Epidural Nerve Block
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Epidural nerve block has become a significant advance in neuraxial anesthesia and analgesia. Dr. James Leonard Corning described the procedure in 1885 [1] and Cuban anesthesiologist Manual Martinez Curbelo, in 1947, first used an epidural catheter. [2]
The procedure is commonly performed as a sole anesthetic or in combination with spinal or general anesthetic. The duration of anesthesia or analgesia is prolonged when epidural catheters are used. Patients are able to control their pain with patient-controlled epidural analgesia (PCEA) in a manner similar manner to that of intravenous patient-controlled analgesia (IV PCA).
Local anesthetic epidural blockade may be useful in conjunction with aggressive physical therapy or manipulation of a painful limb associated with joint stiffness or limited range of motion. Lumbar sympathetic blocks are more appropriate for evaluating and treating complex regional pain syndromes, as they provide a more selective evaluation by providing a discrete sympathetic block.
In comparison to epidural blocks, epidural injections of local anesthetic, steroids, or both are considered for the treatment of radicular pain symptoms secondary to disk herniation or postsurgical radicular pain. Epidural injections do not alter the course of the underlying process but may offer effective pain relief in selected patients. Epidural injections may be performed in the spinal region, including the cervical, thoracic, lumbar, and sacral regions. Fluoroscopic guidance may be necessary in patients with congenitally, surgically, or pathologically altered anatomy. The injections should be delivered into the area of the known pathology using midline, paravertebral, or transforaminal approaches. Caudal steroid injections should only be used for patients with leg pain of sacral origin or in whom direct access to the lumbar region is impossible.
When considering epidural nerve block, clinicians should follow a stepwise approach. First, an accurate diagnosis must be made by obtaining a pertinent neurological history and examination and performing the appropriate diagnostic confirmatory tests.
In the ever-expanding field of interventional pain management, epidural injections of pain medications like steroids play an important role in chronic pain management. Long-term indwelling epidural catheters are helpful in managing severe pain in cancer and noncancer chronic pain conditions. Certain conditions with sympathetic mediated or maintained pain are treated with the epidural local anesthetic since it provides sympathetic blockade.
The cephalad part of the spinal epidural space begins at the level of foramen magnum, where the periosteal and spinal layers of dura fuse together. The caudal part extends to the sacrococcygeal membrane. The anterior portion of the epidural space is formed by the posterior longitudinal ligament, which covers the posterior part of the vertebral body and the intravertebral disk. Posteriorly, the epidural space is formed by the anterior lateral surface of the vertebral lamina and the ligamentum flavum. Laterally, the epidural space is formed by the pedicles of the vertebrae and the intravertebral foramen. The ligamentum flavum is used as the key landmark for identification of the epidural space. It is thinnest in the cervical region. Also note that the epidural space is narrowest in the cervical region, with an anterior/posterior diameter of 2-3 mm. The images below show the interlaminar epidural space.
An understanding of the basic anatomy of the epidural space also requires recognition of the following key anatomic features of the spine. The spine is composed of cervical, thoracic, lumbar, sacral, and coccygeal vertebrae. The cervical spine is much more mobile than the thoracic or lumbar regions of the spine. Unlike the other regions of the spine, the cervical spine has foramina in each vertebra for the arteries supplying blood to the brain. The vertebrae support most of the weight to the spine. A bony projection on either side of the vertebral body called the pedicle supports the arch that protects the spinal canal. The laminae are the parts of the vertebrae that form the back of the bony arch that surrounds and covers the spinal canal. A transverse process is on either side of the arch, where some of the muscles of the spinal column attach to the vertebrae. The spinous process is the bony portion of the vertebral body that can be felt as a series of nodules in the center of an individual’s spine.
Between each vertebra in the spine are disks that act as shock absorbers and also permit some movement between the vertebral bodies. They are made up of a strong outer ring of fibers called the annulus fibrosus and a soft center called the nucleus pulposus. The annulus helps keep the disk’s inner layer intact.
