Ultrasound Ventral Wrist & Carpal Tunnel Syndrome

By Lisa Howell

Cross section of the wrist revealing Carpal Tunnel Credit: Hollinshead WH. Anatomy for surgeons: the back and limbs 3rd edition vol3

Philadelphia PA Harper and Row 1982

Wrist Anatomy ● Radius, ulnar, and 8 carpal bones:

Proximal row: Scaphoid, Lunate, Triquetrum, Pisiform

Distal row: Trapezium, Trapezoid, Capitate, and Hamate

*So long to pinkie here comes the thumb* ● Joints: Distal Radio-ulnar joint (DRUJ), Radiocarpal joint

(RC), midcarpal joints, carpometacarpal joints (CMCJ)

Radial / ulnar deviation occur RC, and midcarpal joints

Pronation / supination occurs at distal and prox RU joints● Blood supply radial and ulnar arteries and veins● Osteofibrous tunnel form floor wrist● Retinaculums forms roofs wrist● Dorsal wrist 6 compartments [ Ref: 7,22,25,26 ]

Ventral Wrist● FCR Flexor Carpi Radialis primary flexor (radial) superficial to FR

Insertion base 2nd and 3rd metacarpal bone

Flexion and radial deviation (abduction) at wrist*FCR has a seperate synovial sheath

● FCU Flexor Carpi Ulnaris, primary flexor (ulnar)

Insertion pisiform bone (sesamoid), hook of hamate, and base 5th metacarpal Flexion and ulnar deviation (adduction)*FCU has no synovial sheath

● FPL Flexor Pollucis Longus 9th tendon of CT (radial)

Insertion base distal phalanx of thumb Flexion of thumb*FPL has seperate synovial sheath

● PL Palmaris longus located superficial to FR, and midline b/w FCR and FCU Insertion Palmar Aponeurosis and FR

Flexes Wrist and tenses Palmar Aponeurosis

*PL Absent 14% population [Ref: 20,21,22,25,26]

Ventral Wrist

● PQ Pronator Quadratus muscle deep to FDS and FDP, and prox to CT Attaches distal ant Radius and Ulna Pronation

● Guyons Canal GC superficial and medial to CT

Ulnar Nerve enters GC with Ulnar Artery and Ulnar veins

Pisform medial (prox) and Hook Hamate lateral (distal)

Transverse carpal ligament forms floor, and Palmar carpal ligament roof● Carpal Tunnel CT

fibro-osseous tunnel of ventral wrist, carpal bones and ligaments form floor and sides

● FR Flexor retinaculum forms roof CT● Median Nerve at wrist deep to FR, superficial to FPL, FCR (Ulnar), and

lat to FDS

*Phalen test volar flexion wrist 90 deg, dorsal aspect hands together 60 sec CTS

*Tinels test tap over MN, ellict pain [Ref: 20,21,22,25,26]

Carpal Tunnel / Ventral Inlet Proximal tunnel: Scaphoid (radial) / Pisiform bone (ulnar)

Outlet Distal tunnel: Trapezium (radial) / Hook Hamate (ulnar)

CT contains 9 tendons: FDS, FDP, and FPL

*FDS and FDP common synovial sheath ● FDS Flexor digitorum superficialis (4 tendons)

Insertion base of middle 2nd to 5th phalanges

Flexion fingers 2nd to 5th MCPJ and PIPJ bend wrist● FDP flexor digitorum profundus (4 tendons)

Insertion base distal 2nd to 5th phalanges

Flexion fingers 2nd to 5th MCPJ, PIPJ, and DIPJ bend wrist

Wrist innervation 3 Nerves:

Radial ( Dorsal ), Median, and Ulnar ( ventral ) nerves superficial and motor branches [Ref: 20,21,22,25,26]

