EXAM

• EDX-ELECTRODIAGNOSIS (EMG/NCS)

• X-RAY-Carpal Canal Views

• ULTRASOUND (high resolution, 12+ MHz)

• MRI“Electrodiagnostic studies remain the gold standard for

verification and diagnosis of a median neuropathy”Vender, et al: Upper extremity compressive neuropathies, In:

Derebery and Kasdan: Injuries and Rehabilitation of the Upper

Extremity, Physical Medicine and Rehab State of Art Reviews,June, 1998; and Strakowski, 2014

8/13/2015

4

ULTRASOUND EVALUATION OF CTS1. a. CSA at pisiform

2. Digit flexion – lumbrical intrusion

3. Digit + wrist extension – sublimus intrusion

1. b. CSA Forearm (if 9-11mm2)

W-F Ratio > 1.5

10-12cmproximal

ULTRASOUND EVALUATION OF CTS

4. Longitudinal MN diameter pre-stress

5. Longitudinal MN diameter stress

6. Transverse MN diameter (optional)

‘Open-Mouth’ view

7. Video MN stress (optional)

a. longitudinal

b. transverse

DIAGNOSTIC ULTRASOUND OF CTS

Normalm = median nervet = flexor tendons

AbnormalEnlarged + loss of fascicular echotexture = nerve edema

Max normal cross-sectional area <12mm2

Lee, Radiol Clin NA, 7/99

Visser, JNNP, Jan 2008‘Accuracy’ similar to EDX

Walker, AANEM, 9/08US and EDX complementary

m

tt

m

t

tt

8/13/2015

5


Normalm = median nervet = flexor tendons

AbnormalEnlarged + loss of fascicular echotexture = nerve edema

Max normal cross-sectional area <12mm2

Median DML = 7.3msDistal (palmar) Amp = 8.9mV, prox = 1.7mV

80% conduction block

Median DSL = 6.6ms to D1Amplitude = 2mcv

US and EDX complementary

m

tt

tt

m

t

DIAGNOSTIC ULTRASOUND OF CTSBifid Median Nerve (high division)


NormalLongitudinal View

NormalAxial View(‘open-mouth’)

Thenar muscles

TCL

TCL

Median nerve

Median nerve

8/13/2015

6

CTS Case #1

70 y/o female with right UE pain, numbness, tingling, and weakness, for

the past 2mos. Symptoms worse at night and with gripping activity.

PE: palpatory restriction over carpal canal, intact sensation

positive Tinel and Phalen tests

EDX:

Median DML 4.8ms (7mV) [Ulnar 2.7 (10mV)]

Median DSL D-1 3.9ms (11mcv) [Radial 2.7 (10mcv)]

DIAGNOSTIC ULTRASOUND Case #1Lumbrical muscle intrusion

More frequent muscle intrusion in CTS

[46-100%]

Cartwright, Holtzhausen

Larger volume of muscleintrusion in CTS

[8mm2 vs. 4mm2]

Cartwright

lumbricals

CSA = 13mm2

CTS Case #2

44 y/o female with UE pain, numbness, tingling, and weakness, R>L, for the past 2 years; employed as a

spa tech with wrists extended as performing pedicures.

PE: normal, except palpatory restriction over carpal canal

EDX:

Median DML 4.5ms [ Ulnar 2.7 ]

Median DSL D-1 4.2ms [ Radial 2.5]

______________________________________________

8/13/2015

7

DIAGNOSTIC ULTRASOUND Case #2

Sublimus muscle intrusion

CTS Case #342 y/o male with UE pain, numbness, and tingling, R>L, for the

past 2 years. Treatment with wrist braces provided some relief. Works as computer programmer.

