The Dose and Volume-Response Relationship of an Ethanol-Induced Tibial Nerve Block in a Rabbit Model

Ethyl Alcohol Versus Botulinum Toxin A: A Comparative Study of the Visual and Histopathological Outcomes in the Rabbit Anterior Auricular Muscle Model

BACKGROUND

Botulinum toxin has long been known for its paralytic effects at the neuromuscular junction. Although it has been widely used for vascular and nervous tissues, there has been no study of the aesthetic effects of the application of ethanol to muscle tissues to date.

OBJECTIVE

The authors aimed to demonstrate the effects of the application of ethanol to muscle tissues after an intramuscular injection and to compare the effects of botulinum toxin A (BTA) and ethanol.

METHODS AND MATERIALS

A total of 28 rabbits were divided into 4 groups (n = 7 each). Botulinum toxin A (5 units) and different concentrations of ethanol (5 cc) were injected into the left and right anterior auricular muscles of all rabbits, respectively. Ear ptosis was assessed, and histopathological examination was performed after all rabbits were euthanized in the eighth week.

RESULTS

Muscle function was affected earlier in ethanol-treated ears than in botulinum-treated ears; however, the ptotic effect lasted for a significantly shorter duration in ethanol-injected ears than in BTA-applied ears.

CONCLUSION

Ethanol can block muscle function reversibly and can serve as an alternative to BTA, particularly when rapid results are desirable.

Effect of perivascular low dose ethanol on rat femoral vessels: Preliminary study

Vasospasm is one of the important causes of morbidity in free flap and replantation surgery. In secondary Raynaud's phenomenon, nearly half of the patients experience digital ulceration, pain and loss of function at least once in their lifetime. The aim of this study is to investigate the vasodilation effect of ethanol-mediated chemical denervation on peripheral vessels by topical administration. In this study, 27 Wistar albino male rats weighing 250-300 grams were used. The rats were randomly divided into three groups: saline (group S, n = 8), lidocaine (group L, n = 9) and 96% ethanol (group E, n = 9). According to group, 0.1 mL saline, 0.1 mL lidocaine and 0.1 mL ethanol were applied around the rat femoral neurovascular bundle. After the application, on the 0th day and 3th weeks, femoral artery and vein diameters were measured. After 3. weeks, histopathological samples from femoral artery, vein and nerve were evaluated. On the 0th day, the mean diameter of the femoral artery and vein was similar in group E and L and higher than group S. After three weeks, the vasodilatation effect of ethanol was increased in group E. In Group L and S, the vasodilatation effect was lost. Histopathological examination showed that ethanol significantly caused perivascular inflammation and nerve degeneration compared to other agents and did not cause endothelial damage. Vasodilatation obtained by ethanol is a rapid onset and long-lasting effect. It is also inexpensive and effective for peripheral vasodilatation.

Improved Injection Technique of Ethanol for Morton's Neuroma

BACKGROUND

Morton's neuroma is a common cause of forefoot pain. Various conservative methods (injections of various pharmacologic agents) have been published with an outcome of 6%-75% success rate (free of pain in daily life) per injection. The aim of the present study was to assess the outcome of an improved localization technique, a higher dosage, and a higher percentage of ethanol.

METHODS

Using fluoroscopic and electroneurographic guidance, 2.5 mL of 70% ethanol were injected into 33 feet with a magnetic resonance imaging (MRI)-verified neuroma. We evaluated patients at up to 5-year follow-up.

RESULTS

A "success rate" of more than 82% per single injection (defined as free of pain in daily life) was achieved and no recurrence was seen over 5 years. All scores (visual analog scale; Short Form-36 subscales, American Orthopaedic Foot & Ankle Society ankle-hindfoot score) showed significant improvement (P < .0001). Mean 1.2 injections were necessary. No significant side effects were seen. However, some mild pain persisted in some patients who participated in sports.

CONCLUSION

The injection of 2.5 mL of 70% ethanol under fluoroscopic and electroneurographic guidance was a safe method for the treatment of MRI-verified Morton's neuromas. Combining the effect of a higher percentage of alcohol and a higher dosage and an improved localization technique resulted in a high rate of patients without pain.

LEVEL OF EVIDENCE

Level IV, cases series, prospective.