Median Nerve / Ventral

MN 2 forearm branches: ● AIN Anterior interosseous nerve motor branch, ant to

interosseous membrane b/w FPL and FDP to beneath PQ innervates PQ, FPL, and FDP

● PCMN Palmar cutaneous branch MN, superficial to FR, b/w FCR (ulnar) and PL Sensory innervation to palm *Injury to PCMN most common complication CT surgery

*Kiloh-Nevin syndrome AIN compressive neuropathy, severe weakness pincer movement thumb, and index finger(absent OK sign) RA predispose

MN 2 wrist branches: ● Recurrent branch innervates Thenar muscles of thumb● PDCMN Palmar Digital cutaneous branch MN Innervates

palmar surface, and finger tips (radial), 3 ½ digits and 2 lumbricals muscles in hand [Ref: 7,25,26, 30]

Ulnar nerve / Ventral UN distal forearm b/w FCU (radial), and UA (ulnar)

UN 2 branches within GC:

● Superficial sensory branch UN lies superficial to Hook of Hamate

Innervates medial aspect palm, little finger and ring finger (ulnar)

● Deep motor branch UN located ulnar side Hook of Hamate

Innervates adductor pollicus, 2 medial lumbricals, hypothenar and interosseous muscles*Guyons canal syndrome compression of UN, eg cyclists palsy (handlebars), hypothenar hammer syndrome (hook hamate)

*Froment sign inability pinch piece of paper b/w 1st and 2nd fingers, palsy of ulnar nerve

*Wartenberg test involuntary abduction of 5th finger, injury to ulnar nerve

[Ref: 25,26,30]

Radial nerve / Dorsal wristRN innervation posterior forearm / wrist bifurcates prox

RN 2 forearm branches:● PIN Posterior interosseous nerve is deep RN. Located beneath

C4 tendons

motor innervation extensors in post forearm ECU,EDC,EDM, APL, EPL, and EPB

● SRN superficial radial nerve, located superficial to C1 at wrist

sensory innervation to dorsum wrist, hand and thumb, and prox portion radial fingers*Cheiralgia paresthetica SRN compression neuropathy caused by wrist watches, or

by forearm fracture *Associated with De Quervains disease 20-50%

*Radial nerve wrist extension test, and Grip strength test

*PIN extension test with 3rd MCPJ [ Ref:22,25]

Carpal Tunnel SyndromeCTS compression or entrapment of MN beneath FR at wrist, proximal swelling, with clinical presentation of sensory and/or motor weakness

Occurs 1-5% population

Most common entrapment, higher incidence women over 55yrs

CTS symptoms can occur in forearm, wrist and hand

Acute symptoms:● painful sensations burning, electric shock like pain in radial three and

half digits, often nocturnal● Tingling, numbness and Clumsiness / difficulty grasping small objects

Chronic permanent sensory and motor deficits of MN ● Sensory loss of sensations of pain, pressure and temperature● Loss of feeling, grip strength, impaired movement● Motor muscular weakness and atrophy Thenar muscle● Autonomic altered microvascular circulation [Ref: 25,28,30,36]

Peripheral Neuropathy/ CTS

● Peripheral neuropathy disease or degenerative state of peripheral nerves in which motor, sensory, or vasomotor nerve fibres are affected

● may affect entire nerve, multiple sites along nerve, or multiple nerves within a limb

CTS : Flexor Retinaculum restricts size of Tunnel● Increased pressure caused by intrinsic and extrinsic forces within

Tunnel causes compression of MN and/ or its branches● Alterations in blood-nerve barrier● Nerve oedema and swelling increase● Slowing of axonal transport● Thickening of nerve connective tissue ● Vascular compromise as pressure increases on nerves● Nerve susceptible to compression [Ref: 25,28,35,36]

Anatomy peripheral nerves

Mesoneurium connective tissue sheath that suspends nerve trunk

Epineurium Outer epineurium is continous with mesoneurium, and forms outer sheath of nerve

