The use of phenol as a neurolytic agent: a review

Spasticity Treatment Beyond Botulinum Toxins

Botulinum toxin (BonT) is the mainstream treatment option for post-stroke spasticity. BoNT therapy may not be adequate in those with severe spasticity. There are a number of emerging treatment options for spasticity management. In this paper, we focus on innovative and revived treatment options that can be alternative or complementary to BoNT therapy, including phenol neurolysis, cryoneurolysis, and extracorporeal shock wave therapy.

Interventional Treatment Modalities for Chronic Abdominal and Pelvic Visceral Pain

PURPOSE OF REVIEW

Chronic abdominal and pelvic visceral pain is an oftentimes difficult to treat pain condition that requires a multidisciplinary approach. This article specifically reviews the interventional treatment options for pain resulting from visceral abdominal and pelvic pain.

RECENT FINDINGS

Sympathetic nerve blocks are the main interventional option for the treatment of chronic abdominal and pelvic visceral pain. Initially, nerve blocks are performed, and subsequently, neurolytic injections (alcohol or phenol) are longer term options. This review describes different techniques for sympathetic blockade. Neuromodulation is a potential option via dorsal column stimulation or dorsal root ganglion stimulation. Finally, intrathecal drug delivery is sometimes appropriate for refractory cases. This paper will review interventional options for the treatment of chronic abdominal and pelvic visceral pain.

Finding possible pharmacological effects of identified organic compounds in medicinal waters (BTEX and phenolic compounds)

Medicinal thermal waters consist of a mixture of different organic and inorganic compounds. Traditionally, these waters are only characterized and classified by their inorganic composition; however, the bioavailability of the majority of these inorganic compounds is limited. Many authors investigate the organic fractions of thermal waters. These authors propose that these compounds have a potential effect on health. To elucidate the underlying mechanisms, it is crucial to know the composition of the organic fractions. The absorption of these compounds on intact skin or mucosa is notable. Some of them have local anaesthetic effect or affect receptors in the central nervous system. In the knowledge of the chemical composition, we are able to estimate the possible pharmacological effect or might be able to assess possible toxicity risks. In the present article, we aim to review possible health effects of two of the identified organic fractions: benzene and alkylbenzenes and phenolic compounds that might correlate with the therapeutic effect on rheumatological or other diseases.

Can percutaneous alcoholization of Morton's neuroma with phenol by electrostimulation guidance be an alternative to surgical excision? Long-term results

BACKGROUND

Percutaneous alcoholization with phenol by electrostimulation guidance for the treatment of Morton's neuroma is proposed to determine a permanent chemical neurolysis.

METHODS

115 patients for 125 Morton's neuromas were treated. Ten patients were affected by multiple neuromas. Visual Analogue Scale and AOFAS score were used for the clinical assessment.

RESULTS

The mean follow-up was 8,3 years. The pre-alcoholization VAS was 85.84 ± 12.00, while at follow-up scored 28.85 ± 31.35, showing a significant decrease improving in 113/125 cases (90.4%). Treatment was considered successful with a reduction of the VAS value superior to 50% in 89 out of 125 patients (71.2%). The mean overall AOFAS score at -up was 85.09 ± 13.41.

CONCLUSIONS

Needle-electrode guided percutaneous alcoholization is an outpatient, minimally invasive procedure with low rate of complications. Better results of those obtained with traditional conservative treatments and comparable with those reported with other alcohols injections or surgical nerve excision were observed.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Molecular reactors for synthesis of polymeric nanocomposites with noble metal nanoparticles for catalytic decomposition of 4-nitrophenol

HYPOTHESIS

A new, facile in-situ method for synthesis of polymeric nanocomposites (NCs) with nanoparticles (NPs) of Au, Pt and Pd is proposed. The method involves reduction-coupled sorption of Au(III), Pt(VI), and Pd(II), which avoids diffusion limitations, allowing the precipitation and stabilization of the NPs directly in the polymeric matrix.

EXPERIMENTS

The obtained nanomaterials were characterized by transmission electron microscopy (TEM), and Fourier-transformation infrared spectroscopy (FT-IR). NPs loaded into polymers were also investigated using X-ray diffraction (XRD).