In addition to the invertebral discs, facet joints between each of the vertebral bodies allow the individual bones of the spine to move and rotate with respect to each other. Several muscle groups that move the trunk and the limbs also attach to the spinal column. The neural foramen is the opening where the nerve roots exit the spine and travel to the rest of the body. Between each pair of vertebrae are 2 neural foramina (1 on each side). Finally, the spinal cord extends from the base of the brain and ends at the lower level of the first lumbar vertebra and the top of the second lumbar vertebra. The group of nerves at the end of the spinal cord is called the cauda equina. The dura mater forms a protective watertight sac around the spinal cord and nerves. The spinal cord is surrounded by spinal fluid inside this sac.
Indications for epidural nerve block can be divided into the following categories:
Sole epidural anesthetic
Orthopedics – Surgeries of lower limbs, including hip, knee, and pelvic areas
Vascular surgery – Lower limbs, amputations
Obstetrics – Cesarean delivery
Gynecology – Surgeries of female pelvic organs
Urology – Prostate and bladder surgeries
General surgery – Lower abdominal surgeries, including appendectomy, bowel surgeries, hernia repair
Epidural anesthetic in combination with spinal anesthetic
This combination is referred to as combined spinal epidural (CSE).
All of the indications noted above for sole epidural anesthetic may also be performed with CSE.
Epidural anesthetic in combination with general anesthetic
All of the indications noted above for sole epidural anesthetic may also be performed with CSE.
Pediatric surgery – Penile procedures, inguinal hernia repair, lower limb orthopedic procedures
Thoracic surgery –Thoracotomy, cardiac bypass, other cardiac surgeries
Epidural analgesia combined with general anesthesia reduces the incidence of postoperative pneumonia in patients with chronic obstructive pulmonary disease who are undergoing major abdominal surgery. [3]
Prolonged postoperative analgesia obtained by continuous or patient-controlled infusions of local anesthetics, opioids, adjuvants, or a combination thereof
Labor epidural analgesia
Single-shot epidural injection of depot form of morphine (Duramorph) can provide 6-24 hours of analgesia. DepoDur (EKR Therapeutics, Bedminster, NJ) is a formulation that provides more than 2 days of analgesia with a single injection.
Epidural for chronic pain management [6, 7, 8, 9]
Disk herniation, degeneration, and spondylosis
Radiculopathy –Cervical, thoracic, lumbosacral
Spinal stenosis and facet arthropathy
Sympathetic mediated/maintained pain of upper or lower extremities
Pelvic pain – Aid with pelvic floor physical therapy
See the list below:
Patient refusal
Uncorrected hypovolemia
Increased intracranial pressure
Infection at the site
Allergy to local anesthetic (For more information, see Local Anesthetic Agents, Infiltrative Administration.)
See the list below:
Coagulopathy
Platelet count < 100,000
Uncooperative patient
Spine abnormalities and surgeries
Unstable spine from trauma
Positioning problems
General anesthesia (controversial)
Because of the rare occurrence of spinal hematoma associated with neuraxial anesthesia in patients taking anticoagulants, a consensus statement has been developed by the American Society of Regional Anesthesia and Pain Medicine (ASRA). [10] Recommendations from the consensus statement are depicted in the table below. For more information, see ASRA’s consensus statement on Regional Anesthesia in the Anticoagulated Patient.
