Identifying Peroneal Neuropathy Before Foot Drop
Johnny Chuieng - Yi Lu, M.D., Washington University in St. Louis, St. Louis, MO, Jana Dengler, M.D., Washington University School of Medicine, Saint Louis, MO, Louis Poppler, M.D., Washington University in St.Louis, St. Louis, MO and Susan E. Mackinnon, MD, Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO
Background: Entrapment common peroneal neuropathy (CPN) is often associated with foot drop and associated risk of falling. This presentation, however, represents the advanced stages of neuropathy. We hypothesize that CPN presents along a spectrum of severity, that yields varying responses to surgical decompression. Earlier recognition of CPN can prevent clinical deterioration to the point of foot drop, and decrease associated morbidity from falls.
The authors sought to elucidate the range of symptomatology associated with CPN, evaluate the responses to surgery and identify variables that predict successful outcome following surgical decompression.
Material and Methods: We performed a retrospective chart review of 185 CPN patients who received surgical decompression between the years 2011 and 2017. Patients were divided into 3 stages of severity based on previously published classification: mild, subclinical and overt CPN (most severe). Demographics, presenting symptoms, clinical signs, electrodiagnostic studies and response to surgery were evaluated. Multivariate regression analysis was used to identify variables that predicted outcome following surgery.
Results: Overt CPN presented with significantly higher frequency of foot drop (93.9%), abnormal motor nerve conduction studies (37.4%) and lower preoperative motor function (MRC grade 0.80 ±0.13). Subclinical CPN presented with a higher percentage of pain as the presenting complaint (60.5%), normal electrodiagnostic studies (31.4%), and higher preoperative pain VAS score (6.18 ±0.22). Postoperatively, overt CPN showed greater improvement in motor function (2.32 ±0.22, p < 0.001), while subclinical CPN showed greater improvement in pain scores (1.72 ±0.29, p = 0.287). Both groups showed surgical decompression had a greater impact on quality of life than in mild CPN. Age, history of falling, history of lumbar radioculopathy, obesity, preoperative motor function and pain VAS scores predict outcomes after surgery.
Conclusion: CPN presents with varying signs and symptoms based on the degree of severity, which can be distinguished without electrodiagnostic studies. Clinical suspicion can assist in early diagnosis, appropriate treatment and help prevent associated morbidity.
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