SPINAL AND OCCIPITAL STIMULATION/REGIONAL ANESTHESIA
From the 15th Annual Current Topics in Anesthesia, presented by Mayo Clinic College of Medicine, February 23-26,
2005
| SPINAL AND OCCIPITAL STIMULATION —Terrence L. Trentman, MD, Staff Anesthesiologist and Director, Chronic
Pain Clinic, Mayo Clinic, Scottsdale, Arizona
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 | Equipment: manufactured primarily by Medtronics, Advanced Neuromodulation Systems, and Advanced Bionics; wires inserted
into epidural space; either percutaneous (wire) lead or paddle (surgical) lead; each lead has varying number of electrodes;
surgical lead shielded on one side (directs all current toward structure being stimulated; may also be more stable)
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| Patient selection: primarily for refractory lower extremity neuropathic pain; bilateral leg pain also treatable; back pain or axial
pain more difficult to treat; psychologic screening performed before procedure to look for untreated depression, anxiety disorder,
or drug abuse; also used to determine if patient can give informed consent about having something implanted in body
and able to understand and use stimulator
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| Mechanisms: gate control theory (stimulating A- β fibers inhibits A-delta and C fiber input); also decreases “wind-up” of
wide dynamic range neurons (second-order neurons in spinal cord); decreases concentration of excitatory neurotransmitters
(eg, glutamate, aspartate); increases inhibitory neurotransmitter γ-aminobutyric acid (GABA) and local blood
flow
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| Implantation technique: place trial lead in epidural space; for leg pain, puncture at L1-L2 and thread lead up to T8-T10;
for arm pain, puncture at T1-T2 and thread lead to C3-C4 level; follow-up includes removing percutaneous lead, determination
of pain coverage during trial, and quantifying decrease in pain (should be ≥50% decrease in pain to justify
permanent implantation); also determine if patient more active during trial or used less medication, then make decision
about type of wire to be permanently implanted
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| Outcomes: Van Buyten found 68% of interviewed patients had good-to-excellent long-term results; 31% of patients who
were off work able to return to work; Kay concluded that 60% of interviewed patients had substantial pain relief
(>50% improvement); in 70 patients, there were 72 revisions for technical problems with devices; North found that
52% of 320 patients had ≥50% pain relief
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| Chronic daily headache: ≥15 headache days per month; ≈5% incidence in general population; greater incidence in headache
clinic population
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| Primary vs secondary headache disorders: secondary disorders include those caused by tumor, sinusitis, meningitis, and
posttraumatic stress (≈300 known causes of secondary headaches); primary disorders include short duration (<4 hr) [eg,
cluster headache] and long duration (>4 hr) [eg, chronic migraine; chronic tension-type headache]
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| Occipital pain in cluster headache and migraine: probably referred pain; anatomic and functional relationship between
trigeminal and cervical complex; authors have suggested anesthesia of occipital nerve in refractory headache and occipital
nerve blockade for cluster headache; Weiner one of first to use occipital nerve stimulation to treat primary refractory
headache disorders
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| Assessment tools: first part known as migraine disability assessment score (MIDAS); 5 questions ask patient about impact
of headaches on his or her life over last 3 mo; second score measures frequency and intensity
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| Results: from patients with chronic migraine, hemicrania continua, and chronic cluster headaches
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| Recent imaging: suggests migraines actually form of brain dysfunction (neurologic disorder; neurovascular changes secondary);
positron emission tomography (PET) has shown that patients with migraine consistently have areas of brain
that “light up” (eg, periaqueductal gray; dorsal-rostral pons); lack of synchrony with certain stimuli (eg, light, smell,
hormones, or stress) within brain
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| Mechanism of action: pulvinar nucleus part of thalamus (“relay station” for pain messages); second-order neurons come
to thalamus; projects third-order neurons to cortex where pain perceived
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| Future directions: occipital nerve stimulation for treatment of chronic refractory migraines
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| HOW TO MAKE REGIONAL BLOCKS WORK —Sandra L. Kopp, MD, Instructor in Anesthesiology, Mayo Clinic College
of Medicine, Rochester, Minnesota
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| Advantages of regional anesthesia: decreased nausea and vomiting; decreased recovery times; increased postoperative
alertness; potential economic savings
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| Start with basics: appropriate patient for first time; familiarity with block technique; knowledge of anatomy; communication
with surgeon; marking of surface landmarks
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| Clonidine: for single-injection nerve blocks, increases duration of sensory and motor blockade, prolongs postoperative