Table. ASRA Recommendations (Open Table in a new window)
Drug
Catheter Insertion
Catheter Removal
NSAIDs
No contraindication; may increase frequency of spontaneous hemorrhagic complications when combined with warfarin, heparin, or thrombolytics
No contraindication
Ticlopidine
(Ticlid)
Discontinue 14 d before epidural block
Clopidogrel
(Plavix)
Discontinue 7 d before epidural block
GP IIb/IIIa inhibitors*
Discontinue 8-48 h before epidural block
Heparin
SC/IV: Do not heparinize until at least 1 h after the epidural block
IV infusion: Discontinue heparin infusion for 2-4 h and check partial thromboplastin (PTT) prior to block
Wait 2-4 h after last SC heparin dose or discontinuing IV heparin infusion; check PTT prior to removal
Warfarin
(Coumadin)
Discontinue 4-5 d prior to neuraxial manipulation; INR should be normal prior to block
May remove catheter when INR is ≤ 1.5 after discontinuing warfarin
Low molecular weight heparin (LMWH)†
Wait for 12-24 h after the last dose
Remove 2 h prior to first LMWH dose, which is given 24 hours postsurgery, provided that hemostasis is adequate
Thrombolytics‡
Data limited; follow fibrinogen levels; original contraindications called for avoidance of drugs for 10 days following puncture of noncompressible vessels
No definite recommendations; measure fibrinogen level to help decide between catheter removal or maintenance
Herbals
No definitive recommendations; watch for “3 Gs” (ginseng, garlic, ginkgo biloba) that are known to either have antiplatelet properties or enhance effect of antiplatelet drugs
*GP IIb/IIIa inhibitors include tirofiban (Aggrastat), eptifibatide (Integrilin), abciximab (ReoPro)
† LMWHs include ardeparin (Normiflo), dalteparin (Fragmin), danaparoid (Orgaran), enoxaparin (Lovenox), and tinzaparin (Innohep)
‡Thrombolytics include urokinase, streptokinase, endogenous t-PA formulations (alteplase and tenecteplase)
Epidural nerve block is usually well tolerated. Apart from adequate counseling and allaying the fears of the patient, a dose of oral diazepam the night before the procedure might help.
Midazolam and fentanyl may be titrated to respond to anxiety and pain from the procedure.
Skin and subcutaneous tissues are infiltrated with a local anesthetic (usually lidocaine 1%). Adding sodium bicarbonate to lidocaine can minimize the burning sensation during the injection of lidocaine (usually 2 mL of sodium bicarbonate added to 8 mL of lidocaine).
For more information, see Local Anesthetic Agents, Infiltrative Administration and Procedural Sedation.
General anesthesia is commonly required for pediatric epidural procedures.
Commercial epidural kits are available, and manufacturers can customize kits to particular institutions. The kit in the author’s institution contains the following:
Tuohy epidural needle, 17 gauge (ga), 3.5″ (see image below)
Glass syringe to help with the loss of resistance technique (see image below)
Epidural catheter, 19 or 20 ga
Lidocaine 1%, 5 mL ampule, for skin infiltration
Lidocaine 1.5% with epinephrine 1:200,000, 5 mL ampule, for epidural test dose and bolus
Appropriate needles and syringes
Povidone-iodine solution
Tegaderm dressing
Transparent drape with central opening and adhesive
Preservative-free normal saline, 10 mL (Saline is sometimes used for the loss of resistance technique. Saline is also useful to expand the epidural space and to facilitate the passage of the epidural catheter.)
The following image shows the entire epidural kit.
Other required equipment includes the following:
Airway and resuscitation equipment, including oxygen, masks, bag-valve-mask, laryngoscopes, endotracheal tubes
Intravenous access supplies, including fluids and tubing
Procedure table that can be adjusted for height or Trendelenburg positioning
Cushions and pillows for support and pressure point padding
Step stool to support the legs
Monitors, including heart rate and blood pressure, pulse oximeter, invasive monitoring ability (arterial line, central venous pressure [CVP], pulmonary artery [PA] catheter), capnograph (Standard monitors are applied according to American Society of Anesthesiologists [ASA] guidelines.)
Essential drugs (eg, atropine, ephedrine, midazolam, fentanyl)
Local anesthetics (eg, lidocaine, bupivacaine, ropivacaine)
Adjuvants like clonidine
Corticosteroids (eg, methylprednisolone, triamcinolone) that provide anti-inflammatory effects for chronic pain management
C-arm fluoroscopy, lead protection coats, gloves, eye shields, radiography technician (also for chronic pain management)
Sterile gloves, mask, gown, cap, shoe covers, and other precautionary equipment, according to institutional policies
Latex-free equipment, when necessary
The sitting position is commonly employed. Instruct the patient rest his or her legs on a step stool and hold a pillow. Instruct the patient to arch forward like an angry cat to decrease lumbar lordosis.
The lateral decubitus position is another possible position.
