ASRA Pain Medicine Update

A 70-year-old female with a history of chronic low back pain presents to the neurology clinic with six months of progressive right leg pain and weakness. She describes the pain as sharp, "electric," and radiating down the right leg. Both the pain and weakness worsen after her morning walks, especially when walking downhill. She denies urinary incontinence or saddle anesthesia. She reports minimal improvement with conservative measures such as heat, stretching, and oral analgesics including acetaminophen and tramadol. She completes the Oswestry Disability Index and scores 43%.

Her medical history is also significant for type 2 diabetes mellitus, hypercholesterolemia, hypertension, and irritable bowel syndrome with constipation. Past surgical history includes a sleeve gastrectomy 15 years ago for morbid obesity. She is a lifelong non-smoker and drinks alcohol socially.

On a physical exam, the pain is reproduced with extension of the patient's spine and relieved with flexion. Her gait is normal. Patellar and Achilles deep tendon reflexes are 2/4 bilaterally. Muscle strength is 3/5 in the right leg, and 5/5 in the left leg. The straight leg raise test and Babinski sign are negative. Plain anteroposterior and lateral radiographs show nonspecific degenerative changes from L1 to L4. A magnetic resonance imaging (MRI) scan reveals multilevel degenerative disc disease, particularly at L2-L4, with central canal and foraminal narrowing from L2-L4, indicating moderate spinal stenosis.

Interventional pain procedures such as epidural spinal injections and medial branch blocks were discussed; however, the patient refused, requesting a more "definitive" solution. A decompressive laminectomy from L2 to L4 with spinal fusion is then recommended. A perioperative multimodal analgesic approach is reviewed with the patient, who agrees with the plan.

What is multimodal anesthesia and what is its role in spine surgery?

Multimodal analgesia refers to the use of two or more analgesia methods that target different pain pathways including inflammatory, nociceptive, and neuropathic mechanisms. Combining multiple agents with complementary mechanisms at lower doses allows for synergistic pain relief while minimizing the side effects of each medication.¹ The American Society for Enhanced Recovery recommends multimodal regimens, such as lidocaine and ketamine infusions, acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), and regional techniques, as standard components of enhanced recovery after surgery (ERAS) for spine surgery² (Table 1). Incorporating nonopioid analgesics, adjuvant medications, and regional anesthesia techniques into ERAS protocols have been shown to reduce opioid consumption, improve pain control, and enhance recovery, including earlier mobilization and shorter hospital stays.

When high doses of opioids are used, side effects such as constipation, respiratory depression, urinary retention, opioid-induced hyperalgesia, and drowsiness increase the risk for postoperative complications and hyperalgesia. Multiple studies have shown that multimodal analgesia approaches can reduce postoperative use of narcotics and length of hospital stay in spinal surgery patients.³

Table 1. Commonly used components of multimodal analgesia with dosing recommendations^1,2,4-6

What is the role of oral preemptive analgesia in the preoperative period for this patient?

Oral preemptive analgesia can play an important accessory role in the preoperative period by potentially decreasing new peripheral and central sensitization and addressing preexisting maladaptive central changes, which are key drivers of persistent postoperative pain.⁷ Central sensitization is characterized by increased responsiveness of the central nervous system to peripheral nociceptive input, which amplifies pain perception and hyperalgesia.⁸ As seen in our patient, persistent peripheral nociceptive input from chronic nerve root compression, inflammation, and degenerative changes further increases the risk of prolonged postoperative pain and the need for chronic opioid therapy, complicating recovery.

Multimodal analgesia within ERAS protocols⁷ targets multiple pain pathways to prevent these sensitization processes, addressing peripheral inflammatory and nociceptive signaling while modulating central neuronal excitability. Growing evidence supporting preemptive analgesia provides clinicians with an additional option within multimodal ERAS-based strategies, which most commonly include acetaminophen, NSAIDs, and gabapentinoids.⁹ Combining preemptive and perioperative nonopioid strategies decreases postoperative pain intensity, reduces opioid requirements and related side effects, facilitates earlier mobilization, shortens hospital stays, and improves overall functional recovery.

However, the routine use of oral preemptive analgesia on the day of surgery has become less consistent across institutions, particularly given the increasing prevalence of patients treated with GLP-1 receptor agonists. These agents are associated with delayed gastric emptying and may increase aspiration risk. At present, specific recommendations from the American Society of Anesthesiologists regarding modified fasting times for patients on GLP-1 agonists are evolving, and institutional policies vary. As a result, some centers avoid routine oral premedication on the day of surgery, emphasizing the need for individualized risk assessment when considering oral preemptive analgesia.¹⁰

What role do intraoperative drips like ketamine, lidocaine, and dexmedetomidine play in multimodal analgesia for spine surgery?