Inner epineurium connective tissue intervening b/w outer sheath and fascicles

Endoneurium fascicle of nerve, contain nerve tissue (axons, myelin sheaths, and schwann cells)

Perineurium connective tissue /sheath surrounds fascicles (inner epi and per-neurium)

Vaso nervorum vascular supply each nerve

ensures impulse transmission and axonal transport

-Perineural vessels course longitudinally in external epineurium

-Intraneural vessels branch amongst fascicles in perinerium

-Vascular plexuses connect peri- and intra-neural vessels [Ref:25,28,35 ]

Pearson education Inc

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Normal U/S appearance PN

Epineurium is hyperechoic rim

Longitudinal axis: Tubular structures

PN appear as multiple hypoechoic parallel lines (fascicles), seperated by hyperechoic lines (perinerium)

Short axis: Honeycomb appearance

PN appear as hyperchoic ovoid area, with multiple hypoechoic dots (fascicles)

Size and number fascicles vary in each nerve

-depends on distance from origin

-amount of pressure to which nerve is subjected

-occurrence of nerve branching

BMI, age, and gender, may also influence nerve calibre

[Ref: 20,25,28,35 ]

Abnormal U/S appearance PN

● Nerve / fascicle enlargement● Nerve compression within carpal Tunnel, with proximal swelling

of nerve● Loss of normal fascicular architecture of nerve● Loss of normal nerve sliding movement● Nerve appears hyperechoic in relation to tendons● Vas nervorum hyperaemia

Additional abnormal U/S PN findings:● Focal or diffuse thickening of nerve● Fusiform swelling of nerve● Lesion dissecting the fascicles within the nerve● Subluxation / dislocation of nerve● Partial or complete severance of nerve [Ref: 20,25]

Ultrasound Technique WristHRUS Tx 10 MHZ-18MHz (Hockey stick Tx)

Optimise settings Focal zone, B Mode, TGC, depth, etc

Clinical indication and Past history

Position: Patient sitting opposite examiner with wrists resting on table

Dorsal: C1 position wrist in lateral (Thumb up) , and C2-C6 Extensor tendons wrist in pronation

Ventral / Carpal Tunnel: Position wrist in supination

U/S Examine Tendons, ligaments, muscles, and nerves, and image intrinsic and extrinsic pathology

Elevator technique scan wrist distally to tendon insertions, and proximally to myotendinous junction and muscle

Dynamic study: Flexion /extension, radial /ulnar deviation, pronation / supination, wriggle fingers

Colour doppler Intraneural hyperaemia

Compare to contralateral side

Case 1 CTS Phx Gestational Diabetes

Case 1 2yrs post partumCTS MN long

Case 1 Bilateral CTS2 yrs post partum

Case 2 Crush injury/ Dorsal Haematoma

Case 2 Crush injury/ CTS

Case 2 Ventral CTSCrush injury

Case 3 RA/ synovitis Dorsal wrist

Case 3 RA/ Ventral wrist FCR Full thickness tear

Case 3 RA/ ventral wrist FCR tear comparison

Case 3 RA MN Full thickness tear FCR

Peripheral Nerve InjurySeddon classifications : Sunderland (used by surgeons)

● Neuropraxia Grade 1 Mild injury

Endonerium, perineurium, and epineurium intact

Nerve contusion, dislocation, or nerve swelling (No wallerian degeneration) eg compression of SRN

*Low grade injuries have a better outcome than high grade injuries

● Axonotmesis Grade 2 Moderate injury

disruption of axons and myelin

Epineurium and perineurium intact

Motor and sensory dysfunction present (Wallerian degeneration)

eg traction and crush injury● Neurotmesis Grade 3 Severe injury

Laceration, partial or complete severance of nerve

*High grade injuries require surgical intervention [Ref: 19,20,28,36]