analgesia, and has few systemic side effects; typical dose 1 to 2 µg/kg; α2 -adrenergic receptor agonist; mechanism
of action vague; may be translocation via nerves or blood to spinal cord; may cause vasoconstriction (similar to epinephrine);
may have direct action on A-delta and C nerve fiber conduction; may work synergistically with local anesthetic
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| Axillary block: no conclusive data to show one technique more successful than others; with transarterial technique, inject
as close to artery as possible and watch for intravascular injection; with nerve stimulator, evidence suggests multiple
stimulations lead to higher success (1-2 nerves, 65%-85%; 3-4 nerves, 84%-94%); 3 nerves typically stimulated are radial,
musculocutaneous, and median (fourth would be ulnar); requires 10 to 12 min; risk for accidental injury to previously
blocked nerve; always block musculocutaneous nerve for surgery to lateral forearm; located superior and
posterior to axillary artery; must block it separately (either in axilla deep to humeral head or in intraepicondylar line);
general tips for successful brachial plexus blockade include choosing appropriate type of block, safely maximizing local
anesthetic dosage, using multiple nerve stimulations, adding clonidine, blocking musculocutaneous nerve separately,
and allowing ≥15 min onset time
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| Supplementation: risk of injuring already anesthetized nerve; safest to supplement early (specifically if no block present);
nerve stimulator does not guarantee safety; avoid ulnar nerve (many opportunities for injury)
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| Intrathecal opioids: may allow decreased dose of local anesthetic; short-acting (lipophilic) opioids have minimal side effects;
long-acting (hydrophilic) opioids provide extended analgesia; maintain or improve anesthetic success;
fentanyl—10 to 25 µg; rapid onset and duration of 3 to 6 hr; pruritus only major side effect; sufentanil—similar onset
and duration to fentanyl; somewhat higher incidence of nausea and vomiting (pruritus also seen); morphine—0.1
to 0.5 mg; onset in 30 min; duration 8 to 24 hr (maybe more); side effects include delayed respiratory depression, pruritus,
and fairly significant nausea and vomiting
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| Use of opioids in outpatient intrathecals: study showed significantly better sensory block but no increased time to discharge
with use of fentanyl
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| Tips for success: stay midline; add low-dose opioids (hydrophilic vs lipophilic); add dilute local anesthesia to postoperative
epidural infusions
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| Preoperative: long-acting opioid (eg, oxycodone [Oxycontin]); nonsteroidal anti-inflammatory drugs (NSAIDs; if not
contraindicated)
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| Postoperative: oxycodone (bid; dose depends on age) for acute pain during hospitalization; acetaminophen (Tylenol); ketorolac
(if not contraindicated); peripheral nerve catheter with local anesthetic infusion for 48 hr
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| Realize limitations: allow sufficient onset time; administer appropriate sedation; ask for help; be prepared for general anesthetic
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| Tips for success: choose correct patient; use correct block; know anatomy; understand potential complications; communicate
with surgeon; know when to ask for help
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| Successful regional blocks: patient satisfaction; fewer side effects; less pain; shorter hospital stay
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| COMPLICATIONS OF REGIONAL ANESTHESIA —James R. Hebl, MD, Chair, North Division of Anesthesia, and Assistant
Professor of Anesthesiology, Mayo Clinic College of Medicine, Rochester, Minnesota
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| Advantages of regional anesthesia: avoidance of general anesthesia; superior postoperative analgesia; early mobilization;
early outpatient dismissal; shorter inpatient stays; development of continuous catheter techniques; improved rehabilitation
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| Complications of regional anesthesia: prospective survey of >100,000 anesthetics; end points include cardiac arrest,
death, neurologic injury, and seizure activity; spinal anesthesia had highest complication rate (leading cause of cardiac
arrest and nerve injury); peripheral nerve blockade had highest frequency of seizure activity
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| Peripheral nerve injury
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| Patient risk factors: include preexisting neurologic deficits, male sex, increasing age, extremes of body habitus, and
preexisting diabetes mellitus
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| Surgical risk factors: include intraoperative surgical trauma or stretch to nerve, prolonged tourniquet inflation times, vascular
compromise, perioperative inflammation or infection, hematoma, cast compression, and patient positioning
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| Anesthetic risk factors: include mechanical trauma (needle or catheter; painful paresthesia), chemical injury (direct local
anesthetic neurotoxicity), and ischemic nerve injury (epinephrine; perineural edema)
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| Neuraxial injury
