Ablative Nerve Block


Article Author:
Shayan Senthelal


Article Editor:
Fassil Mesfin


Editors In Chief:
Patricia Maani-Fogelman
Julianne Oates


Managing Editors:
Frank Smeeks
Scott Dulebohn
Erin Hughes
Pritesh Sheth
Mark Pellegrini
James Hughes
Richard Ciresi
Phillip Hynes


Updated:
11/22/2018 11:52:56 AM

Introduction

In 1975, ablation was initially used to treat chronic back pain and sciatica of unknown etiology as an alternative to the prior treatment of severing the dorsal rami via the intertransverse ligaments. It is a minimally-invasive procedure that involves coagulation necrosis of afferent nociceptive signals via high-frequency waves (300 to 500 Hz). Currently, ablation is most commonly used to destroy the medial branches of the dorsal rami which are responsible for facet-joint-mediated back pain. However, ablation of peripheral nerves that have a primary role in nociception for the treatment of pain is supported by the recent literature, particularly when symptomatology has been refractory to conservative management but is relieved with targeted blocks using short-acting anesthetic agents.[1][1]

Anatomy

Facet-mediated pain is due to facet arthropathy or facet arthritis which arise during the degenerative process of the spinal column. A single facet joint is composed of the inferior articulating process of one vertebra and the superior articulating process of the vertebra directly inferior. Medial branches from the dorsal rami of spinal nerve roots at the same level and one level above provide sensory innervation to the facet (for example, the L4-L5 facet joint is innervated by the medial branches of L3 and L4). The medial branches typically course over the lateral border of the superior articulating process.

An insulated electrode with a non-insulated tip is advanced toward the concavity that is formed between the superior articulating process and the adjacent transverse process, which is in proximity to the nerve that is suspected of causing the symptoms. It is in this region where the use of high-frequency or radiofrequency energy is generated to produce a lesion via coagulative necrosis, thereby disrupting afferent pain signals. In pain medicine, the use of radiofrequency ablation most commonly involves targeting the specific medial branches of the dorsal rami that innervate pain-producing facet joints under fluoroscopic guidance. However, further investigations regarding the efficacy of ablation in other common pain syndromes continue to diversify its use.

Indications

Nerve ablation has typically been used in the treatment of facet-mediated axial back pain of the cervical and lumbar spine that has failed conservative therapy. Additionally, it has other uses such as relief of chronic neck pain after whiplash and chronic headache syndromes due to occipital and trigeminal neuralgia. Ablation is performed after successful analgesia of the suspected trouble-causing nerve with a local anesthetic. There continue to be studies investigating the role of ablation in peripheral nerve-mediated pain outside of the spinal column, particularly in knee osteoarthritis and plantar fasciitis.[2][3]

Contraindications

Absolute contraindications for ablative nerve blocks are few, but these include active local infection at the site of needle insertion and elevated intracranial pressure. The use of anti-coagulants provides a unique challenge for practitioners, as clinical judgment must be used following accepted guidelines. Current guidelines put forth by ASRA (American Society of Regional Anesthesia and Pain Medicine) recommend that:

  • Aspirin to be stopped 6 days before the procedure
  • Clopidogrel to be stopped 7 days before the procedure
  • Apixaban to be stopped 3 to 5 days before the procedure
  • Rivaroxaban to be stopped 3 days before the procedure
  • Warfarin to be stopped 5 days before the procedure
  • Intravenous heparin to be stopped 4 hours before the procedure

Other relative contraindications that the clinician must consider before the procedure include:

  • Neurologic abnormalities
  • Concerning clinical or imaging finding
  • Definitive causes of low back pain (for example, disc herniation, spondylolisthesis, spondylosis, spinal stenosis, malignancy, infection or trauma)
  • Lack of pain relief from prior diagnostic nerve blocks

Equipment

The procedure is routinely done in a sterile procedure suite, with the patient lying prone on a procedure table.

 Key components of the procedure include:

  • C-arm mobile fluoroscopic unit
  • Local anesthetic
  • continuous high-frequency generator with built-in thermocouple, impedance, voltage and amperage monitor
  • Introducer needles (50 to 150 mm in length, 18 to 22 gauge in diameter)
  • Active and ground electrodes

The active electrode delivers the high-frequency current which is dissipated through a ground electrode that is attached to the patient.

Personnel

As with other interventional spinal procedures, only physicians specifically trained in fluoroscopically guidance procedures should perform radiofrequency ablation. Qualified physicians typically undergo residency training in the fields of anesthesiology, physiatry, neurology, psychiatry or neurosurgery. This is followed by an interventional pain or spine fellowship that allows adequate training under an experienced interventionalist prior to performing the procedure independently. Support staff for the procedure can include an assistant to draw up medications and operate the radiofrequency generator and radiology technician to operate the C-arm, under the guidance of the practicing physician.

Technique

The destruction of tissue via radiofrequency must occur after successful diagnostic anesthetic nerve blocks have located the target nerve. During the procedure, the patient should receive little to no sedation, as they must define what they are experiencing during stimulation and lesioning of the nerve.

  1. The patient is placed in a comfortable position with adequate exposure of the region overlying the target nerve. The skin is cleaned and prepped, and the target is found using fluoroscopy. A small amount of local anesthetic is injected subcutaneously at the point of needle insertion.
  2. The introducer needle is then inserted through the skin, subcutaneous tissue, and muscle toward the target using fluoroscopy to guide the trajectory.
  3. Once the tip of the needle is placed satisfactorily close to the target, the active electrode is inserted through the needle.
  4. Sensory stimulation is used at first, to recreate the painful symptoms that the patient experiences, thus locating the target. 
  5. This is followed by motor stimulation to ensure that the active tip is not close to the motor nerves.
  6. Once confirmed, the generator produces a continuous output of voltage at the tip of the electrode, where it will be kept at 80oC for approximately one minute, creating a zone of thermally induced coagulation.

