Effects of alcohol injection in rat sciatic nerve as a model for Morton's neuroma treatment

Bone marrow stem cells with or without superparamagnetic iron oxide nanoparticles as a magnetic targeting tool: Which is better in regeneration of neurolysed facial nerve? An experimental study

Aim

This study was performed to evaluate neural regenerative capacities of bone marrow stem cells (BMSCs) with or without superparamagnetic iron oxide nanoparticles (SPIONs) as a magnetic targeting tool after neurolysis of the facial nerve (FN) in albino rats.

Methods

Thirty-eight male albino rats were selected. Two of them were euthanized for normal FN histology assessment. Thirty-six rats were injected with ethanol in the FN nerve for neurolysis induction and assessed one week post-operatively by eye blinking test. Animals were divided into three groups, each containing twelve rats: Group I (positive control) was injected with Dulbecco Modified Eagle's medium (DMEM-F12), group II was injected with BMSCs in DMEM-F12, and group III was injected with BMSCs in DMEM-F12 with poly l-lysine coated SPIONs (0.5 mmol/mL). Monitoring of SPIONs in the rat's body was carried out by MRI. A circular neodymium magnet N52 (0.57 T, 2 × 5 mm) was placed on each rat in group III just below the right ear at the site of surgery to attract SPIONs labeled BMSCs, left in place for 24 h, and then removed. From each group, six rats were euthanized at the end of the 4th and 8th week of treatment, respectively. The right FN trunks were extracted for routine histological examination using H&E stain. Immunohistochemical examination by anti-S100B was performed to characterize the thickness of the myelin sheath formed by the Schwann cells. Ultra-structural examination was performed to study changes in axons, myelin sheaths, and Schwann cells.

Results

Regeneration of nerve fibers, Schwan cells, and myelin sheaths was better in group II than in groups I and III histologically, immunohistochemically, and ultra-structurally.

Conclusion

BMSCs alone could ameliorate FN regeneration better than magnetic targeting treatment using BMSCs labeled with SPIONs.

Complications of alcohol injections for Morton’s neuroma

Introduction

Morton’s neuroma (MN) is a neuropathic metatarsalgia that causes pain in the plantar aspect of the forefoot generally between the third and fourth metatarsal heads. Treatment can be nonoperative or surgical. Among nonoperative procedures, alcohol injections are still commonly used as considered simple, relatively safe and well-tolerated treatment. However, they present transient and minor complications.

Methods

Two hundred patients with a diagnosis of MN underwent ultrasound-guided injections with a 47.5% alcohol solution between 2013 and 2020. We reviewed the current literature to highlight the known complications of this treatment, comparing them to the complications developed by our patients.

Results

Three patients out of 200 patients, developed necrosis of skin and subcutaneous tissue not described in previous studies about MN.

Conclusions

Our study focuses attention on the complications subsequent to the alcohol injection therapy for MN. Patients and surgeons should be aware that in a small number of cases this therapy can be burdened by necrotic complications of the skin.

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.

Effects of 4% Ethanol Sclerosing Injection on Morton's Neuroma: A Histologic Study

BACKGROUND

Nonoperational treatments for Morton's neuroma remain controversial because it is believed that sclerosing injections do not change nerve fibers on a cellular level. Up to 80% success rates with 4% ethanol sclerosing have been documented, and the remainder required operational removal of the painful nerve. We sought to evaluate the histologic characteristics of Morton's neuromas treated with 4% ethanol sclerosing injection versus corticosteroid injection alone in patients who required removal of the nerve for pain relief.

METHODS

A retrospective histologic review was performed of 23 consecutive patients who were treated with either sclerosing injection or nonsclerosing injection and underwent nerve removal between September 1, 2012, and February 28, 2015.

RESULTS

Of 19 patients who met the inclusion criteria, eight received sclerosing injections and 11 received nonsclerosing injections. Intraneural fibrosis was more severe in the nonsclerosing injection group (P = .008).

CONCLUSION

Histologic changes are seen in Morton's neuroma with the use of 4% ethanol sclerosing injection, contrary to findings from previous studies.

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.