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| Transient neurologic symptoms: clinical features include low back pain (may radiate into buttocks or lateral thighs) and burning,
aching, or cramping pain; 50% radiation to lower extremities; mean visual analog scale (VAS) pain score 6.2 (on 10-
point scale); onset 12 to 24 hr after injection; duration 6 hr to 4 days; no reported motor weakness or abnormal neurologic
examination; risk factors include spinal anesthesia with lidocaine (not concentration-dependent; hyperosmolarity, hyperbaricity,
glucose, and epinephrine do not influence incidence), patient positioning (lithotomy position highest risk; supine
position lowest risk), and ambulatory status
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| Neuraxial hematoma: low molecular weight heparin (LMWH) introduced in United States in 1993; within 5 yr, >40 spinal
hematomas reported in patients undergoing spinal blockade with LMWH; Food and Drug Administration (FDA)
issued advisory warning in December 1997 about performing spinal anesthetics in patients on LMWH; prompted
American Society of Regional Anesthesia (ASRA) Consensus Conference to develop guidelines and recommendations
(May 1998); 8 additional hematomas reported since that time
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| ASRA guidelines for neuraxial anesthesia and anticoagulation
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| Preoperative LMWH dosing
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| Low dose (prophylactic): needle placement 10 to 12 hr after last dose
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| High dose (therapeutic): needle placement 24 hr after last dose
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| Postoperative LMWH dosing
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| Twice-daily dosing: no indwelling neuraxial catheters or deep peripheral catheters recommended; initiated 24 hr
postoperatively; first dose administered 2 hr after catheter removal
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| Single daily dosing: indwelling catheters acceptable; initiated 6 to 8 hr postoperatively, with second dose given 24 hr
later; catheter removed 12 hr after last dose and 2 hr before next dose
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| Meningitis: conflicting evidence on risk for meningitis after dural puncture in bacteremic patients; incidence 1.8% to 27%;
etiology includes disruption of blood-brain barrier, introduction of contaminated blood into intrathecal space, and poor
aseptic technique; antibiotic treatment before dural puncture reduces risk
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| Recommendations: dural puncture should not be performed in patients with untreated systemic infections; spinal anesthesia
may be safely performed in bacteremic patients if treated with antibiotics before dural puncture
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| Epidural abscess: most not secondary to catheterization (instead, due to skin or soft tissue infections, hematogenous spread, or
osteomyelitis); incidence 0.2 to 1.2 per 10,000; Staphylococcus aureus most common microorganism; abscess formation
superficial or deep; magnetic resonance imaging (MRI) diagnostic technique of choice; rapid surgical intervention
mandatory for successful outcome (within 12 hr)
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| Catheter disconnections
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| Static fluid: disconnection within 8 hr; reconnect catheter at any point >10 in from contaminated end; soak catheter in
povidone iodine (Betadine), air dry, then cut with sterile instrument
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| Displaced fluid: bacteria advance rapidly when fluid displaced; if fluid displacement significant, remove catheter
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| Antiseptic solutions: effective against wide array of microorganisms; immediate onset and efficacy; extended effect; nontoxic
or not irritating to skin; not inactivated by organic material; penetrate stratum corneum; chlorhexidine significantly
reduces likelihood of colonization (effective against wide array of pathogens; rapid and effective; definitive
conclusions cannot be made about reducing clinical infections; contraindicated for lumbar puncture)
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| Central nervous system (CNS) seizure activity
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| Cardiovascular collapse (cardiac arrest): recommendations—pulse oximeter should always be used; epinephrine should
be considered early in treatment of sudden bradycardia; full resuscitation dose of epinephrine should be given immediately
upon recognition of cardiac arrest
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Educational Objectives
| The goal of this program is to educate the listener about refractory headache disorders and regional anesthesia. After hearing
and assimilating this program, the participant will be better able to:
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| 1. Discuss spinal cord stimulation for refractory lower extremity neuropathic pain.
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| 2. Examine primary vs secondary headache disorders.
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| 3. Review occipital stimulation for refractory headache disorders.
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| 4. Compare peripheral nerve blockade, neuraxial blockade, and a multimodal approach to regional anesthesia.
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| 5. Describe complications and controversies associated with regional anesthesia.