The prone position is employed when epidural nerve block is used in chronic pain management; fluoroscopy is usually required.
Several methods can be used to identify the epidural space. They include the following:
Loss of resistance to air or preservative-free normal saline
Compression of a small air bubble in saline (This method is the author’s preference.)
Hanging drop technique
Pop-off feeling
Nerve stimulation
Ultrasound: Although often perceived as difficult to use in this capacity, ultrasonography is useful for identifying intervertebral levels, estimating the depth to epidural and intrathecal spaces, and locating important landmarks. [11, 12]
Interlaminar technique
In the interlaminar technique, the needle is introduced into the interspinous space and advanced between the laminae into the epidural space. The following 3 interlaminar approaches are available:
Midline interlaminar approach (see image below)
Paramedian interlaminar approach
Lateral parasagittal interlaminar approach (see image below)
Transforaminal technique
In the transforaminal technique, the needle is introduced into the cephalodorsal portion of the concerned neural foramen. This technique is employed more often by interventional pain clinicians using fluoroscopic guidance.
The level of insertion is determined by the indication for epidural placement.
See the list below [13] :
Use the lumbar level of insertion for anesthesia and postoperative analgesia for lower abdominal, pelvic, and lower extremity procedures.
Start a peripheral intravenous line to administer fluids and medications.
Position the patient in the seated or lateral decubitus position with the back arched to minimize the lumbar lordosis.
Prepare the back with povidone-iodine solution (eg, Betadine) and place a sterile drape. Use chlorhexidine gluconate (Hibiclens) for patients who are allergic to povidone-iodine solution.
Palpate the spinous processes. The midline interlaminar approach is used in lumbar regions because the spinous processes are less angulated in these regions.
After the skin and subcutaneous tissues are anesthetized with local anesthetic, introduce the Tuohy needle into the lower part of the interspace and advance for about 2-3 cm until the needle is firmly placed in the interspace.
Attach the glass syringe (prefilled with air or saline 2 mL) to the needle and continue advancing in slow increments, frequently checking for loss of resistance. A gentle tap on the glass syringe piston is enough to determine the resistance. Sometimes, a small bubble of air in the saline is helpful. The bubble compresses with every tap on the piston.
As the ligamentum flavum is reached, the resistance increases to a firm and gritty feeling. Once the epidural space is reached, resistance is lost. When the piston is gently tapped, it easily plunges in the syringe. The air bubble in the saline no longer compresses, and saline is easily injected into the epidural space.
Once the epidural space is reached, aspirate to rule out cerebrospinal fluid (CSF) or heme.
If performing a single shot procedure, inject the medication and remove the needle.
If placing a catheter, gently advance the catheter through the needle for about 4-5 cm and then remove the needle.
Connect a connector to the end of the catheter and remove the sterile drape.
Secure the epidural catheter to the patient’s back with sterile Tegaderm dressing, and inject a test dose of medication. The test dose rules out intrathecal or intravascular location of the catheter.
With a successful neuraxial blockade, a zone of differential sympathetic nervous system blockade typically occurs at the spinal level. The zone of differential motor blockade may average up to 4 segments below the sensory level in epidural rather than spinal blockade.
For interventional pain epidural injections, confirm the needle position with the loss of resistance technique as well as fluoroscopic guidance.
Inject the radiopaque contrast medium and study the spread of the dye in the epidural space (epidurograph). The author employs the lateral parasagittal interlaminar approach to direct the medication to the site of pain and as close to the pain generators as possible.
With disk herniation, the pain is usually generated in the disk-anterior epidural space interface. Therefore, the medication should be placed into the anterior epidural space rather than the posterior epidural space. In a study conducted in the author’s institution, the lateral parasagittal and transforaminal approaches were compared. [14] The dye spread into the anterior epidural space more often with the lateral parasagittal approach. With this approach, the needle is placed as far lateral in the epidural space as possible, maintaining the parasagittal orientation of the needle until the epidural space is reached.
See the list below:
A lumbar epidural steroid injection may be used to treat a lumbar disk bulge, as shown in the images below.