FINDINGS

Based on the results, it was concluded that the amino functionalities simultaneously reduced noble metals ions and capped the NPs. The average diameter of the obtained AuNPs ranged from 25 to 109 nm, while reduction-coupled sorption was carried out in 1 and 3 mol L^-1 HCl solutions, respectively. Applying a 0.1 mol L^-1 HCl solution containing Au(III), Pd(II) and Pt(VI), a NC with AuNPs and cubic-like PdNPs was fabricated, while using a solution of the same composition, but in 3 mol L^-1 HCl, resulted in formation of a NC with flower-like PtNPs. Ultimately, the selected NC based on a resin with functionalities derived from 1-(2-aminoethyl)piperazine and with bi-metallic active sites, i.e. AuNPs and PdNPs, revealed catalytic activity in the reduction of 4-nitrophenol.

An overview of interventional strategies for the management of oncologic pain

Pain is a ubiquitous part of the cancer experience. Often the presenting symptom of malignancy, pain becomes more prevalent in advanced or metastatic disease and often persists despite curative treatment. Although management of cancer pain improved following publication of the WHO's analgesic ladder, when used in isolation, conservative approaches often fail to control pain and are limited by intolerable side effects. Interventional strategies provide an option for managing cancer pain that remains refractory to pharmacologic therapy. The purpose of this review is to investigate these strategies and discuss the risks and benefits which must be weighed when considering their use. Therapies anticipated to have an increasingly important role in the future of cancer pain management are also discussed.

Nonsurgical Treatment Options for Upper Limb Spasticity

There are many nonsurgical treatment options for patients with upper limb spasticity. This article presents an algorithmic approach to management, encompassing evidence-based rehabilitation therapies, medications, and promising new orthotic and robotic innovations.

Ultrasound-Guided Neurolysis of Six Genicular Nerves for Intractable Pain from Knee Osteoarthritis: A Case Series

INTRODUCTION

Among the elderly population, chronic osteoarthritis of the knee joint is one of the leading causes of disability and causes considerable pain, joint stiffness, and functional limitations. Although knee replacement is a good option for advanced osteoarthritis, many patients could not undergo surgery due to comorbidities or other reasons.

METHODS

Four patients with severe pain from grade 3 and 4 osteoarthritis of the knee had undergone ultrasound-guided alcohol neurolysis of the 6 genicular nerves after a positive genicular nerve block with local anesthetics. The demographics, pain intensity (NRS), Oxford Knee Score (OKS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and quality of life (SF-36) were analyzed.

RESULTS

There was significant improvement in pain intensity at rest, on movement, and on weight bearing after the neurolysis and it has continued for 6 months (P < 0.05). The OKS and WOMAC score had improved from 7.75 ± 1.25 and 77.75 ± 4.34 at baseline, to 20.75 ± 1.70 and 56.25 ± 3.09 at 1 month, and to 18.25 ± 0.95 and 52.00 ± 2.16 at 6 months after the procedure, respectively (P < 0.05). There was also significant improvement in the quality of life after the procedure (P < 0.05).

CONCLUSION

Ultrasound-guided alcohol neurolysis is a good alternative for patients having severe pain from knee osteoarthritis and provides significant pain relief for more than 6 months.

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.

Iatrogenic Phenol Injury Causing Facial Paralysis With Tympanic Membrane and Ossicular Necrosis

OBJECTIVE

To describe a serious iatrogenic injury and propose means of reducing the risk of its reoccurrence.

PATIENTS

A 21-year-old man who suffered facial paralysis, complete necrosis of the tympanic membrane, and ossicular discontinuity because of chemical burn from accidental application of copious amounts of topical anesthetic phenol into the ear.

INTERVENTIONS

Conservative management of facial paralysis and delayed reconstruction of the tympanic membrane and ossicular chain.

MAIN OUTCOME MEASURES

Gradual recovery to grade 1/6 facial function, successful repair of the tympanic membrane, but persistent 30-dB conductive hearing loss after partial ossicular replacement prosthesis presumably because of scarring.

CONCLUSION

Phenol is a highly toxic chemical, topically to both skin and eyes. Absorbed through the skin it can have lethal cardiotoxicity. It is also potent neurotoxin at concentrations much lower (4-7%) than used for tympanic membrane anesthesia (89%) and has long been used therapeutically to destroy nerves in patients of contractions or intractable pain. Otologists need to have a healthy respect for the dangers of using phenol. As only a minute quantity is needed for tympanic anesthesia, commercially available prepackaged applicators are preferred. Storage of stock bottles of 89% phenol solutions in clinical settings risks injury to both patients and practitioners.

