Electrophysiologic features of fibular neuropathy in childhood and adolescence.

INTRODUCTION: We studied patterns of nerve injury in pediatric common fibular (peroneal) neuropathy (CFN). METHODS: A retrospective analysis was performed on data from 53 children with CFN at a pediatric electromyography laboratory. RESULTS: Conduction block at the fibular head was present in 35% of patients. Deep fibular axonal loss was identified in 77%, while superficial fibular axonal loss was identified in 45%. The pathophysiology was predominantly axonal in 72%, mostly demyelinating in 6%, and mixed in 22%. Predominantly demyelinating lesions at the fibular head demonstrated sparing of the superficial fibular sensory nerve (P = 0.01, Fischer exact test). Predominantly axonal lesions had a moderate correlation between superficial and deep fibular axonal loss (Spearman r = 0.52; P = 0.0001). CONCLUSIONS: There is frequent axonal and fascicular injury in pediatric CFN, similar to adults. Deep and superficial fibular nerve involvements correlate in axonal lesions, whereas superficial fibular sensory fibers are often spared in demyelinating lesions. Muscle Nerve, 2016 Muscle Nerve 55: 693-697, 2017.

Core outcomes in nerve surgery: development of a core outcome set for common peroneal (fibular) neuropathy.

OBJECTIVE: Common peroneal (fibular) neuropathy is the most common mononeuropathy of the lower extremity. Despite this, there are surprisingly few studies on the topic, and a knowledge gap remains in the literature. As one attempts to address this knowledge gap, a core outcome set (COS) is needed to guide the planning phases of future studies to allow synthesis and comparability of these studies. The objective of this study was to develop the COS-common peroneal neuropathy (CoPe) using a modified Delphi approach. METHODS: A 5-stage approach was used to develop the COS-CoPe: 1) stage 1, consortium development; 2) stage 2, a literature review to identify potential outcome measures; 3) stage 3, a Delphi survey to develop consensus on outcomes for inclusion; 4) stage 4, a Delphi survey to develop definitions; and 5) stage 5, a consensus meeting to finalize COS and definitions. The study followed the COS-STAndards for Development (COS-STAD) recommendations. RESULTS: The Core Outcomes in Nerve Surgery (COINS) Consortium comprised 23 participants, all neurological surgeons, representing 13 countries. The final COS-CoPe consisted of 31 data points/outcomes covering domains of demographics, diagnostics, patient-reported outcomes, motor/sensory outcomes, and complications. Appropriate instruments, methods of testing, and definitions were set. The consensus minimum duration of follow-up was 12 months. The consensus optimal time points for assessment were preoperatively and 3, 6, 12, and 24 months postoperatively. CONCLUSIONS: The COINS Consortium developed a consensus COS and provided definitions, methods of implementation, and time points for assessment. The COS-CoPe should serve as a minimum set of data that should be collected in all future neurosurgical studies on common peroneal neuropathy. Incorporation of this COS should help improve consistency in reporting, data synthesis, and comparability, and should minimize outcome reporting bias.

Branching Patterns and Anatomical Course of the Common Fibular Nerve.

OBJECTIVE: To present the branching patterns and anatomical course of the common fibular nerve (CFN) and its relationship with fibular head (FH). METHODS: A total of 21 limbs from 12 fresh cadavers were dissected. The FH width (FH_width), distance between the FH and CFN (FH_CFN), and thickness of the nerve were measured. The ratio of the FH_CFN to FH_width was calculated as follows: <1, cross type and ≥1, posterior type. Angle between the CFN and vertical line of the lower limb 5 cm proximal to the tip of the FH was measured. Branching patterns of the lateral cutaneous nerve of the calf (LCNC) were classified into four types according to its origin and direction as follows: type 1a, lateral margin of the CFN; type 1b, medial margin of the CFN; type 2, lateral sural cutaneous nerve (LSCN); and type 3, CFN and LSCN. RESULTS: In the cross type (15 cases, 71.4%), the ratio of FH_CFN/FH_width was 0.83 and the angle was 13.0°. In the posterior type (6 cases, 28.6%), the ratio was 1.04 and the angle was 11.0°. In the branching patterns of LCNC, type 2 was the most common (10 cases), followed by types 1a and 1b (both, 5 cases). CONCLUSION: Location of the CFN around the FH might be related to the development of its neuropathy, especially in the cross type of CFN. The LCNC showed various branching patterns and direction, which could be associated with difficulties of electrophysiologic testing.