Complications

Nerve ablation is a minimally invasive, relatively low-risk procedure. However, adverse events may occur during placement of the introducer needle or during the ablative process. Advancement of the introducer needle has the potential to cause vascular or neural insult along the trajectory that it is traveling, while the process of thermal ablation may lead to burns (due to errors in ground pad placement), worsened pain, sensory loss or new onset neuropathic pain.[4][5]

Complications are most common after intracranial ablation of the trigeminal ganglion, which may manifest as facial numbness, dysesthesia, anesthesia dolorosa, corneal anesthesia, keratitis and trigeminal motor dysfunction.

Adverse events from ablation of lumbar medial branches are far and few between with transient postoperative pain dominating as the premier adverse event.

As with any invasive technique, the risk of allergy to materials or anesthetic, hematoma formation, and infection must be considered.

Clinical Significance

One hundred million Americans suffer from some form of chronic pain that results in more than $100 billion in expenses annually. Furthermore, 84% of American adults will suffer from chronic, low-back pain at some point in their lifetime. While the causes of low-back pain are often multifactorial and can be due to many causes, the degenerative cascade that affects the spine plays a significant role. Destruction of cartilage that comprises the spinal facet joints results in severe discomfort when placed under stress, typically in extension or rotation of the spine. The sensory nerves responsible are the medial branches of the dorsal rami, which are the most common target in ablative procedures. Radiofrequency ablation has been shown to be efficacious in reducing the severity of back pain for extended periods of time (ranging from 6 months to 24 months in duration) but also has utility in the treatment of trigeminal and occipital neuralgia, complex regional pain syndrome, hip and knee osteoarthritis, and plantar fasciitis. As with other interventional procedures that provide pain relief, ablation aims to play a significant role in the reduction of opiates and other habit-forming pain medications.

This review focuses on the use of conventional radiofrequency ablation, which utilizes a continuous energy source causing coagulative thermal necrosis. Other forms of ablation used in pain management include:

  • Pulsed radiofrequency: Applies heat in a pulsatile manner, but uses lower temperatures in a than conventional radiofrequency to avoid neurolysis
  • Cooled radiofrequency: Utilizes specialized electrodes that are cooled with water-flowing along its shaft, but not at the active tip. This allows higher temperatures and more spherical lesion sizes to be achieved at the target site and less risk of tissue damage superficial to the target.
  • Cryoablation: Causes destruction of axons by disrupting the vasa nervorum. It is increasing in popularity due to a decreased incidence of post-procedural hyperalgesia and neuroma formation compared to conventional radiofrequency.

Enhancing Healthcare Team Outcomes

Nerve ablation for back pain is commonly done as an outpatient. While the actual ablation is done by a physician, the patient monitoring is frequently done by a dedicated nurse/nurse anesthetist. The patient must have the vital signs monitored at regular intervals and if any sedation is used, the pulse oximeter must be continuously monitored. An IV should be in place in case the patient develops hypotension or requires more sedation. Finally, if conscious sedation is used, the antidotes to the medications used must be in the room. After the procedure, the patient should be monitored in the recovery room for several hours by the post-anesthesia recovery nurse. Before discharge, the patient should be informed about the possible side effects of the procedure and when to return to the hospital.[6]


Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE courses, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Ablative Nerve Block - Questions

Take a quiz of the questions on this article.

Take Quiz
Which of the following is not true of diagnostic nerve blocks?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 65-year-old having a nerve block may develop vasospasm when he is treated with which method?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following is false about nerve blocks?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
What is a useful landmark in anesthetizing the maxillary nerve using the high tuberosity approach?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
According to current ASRA (American Society of Regional Anesthesia and Pain Medicine) guidelines, which of the following statements is correct?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following ablative procedures has been documented to have the highest incidence of adverse events?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following methods of ablation does not result in complete neurolysis of the target nerve?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Ablative Nerve Block - References

References

Choi EJ,Choi YM,Jang EJ,Kim JY,Kim TK,Kim KH, Neural Ablation and Regeneration in Pain Practice. The Korean journal of pain. 2016 Jan     [PubMed]
Zakrzewska JM,Akram H, Neurosurgical interventions for the treatment of classical trigeminal neuralgia. The Cochrane database of systematic reviews. 2011 Sep 7     [PubMed]
Saedi N,Hamilton HK,Arndt KA,Dover JS, How to prepare patients for ablative laser procedures. Journal of the American Academy of Dermatology. 2013 Aug     [PubMed]
Djebbar S,Rossi IM,Adler RS, Ultrasound-Guided Cryoanalgesia of Peripheral Nerve Lesions. Seminars in musculoskeletal radiology. 2016 Nov     [PubMed]
Toukhy ME,Campkin NT, Severe diarrhea following neurolytic coeliac plexus block: case report and literature review. The American journal of hospice     [PubMed]
Zakrzewska JM,Linskey ME, Trigeminal neuralgia. BMJ clinical evidence. 2009 Mar 12     [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Nurse-Hospice/Palliative CHPN. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Nurse-Hospice/Palliative CHPN, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Nurse-Hospice/Palliative CHPN, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Nurse-Hospice/Palliative CHPN. When it is time for the Nurse-Hospice/Palliative CHPN board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Nurse-Hospice/Palliative CHPN.