PE: normal, except for Tinel & Phalen tests positive bilaterally

EDX:

Median DML 2.8ms R; 2.9ms L [ Ulnar 2.5 R+L]

Median DSL D-1 2.8ms R; 2.7ms L [ Radial 2.4 R+L] (.4/.3)

Median DSL D-4 3.2ms R+L [Ulnar 3.0 R+L] (.2/.2)

Median mixed 1.8ms R; 1.9ms L [Ulnar 1.8 R; 1.9 L]

__________________________________________________

CSI = .6ms R; .5ms L

DIAGNOSTIC ULTRASOUND Case #3Sublimus muscle intrusion

8/13/2015

8


‘Notching’ of the median nerveon longitudinal/sagittal view

Lee, Radiol Clin NA, 7/99

Beekman and Visser, Muscle & Nerve, Jan 2003,

‘Only in severe cases’

Transverse carpal ligament

Maximal site of compression,at distal tunnel

DDDDDD

Median nerve Stress testing - Normal

Thenar Digital Flexion Stress Test

No median nerve narrowing

Pre-Stress (neutral)

Actual increase in diameter 30%!

Stress

Median Nerve Stress Testing - CTSCompression of the median nerve

on longitudinal/sagittal view

Median nerve narrowing (58%)

(Maximal site of compression at mid-distal tunnel)

Pre-stress

Stress

No compression

Med DSL = 3.4msRadial DSL = 2.5ms

8/13/2015

9


PRE-StressMed DML = 5.3ms; 75%CBMed DSL = NR

StressMedian nerve compression

(46% narrowing)


PRE-StressMed DML = 5.2msMed DSL = 4.4ms

StressMedian nerve compression

(41% narrowing)

capitate #3 metacarpal

#3CMC

DYNAMIC STRESS TESTING OF CTS

Longitudinal Imaging - video

40 y/o female, Left UE pain, numb, tingling, weak, x 3mos, 1st 3 digits, worse at nite+activity, + Tinel/Phalen, palp restricLeft DML = 5.3ms (ulnar 2.8), DSL (D-1) = 4.4ms 7mcv,

needle exam normal

8/13/2015

10

Median Nerve Stress Testing for CTS

Pre-stress

Stress(Median nerve flattening - 36%)

Compression of the median nerveon axial ‘open-mouth’ imaging

During dynamic thenar stress

(Transverse Imaging)

DYNAMIC STRESS TESTING OF CTS

Transverse Imaging - video

Hx: typical CTS x 2mos

PE: + Tinel, Phalen, mild thenar weaknessdec median sensat; palp restrict

Med DML = 6.0ms (Ulnar 3.0ms)Med Mot Amp = 15mV

Med DSL = 4.6ms (Radial 2.9ms); amp wnl

Needle emg: inc insert activity thenar mm

DIAGNOSTIC ULTRASOUND OF CTSPost-op – scar tissue

Korstanje, et al: M&N, May, 2012

‘Thickening and fibrosis of the SSCT(subsynovial connective tissue),

Increased adhesions and decreased excursion of the median nerve andFDP tendons’.

8/13/2015

11

Anatomy of Carpal Tunnel

Variations of Thenar Muscle Attachment

TCL Myofibroblasts in CTS

Electron-microscopy of the TCL

Myofibroblasts detected in the TCL; fibroblasts with properties of smooth muscle cells

Faster growth rate in TCL cells of CTS patients, may be due to cellular response to trauma.

Allampallan, et al: JOEM, 1996

Constant state of contraction:Decrease in the volume of the carpal tunnel

Increasing pressure on the median nerve

Etiology of CTS

Sucher: JAOA + Curr Rev Musculoskel Med, 2009; Korstanje: M&N, 2012

Multifactorial:

1. Increased intracarpal pressure (+ muscle intrusion during activity)

2. Decreased median nerve mobility (fibrous fixation, SSCT adhesions)

3. Median nerve deformation (traction, stretching, compression; SSCT?)

4. Increased ‘stiffness’ of synovium (and SSCT) and TCL

5. Thenar muscle mass effect +TCL protrusion into the carpal tunnel

6. Flexor tendon thickening and tightening during activity; SSCT ‘tethering’?

7. Combine #5-6: direct compression between muscle and tendon

[Lower the ‘Roof’ (TCL, thenar muscle) + Raise the ‘Floor’ (tendons)]

8/13/2015

12

CTS is Not IdiopathicIt does not just ‘happen to you’

It is a self-defense mechanism, nature’s way of protecting itself from overuse:

The activity compresses the nerve supplying the muscle that generates the activity, leading to weakness and

atrophy of the muscle, which causes the compression to

‘back-off’, and allows the nerve to recover.

