Presenters

Julia AguirreFollow

Academic department under which the project should be listed

CSM - Molecular and Cellular Biology

Faculty Sponsor Name

Dr. Stephen Barrett

Abstract (300 words maximum)

A neurological phenomenon has been observed clinically that when after a small amount of 1% lidocaine (usually less than .5cc’s) has been infiltrated adjacent to the Common Fibular (Peroneal) nerve under sonographic guidance, in patients with drop foot, or significantly weakened motor potentials of the lower extremity dorsiflexors (Extensor Hallucis Longus (EHL), Tibialis Anterior (TA), and Extensor Digitorum Longus (EDL)), the patient will regain partial or full dorsiflexion temporarily during the effect of this nerve block. This has been named the Phoenix Sign, in reference to ancient Greek folklore, as the non-functioning nerve (like the bird) becomes functional due to the effect of lidocaine, similar in a way that the mythical bird rose from the ashes. This sign has significant benefit to the diagnosis and assessment of Common Fibular (Peroneal) nerve palsy as clinically when a nerve does not manifest a Tinel’s or Provocation sign it is believed that the nerve damage is so severe that peripheral nerve decompression will not likely benefit the patient. However, when a patient manifests a “positive Phoenix sign” the prognosis has been greater than 90%--that the patient will gain improvement in motor function of the dorsiflexors of the lower extremity after surgical decompression. Thus, many patients with this crippling condition are not receiving definitive treatment because of the inability of standard clinical work-up and diagnosis. A “positive Phoenix sign” also differentiates a focal nerve compression peripherally versus a central CNS manifestation. It is hypothesized that this observation of improved nerve function is due to the vasodilatory nature of the local anesthetic. By comparing the block given with lidocaine versus papaverine (a known vasodilator), the vasodilation hypothesis can be tested. The purpose of this study is to help determine if this is a valid explanation for the phenomenon.

Project Type

Event

Honors Capstone Proposal pdf.pdf (82 kB)
Honors Capstone Proposal detailing study

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The Phoenix Sign: Is it due to vasodilation? Blinded prospective comparing the effects of papaverine to lidocaine without epinephrine

A neurological phenomenon has been observed clinically that when after a small amount of 1% lidocaine (usually less than .5cc’s) has been infiltrated adjacent to the Common Fibular (Peroneal) nerve under sonographic guidance, in patients with drop foot, or significantly weakened motor potentials of the lower extremity dorsiflexors (Extensor Hallucis Longus (EHL), Tibialis Anterior (TA), and Extensor Digitorum Longus (EDL)), the patient will regain partial or full dorsiflexion temporarily during the effect of this nerve block. This has been named the Phoenix Sign, in reference to ancient Greek folklore, as the non-functioning nerve (like the bird) becomes functional due to the effect of lidocaine, similar in a way that the mythical bird rose from the ashes. This sign has significant benefit to the diagnosis and assessment of Common Fibular (Peroneal) nerve palsy as clinically when a nerve does not manifest a Tinel’s or Provocation sign it is believed that the nerve damage is so severe that peripheral nerve decompression will not likely benefit the patient. However, when a patient manifests a “positive Phoenix sign” the prognosis has been greater than 90%--that the patient will gain improvement in motor function of the dorsiflexors of the lower extremity after surgical decompression. Thus, many patients with this crippling condition are not receiving definitive treatment because of the inability of standard clinical work-up and diagnosis. A “positive Phoenix sign” also differentiates a focal nerve compression peripherally versus a central CNS manifestation. It is hypothesized that this observation of improved nerve function is due to the vasodilatory nature of the local anesthetic. By comparing the block given with lidocaine versus papaverine (a known vasodilator), the vasodilation hypothesis can be tested. The purpose of this study is to help determine if this is a valid explanation for the phenomenon.