Peripheral Nerve TumoursPN Tumours neoplasm derived from schwann cells

-have entering and exiting nerve, often homogenous, and hypoechoic● Schwannoma has defined nerve/ tumour transistion

eccentric or central nerve entry

smaller size than neurofibromas

smooth contour, cystic portions , hyperaemia, may have calcifications*Surgery to nerve with preservation of nerve continuity

● Neurofibroma central nerve location

single tumour, fusiform or lobulated shape *Excision usually compromises affected nerve

● Neurofibromatosis diffuse form, multiple neurofibromas / plexiform● Traumatic neuroma caused by catherisation or amputation stump● Neurofibrolipomas found along median nerve [Ref: 12,29]

Case 4 SRN Traumatic Neuroma

Case 4 SRN Traumatic Neuroma

Case 4 SRN post arterial puncture

CTS Decompression surgery

Surgical division of Flexor retinaculum, and release of pressure on entrapped MN

Open release

larger scar formation, greater risk of scar tethering if incision directly over MN (reduce this complication with incision made ulnar to MN)

Endoscopic surgery

smaller incision, and less scar tenderness

patients have better function, and reduced recovery time

R Malhotra et al 2007 [ Ref:32]

MN maximum CSA at CT, hypervasculization, echogenicity, compression, deformation, and movability

“Ultrasound imaging with the use of high frequency transducer is a valuable diagnostic tool for post operative assessment of CTS treatment efficacy” K. Kapuscinska et al 2016 [ Ref:33]

Case 5 Post CTS surgery abscess / 9wks

Case 5 Post Carpal Tunnel surgery 9wks

Case 5 Post CT surgery 9wks

Causes of CTS

● Bifid Median nerve presence of two paired nerves within CT

Measure individual CSA bifid branches for combined CSA● Persistent median artery accessory artery from UA● Tumours Lipoma, Neurofibroma, or Schwannoma● Ganglion cyst assoc with joint, or tendon sheath

dorsal SL ligament (60-70 percent), Flexor tendon sheath (10 percent),Ventral radio SL interval (20 percent)

● Accessory muscles Anomalous Palmaris muscle, and Gantzar muscle (accessory FPL)

Presence of Flexor muscle bellies in CT increases statistical risk of CTS, increased pressure during wrist and finger extension

● Square internal shaped carpal tunnel more likely to develop CTS (Square vs rectangle)

● Surgical complications haematoma, infection, scar formation, Neuroma, or incomplete dissection of FR [ Ref: 5,6,25,35,36]

Causes of CTS

● Work / sporting activities using repetitive movements● Trauma bone fracture ● Soft tissue injury compression injury, or catheterisation ● Inflammatory conditions Arthritis, Tenosynovitis flexor tendons● Nutrient deficiency B12, Vitamin D, Dopamine,Omega 3 ● Toxins: insecticides, poisons eg mercury, lead, arsenic● Alcohol or smoking● Infective diseases Retroviruses (HIV), CMV, EBV, Tuberculosis,

Leprosy, Lyme disease, and Herpes Virus● Immune mediated CIPD, Guillain Barre Syndrome● Uraemic neuropathy Chronic kidney disease 90% Dialysis patients● Hereditary neuropathy Charcot-Marie-Tooth disease

[Ref:25,30,35,36]

Causes PN

HRUS emerging diagnostic tool for monitoring, staging, and efficiacy of treament of peripheral neuropathy

● Drug induced neuropathy Antiviral medications, and

Chemotherapy induced PN frequent side effect of treatment, may occur during, or months after treatment is completedOvarian, Breast, Lung, and Prostate cancer, the more radical the surgery, higher the level of severity of PN

● Hormonal Neuropathy oophorectomy, OCP, and menopause

Pregnancy 34% experienced CTS, severity of symptoms and functional impairment increased with Term

Higher prevalence of CTS with Obesity, Gestational weight gain, BMI>30kg/m2, and Parity (more two live births)

Post partum persistence of symptoms with earlier clinical onset

[Ref: 11,13, 14,20]

