update on the use of ultrasound in the diagnosis of carpal tunnel syndrome renato a. sernik, md, phd
TRANSCRIPT
Update on the Use of Ultrasound in the Diagnosis of Carpal Tunnel
Syndrome
Renato A. Sernik, MD, PhD
t
Flexor retinaculum
median nerve
median nerve
carpal tunnel
• Common compressive neuropathy.• Initially, pain and sensitivity changes in the median nerve territory.• Advanced stages – weakness and atrophy of the thenar muscles.
Carpal Tunnel Syndrome
Carpal Tunnel Syndrome
- useful as a screening test, reducing the cost of diagnosis of carpal tunnel syndrome.
Fowler JR, Maltenfort MG, Ilyas AM. Ultrasound as a first-line test in the diagnosis of carpal tunnel syndrome: a cost-effectiveness analysis. Clin Orthop Relat Res. 2013 Mar;471(3):932-7.
Ultrasonography
Linear transducers:-12 –18 MHz.-High resolution.
PERIPHERAL NERVE ANATOMY
fiber
fasciclenerve
perineurium
scaphoid pisiform
trapeziumhamate
flexor retinaculum
Carpal Tunnel
PIS
CARPAL TUNNEL
* a
n
scaphoidpisiform
a u fu
* PIS
scaphoid pisiform
trapezium
hamatetrapezium
hamate
ULTRASONOGRAPHY
Median Nerve Evaluation
• Qualitative• Quantitative
Qualitative Evaluation
- shape-echogenicity-structure
Echogenicity / structures
Shape
• COMPRESSION• EDEMA HOURGLASS SHAPE
carpal tunnel
median nerve
proximal distal
Quantitative Evaluation
In 1991, Buchberger et al. proposed 3 criteria for sonographic diagnosis of the carpal tunnel syndrome:
- increase in cross-sectional area of the median nerve, proximal to the compression.- thinning of the median nerve at the site of the compression, measured by the ratio of two diameters of the nerve.- bulging of the flexor retinaculum.
Carpal Tunnel Syndrome
In 1991, Buchberger et al. proposed 3 criteria for sonographic diagnosis of the carpal tunnel syndrome:
- increase in cross-sectional area of the median nerve, proximal to the compression.- thinning of the median nerve at the site of the compression, measured by the ratio of two diameters of the nerve.- bulging of the flexor retinaculum.
Carpal Tunnel Syndrome
Quantitative Evaluation
The measurement of the area must be made where it is greater
At the entrance carpal tunnel or in the proximal carpal tunnel
Median Nerve Área
Fowler JR, Gaughan JP, Ilyas AM. The sensitivity and specificity of ultrasound for the diagnosis of carpal tunnel syndrome: a meta-analysis. Clin Orthop Relat Res. 2011 Apr;469(4):1089-94.
Tai TW, Wu CY, Su FC, Chern TC, Jou IM. Ultrasonography for diagnosing carpal tunnel syndrome: a meta-analysis of diagnostic test accuracy. Ultrasound Med Biol. 2012 Jul;38(7):1121-8.
Fowler JR, Gaughan JP, Ilyas AM. The sensitivity and specificity of ultrasound for the diagnosis of carpal tunnel syndrome: a meta-analysis. Clin Orthop Relat Res. 2011 Apr;469(4):1089-94.
- increase the area of the median nerve used as diagnostic criteria. - Cutoff 9 -11mm².- sensitivity 77.6% and specificity 86.8%.
Tai TW, Wu CY, Su FC, Chern TC, Jou IM. Ultrasonography for diagnosing carpal tunnel syndrome: a meta-analysis of diagnostic test accuracy. Ultrasound Med Biol. 2012 Jul;38(7):1121-8.
Mhoon JT, Juel VC, 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 Dec;46(6):871-8.
Ultrasonography in Carpal Tunnel Syndrome
Fowler JR, Maltenfort MG, Ilyas AM. Ultrasound as a first-line test in the diagnosis of carpal tunnel syndrome: a cost-effectiveness analysis. Clin Orthop Relat Res. 2013 Mar;471(3):932-7.
Cutoff- 10 mm2 sensitivity – 85.0%
specificity – 92.1%
accuracy – 89.3%
Tai TW, Wu CY, Su FC, Chern TC, Jou IM. Ultrasonography for diagnosing carpal tunnel syndrome: a meta-analysis of diagnostic test accuracy. Ultrasound Med Biol. 2012 Jul;38(7):1121-8.
pronador quadratus
Comparative Evaluation
carpal tunnel
A1
A2
Normal Nerve:A1- A2 ≤ 2mm²
Thickened Nerve:A1- A2 ≥ 2mm²
pronador quadratus
A1
A2
carpal tunnel
Palmar Cutaneus Branch(PCB) of the Median Nerve
antebrachial fascia
flexor retinaculum
median nerve median nerve
FCRT
palmaris longus t
Palmar Cutaneus Branch of the Median Nerve
• Compression in the tunnel.• Stretching as a consequence to reduced mobility of the
median nerve.
FCRT
median nerve
PCB
median nerve FCRT
palmaris longus t
Median nerve
median nerve
median nerve
Post-Operative - Carpal Tunnel Syndrome
Post-Operative - Carpal Tunnel Syndrome
median nerve
median nerve
CONCLUSION
Ultrasound in Carpal Tunnel Syndrome
• The method doesn’t predict severity.• useful as a screening test, reducing the cost of diagnosis
of carpal tunnel syndrome.• post-operative evaluation.