Position the patient prone on the procedure table with a pillow under the waist to decrease the lumbar lordosis (see image below).
Prepare the insertion site and field with povidone-iodine solution (see image below).
Cover the field with a sterile drape (see image below).
Place a skin marker to confirm laterality (see image below).
Infiltrate the skin with a local anesthetic (see image below).
Place a 20-ga, 3.5-inch Tuohy needle (see image below). The needle has marking at 1-cm intervals.
Advance the needle toward the epidural space, maintaining the lateral parasagittal orientation.
Connect a glass syringe filled with 2 mL of air to the needle and advance it with intermittent pauses while checking the resistance level and position of the needle with intermittent fluoroscopy. As the ligamentum flavum is encountered, the resistance increases slightly, producing a gritty sensation (see image below).
Once the epidural space is reached, resistance ceases and the piston advances easily in the glass syringe. Take care not to inject too much air into the epidural space, and remove the glass syringe.
Obtain fluoroscopy view in the lateral projection to confirm the needle tip in the posterior part of the epidural space (see image below).
Attach a syringe filled with radiocontrast dye to extension tubing and connect it to the epidural needle (see image below).
After negative aspiration for heme or CSF, inject the dye. (Usually, 2-3 mL is sufficient to produce a good epidurogram.) See images below.
Once the epidurogram shows satisfactory placement of the needle, slowly inject the corticosteroid mixture (methylprednisolone [Depo Medrol] 80 mg, lidocaine 1% 0.5 mL, preservative-free 0.9% NaCl 1 mL). See image below.
After the steroid is injected, flush the needle with 0.5 mL saline and remove it.
Apply pressure at the injection site to prevent any bleeding. Cover the injection site with an adhesive bandage.
Observe the patient in the pain clinic until he or she is stable to go home in ambulatory condition. Give suitable written and verbal instructions. Advise the patient to follow up in the pain clinic in 3-4 weeks for reevaluation.
See the list below:
At the low thoracic levels, the angulation of the spinous processes is increased, and less interlaminar space is available (see images below). Greater access to the epidural space is available when the paramedian approach is used; therefore, the paramedian interlaminar approach is easier and desirable at low thoracic levels.
In the paramedian approach, insert the needle slightly to the side of the midline and advance it straight until the lamina is reached.
Subsequently, direct the needle in a cephalad and medial direction until it is walked off the superior aspect of the lamina, then advance it toward the ligamentum flavum, using the loss of resistance technique. Either air or saline can be used to aid with the loss of resistance technique.
The rest of the procedure is the same as described for the lumbar level above.
See the list below:
Place a peripheral IV prior to the procedure. The patient sits on the side of the bed with feet resting on a stool. Advise the patient to bend forward and support the arms on a rest or by hugging onto a pillow. Monitor vital signs throughout the procedure.
Prepare the skin with povidone-iodine solution (see image below).
Place a sterile drape.
Infiltrate the injection site with local anesthetic.
The skin entry site is just lateral to the spinous process of T6.
Advance the Tuohy needle at a perpendicular angle until the lamina is reached (see image below).
Withdraw the needle slightly and orient it cephalad and slightly medially (see image above). Then, walk the needle off the superior aspect of the lamina, and attach the glass syringe filled with air.
Advance the needle until loss of resistance is obtained (see image below).
After negative aspiration for heme/CSF/paresthesia, advance the epidural catheter about 3-5 cm into the epidural space and remove the needle (see image below).
Connect the epidural catheter to the connector (see image below).
Secure the epidural catheter to the skin (see image below).
Inject a test dose of lidocaine 1.5% 3 mL with epinephrine 1:200,000 through the catheter after negative aspiration for heme and CSF. The test dose rules out intrathecal and intravascular location of the catheter.
The epidural catheter is used postoperatively. To do so, mount an epidural infusion pump (see image below) with a bag containing 250 mL of epidural analgesic mixture (bupivacaine 2.5 mg plus fentanyl 5 mcg/mL). Patient-controlled epidural anesthesia (PCEA) settings can be set at 3 mL basal, 3 mL PCA dose every 30 minutes, with a 1-hr limit of 9 mL.