Causes PNHypothyroidism Peripheral Neuropathy

● “CSA of the Median nerve is increased in primary autoimmune hypothyroidism and decreases upon treatment with Thyroxine”

“Newly diagnosed primary hypothyroid patients

10mmsq is pathological to diagnose CTS level of tunnel inlet “

*Ultrasound Staging MN Initial, and 3 month

“Ultrasound is a sensitive noninvasive method of diagnosing CTS associated with hypothyroidism D.Holovacova et al 2016 [Ref:15]

CSA prox inlet, distal wrist, 12cm prox in forearm

“With thyroxine treatment, CTS can be controlled in patients with hypothyroidism after 3 months”

“symptomatic MN entrapment, the MN CSA can be used as a guide for selection of patients that may benefit from surgery”

M V Kameswar Rao et al 2019 [Ref: 16]

Case 6 Volar Ganglion

Case 6 Volar Ganglion

Case 6 Bifid MN CTS

CTS measurement CSA *CSA MN 9mmsq healthy EDx confirmed CTS

*CSA MN inlet at Carpal Tunnel max enlargement

*CSA MN prox 1/3 of Pronator Quadratus

*Difference CSA 2mmsq for CTS*99% sensitivity 100% specificity for CTS

“US features MN echogenicity, mobility, flattening ratio in the distal part, FR bulging can be helpful in diagnosing CTS” AS Klauser et al 2009 [ Ref: 17 ]

*Difference CSA 2.5mmsq for CTS

“HRUS is a valid and accurate diagnostic modality in CTS and correlated to CTS severity”

“CTS patients with Diabetes tend to have a greater MN US measurement values than hypothyroid or idiopathic B.Elnady et al Results Agreement 2019 [Ref: 1]

CTS measurement WFR

*MN CSA >9mmsq 99% sensitivity

*WFR>1.4 Wrist / Forearm Ratio 97% sensitivity

Mhoon et al, 2012 [Ref:2]

CT inlet MN CSA distal wrist crease

WFR MN CSA 12cm prox to distal wrist crease

“Data suggest US may have use a screening tool prior to performing EDx testing for CTS”S.Billakota & L.Hobson-Webb. 2017 Standard MN US in CTS: A retrospective review of 1021 cases (1904 extremities) [Ref: 3 ]

Inlet-to-outlet MN ratio IOR 1.3

CSA inlet (pisform/scaphoid) and outlet (Hook Hamate/ Trapezium)

93% specificity 91% sensitivity T. Fu et al 2015 [Ref: 4]

US CTS severity

MN CSA measured distal wrist crease(inlet) Severity correlated by Nerve Conduction Studies:

<10mmsq Normal

10mmsq-12mmsq Mild

13mmsq-15mmsq Moderate

15mmsq> SevereT.Khanbhai et al a prospective study examining the sensitivity of ultrasound determined MN CSA with nerve conduction investigation in the diagnosis of CTS. International MSK Medicine 2015 [Ref: 27]

M.Sahebari et al High resolution ultrasonography of CSA of MN compared with electro-diagnostic study in CTS Rheumatol Research Journal 2017 [Ref: 24]

Y.S Karatag et al Severity of Carpal Tunnel Syndrome assessed with high frequency ultrasound Rheumatol Int 2010 April [Ref: 31 ]

CTS “Colour doppler is more accurate than grey scale sonography for characterizing MN in patients with suspected CTS”

*Intraneural vascularity colour doppler

95% sensitivity specificity 71%

*Decreased echogenicity above compression site

80% sensitivity

*Nerve flattening width

60% sensitivity A.Malouhi et al 2006 [ Ref: 23]

“PI Radialis indicis artery (branch RA index finger)

“was significantly lower in CTS patients compared to healthy controls”

A R Ghasemi-Esfe et al 2012 [ Ref: 34]

Diabetic / DPN

“morphological changes in peripheral nerves of Type 2 Diabetic patients were found before the onset of neuropathy, and were closely correlated with the severity of DPN”