In spine surgery, intraoperative multimodal analgesia with ketamine, lidocaine, dexmedetomidine, and methadone can reduce perioperative pain, maladaptive central sensitization, and postoperative opioid requirements.¹¹ Ketamine is an N-methyl-D-aspartate (NMDA) receptor antagonist that attenuates central sensitization and opioid tolerance, particularly in patients on chronic opioid therapy. Ketamine has been shown to reduce immediate postoperative opioid consumption, improve back pain, and enhance walking distance at six months.¹² Lidocaine provides analgesia through sodium channel blockade and anti-inflammatory effects. Although its efficacy in spine surgery is variable, it may reduce postoperative pain, lower opioid use, and promote bowel function recovery.^{13, 14} Dexmedetomidine, an α2-adrenergic agonist, offers sedation and opioid-sparing analgesia and is associated with prolonged pain-free intervals, improved sleep quality, and reduced risk of postoperative delirium in older adults.^{15, 16}

Intraoperative methadone has gained increasing interest in spine surgery due to its favorable pharmacologic profile. In addition to potent µ-opioid receptor agonism, methadone functions as an NMDA receptor antagonist and inhibits serotonin and norepinephrine reuptake. These properties may reduce opioid tolerance, opioid-induced hyperalgesia, and the transition from acute to chronic postoperative pain. Methadone has been shown to improve postoperative pain control and reduce overall opioid requirements following complex spine surgery.¹⁷ Earlier concerns regarding delayed respiratory depression and arrhythmias have been challenged by more recent studies, suggesting that with appropriate dosing and monitoring, methadone can be safely incorporated, particularly in shorter spine procedures, while improving patient comfort and reducing supplemental opioid needs.^{18, 19}

Despite these complementary benefits, it is essential to develop a multimodal and individualized dosing plan while paying careful attention to potential side effects, including local anesthetic systemic toxicity, bradycardia, hypotension, and prolonged postoperative sedation.

Would your management change if the patient was a chronic opioid user for low back pain? How about if they were prescribed buprenorphine?

Chronic opioid users often develop opioid tolerance and/or opioid-induced hyperalgesia, resulting in higher analgesic requirements and an increased risk of withdrawal with changes in their usual opioid dosage.²⁰ In the perioperative setting, providers should anticipate and prepare for increased intraoperative and postoperative opioid requirements in these patient populations. Appropriate multimodal analgesia and regional anesthesia interventions can provide effective perioperative pain control and meaningfully enhance patient recovery.²⁰

Buprenorphine should not be routinely discontinued in the perioperative setting, and continuing at the preoperative dose is recommended for most patients.²¹ For complex patients, a pain management or addiction specialist may be consulted for recommendations on perioperative pain management or for buprenorphine dose adjustment.²¹

Patients undergoing spine surgery, particularly those with preexisting chronic pain or opioid exposure, may benefit from a dedicated acute pain service. Early involvement of an acute pain team can facilitate individualized postoperative analgesic plans, optimize multimodal strategies, manage opioid tapering, and potentially reduce the risk of persistent postoperative pain.

Is there any utility of regional or neuraxial anesthesia for spinal surgery?

With the advent of ERAS protocols, interest in regional and neuraxial anesthesia for spinal surgery has increased, though practice widely varies between institutions.

There have been a few reports of spinal and combined spinal-epidural (CSE) anesthesia being used both as primary anesthetic and as an analgesic adjunct in spine surgery, particularly in patients who are otherwise high-risk for general anesthesia.²² Advantages include shorter operative time, cost savings, and reduced blood loss.²² However, these techniques are far less commonly used than general anesthesia in the United States for spine surgeries. CSE is likely often not a viable option due to the catheter potentially being in the surgeon's field, as well as disruption of the epidural space. The duration of action of a single-shot spinal may be shorter than the duration of the procedure, but some surgeons may be able to inject a second dose under direct visualization. Neuraxial anesthesia also may not be an ideal sole anesthetic for complex or prolonged surgeries, especially those requiring prone positioning and more secure airway establishment.²² When considering neuraxial anesthesia, patient selection is extremely important while balancing risks of prone position, unsecure airway, and minimal sedation compared to general anesthesia.

Regional anesthesia is more often used to enhance multimodal analgesia. Fascial plane blocks, particularly the erector spinae plane (ESP) block, have gained much popularity in recent years.²³ ESP catheters can also be placed for postoperative analgesia. The thoracolumbar interfascial plane (TLIP) block is another regional anesthesia technique for analgesia, though its use is less widespread.²² Currently, no gold-standard regional anesthesia technique exists for spine surgery.

In addition to the considerations above, what is the role of multimodal analgesia in the immediate postoperative setting after spine surgery?

A well-planned preoperative and intraoperative multimodal analgesic regimen, as outlined above, forms the foundation of ERAS-based postoperative pain management. Continuing these nonopioid and adjuvant strategies into the postoperative period is key to reducing opioid requirements and facilitating recovery.