Pharmacological management of spasticity in multiple sclerosis: Systematic review and consensus paper

Background and objectives:

Treatment of spasticity poses a major challenge given the complex clinical presentation and variable efficacy and safety profiles of available drugs. We present a systematic review of the pharmacological treatment of spasticity in multiple sclerosis (MS) patients.

Methods:

Controlled trials and observational studies were identified. Scientific evidence was evaluated according to pre-specified levels of certainty.

Results:

The evidence supports the use of baclofen, tizanidine and gabapentin as first-line options. Diazepam or dantrolene could be considered if no clinical improvement is seen with the previous drugs. Nabiximols has a positive effect when used as add-on therapy in patients with poor response and/or tolerance to first-line oral treatments. Despite limited evidence, intrathecal baclofen and intrathecal phenol show a positive effect in severe spasticity and suboptimal response to oral drugs.

Conclusion:

The available studies on spasticity treatment offer some insight to guide clinical practice but are of variable methodological quality. Large, well-designed trials are needed to confirm the effectiveness of antispasticity agents and to produce evidence-based treatment algorithms.

The effectiveness of chemical neurolysis in the treatment of lower limb muscle spasticity

The use of phenol and alcohol nerve blocks in the treatment of localized muscle spasticity is well established. However, a number of questions relating to this procedure are still unanswered. This article presents experience of the effectiveness of chemical neurolysis in the treatment of severe lower limb muscle spasticity in 28 patients who had a total of 56 nerve blocks performed during a follow-up period of between four and 18 months.

Presentation of Neurolytic Effect of 10% Lidocaine after Perineural Ultrasound Guided Injection of a Canine Sciatic Nerve: A Pilot Study

BACKGROUND

Phenol and alcohol have been used to ablate nerves to treat pain but are not specific for nerves and can damage surrounding soft tissue. Lidocaine at concentrations > 8% injected intrathecal in the animal model has been shown to be neurotoxic. Tests the hypothesis that 10% lidocaine is neurolytic after a peri-neural blockade in an ex vivo experiment on the canine sciatic nerve.

METHODS

Under ultrasound, one canine sciatic nerve was injected peri-neurally with 10 cc saline and another with 10 cc of 10% lidocaine. After 20 minutes, the sciatic nerve was dissected with gross inspection. A 3 cm segment was excised and preserved in 10% buffered formalin fixative solution. Both samples underwent progressive dehydration and infusion of paraffin after which they were placed on paraffin blocks. The sections were cut at 4 µm and stained with hemoxylin and eosin. Microscopic review was performed by a pathologist from Henry Ford Hospital who was blinded to which experimental group each sample was in.

RESULTS

The lidocaine injected nerve demonstrated loss of gross architecture on visual inspection while the saline injected nerve did not. No gross changes were seen in the surrounding soft tissue seen in either group. The lidocaine injected sample showed basophilic degeneration with marked cytoplasmic vacuolation in the nerve fibers with separation of individual fibers and endoneurial edema. The saline injected sample showed normal neural tissue.

CONCLUSIONS

Ten percent lidocaine causes rapid neurolytic changes with ultrasound guided peri-neural injection. The study was limited by only a single nerve being tested with acute exposure.

Formation of An Ionic PTCA-β-CDNH2 Complex and Its Application for Phenol Sensing in Aqueous Phase

On the basis of proton transfer in aqueous phase, we prepared a water-soluble and highly fluorescent ionic complex of 3,4,9,10-perylene tetracarboxylic acid (PTCA) and 6-deoxy-6-amino-β-CD (β-CDNH2) and studied its fluorescence behavior. It was found that the fluorescence emission of the complex is sensitive and selective to the presence of trace amount of toxic phenolic compounds, in particular phenol, which is crucial for water quality control. The detection limit (DL) of the method to the analyte is ~0.03 μM, a lowest value reported in literatures for similar techniques. Interestingly, the detection at an unprecedented subnanogram (DL, ~0.12 ng/cm(2)) level can also be conducted in a visualized manner, which may provide a simple and low-cost protocol for on-site and real-time detection of the analyte. Moreover, the complex is humidity sensitive in dry state, and its color changes from bright yellow to bright green when exposed to wet vapor. Unlike other PTCA bisimide derivatives, preparation of the ionic complex of PTCA/β-CDNH2 is simple and avoids complicated synthetic burden. Furthermore, introduction of methanol into the aqueous solution of the complex resulted in aggregation as indicated by solution color change and proved by transmission electron microscopy and dynamic light scattering studies, which explains why the compound in dry state is sensitive to the presence of water and water vapor. X-ray diffraction, UV-vis, and fluorescence studies uncovered the H-packing nature of the structure of the aggregate.

