Predictive Reliability of the Phoenix Sign for the Outcome of Common Fibular (Peroneal) Nerve Decompression Surgery

A positive Phoenix sign occurs when a patient, with a suspected focal nerve entrapment of the Common Fibular (Peroneal) Nerve (CFN) at the level of the fibular neck, demonstrates an improvement in dorsifexion after an ultrasound guided infiltration of a sub-anesthetic dose of lidocaine. Less than 5 cc’s of 1% or 2% lidocaine is utilized and the effect is seen within minutes after the infiltration, but usually lasts only 10 minutes. This effect may be due to the vasodilatory action of lidocaine on the microcirculation in the area of infiltration. This nerve block has significant diagnostic utility as it is highly specific in the confirmation of true focal entrapment of the CFN, has high predictive value for a patient who may undergo surgical nerve decompression if they have demonstrated a positive Phoenix Sign, and may help in the surgical decision-making process in patients who have had a drop foot for many years but still may regain some motor function after decompression. In this retrospective review, 26 patients were tested, and 25 of this cohort demonstrated a Positive Phoenix Sign (an increase in dorsiflexion strength of the Extensor Hallucis Longus muscle (EHL)). One patient had no response to the peripheral nerve block. Of the 25 patients who demonstrated a positive “Phoenix Sign” and underwent nerve decompression of the CFN, and 25 (100%) showed an increase in dorsiflexion strength of the EHL after nerve decompression surgery of the CFN. The one patient in this cohort who did not demonstrate any improvement in dorsiflexion of the EHL after the nerve block did not have any improvement after surgery.

Endocsopic Decompression of Intermetatarsal Nerve (EDIN) for the Treatment of Morton’s Entrapment— Multicenter Retrospective Review

Background: The authors present the results of a four surgeon, multicenter study of endoscopic decompression for the treatment of Civinini-Morton’s entrapment of 193 interspaces. Methods: A retrospective review of 193 interspaces, which were decompressed by four different surgeons. Results: The overall success rate was high, with 92% of patients reporting a good or fair outcome. Higher success rates were reported in the 3rd interspace decompression group (95%) compared to the 2nd interspace decompression group (85%). Complications reported were minimal, with only seven cases requiring a revision with traditional neurectomy. No revisions were required in the 3rd interspace decompression group. Five of the revisions were in the 2nd interspace decompression group, with the remaining two revisions in the combined 2nd/3rd interspace decompression group. Conclusions: Endoscopic decompression for the treatment of Civinnini-Morton’s entrapment is a safe and efficacious method of treatment of this nerve entrapment, with very low complication rates and rapid return to normal activity.