PCEA provides excellent postoperative analgesia and is continued typically for 3 days. The patient is able to perform incentive spirometry and deep breathing exercises. The Anesthesia Pain Service in the hospital manages the PCEA.
See the list below [13] :
The interlaminar approach is used in interventional pain management.
Take great precautions to ensure that dural puncture is avoided. The spinal cord is in close proximity.
All patients undergoing this approach should receive a peripheral IV for administration of emergency medicines and sedation if necessary.
The images below show cervical spine anatomy.
A seated position with the head rested on the table with a chin support is used for older patients who are unable to lie prone. If the patient is in a sitting position, then the author uses the hanging drop method of identifying the cervical epidural space. The sitting position is best avoided in younger patients, especially male patients, because of the high incidence of vasovagal episode. Prone position with the arms tucked to the side is the preferred position for younger patients. However, prone positioning makes it harder to visualize the lower cervical levels clearly on fluoroscopy. The author advises patients to bring their arms as low as they can for better visualization of the lower cervical levels.
The rest of the procedure is similar to the lumbar interlaminar approach.
While the midline is identified using an anteroposterior view, the needle is advanced with lateral fluoroscopy (see images below).
The transforaminal approach is used less because of the risk of spinal cord injury.
See the list below:
The transcaudal approach is used for patients who have had previous lumbar spine surgery.
Position patients prone in the usual manner. The lowest part of the epidural space can be accessed at the caudal level.
Fluoroscopy is recommended for accurate placement of the transcaudal catheter.
At the lower part of the sacrum, the sacral hiatus is formed by unfused sacral cornua, which allows easy access to the epidural space (see image below). The sacrococcygeal ligament covers the hiatus.
After the usual skin antiseptic preparation and local anesthetic infiltration, insert the introducer needle midline, between the sacral cornua, and advance it until it penetrates the sacrococcygeal ligament with a pop-off or a give-way feeling (see image below). The lateral view fluoroscopy increases the accuracy.
Subsequently, remove the stylette and advance a radio-opaque catheter with fluoroscopic guidance until the lower part of the surgical area is reached (see images below).
Usually, the cephalad advancement is limited to the L5-S1 level. If the catheter is advanced any more cephalad, the chance of dural puncture and subsequent spinal headache is high.
After negative aspiration for CSF and heme, inject iodinated contrast medium to confirm the epidural location. The epidurograph also provides valuable information on the cephalad cut-off due to the surgical scar tissue (see image below).
Gentle scar mobilization may be performed with the injectate.
The author uses Depo Medrol, 80 mg, with 3-4 mL of preservative-free normal saline and 0.5-1.0 mL of preservative-free lidocaine 1%.
Once the injection is performed, remove the catheter en bloc with the introducer cannula.
Apply firm pressure to prevent bleeding and place an adhesive bandage at the injection site.
Instruct the patient to arch forward like a mad cat to decrease lumbar lordosis.
With disk herniation, the pain is usually generated in the disk-anterior epidural space interface. Therefore, the medication should be placed into the anterior epidural space rather than the posterior epidural space.
Usually, 2-3 mL of dye is sufficient to produce a good epidurogram.
Epidural and spinal anesthesia are used extensively, consistently, and securely in modern practice. Although the technique appears relatively straightforward in experienced hands, it is not free of potential complications. [15] Awareness of complications is required for a safe practice of these techniques. [15]
Severe complications of regional anesthesia are far less commonly disclosed. According to a 2003 survey of 79 regional anesthesiologists and regional anesthesia fellows, the complication rates provided to patients may not match those cited in the literature. [16] The risks of regional anesthesia that are most commonly disclosed to patients by academic regional anesthesiologists occur frequently and are benign in nature.
Severe complications (eg, spinal epidural hematoma) leading to temporary or permanent disability have been attributed to central neuraxial blocks. [17] Infections like meningitis and abscesses, or cerebral ischemia or hemorrhage have also been linked directly or indirectly to spinal or epidural anesthesia. [17] On rare occasion, central nerve blocks have caused permanent damage to the spinal cord or nerve roots. [17] The etiology of this damage in many cases remains unclear.