Pharmaceuticals used in image-guided spine interventions

As image-guided (nonvascular) spine interventions have become progressively more common in the interventional radiologic community, there is a growing need for physician expertise regarding the materials and pharmaceuticals that are used for these procedures. This article is intended to provide information to address these needs.

Neurolytic phenol blockade of the obturator nerve for severe adductor spasticity

BACKGROUND

In this study, we present the 3-month follow-up results of a retrospective analysis of obturator nerve (ON) phenol neurolysis performed between 2000 and 2007 in patients with adductor spasticity.

METHODS

The study was performed by retrospective investigation of the clinical follow-up results of 80 ON phenol treatments in 62 patients. Neurolysis using 5-10 ml 6% phenol was applied with the guidance of fluoroscopy and a peripheral nerve stimulator. Pain, spasticity and hygiene were evaluated and the hip abduction range of motion (ROM) was measured at the end of the first week and in the first, second and third months following the intervention.

RESULTS

The visual analogue scale scores decreased significantly in the first week, first month and the second month, but reached their initial values in the third month. A drastic increase in the ROM values was shown in hip abduction in the first week, first month and second month. An increase in the Ashworth Scale values was observed in the second and third months, but they did not reach their initial values. The hygiene score decreased drastically in the first week and the first and second months, but worsened in the third month. The success rate in nerve localization during ON neurolysis was 100%.

CONCLUSION

ON phenol blockade with fluoroscopy and peripheral nerve stimulator guidance in patients with adductor spasticity led to a decrease in spasticity and pain with an increase in the ROM of the hip and better hygiene with an efficacy lasting for about 3 months.

Increasing physical function through physiatric intervention for children with paediatric neurotransmitter disorders

Most children with paediatric neurotransmitter diseases have global functional deficits secondary to central nervous system damage. Paediatric physiatrists, working in conjunction with a multi-disciplinary team, help to improve physical function by normalizing muscle tone and improving body position. Components of spasticity, rigidity, and dystonia may all need to be considered in a comprehensive treatment programme. Complications of disordered tone include skin breakdown, pain, sleep disturbance, and dysphagia. With an integrated approach to use of medications and equipment as well as implementation of therapy and therapeutic exercise, physiatrists can help maximize functional independence for children with this group of disorders. Pharmacological treatment includes GABA-agonists including baclofen and benzodiazepines, alpha-2 adrenergic agonists, L: -dopa and dopaminergic agents, and dantrolene. Intrathecal baclofen may be used in patients refractory to these medications. In addition, physicians may utilize botulinum toxin, phenol, or surgical interventions such as selective dorsal rhizotomy or tendon lengthening. Pharmacological treatment must be used in conjunction with appropriate adaptive equipment in order to maximize therapeutic benefit. Focus on function in an attempt to increase independence is targeted to improve the child's quality of life. We present a framework and rationale to the management of the functional consequences of the paediatric neurotransmitter diseases.

Acute unilateral total visual loss after retrogasserian phenol injection for the treatment of trigeminal neuralgia: a case report

Phenol is a neurolytic agent that is widely used by percutaneous retrogasserian injection in the treatment of trigeminal neuralgia. We report a 78-year-old man who had acute unilateral total visual loss after retrogasserian phenol injection for the treatment of trigeminal neuralgia. The patient's visual acuity, eye movements and the pupillary defect did not improve in the affected eye even after mechanical decompression within 30 minutes and medical treatment, neither in the early period nor during the following two months. The visual loss in this patient seems to result from phenol neurotoxicity rather than mechanical compression of the intraorbital optic nerve. This case demonstrates that although percutaneous retrogasserian phenol injection is a relatively safe and noninvasive method of treatment for trigeminal neuralgia, severe complications may occur.