Sucher: JAOA + Curr Rev Musculoskel Med, 2009; PM&R Clinics NA, 2014

Treatment Implications:

1. Myofascial release

2. Modified thumb spica

3. Botox thenar muscle?

4. Avoid vigorous or sustained grasping/pinching (padded handgrips)

CTS Stress Testing Pre+Post OM

Pre-stress

Stress Stress Post OM

THE ELECTRODIAGNOSTIC REPORT

Report the abnormality (Interpretation):“…moderate prolongation of the median distal motor and sensory latencies,

consistent with slowing across the wrist due to focal demyelination…loss of amplitude consistent with conduction block (or axon loss)….”

Summarize with ‘Impressions’ or ‘Conclusions’:“Median mononeuropathy (consistent with carpal tunnel syndrome); mild-

moderate on the right and mild on the left, electrically”

Diagnostic ultrasound imaging (high resolution, 4-15MHz linear transducer) of the right wrist reveals moderate increase in the cross-sectional area of the median nerve (18mm2;

normal <12mm2) at the level of the pisiform (transverse imaging), and partial loss of fascicular echotexture, consistent with nerve edema and carpal tunnel syndrome. The flexor tendons appear normal. Thenar flexion stress test (longitudinal imaging) reveals median nerve

compression between the thenar muscles and flexor tendons in the distal carpal canal. Motion studies (transverse imaging) reveal mild lumbrical muscle intrusion into the carpal canal during digit flexion (grasp), with mild median nerve compressive effect; but no muscle intrusion

during wrist and digit extension.

8/13/2015

13

Ultrasound v. EDXUS is painless, lower cost, less time

US provides detailed anatomic information:Muscle atrophy

Nerve mobility (sliding in sagittal and axial planes)Precise localization/extent of edema

Anomalous nerve branching

Anomalous muscle penetration into the canalPost-op incomplete TCL transection

Presence of cysts, tumor, persistent median artery

EDX provides physiologic information:

Specific – axon v. myelin, CB; prognosis

EDX is painful

Both have fairly high specificity and sensitivity for CTS

Key References:

1. Strakowski JA: Ultrasound Evaluation of Focal Neuropathies:

Correlation with Electrodiagnosis. New York, Demos Medical

Publishing, 2014.

2. Walker FO and Cartwright MS: Neuromuscular Ultrasound.

Philadelphia, Elsevier Saunders. 2011

3. Peer S and Bodner G: High-Resolution Sonography of the

Peripheral Nervous System, 2nd Ed. Berlin, Springer-Verlag, 2008

4. Ahuja AT: Diagnostic and Surgical Imaging Anatomy Ultrasound.

Salt Lake City, Amirys. 2007

3. Jacobson JA: Fundamentals of Musculoskeletal Ultrasound.

Philadelphia, Saunders, 2012.

8/13/2015

14

References:1. Sucher BM and Schreiber AL: Carpal tunnel syndrome diagnosis. Phys Med Rehabil Clin N

Am 2014;25:229-247.

2. Strakowski JA: Ultrasound Evaluation of Focal Neuropathies: Correlation with

Electrodiagnosis. New York, Demos Medical Publishing, 2014.

3. Sucher BM: Ultrasound imaging of the carpal tunnel during median nerve compression.

Curr Rev Musculoskelet Med 2009; DOI 10.1007/s12178-009-9056-5 (online).

4. Sucher BM: Carpal tunnel syndrome: Ultrasonographic imaging and pathologic

mechanisms of median nerve compression. JAOA 2009;109:641-647.

5. Lee D, van Holsbeeck MT, Janevski PK, et al: Diagnosis of carpal tunnel syndrome:

Ultrasound versus electromyography. In: Musculoskeletal Ultrasound. Radiologic Clinics

of North America. 1999;37 (No. 4): 859-872,

6. Beekman R and Visser LH: Sonography in the diagnosis of carpal tunnel syndrome: A

critical review of the literature. Muscle and Nerve. 2003;27:26-33.

