Learning objectives
To understand the basic anatomy of the common peroneal nerve and adjacent structures of the knee to perform routine ultrasound (US) exams when neuropathy is suspected.
To know the frequent causes of common peroneal nerve neuropathy and their corresponding imaging findings on US examinations.
To know the limits of an ultrasound examination.
Background
The common peroneal nerve (CPN) is a frequent site of focal neuropathy of the lower limbs.
ANATOMY (Fig. 1
CPN is the lateral branch of division of the sciatic nerve at the level of the popliteal fossa.
Main landmarks used for ultrasound are (Fig. 2):
medially: the lateral head of the gastrocnemius muscle
laterally: biceps femoris tendon
The CPN then courses around the neck of the fibula just beneath the proximal aspect of the peroneus longus tendon: this is the fibular tunnel (Fig. 3 ....
Imaging findings OR Procedure Details
Standard knee x-ray must be performed before any ultrasound procedure:
Proximal tibiofibular joint osteoarthritis,
tumor of the fibular head and presence of fabella must be assessed.
Prior to the ultrasound exam,
it is also essential to get full medical history of the patient to look for occupationnal or microtraumatic causes,
prior trauma or surgery.
NORMAL ULTRASOUND FINDINGS (Fig. 5 and Fig. 6)
For an optimal resolution,
a high-end ultrasound unit equipped with a high-resolution broadband linear-array probe and corresponding soft-tissue software are necessary.
CPN is...
Conclusion
When performing ultrasound scan for suspected common peroneal nerveneuropathy,
it must be kept in mind that:
- X-Ray and full medical history must be available before performing the exam.
- Anormal ultrasound does not exclude the diagnosis.
- The examination must be comparative to detect subtle changes in size and echogenicity of the nerve to diagnose beginning neuropathy.
- The second step is to look for the cause and ultrasound is especially helpful in demonstrating tumoral causes.
- When the findings are not typical of...
References
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Marciniak C.
Fibular (peroneal) neuropathy: electrodiagnostic features and clinical correlates.
Phys Med Rehabil Clin N Am.
févr 2013;24(1):121-37.
2.
Ryan W,
Mahony N,
Delaney M,
O’Brien M,
Murray P.
Relationship of the common peroneal nerve and its branches to the head and neck of the fibula.
Clin Anat N Y N.
nov 2003;16(6):501-5.
3.
Spinner RJ,
Atkinson JLD,
Tiel RL.
Peroneal intraneural ganglia: the importance of the articular branch.
A unifying theory.
J Neurosurg.
août 2003;99(2):330-43.
4.
Sunderland S.
Blood supply of the sciatic...