Perhaps the clearest picture of the numbers and types of injuries from regional anesthesia is provided by the American Society of Anesthesiologists (ASA) Closed Claims Project database. [18] The report clearly noted twice the complications with general anesthesia than with regional anesthesia. The primary reason for death remains cardiac arrest associated with neuraxial blockade. [19] This complication now represents only 30% of deaths (vs 61% in the 1970s and 40% in the 1980s). [19]
A database on early and delayed complications was collected in a prospective study of 6 weeks’ duration. [20] Two hundred and fifteen patients who underwent 790 consecutive cervical epidural nerve blocks were observed. Unintentional dural puncture and superficial infection at the injection site were reported. This study concluded that cervical epidural nerve block has been reported as a safe modality in the treatment of various painful conditions.
A report reviewed 32 studies published between January 1, 1995, and December 31, 2005. [21] The main objective was to investigate neurological complications of regional anesthesia. The review suggested that the rate of neurological complications after central nerve blockade is less than 0.04% and that the rate of neuropathy after peripheral nerve blockade is less than 3%.
An epidural block interrupts both somatic and sympathetic nerve conduction; thus, cardiovascular changes, including hypotension and tachycardia, may occur. These cardiovascular changes can produce overwhelming complications if not promptly identified and treated. Respiratory compromise or failure can occur if the phrenic nerve or respiratory centers of the brain stem are inadvertently blocked. For this reason, epidural nerve blocks should be performed only by clinicians trained in airway management and resuscitation. Appropriate monitoring of vital signs is imperative, and resuscitation equipment must be readily available during the procedure.
Minor adverse effects and complications of epidural nerve block include pain at the injection site, unintentional dural puncture [22] , and vasovagal syncope. Major complications include damage to neural structures, epidural hematoma, and epidural abscess. These major complications are rare but can be life-threatening when they occur. Coexisting Harlequin and Horner syndromes after high thoracic paravertebral block have also been reported. [23]
With the exception of the decreased incidence of inadvertent dural puncture, the complications of the caudal approach to the epidural space mirror those of the lumbar approach. Because of the proximity of the rectum, conscientious attention to sterile technique must be observed to avoid infection, which can easily spread to the epidural space via the Batson plexus. Because of the vascular nature of the caudal epidural space, the potential for local anesthetic toxicity remains ever present.
During the postoperative period, patients should be observed closely to detect potentially treatable sources of neurologic injury, including expanding spinal hematoma or epidural abscess on neurologically vulnerable sites. [24] New neurologic deficits should be evaluated promptly by a neurologist to formally document the patient’s evolving neurologic status. [24] If necessary, the neurologist can arrange further testing or intervention and provide long-term follow-up and prognosis.
Cauda equina is formed by nerve roots caudal to the level of spinal cord termination. Cauda equina syndrome has been defined as low back pain, unilateral or usually bilateral symptoms in the distribution of sciatic nerve, saddle sensory disturbances, bladder and bowel dysfunction, and variable lower extremity motor and sensory loss. This may occur with neurotoxicity from local anesthesia. In the past, continuous spinal catheters with local anesthetics were associated with this syndrome. Those types of catheters and infusions are no longer in use.
Neurotoxicity associated with lower back pain that radiates to the buttocks and posterior thighs is likely due to transient lumbosacral nerve root irritation.
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De Tommaso O, Caporuscio A, Tagariello V. Neurological complications following central neuraxial blocks: are there predictive factors?. Eur J Anaesthesiol. 2002 Oct. 19(10):705-16. [Medline].
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Ben-David B. Complications of regional anesthesia: an overview. Anesthesiol Clin North America. 2002 Sep. 20(3):665-667, ix. [Medline].
Waldman SD. Complications of cervical epidural nerve blocks with steroids: a prospective study of 790 consecutive blocks. Reg Anesth. 1989 May-Jun. 14(3):149-51. [Medline].
