High-Resolution Ultrasound as a Diagnostic Adjunct in Common Peroneal Neuropathy

Abstract

High-Resolution Ultrasound as a Diagnostic Adjunct in Common Peroneal Neuropathy E ntrapment neuropathy of the common peroneal nerve is caused mostly by compression at the fibula head region. 1 In cases of severe axon loss, demonstration of conduction block or reduction of conduction velocity would be difficult. Apart from demyelination, mechanical factors and ischemic mechanisms may play a role. 2 Differing degrees of damage to individual nerve fascicles may occur within the common peroneal nerve, 3 rendering interpretation of needle electromyography (EMG) difficult. High sciatic nerve lesions are also known to mimic peroneal neuropathy at the fibular head if electrodiagnostic examination is not performed adequately. 1 High-resolution ultrasonography (US) may be a potential diagnostic tool in these technically challenging circumstances. Methods. Over a 1-year period, we studied 32 healthy controls and 8 otherwise well patients who presented with footdrop. All controls and patients underwent US of the peroneal nerve as well as electrodiagnostic studies. Peroneal sensory and motor nerve conduction studies (NCS) were performed with standard techniques. Blinded US examination was conducted with a General Electric Logiq 7 Pro machine (GE Healthcare, Chalfont St Giles, England), using a 5-to 10-MHz linear array transducer. Transverse scans of the peroneal nerves were obtained at the level of the fibula head bilaterally with the subject's legs supported and slightly flexed (20°to 30°) at the knees in the lateral position (Figure 1). We measured the maximum transverse length, maximum transverse breadth (perpendicular to transverse length), ratio of these 2 parameters (breadth/length), and cross-sectional area (Figure 2). The upper limit of normality was 2 SDs above the mean. PϽ.05 was considered statistically significant.

Diagnostic Cutoff Value for Ultrasonography of the Common Fibular Neuropathy at the Fibular Head

“…To date, many studies have reported that ultrasonographic measurement is a beneficial diagnostic tool for nerve disorders with significant positive correlation with electrodiagnostic study [111516171819]. Ultrasonography visualizes the anatomy of the affected structures and provides morphological information.…”

“…In case of CFN at the FH secondary to the intraneural ganglion cyst that needs surgical procedure, ultrasonography leads to more accurate prognosis by detecting the etiology, which might not be identified by electrophysiological study alone [15]. Moreover, if electrodiagnostic study is performed inadequately or insufficiently, ultrasonography could be a supplementary tool for accurate diagnosis by differentiating from lesions that mimic CFN at the FH such as high sciatic nerve lesion [11]. Ultrasonography in addition to electrodiagnostic study reportedly improves specificity to 88% in CFN at the FH [10] and sensitivity up to 98% in ulnar neuropathy at the elbow [18].…”

“…Thus, determination of reference value of CSA is crucial to identification of nerve pathology and proper diagnosis [69]. However, there are few systemic studies and no standard consensus on ultrasonographic measurements and diagnostic cutoff value for the CFN at the FH [169101112]. Several studies reported ultrasonographic findings of patients with foot drop and demonstrated the value of ultrasonography as a diagnostic tool; however, they included small number of patients [11112].…”

“…However, there are few systemic studies and no standard consensus on ultrasonographic measurements and diagnostic cutoff value for the CFN at the FH [169101112]. Several studies reported ultrasonographic findings of patients with foot drop and demonstrated the value of ultrasonography as a diagnostic tool; however, they included small number of patients [11112]. Moreover, one of the studies on subjects whose etiology was confined to weight loss showed no significant difference in nerve thickening between symptomatic and asymptomatic sides [12].…”

Rapid ultrasonographic diagnosis of radial entrapment neuropathy at the spiral groove

“…The pathophysiology of nerve swelling and thickening is complex, and may involve endoneural edema, demyelination, axonal degeneration, and fibrosis [16,17]. To this end, future research may further explore this intriguing issue [18].…”