7. D’Costa S, Jiji, Nayak SR, Sivanadan R, Abhishek: Anomalous muscle belly to the index

finger. Ann Anat. 2006 Sep; 188(5):473-5.

8. Holtzhausen LM, Constand D, de Jager W: The prevalence of flexor digitorum superficialis

and profundus muscle bellies beyond the proximal limit of the carpal tunnel: A cadaveric

study. J Hand Surg Am. 1998;23:32-7.

9. Robinson D, Aghasi M, Halperin N: The treatment of carpal tunnel syndrome caused by

hypertrophied lumbrical muscles: Case reports. Scand Hand Surg. 1989;23(2):149-51.

10. Siegel DB, Kuzma G, Eakins D: Anatomic investigaton of the lumbrical muscles in carpal

tunnel syndrome. J Hand Surg Am. 1995;20:860-3.

11. Cobb TK, An K-N, Cooney WP: Effect of lumbrical muscle incursion within the carpal tunnel

on carpal tunnel pressure: A cadveric study. J. Hand Surg Am. 1995;20(2)186-92.

12. Caress JB and Walker, FO: Ultrasound of peripheral nerves: An AANEM Workshop.

AANEM, 2006.

13. Robinson LR, Micklesen PJ, and Wang L: Strategies for analyzing nerve conduction data:

Superiority of a summary index over single tests. Muscle & Nerve. 1998;21:1166-1171.

References (cont):14. Robinson LR, Micklesen PJ, and Wang L: Optimizing the number of tests for carpal tunnel syndrome.

Muscle & Nerve. 2000;23:1880-1882.

15. Klauser AS, Halpern EJ, DeZordo T, et al: Carpal tunnel syndrome assessment with ultrasound: Value of

additional cross-sectional area measurements of the median nerve in patients versus healthy volunteers.

Radiology 2009;250(1);171-7.

16. Hobson-Webb L and Paduca L: Median nerve ultrasonography in carpal tunnel syndrome: Findings from

two laboratories. Muscle & Nerve. 2009;40:94-97.

17. Wilson, F: The Hand, How Its Use Shapes The Brain, Language, and Human Culture. New York, Pantheon

Books. 1998.

18. Cartwright MS, et al. : Muscle intrusion into the tunnel in carpal tunnel syndrome. AANEM 2010 Annual Meeting

Abstract Guide.

19. Joshi SD, Joshi SS, and Athavale SA: Lumbrical muscles and carpal tunnel. J Anat Soc India. 2005;54:12-15.

20. Walker FO and Cartwright MS: Neuromuscular Ultrasound. Philadelphia, Elsevier Saunders. 2011

21. Walker FO and Cartwright MS: Neuromuscular ultrasound: Emerging from the twilight. Muscle & Nerve.

2011;43:777-779.

22. Padua L: Repeated ultrasound studies may help us understand what’s going on inside the nerve. Muscle &

Nerve. 2012;44:6-7.

23. Therimadasamy A, Peng YP, and Wilder-Smith EP (Letter to Editor): Carpal tunnel syndrome – Median nerve

enlargement restricted to the distal carpal tunnel. Muscle & Nerve. 2012;46: 455-7.

24. Mhoon JT, Juel VC, and Hobson-Webb LD: Median nerve ultrasound as a screening tool in carpal tunnel

syndrome: Correlation of cross-sectional area measures with electrodiagnostic abnormality. Muscle & Nerve.

2012;46:871-878.

25. Cartwright MS, Hobson-Webb LD, Boon AJ, et.al: Evidence-based guideline: Neuromuscular ultrasound for the

diagnosis of carpal tunnel syndrome. Muscle & Nerve. 2012;46:287-293.

26. Korstanje JH, et al: Ultrasonographic assessment of longitudinal median nerve and

hand flexor tendon dynamics in carpal tunnel syndrome. Muscle & Nerve. 2012;45:721-729.

Documents

CTS-US AANEM Scottsdale 2015...‘Thickening and fibrosis of the SSCT (subsynovial connective tissue), Increased adhesions and decreased excursion of the median nerve and FDP tendons’