Brull R, McCartney CJ, Chan VW, El-Beheiry H. Neurological complications after regional anesthesia: contemporary estimates of risk. Anesth Analg. 2007 Apr. 104(4):965-74. [Medline].
Kuroda K, Miyoshi H, Kato T, Nakamura R, Yasuda T, Oshita K, et al. Factors related to accidental dural puncture in epidural anesthesia patients. J Clin Anesth. 2015 Aug 7. [Medline].
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Horlocker TT. Complications of spinal and epidural anesthesia. Anesthesiol Clin North America. 2000 Jun. 18(2):461-85. [Medline].
Cathelin F. Une nouvelle voie d’injection rachidienne:methode des injections epidurales par le procede d canal sacre- applications a l’homme. Comp Rend Soc De Biol. 1901. 53:452-3.
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Drug
Catheter Insertion
Catheter Removal
NSAIDs
No contraindication; may increase frequency of spontaneous hemorrhagic complications when combined with warfarin, heparin, or thrombolytics
No contraindication
Ticlopidine
(Ticlid)
Discontinue 14 d before epidural block
Clopidogrel
(Plavix)
Discontinue 7 d before epidural block
GP IIb/IIIa inhibitors*
Discontinue 8-48 h before epidural block
Heparin
SC/IV: Do not heparinize until at least 1 h after the epidural block
IV infusion: Discontinue heparin infusion for 2-4 h and check partial thromboplastin (PTT) prior to block
Wait 2-4 h after last SC heparin dose or discontinuing IV heparin infusion; check PTT prior to removal
Warfarin
(Coumadin)
Discontinue 4-5 d prior to neuraxial manipulation; INR should be normal prior to block
May remove catheter when INR is ≤ 1.5 after discontinuing warfarin
Low molecular weight heparin (LMWH)†
Wait for 12-24 h after the last dose
Remove 2 h prior to first LMWH dose, which is given 24 hours postsurgery, provided that hemostasis is adequate
Thrombolytics‡
Data limited; follow fibrinogen levels; original contraindications called for avoidance of drugs for 10 days following puncture of noncompressible vessels
No definite recommendations; measure fibrinogen level to help decide between catheter removal or maintenance
Herbals
No definitive recommendations; watch for “3 Gs” (ginseng, garlic, ginkgo biloba) that are known to either have antiplatelet properties or enhance effect of antiplatelet drugs
*GP IIb/IIIa inhibitors include tirofiban (Aggrastat), eptifibatide (Integrilin), abciximab (ReoPro)
† LMWHs include ardeparin (Normiflo), dalteparin (Fragmin), danaparoid (Orgaran), enoxaparin (Lovenox), and tinzaparin (Innohep)
‡Thrombolytics include urokinase, streptokinase, endogenous t-PA formulations (alteplase and tenecteplase)
Jasvinder Chawla, MD, MBA Chief of Neurology, Hines Veterans Affairs Hospital; Professor of Neurology, Loyola University Medical Center
Jasvinder Chawla, MD, MBA is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine, American Clinical Neurophysiology Society, American Medical Association
Disclosure: Nothing to disclose.
Meda Raghavendra (Raghu), MD Associate Professor, Interventional Pain Management, Department of Anesthesiology, Chicago Stritch School of Medicine, Loyola University Medical Center
Meda Raghavendra (Raghu), MD is a member of the following medical societies: American Society of Anesthesiologists, American Society of Regional Anesthesia and Pain Medicine, American Association of Physicians of Indian Origin
Disclosure: Nothing to disclose.
Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Nothing to disclose.
Laurie Scudder, DNP, NP Nurse Planner, Medscape; Senior Clinical Professor of Nursing, George Washington University
Disclosure: Nothing to disclose.
Erik D Schraga, MD Staff Physician, Department of Emergency Medicine, Mills-Peninsula Emergency Medical Associates
Disclosure: Nothing to disclose.
Luis M Lovato, MD Associate Clinical Professor, University of California, Los Angeles, David Geffen School of Medicine; Director of Critical Care, Department of Emergency Medicine, Olive View-UCLA Medical Center
Luis M Lovato, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Emergency Physicians, Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.
Epidural Nerve Block
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