Mechanical Metatarsalgia as a Risk Factor for Relapse of Morton's Neuroma After Ultrasound-Guided Alcohol Injection

Although many treatment modalities are available for Morton's neuroma, the injection of the neuroma with alcohol has gained popularity. However, recently, some investigators have observed a progressive deterioration in pain scores for patients initially pain free after the treatment. The purpose of the present retrospective comparative study was to determine whether mechanical metatarsalgia is related to symptom recurrence. We included 104 consecutive cases of ultrasound-guided alcohol injection for Morton's neuroma in 92 patients. Of these 104 cases, 51 were in group A (49%; Morton's neuroma) and 53 in group B (51%; Morton's neuroma associated with mechanical metatarsalgia). We evaluated each patient using a visual analog scale and American Orthopaedic Foot and Ankle Society forefoot scale, and Johnson satisfaction scale, with a mean follow-up period of 24 (range 12 to 39) months. Concomitant functional and mechanical disorders have been identified and treated with orthopedic inserts. The present study compared the clinical results and recurrence of symptoms in patients with isolated Morton's disease or Morton's disease associated with mechanical metatarsalgia. Of the 104 cases, the patients for 93 cases (89%) were completely satisfied or satisfied with minor reservations. No major complications developed. Symptoms recurred in 6 patients (6%), in whom neuroma was associated with mechanical disorders (p = .0269). Ultrasound-guided alcohol injection of Morton's neuroma is a relatively safe and well-tolerated treatment. Symptom recurrence is often associated with mechanical metatarsalgia. The treatment of the concomitant anatomical and functional disorders that target the genesis of the neuroma has an important role in the prevention of recurrence of this pathology.

Mechanisms and treatment of painful neuromas

A painful neuroma is a common complication of a peripheral nerve injury or amputation, and it can cause tremendous pain that is resistant to most analgesics. Furthermore, painful neuromas have a high postoperative recurrence rate. Painful neuromas are often accompanied by functional disorders, drastically reducing the patient’s quality of life. Several pathophysiological mechanisms have been proposed to explain this type of neuropathic pain, including peripheral and central sensitisation and the involvement of nerve growth factor, α-smooth muscle actin, the cannabinoid CB2 receptor and structural changes in neuroma fibres. Nevertheless, the mechanisms of neuroma-associated pain are not fully understood, contributing to the challenge of managing patients with painful neuromas. There are several effective treatment methods, although none are universally accepted. This review summarises the common mechanisms and treatments of painful neuromas, attempting to link the mechanisms and treatments. We hope to provide useful guidelines for choosing the appropriate treatment for the management of painful neuromas.

Sclerosing alcohol injections for the management of intermetatarsal neuromas: A systematic review

An intermetatarsal neuroma is a plantar digital neuritis causing metatarsalgia of the affected inter-metatarsal space. At present the evidence to support the management of the condition is poor with only some quality evidence supporting the short-term management of intermetatarsal neuromas using steroid injections. Some authors have supported the use of alcohol sclerosing intra-lesional injections to treat intermetatarsal neuromas. Following a search of the evidence 11 articles were identified. The systematic review found that alcohol injections appear to be safe although some papers report a short-term side effect of a flogistic reaction and there are variances in the alcohol concentration used and guiding verses not guiding the injection using ultrasound imaging. Some of the evidence may suggest a sclerosing histological effect of the nerve. However, all the studies reviewed present a research design offering a low level of evidence that is open to methodological biases and interpretation. Thus, this review found insufficient high-quality research evidence to afford conclusions on the management of intermetatarsal neuromas with alcohol sclerosing agent injections.

Conservative Management of Metatarsalgia and Lesser Toe Deformities

There are several forefoot conditions that can result in metatarsal head pain. Various points of the gait cycle can predispose the metatarsal heads to pain based on intrinsic and extrinsic imbalances. Metatarsalgia can further be classified according to primary, secondary, or iatrogenic etiologies. Within these groups, conservative management is the first line of treatment and can often obviate surgical intervention. Depending on the cause of pain, proper shoewear, orthoses, and inserts coupled with targeted physical therapy can alleviate most symptoms of metatarsalgia and lesser toe deformities.