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Discussed on This Program
Acetaminophen (N -acetyl-P -aminophenol; APAP) [Tylenol, others]
Atropine sulfate (several trade names)
Bupivacaine HCl (several trade names)
Cisplatin (CDDP) [Platinol-AQ]
Clonidine HCl [Catapres, Duraclon]
Dalteparin sodium [Fragmin]
Doxorubicin [Adriamycin PFS, Adriamycin RDF, Doxil, Rubex]
Enoxaparin sodium [Lovenox]
Ephedrine sulfate [Pretz-D]
Epinephrine (several trade names)
Fentanyl [Sublimaze]
Ifosfamide [Ifex]
Ketorolac tromethamine [Acular, Acular LS, Toradol]
Mepivacaine HCl (Carbocaine, Carbocaine with Neo-Cobefrin, Polocaine, Polocaine MPF)
Methotrexate (amethopterin; MTX) [Methotrexate LPF, Rheumatrex Dose Pack, Trexall]
Midazolam HCl [Versed]
Morphine sulfate (several trade names)
Oxycodone HCl [OxyContin, others]
Phenylephrine HCl (many trade names)
Povidone iodine [Betadine, many others]
Propofol [Diprivan]
Sufentanil citrate [Sufenta]
Tinzaparin sodium [Innohep]
Suggested Reading
Auroy Y et al: Serious complications related to regional anesthesia: results of a prospective survey in France. Anesthesiology
87:479, 1997; Bartsch T et al: Stimulation of the greater occipital nerve induces increased central excitability of dural
afferent input. Brain 125:1496, 2002; Ben-David B et al: Intrathecal fentanyl with small-dose dilute bupivacaine: better
anesthesia without prolonging recovery. Anesth Analg 85:560, 1997; Caplan RA et al: Unexpected cardiac arrest during
spinal anesthesia: a closed claims analysis of predisposing factors. Anesthesiology 68:5, 1988; Eng RH et al: Lumbar
puncture-induced meningitis. JAMA 245:1456, 1981; Gawel MJ et al: Occipital nerve block in the management of headache
and cervical pain. Cephalalgia 12:9, 1992; Horlocker TT et al: Regional anesthesia in the anticoagulated patient:
defining the risks. Reg Anesth Pain Med 28:172, 2003; Kaniecki R: Headache assessment and management. JAMA
289:1430, 2003; Kaniecki RG: Migraine and tension-type headache: an assessment of challenges in diagnosis. Neurology
58:S15, 2002; Kay AD et al: Spinal cord stimulation--a long-term evaluation in patients with chronic pain. Br J Neurosurg
15:335, 2001; Langevin PB et al: Epidural catheter reconnection. Safe and unsafe practice. Anesthesiology 85:883,
1996; Matharu MS et al: Managing the patient with migraine. Practitioner 245:511, 515, 2001; Melzack R et al: Acute
pain in an emergency clinic: latency of onset and descriptor patterns related to different injuries. Pain 14:33, 1982;
Melzack R et al: Evolution of pain theories. Int Anesthesiol Clin 8:3, 1970; Neal JM: Assessment of lower extremity
nerve block: reprise of the Four P's acronym. Reg Anesth Pain Med 27:618, 2002; North RB et al: Spinal cord stimulation
for chronic, intractable pain: experience over two decades. Neurosurgery 32:384, 1993; Peres MF et al: Greater occipital
nerve blockade for cluster headache. Cephalalgia 22:520, 2002; Pollock JE: Transient neurologic symptoms:
etiology, risk factors, and management. Reg Anesth Pain Med 27:581, 2002; Rigler ML et al: Cauda equina syndrome after
continuous spinal anesthesia. Anesth Analg 72:275, 1991; Schell RM et al: Persistent sacral nerve root deficits after
continuous spinal anaesthesia. Can J Anaesth 38:908, 1991; Schneider M et al: Transient neurologic toxicity after hyperbaric
subarachnoid anesthesia with 5% lidocaine. Anesth Analg 76:1154, 1993; Selander D et al: Local anesthetics: importance
of mode of application, concentration and adrenaline for the appearance of nerve lesions. An experimental study
of axonal degeneration and barrier damage after intrafascicular injection or topical application of bupivacaine (Marcain).
Acta Anaesthesiol Scand 23:127, 1979; Selander D et al: Paresthesiae or no paresthesiae? Nerve lesions after axillary
blocks. Acta Anaesthesiol Scand 23:27, 1979; Singelyn FJ et al: Adding clonidine to mepivacaine prolongs the duration
of anesthesia and analgesia after axillary brachial plexus block. Reg Anesth 17:148, 1992; Stan TC et al: The incidence of
neurovascular complications following axillary brachial plexus block using a transarterial approach. A prospective study of
1,000 consecutive patients. Reg Anesth 20:486, 1995; Van Buyten JP et al: Efficacy of spinal cord stimulation: 10 years
of experience in a pain centre in Belgium. Eur J Pain 5:299, 2001;Warner MA et al: Ulnar neuropathy in surgical patients.
Anesthesiology 90:54, 1999.
Faculty Disclosure
In adherence to ACCME guidelines, the Audio-Digest Foundation requests all lecturers to disclose any significant financial
relationship with the manufacturer or provider of any commercial product or service discussed. The following
has been disclosed: Dr. Trentman is a consultant to and receives research support from Medtronics and Advanced
Bionics.
Drs. Trentman, Kopp, and Hebl spoke in Scottsdale, Arizona at the 15th Annual Current Topics in Anesthesia, held
February 23-26, 2005, and sponsored by Mayo Clinic College of Medicine. The Audio-Digest Foundation thanks the
speakers and the sponsor for their cooperation in the production of this program.
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