Quantitative assessment of nerve echogenicity as an additional tool for evaluation of common fibular neuropathy.

OBJECTIVE: Quantitative assessment of nerve echogenicity using the MaxEntropy, RenyiEntropy and Yen methods has shown promise in the assessment of ulnar neuropathy at the elbow. The purpose of this study was to determine the clinical usefulness of quantitative echogenicity measurement when using these three automatic thresholding methods in the evaluation of patients with common fibular (CF) neuropathy. METHODS: High-resolution ultrasonography (HRUS) images of the CF nerve from 45 patients with CF neuropathy were compared to 42 healthy controls. RESULTS: With all three methods patients with CF neuropathy had significantly higher mean hypoechoic fraction than healthy controls at the level of the fibular head (FH): MaxEntropy 87.4% versus 71.9% (p<0.001), RenyiEntropy 84.7% versus 68% (p<0.001) and Yen 87.6% versus 68.2% (p<0.001). Patients with CF neuropathy could be differentiated from healthy controls at a hypoechoic fraction cut-off point of 82% (MaxEntropy), 80% (RenyiEntropy) and 80% (Yen) with a sensitivity of 82%, 82% and 84% respectively, and a specificity of 93%, 95% and 83% respectively. Similar results were found for sonographic measurements above the FH. CONCLUSION: Quantitative assessment of nerve echogenicity using the MaxEntropy, RenyiEntropy and Yen methods can be used to distinguish between patients with CF neuropathy and healthy controls with high sensitivity and specificity. SIGNIFICANCE: These three proven automatic thresholding methods can be used to assess nerve echogenicity in future studies. Quantitative echogenicity assessment with HRUS shows promise for the future as a potential diagnostic tool in daily clinical practice.

Ultrasound and neurophysiological correlation in common fibular nerve conduction block at fibular head.

OBJECTIVE: Ultrasound (US) and neurophysiological examination are useful tools in the evaluation of common fibular mononeuropathy. There is only a report comparing US and electrophysiological parameters in patients with common fibular nerve (CFN) conduction block at fibular head. We investigated the correlation between US and neurophysiologic findings in this condition. METHODS: We retrospectively reviewed patients with CFN assessed in our lab during last 2 years. Each patient underwent to clinical, neurophysiological and ultrasound evaluations. Cross sectional area (CSA) of CFN at fibular head was assessed. RESULTS: Twenty-four patients were included. Motor nerve conduction study showed a reduction of distal compound muscle action potential (CMAP) amplitude in 10 patients (mean 1.3 mV). US showed an increased CSA in 10 patients. Statistical analysis revealed a strong correlation between the increased CSA and the CMAP reduction of CFN. CONCLUSION: Our data suggest that usually US examination is normal in CFN conduction block at fibular head. However the association with axonal damage is frequently accompanied by an increase of CSA. SIGNIFICANCE: Ultrasound evaluation may represent a powerful diagnostic/prognostic tool in cases with CPN conduction block at fibular head because it usually shows normal pattern in pure conduction block and increase of CSA in associated axonal damage.

Branching Patterns and Anatomical Course of the Common Fibular Nerve

OBJECTIVE: To present the branching patterns and anatomical course of the common fibular nerve (CFN) and its relationship with fibular head (FH).METHODS: A total of 21 limbs from 12 fresh cadavers were dissected. The FH width (FH_width), distance between the FH and CFN (FH_CFN), and thickness of the nerve were measured. The ratio of the FH_CFN to FH_width was calculated as follows: < 1, cross type and ≥1, posterior type. Angle between the CFN and vertical line of the lower limb 5 cm proximal to the tip of the FH was measured. Branching patterns of the lateral cutaneous nerve of the calf (LCNC) were classified into four types according to its origin and direction as follows: type 1a, lateral margin of the CFN; type 1b, medial margin of the CFN; type 2, lateral sural cutaneous nerve (LSCN); and type 3, CFN and LSCN.RESULTS: In the cross type (15 cases, 71.4%), the ratio of FH_CFN/FH_width was 0.83 and the angle was 13.0°. In the posterior type (6 cases, 28.6%), the ratio was 1.04 and the angle was 11.0°. In the branching patterns of LCNC, type 2 was the most common (10 cases), followed by types 1a and 1b (both, 5 cases).CONCLUSION: Location of the CFN around the FH might be related to the development of its neuropathy, especially in the cross type of CFN. The LCNC showed various branching patterns and direction, which could be associated with difficulties of electrophysiologic testing.