The perineurium modifies the effects of phenol and glycerol in rat sciatic nerve

Endoneurial cell response and type of nerve fibre damage were studied after perineural injections of 7% phenol-aqua and pure glycerol. Our previous studies have shown that phenol and glycerol induce different types of nerve fibre degeneration after intraneural injections: phenol dissolves axons and Schwann cells inside the basal lamina tubes but glycerol breaks them down into cellular flakes. The current study investigated whether the difference in type of endoneurial damage also appears after perineural application and how the perineurium affects the effect of these neurolytic agents. Rat sciatic nerves were treated with perineural injections of 7% phenol-aqua or pure glycerol and were followed up to 6 months. The results support the previous findings that perineural phenol injection induces damage that covers almost the whole endoneurium, but glycerol injection results in minor subperineurial damage. An ultrastructural study showed that the endoneurial effects are much milder after perineural injection than after intraneural injections. Phenol-induced nerve fibre dissolving was only rarely seen and the nerve fibre damage appeared similar to that after regular Wallerian degeneration in both groups. Axonal regeneration began within 2 weeks of the injections. Endoneurial macrophages were numerous in the damaged area in many individual nerves even at 3-6 months in both groups, which may indicate impaired phagocytotic activity. Regenerating axonal sprouts were seen first at 1 week post injection and Schwann cells proliferated within 2 weeks in both groups. However, the number of axonal sprouts was higher (P=0.002) and the size of the sprouts appeared larger after glycerol injection at 4 weeks post injection. The present study shows that the effects of extraneurally applied neurolytic agents phenol and glycerol are modified by the perineurium. Phenol readily penetrates the perineurium, but glycerol causes only subperineurial damage. The type of damage is rather similar to regular Wallerian degeneration in both groups and the endoneurial effects differ from those seen after intraneural injections.

Combining botulinum toxin and phenol to manage spasticity in children

OBJECTIVE

To describe the specific techniques and adverse reactions of using concurrent, multiple injections of both botulinum toxin and phenol to manage spasticity in children with cerebral palsy (CP) and other neurologic conditions.

DESIGN

A retrospective case series.

SETTING

A tertiary care children's hospital.

PARTICIPANTS

Consecutive patients (N=68) with spasticity related to CP or other neurologic conditions.

INTERVENTION

Ninety injection sessions combining botulinum toxin and phenol to manage spasticity.

MAIN OUTCOME MEASURE

Documentation of adverse reactions.

RESULTS

The mean phenol dosage was 9.5mL at a mean of 0.6mL/kg per injection dose. The mean botulinum toxin type A (Botox) dose injected was 193U (12U/kg), and the mean of botulinum toxin type B (Myobloc) dose injected was 7750U (530U/kg). The mean number of muscles injected was 14. Adverse reactions are described but were infrequent. Dysesthetic hand pain occurred in 2 patients. One patient developed a systemic reaction to Myobloc.

CONCLUSIONS

Using botulinum toxin and phenol injections allowed many muscles to be injected to manage spasticity in children with CP and other neurologic conditions. Using this combination allowed an increased number of injections at the maximal recommended dose.

Intrathecal neurolytic blocks for the relief of cancer pain

Intrathecal neurolytic blocks for the treatment of chronic pain were first described by Dogliotti in 1931. Since then, many authors have described the intrathecal injection of various neurolytic substances for the treatment of oncologic pain. In recent years, alcohol and phenol have been the substances most commonly used for this purpose. There are no controlled studies, so the literature consists of observations, reports and book chapters reflecting the opinions of experienced clinicians. This chapter describes the indications, contraindications, potential complications, and expected benefits of intrathecal injection of alcohol and phenol in the treatment of cancer pain. Four cases of cancer patients whose intractable pain was treated by the authors using intrathecal neurolysis are presented. Pertinent literature is reviewed. In this account, the emphasis is on proper selection of patients and techniques.