“CSA, hypoechoic area, and maximum thickness of the nerve in patients without DPN were larger than those in control subjects, and further increased relative to severity of Neuropathy”

MN CSA measured 5cm prox to wrist crease

MTNF Max Thickness of Nerve Fascicle (short axis)

MTNF MN Control mean 0.21mm Max 0.5mm stage 4 / 5

F.Ishibashi et al 2015 [ Ref: 10 ]

Diabetic NeuropathyDiabetes Mellitus is a chronic metabolic disease characterized by hyperglycaemia

DPN is present in approx 50% of all patients with DM

Prevalence of CTS is higher in patients with DPN

“CTS accurate diagnosis if WFR can be applied regardless of presence or absence of DM”

CSA prox PQ max enlargement and CSA 12cm prox to wrist

CSA control 10mmsq and WFR 1.52

CSA Diabetic 12.5mmsq and WFR 1.87

C H Lee et al 2018 [ Ref: 9]

DPN patients CSA measured CSA MN 5cm prox to wrist, mid forearm, and at elbow joint

“Mean CSA at 3 levels significantly higher in DPN patients than healthy volunteers” Y. Singh High 2019 [ Ref: 8]

Treatment CTS● Early diagnosis to alleviate permanent nerve damage, and functional

disability ● Conservative treatment: Rest, RICE● Medical care for under lying diseases eg Hypothyroidism, Diabetes, RA● Hand therapy Splinting, Brace ● Modify activities wrist position ergonomics● NSAIDS● Surgery: Open release, or Endoscopic ● U/S Guided Interventional procedures:

-aspiration fluid / ganglions

-biopsy mass / nerve

-steroid injections *failure to improve after injection is poor prognostic factor

*Beware cortisone can affect Diabetics insulin levels [Ref: 7,25,30]

Role of ultrasound of wrist ● US has wide availability, lower cost, and is non invasive● Assess anatomy and dynamics of tendons, muscles and, nerves● Diagnose intrinsic and extrinsic pathology● US can be used as first line investigation to diagnose CTS● US can be used to differentiate between DPN and CTS (WFR)● Assist in diagnosis monitoring, and staging of severity CTS● Assist in diagnosis and monitoring of hormonal, Hypothyroidism,

and drug induced neuropathy treatment● Dynamic study and comparison to contralateral side● Guide interventional therapy● US used to guide selection of patients for surgery● US diagnose post surgical complications

References1. B.Elnady et al Diagnostic potential of ultrasound in CTS with different etiologies: correlation of sonographic median nerve measures with electrodiagnostic severity

BMC Musculoskeletal Disorders 2019. Open access.

2 M.hoon et al 2012 Duke Uni, USA

3. S.Billakota & L.Hobson-Webb Duke Uni, USA. Standard MN ultrasound in CTS: A retrospective review of 1021 cases.(1904 extremities) Sept 2017 Clin.Neurophysiol Pract.

4. T. Fu et al CTS Assessment with ultrasonography: value of Inlet-to-Outlet MN area ratio in patients versus healthy volunteers PLOS Jan, 2015

5 E.Vogelin et al Sonographic Wrist Measurements and detection of Anatomical features in CTS. The Scientific World Journal vol 2014

6. G.Smerilli et al Ultrasound assessment of carpal tunnel in rheumatoid arthritis and idiopathic CTS. Clinical Rheumatology July 2020

7. Orthobullets Wrist Ligaments & biomechanics 2016

8. Y. Singh et al High resolution ultrasonography of Peripheral Nerve in Diabetic Peripheral Neuropathy Neurology India vol 6, 2019

9. CH.Lee et al CTS Assessment with Ultrasonography: A comparison between Non -diabetic and Diabetic patients. Ann Rehab Med 2018

10. F.Ishibashi Morphological changes of the PN evaluated by high-resolution ultrasonography are associated with the severity of DPN, but not corneal fibre pathology in patients with type 2 Journal diabetes investigation 2015

