Common Peroneal Neuropathy Clinical Trial
Official title:
Role of Sensory Potentials and High-resolution Ultrasonography in Confirmation of Common Peroneal Mononeuropathy at the Fibular Neck
Common peroneal mononeuropathy at the fibular neck (CPN) is one of the most frequent
mononeuropathies of the lower extremities.
The common peroneal nerve sub serves sensation to the dorsum of the foot and toes. In CPN
motor fibers of the deep peroneal nerve are more frequently affected than those of the
superficial peroneal nerve. Fascicles of the deep branch of the common peroneal nerve are
more anteriorly located and more vulnerable to injury than those of the superficial peroneal
branch. The clinical and electrodiagnostic findings in CPN resemble the anatomical structure
of the common peroneal nerve, indeed fibers for the deep peroneal nerve and the superficial
peroneal nerve are bounded in separate fascicles along the course of the nerve.
Superficial peroneal nerve sensory potential (SPSP) should be performed to localize the site
of injury.
Electrodiagnostic testing is used widely to evaluate the function of the common peroneal
nerve. SPSP have been examined in CPN with conflicting results. A loss in amplitude of this
response implies some axonal loss affecting either the common peroneal nerve or its
superficial branch. Prominent axonal loss is the hallmark of most CPN lesions and suggested
that abnormalities in sensory nerves mirror those in motor nerves.
Moreover, assessment of the structure of the common peroneal nerve is likely to improve the
diagnostic yield" by using high-resolution ultrasonography. Ultrasound imaging is painless,
does not expose the patient to radiation, and has several advantages compared with magnetic
resonance imaging in the laboratory setting, including reduced cost, accessibility, ability
to image the entire length of the nerve in a single study, and the ability to image both
statically and dynamically.
This study was conducted to evaluate the superficial peroneal sensory potential and
high-resolution ultrasonography role in confirmation of common peroneal mononeuropathy at the
fibular neck.
The current study is a case control study that was done in the period from January 2015 to
January 2016. The study included 70 participants presented with clinical and
electrophysiological evidence of common peroneal neuropathy at the fibular neck (CPN)
attending to Zagazig University Hospitals (Neurology, Rheumatology& Rehabilitation, and
Orthopedic departments) and insurance hospitals of Sharkia governorate (47 male and 23
female). Their age (mean ± SD/years) was 40.4± 12.9, the duration between the onset of
symptom and enrollment in the study ranged between 21 days to 6 months. Seventy (45 males and
25 females) apparently healthy volunteers were included as controls, and their age (mean ±
SD/ years) was 41.3 ± 11.8. They were selected from the persons attending to blood bank for
blood donation.
All participants included in the present study are subjected to:
1. Full history taking.
2. Thorough clinical and neurological examination.
3. Routine laboratories tests for exclusion of other systemic affection like diabetes
mellitus, renal or hepatic failure.
4. Electrodiagnostic studies
All tests were done in the same room, at the time of clinical diagnosis using a Nicolet
Viking Quest cart electrodiagnostic system. Lower extremity temperature was maintained
at or above 30º C at time of examination. The electrophysiological studies included the
following:
A-Motor nerve conduction studies:
Motor conduction study of the common peroneal nerve (ankle-fibular neck -popliteal
fossa), tibial motor nerve conduction study were performed with surface disc recording
electrodes for the affected limb and the contralateral limb in all subjects. Evaluations
of both upper limbs were added to exclude more wide lesions if suspected.
Common peroneal CMAPs were recorded over extensor digitorum brevis and tibialis
anterior.
Investigators considered that the lesion is axonal via axonal loss estimation:
Axonal loss of the motor branch of the common peroneal nerve was estimated by comparing
the CMAP amplitude recorded from the extensor digitorum brevis on the affected and
contralateral sides.
An estimate of EDB axonal loss was obtained from the formula (U -A)/U ×100 U : (extensor
digitorum brevis response amplitude from the unaffected side).
A : (extensor digitorum brevis response amplitude from the affected side).
Categorization based on the motor estimated axonal loss as follow:
No loss: (<50%). Mild to moderate loss: (50-75%). Severe loss: (>75%).
B- Sensory nerve conduction studies:
Antidromic evaluation of the superficial peroneal nerve sensory potential (SPSP) at the
ankle was studied with surface stimulating and recording electrodes on the affected limb
and the contralateral limb in all subjects. The site of stimulation was just anterior to
the edge of the shaft of the fibula and 14 cm proximal to the active ankle electrode.
The active recording electrode was placed midway between the edge of the tibia and the
tip of the lateral malleolus or 3 cm proximal to the bimalleolar line. The reference
recording electrode was placed 3 cm distal to the active electrode.
SPSP was considered affected when any one of the following is detected :
- No constant wave forms could be detected.
- SPSP amplitudes < 5 μv or < 50% of the contra lateral side.
- Increased peak latency ≥ 4.4 ms (based on standard distance of 14 cm).
C-Electromyographic study (EMG) was carried out using concentric needle in the following
muscles: extensor digitorum brevis (EDB), tibialis anterior, peroneus longus, tibialis
posterior, extensor halucis longus, short head of biceps femoris, vastus lateralis,
medial head of gastrocnemius, iliacus, gluteus medius, tensor fascia lata and Paraspinal
muscles. Concentric needle EMG was performed in all patients. Spontaneous and voluntary
motor unit activity was assessed.
5. Radiological examination:
A) Ultrasonographic assessment of participants:
Ultrasonographic examination by radiologist was conducted with a General Electric Logiq 7 Pro
machine (GE Healthcare, Chalfont St Giles, England), using a 5- to 12-MHz linear array
transducer. The cross sectional area (CSA) of the common peroneal nerve was determined within
the echogenic rim surrounding the nerve at the level of the fibular neck with the probe
perpendicular to the main nerve course in the transverse and longitudinal plane. The
sonographic measurements were done on the same day or within 1 week after the
electrodiagnostic studies.
The radiologist was blinded to the participants' electrophysiological study data. However,
the radiologist was aware of the clinical and electrophysiological suspicion for common
peroneal neuropathy.
Authors of the present study considered that common peroneal nerve is affected by the
sonographic measurements if the value of CSA of the common peroneal nerve at the fibular neck
was >11 mm2 according to the study control group.
B) Plain radiographs were done to detect the underlying traumatic injuries, such as a
proximal fibular head fracture or osseous tumors, or in assessing the severity of angular
deformities about the knee. Lumbosacral plain X ray or MRI were done only if needed to rule
lumbosacral affection.
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