Cancer pain: Neurosurgical management

The management of cancer pain represents a difficult diagnostic and therapeutic problem for the clinician. In a multidisciplinary approach to the management of cancer pain, neurosurgical methods are an essential part of the therapy. Frequently, patients with advanced cancer suffer from an increasing pain, requesting ever higher dosage of narcotics, and finally seeming to respond only to high dosage of intravenous narcotics. Gradually, the opioids produce less satisfactory analgetics effects an more serious side manifestations. These patients can be considered for surgical management of pain. Historically, surgery for cancer pain began with destructive procedures (neurectomy, rhizotomy, sympathectomy), often referred to as ablative. In past two decades, with the help of the current knowledge of cancer pain mechanisms and some of the technological developments, such as microsurgical and stereotactic techniques, computerized tomography and magnetic resonance imaging, the majority of ablative procedures have been replaced by new methods. Among them a few are selectively and minimally ablative (microsurgical spinothalamic cordotomy, dorsal root entry zone operation, limited midline myelotomy) and the others ones are neuroaugumentative operations ( deep brain structures and spinal cord stimulation, drugdelivery systems).

Managing severe lower limb spasticity in multiple sclerosis: does intrathecal phenol have a role?

OBJECTIVE

Established treatment options for managing severe lower limb spasticity and associated pain are of limited value in people with advanced multiple sclerosis (MS). This has resulted in a resurgence of the use of lumbar intrathecal phenol injection (IP). The aim of this study was to investigate the authors' experience with IP.

METHODS

This observational study collected cross sectional data from patients with progressive MS who received IP for severe lower limb spasticity. Data from 25 patients were collected prospectively before and after treatment. In 15 cases the data related to the first treatment and in 10 to serial injections. Outcome measures collected included the Ashworth scale, a spasm frequency scale, a pain rating score, and the percentage achievement of practical goals.

RESULTS

After injection, all patients demonstrated reduced lower limb tone bilaterally. After the initial injection there was significant improvement on the targeted as compared with the non-targeted side (Wilcoxon rank p=0.003), while no difference in the degree of improvement between the targeted and non-targeted side was seen after serial injections (Wilcoxon rank p=0.731). Twenty four patients were easier to position and 21 had a reduction in their spasm frequency and intensity. Eleven patients with pain reported benefit. Carers found washing and dressing easier in 16 patients and improved safety when using the hoist in 10. Six patients had recurrence of skin breakdown and five patients reported transient adverse changes in their bowel function.

CONCLUSIONS

IP can reduce lower limb tone bilaterally after both initial and serial injections. This is most noticeable on the targeted side after initial injection. IP can reduce spasms and pain, leading to improvements in care and overall comfort. IP is an effective treatment option in the management of severe spasticity. Documented selection criteria are essential.

Acute and chronic pain management in palliative care

Every palliative care patient should have the expectation that acute and chronic pain management will be an integral part of their overall care. However, in all too many instances, the pain of cancer is often grossly under-treated. This issue is of concern because more than 80% of patients with cancer pain can find adequate relief through the use of simple pharmacological methods. It is even more troubling to note that women and minority groups have their cancer pain under-treated more frequently. Physicians with the basic skills of assessment and treatment will be able to control the symptoms in the majority of cancer pain patients. However, there are still some patients who may require other modalities to control their moderate to severe pain. A thorough understanding of all pain management options will help the gynaecological oncologist to maintain an acceptable quality of life for their patients throughout the therapeutic and palliative phases of care.

Phenol block of peripheral nerve conduction: Titrating for optimum effect

OBJECTIVES

To verify the dose-response relationship in phenol nerve block and to determine the concentration and volume of phenol injectate required for effective nerve conduction block.

DESIGN

Before-after, experimental study.

SETTING

A research institute laboratory.

ANIMALS

Seventy-one New Zealand white rabbits.

INTERVENTIONS

Group I (n = 48) received tibial nerve block by perineural injection (phenol, n = 40; saline, n = 8), group II (n = 21) by submerging the nerve in phenol solution. The 6 subgroups of group I each received different concentrations (3%, 4%, 5%) and volumes (0.1mL, 0.2mL, 0.3mL). The 2 subgroups of group II received 3% (n = 8) and 5% (n = 13) phenol.

MAIN OUTCOME MEASURES

Compound muscle action potential (CMAP) and tension of triceps surae muscles by electric stimulation of the sciatic nerve were measured preintervention and at day 1, and weeks 1, 2, 4, and 8 postblock. Histologic studies were performed on 2 animals from group I.