11. R.Zajaczkowska et al Mechanisms of CIPN. International Journal of Molecular Sciences 20, 2019

References12. J Jacobson et al Sonographic characteristics of peripheral nerve sheath tumours AJR:182 March 2004

13. M.Meems et al Prevalence, course and determinants of CTS symptoms during pregnancy: a prospective study. Maternal medicine March 2015

14. C.Wright et al Who develops CTS during pregnancy: An analysis of obesity, gestational weight gain, and parity. Obstetric Medicine vol 7, 2014

15. D.Holovacova et al CSA of the MN is increased in primary autoimmune hypothyroidism and decreases upon treatment with thyroxine European journal of Endocinology 175, 2016

16. MV.Kameswar et al Ultrasonography of MN In CTS in patients with Hypothyroidism Annals of international Medical and Dental research. July 2019

17. AS.Klauser et al CTS assessment with Ultrasound: value of additional CSA measurements of the MN in patients vs healthy volunteers. Radiology vol 250,2009

18. K.Kapuscinska et al High frequency ultrasound in CTS: assessment of patient eligibility for surgical treatment Journal of Ultrasonography Sept 2015

19 Duncan Avis et al. Axillary nerve injury associated with Glenohumeral dislocation. Shoulder and Elbow March 2018

20. E.Gallardo et al Ultrasound in the diagnosis of peripheral neuropathy:structure meets function in the neuromuscular clinic. Journal of Neurointerventional Surgery 2017

21. C.Olchowy et al Wrist US examination -scanning technique and US anatomy. Part 2: Ventral wrist June 2017 J Ultrason. Open access

22. Teach me Anatomy. Online /Tutorials for Medicine students. Dr Sam Webster

23. A.Malouhi et al Predictors of CTS: Accuracy of Greyscale and Colour Doppler Sonography American Journal of Roetgenology 186(5) May 2006

References24. Maryam Sahebari et al High resolution ultrasonography of CSA of MN compared with electro-diagnostic study in CTS. Rheumatology Research Journal Oct, 2017

25. S.Bianchi / C.Martonoli Ultrasound of the Musculoskeletal System. Chapter 10 Wrist. Springer 2007 p425-494

26 Brukkner and Khan Clinical Sports Medicine. 5Th Edition. Vol 1 Chapter 26 p463-487

27 T.Khanbhai et al a prospective study examining the sensitivity of ultrasound determined MN CSA with nerve conduction investigation in the diagnosis of CTS. International MSK Medicine 2015 [Ref: 27]

28 A.D.Lawande et al role of ultrasound in evaluation of peripheral nerves. Indian journal radiol imaging Sept 2014

29. Jeong Ah Ryu et al Sonographic differentiation between schwannoma and neurofiboma in the musculoskeletal system journal of ultrasound in Medicine vol 34, Nov 2015

30. Orthobullets Carpal Tunnel syndrome- Hand- 2/24/202

31. Yesim S Karatag et al Severity of Carpal Tunnel Syndrome assessed with high frequency ultrasound Rheumatol Int 2010 Apri

32. R Malhotra et al Endoscopic versus open carpal tunnel release: A short term comparative study Indian journal of Orthopaedics 2007

33 K. Kapuscinska et al Efficacy of high frequency ultrasound in post operative evaluation of CTS treatment Journal of ultrasonography 2016 Mar

34 A R Ghasemi-Esfe et al Colour doppler ultrasound for evaluation of vasomotor activity in patients with CTS Skeletal radiol 2012 Mar

35 Siegfried Peer et al Sonography of Carpal Tunnel Syndrome: why, when, and how Future Medicine

Imaging Medicine 2012

36. I.Ibrahim et al Carpal Tunnel Syndrome : A review of the recent Literature Open Orthopaedic Journal 2012 suppl 1:M8 69-76