RESULTS

Two rabbits in group I died before results were obtained. In the remaining animals, CMAP amplitude reduced significantly (p <.05) as the volume of 5% phenol solution increased from 0.1mL, 0.2mL, to 0.3mL. A high concentration of phenol produced a more pronounced conduction block; however, no significant (p =.0589) difference existed among the 3 concentrations. Submerged tibial nerve had a greater degree of conduction block than perineurally injected nerve. Depth of the degeneration area in nerve fascicle varied with distance from the injection point.

CONCLUSIONS

The nerve block effect of phenol can be titrated by adjusting the concentration and volume of phenol solution if the technique of application and localization of a block site are standardized.

Treatment of neuromuscular and musculoskeletal problems in cerebral palsy

Cerebral palsy typically involves a variety of neuromuscular and musculoskeletal problems. These problems include spasticity, dystonia, contractures, abnormal bone growth, poor balance, and loss of selective motor control. These problems can interfere with function and treating them can improve function. The treatments include physical and occupational therapy, bracing, oral medications, neurolytic blocks, neurosurgical procedures, orthopaedic surgery and others. Using a multidisciplinary treatment team with a good understanding of cerebral palsy, the best treatment options can be determined and functional outcomes maximized.

Chemodenervation of the rat hemilarynx with phenol

In this study, the injection of phenol into the true vocal fold was evaluated on a rat model as a possible treatment for adductor spasmodic dysphonia. A 10% phenol solution was injected into the right true vocal fold. Quantitative measurement of vocal fold adductory force showed reduction to 35% of the preinjection value 3 months after injection (p < .05). Qualitative evaluation by videolaryngoscopy demonstrated maintenance of the normal vocal fold range of motion. Histologic studies showed a transient inflammatory infiltrate and myolysis, while the vocal fold mucosa and the cricoarytenoid joints remained undamaged. Further investigation into the potential use of phenol for treating spasmodic dysphonia is warranted.

Neuromuscular blockade in the management of cerebral palsy

Neuromuscular blocking agents-45% alcohol, 4% to 6% aqueous phenol, local anesthetics, and botulinum A toxin-have been used for many years in the evaluation and management of spasticity and movement disorders in children with cerebral palsy. Recent reports suggest that longer-acting neuromuscular blocking agents may impact positively on the natural history of dynamic deformity and improve health-related quality of life. This review includes the mechanism of action, techniques, indications, complications, and clinical outcomes associated with these agents.

Time course of muscle atrophy and recovery following a phenol-induced nerve block

Clinically, phenol is used often as a neurolytic agent to treat pain and spasticity. The purpose of this study was to examine the time course of denervation and recovery in several hindlimb muscles following application of a 5% aqueous solution of phenol to the sciatic nerve. Phenol was applied to the sciatic nerve of adult female rats either by intraneural or perineural injection. Axonal degeneration was evident within the sciatic nerve 2 days following phenol application, although variable amounts of damage were observed. By 2 weeks, the soleus and tibialis anterior had atrophied to 63% and 51% of control. Reinnervation of hindlimb muscles occurred between 2 and 4 weeks following the nerve block. Following denervation, the soleus became slower in that all of the fibers expressed the slow myosin heavy chain (MHC). At 5 months, maximum tension of the soleus was 74% of control and the muscle consisted of more fast fibers on average, some of which expressed IIx MHC. These data suggest that 5% phenol causes an injury to the nerve that is more severe than a crush injury, and that reinnervation of denervated muscles may be by motoneurons other than those that originally innervated the muscles.

Spinal subdural haematoma as a complication of immediate epidural blood patch

PURPOSE

The authors report a case of a patient who developed spinal subdural haematoma after a series of epidural blood patches to alert anaesthetists to this rare complication.

CLINICAL FEATURES

The patient was a 35-yr-old woman without coagulopathy and was initially treated elsewhere for chronic pain by repetitive epidural phenol injections. When the dura was inadvertently punctured during subsequent attempts to inject phenol, immediate epidural blood patch was performed to treat or prevent headache. The patient developed cauda equina syndrome after six epidural blood patches. The clinical diagnosis was confirmed by magnetic resonance imaging and the intradural haematoma was evacuated surgically. The patient made a complete recovery.

CONCLUSIONS

Epidural blood patch is not without complications. Transient backache and/or radiculopathy may occur in up to one-third of patients receiving a blood patch. If signs and symptoms continue or worsen, a spinal subarachnoid and/or subdural haematoma should be suspected and neurosurgical opinion sought. The technique used to identify the epidural space is important in preventing subdural injection of blood. The needle should be withdrawn after dural puncture and the epidural space identified at a different level. Blood patches may carry a higher risk of serious complications after multiple epidural phenol injections because of fibrosis and obliteration of the epidural space. Magnetic resonance scans reliably demonstrate the extent of the pathology. If diagnosed and treated before irreversible changes occur, spinal intradural haematoma can result in complete recovery.

Treatment of acquired muscle spasticity using phenol peripheral nerve blocks

The use of phenol motor nerve blocks is advantageous in the early period of acquired spasticity (ie, that occurring following traumatic brain injury or incomplete spinal cord injury), when increased muscle tone is often the most severe. Because acquired spasticity is dynamic and usually improves slowly, a temporary treatment method used to ameliorate increased muscle tone is desirable. Phenol nerve infiltration provides a temporary motor nerve block that lasts for weeks or months. It allows passive limb mobilization in a comprehensive rehabilitation program that attempts to prevent fixed soft tissue contractures. Permanent or irreversible methods such as operative tendon lengthening, muscle release or recession, or neurectomy are usually best delayed until the spasticity has become static, when the need for surgical correction becomes more firmly indicated, and outcomes of operative intervention are more predictable. Although phenol nerve blocks were initially administered at the spinal cord level to control spasticity, the potential side effects have caused a loss of popularity of this method of administration. The safer and more common use of phenol infiltration at the peripheral nerve level is now more accepted for brain injury and spinal cord injury patients. This report reviews the indications, current concepts, and development of the different methods used to administer phenol nerve blocks. Comparisons to other methods to control spasticity are discussed.

Selective intrathecal phenol block to improve activities of daily living in patients with spastic quadriplegia. A preliminary report

To eliminate severe leg spasms of 15 quadriplegics, 0.3 ml 10% phenol-glycerin was injected into the subarachnoid space at the T12/L1 interspace. The effectiveness for leg spasm was evaluated by the Penn spasticity and Ashworth rigidity scales. Three patients remained completely flaccid; however three had slight, six had moderate and three had complete recurrence of spasms in a follow up period of observation for 1 to 22 (average 13) months. The result of selective intrathecal phenol block was significantly valuable, improving the activities of daily living (ADL) of quadriplegic patients. There were no systemic side effects nor disturbance of bladder, bowel or sexual functions.

Management of the adult, spastic, equinovarus foot deformity

Management of the persistent, acquired, neurogenic equinovarus foot may be a confounding rehabilitative dilemma. Victims of cerebrovascular accidents and traumatic brain injury commonly develop this neurogenic deformity. The plantarflexed and inverted foot position results from an imbalance of forces about the hindfoot due to exaggerated muscle tone and hyperactive stretch reflexes. Significant functional impairment may ensue if a plantigrade foot position cannot be achieved and maintained. Surgical correction may be necessary if conservative measures fail. Determination of the dynamic and static components contributing to the equinovarus deformity is difficult. Gait analysis and dynamic electromyographic studies are valuable adjuncts for operative planning. The wide-ranging goals of surgery vary from improving transfer and ambulation skills, to assisting wheelchair positioning, to facilitating use of braces and/or shoe wear.

Relief of intractable perineal pain by coccygeal nerve block in anterior sacrococcygeal ligament after surgery for rectal cancer

Intractable perineal pain often appears in the anal region following abdominoperineal resection for the treatment of rectal cancer. In such cases, a subarachnoid block or transsacral block is generally used to control pain. However, these procedures sometimes cause complications such as dysuria or sensory paralysis of the pudendum. A new method of pain control is presented herein using absolute alcohol as a neurolytic agent to relieve localized perineal pain through a coccygeal nerve block in the anterior sacrococcygeal ligament. Five cadavers were necropsied to localize the coccygeal nerve. A loop consisting of S4, S5, and Co was found to exist in the space surrounded by the anterior surface of the coccygeal bone and the anterior sacrococcygeal ligament. Absolute alcohol was injected into this space. It is essential that the neurolytic agent remain localized in this space to avoid complications and to successfully block perineal pain. In all patients, we found that this method was extremely effective in blocking localized perineal pain without any complications.