Nonopioid medications, as outlined above, can also be used in the postoperative setting. This includes NSAIDs, acetaminophen, and gabapentinoids.²⁴ These agents should be scheduled when appropriate to maintain consistent analgesia and reduce opioid requirements. Providers should assess medical records prior to administering additional doses to ensure medications are not given too frequently or above the daily dose limit. There may also be roles for subanesthetic ketamine infusions or IV lidocaine infusions in the immediate postoperative period, particularly in opioid-tolerant patients or those with severe pain, but supporting data is more varied.²⁴

Opioid medications also play a role during the postoperative period. IV opioid boluses should be appropriately titrated for targeted pain control under close monitoring. Depending on the patient's medical history, perioperative course, and pain level, a transition to oral, short-acting, opioid medications can be initiated early, with the goal of titrating the patient off all opioids as soon as able.²⁵

Epidural analgesia may provide an additional opioid-sparing strategy, allowing for titratable postoperative analgesia. By delivering local anesthetics and/or opioids directly to the epidural space, this technique offers targeted, continuous pain control that can be adjusted based on the patient's evolving needs in the postoperative period. Epidural analgesia has been shown to reduce postoperative opioid consumption, increase patient satisfaction, and facilitate earlier mobilization, one of the key goals of ERAS-based recovery in spine surgery.²⁶ Early ambulation following lumbar decompression and fusion procedures is particularly important, as it reduces risks of venous thromboembolism, pulmonary complications, and prolonged deconditioning.

However, the routine use of epidural analgesia in complex spine surgery presents unique practical challenges. In procedures involving laminectomy, the surgical removal of posterior bony and ligamentous structures disrupts the epidural space, complicating catheter placement and increasing the risk of dural puncture, cerebrospinal fluid leak, or catheter misplacement. In multilevel fusion surgeries, instrumentation and bone graft material may further limit reliable catheter positioning and spread of injectate.²⁷ Postoperatively, epidural analgesia may also obscure the neurological examination, potentially delaying the recognition of new motor deficits or compressive hematoma, a critical concern following spine surgery.²⁸ As such, careful patient selection and a multidisciplinary approach are essential, and more robust prospective data are needed to establish the safety and feasibility of routine epidural analgesia in complex spine surgery.

Overall, a multimodal and carefully planned preoperative, intraoperative, and immediate postoperative pain management plan for patients undergoing spine surgery can lead to faster recovery and better outcomes. Successful implementation requires careful coordination between surgeons, anesthesiologists, pain management physicians, rehabilitation providers, and primary care providers to ensure individualized, safe, and effective analgesic care.

Six months after the patient's surgery, she returns with reports of recurrent leg and back pain. What should an evaluation and assessment include?

History-taking should focus on characterizing the pain by location (axial vs. radicular), quality, and severity. These characteristics, along with the timeline and progression of symptoms, should be compared with the presurgical pain. Recurrence of pain that is similar in nature to presurgical pain may indicate inadequate decompression or residual stenosis, disc tissue, or bone fragments. New pain may be suggestive of surgical complications (e.g., instrumentation issues, iatrogenic injury) or adjacent segment disease.²³ Identifying red flag signs (e.g., night pain, fever, unexplained weight loss, loss of bowel and/or bladder function, saddle anesthesia) is important, as they may warrant urgent surgical evaluation. Physical examination should include inspection of posture and gait, as well as comparison of spine range of motion, strength, sensation, and reflexes to presurgical baselines. Special tests including facet loading, straight leg raise, seated slump, and sacroiliac joint provocative maneuvers help distinguish between facetogenic, discogenic, radicular, sacroiliac, or myofascial sources of pain.

Plain radiographs are used to assess alignment and hardware positioning, with standing flexion and extension views revealing dynamic instability. MRI provides evaluation of soft tissues for stenosis, nerve root impingement, disc pathology, or adhesions. Computed tomography is useful for assessing osseous changes like pseudoarthrosis or when MRI is contraindicated. Electrodiagnostic testing is used for motor or sensory deficits not explained by imaging findings.

Differential diagnoses for radicular pain with unrevealing imaging include peripheral nerve involvement, hip pathology, piriformis syndrome, iliotibial band syndrome, peripheral vascular disease, central sensitization, and spinal instability (not visualized on static imaging).

What is Persistent Spinal Pain Syndrome (PSPS)? What preoperative and postoperative factors increase the risk for developing PSPS?

PSPS is a new moniker for "failed back surgery syndrome (FBSS)" that is divided into Type 1 and Type 2. PSPS Type 1 occurs without any prior spinal surgery being performed with the intention of relieving pain. PSPS Type 2 includes a history of surgery that fails to relieve pain and/or is suspected to be causing the pain. FBSS was originally defined by the International Association for the Study of Pain as "lumbar spinal pain of unknown origin either persisting despite surgical intervention or appearing after surgical intervention for spinal pain originally in the same topographical location." PSPS Type I and Type II apply to any spinal level. The incidence of PSPS varies, with reported rates ranging from 10–40%.²⁴ PSPS is multifactorial and influenced by preoperative, intraoperative, and postoperative factors. While intraoperative factors are beyond the scope of this discussion, they remain important considerations in clinical practice. Preoperative psychological factors such as depression, anxiety, poor coping, and hypochondriasis are associated with poor outcomes. Socioeconomically, patients receiving workers' compensation or involved in litigation demonstrate higher pain scores and poor functional outcomes, potentially related to secondary gain.²⁹ Behavioral risks include smoking and obesity. Smoking impairs wound healing, increases postoperative infection rates, and is associated with more frequent analgesic use and lower quality of life postoperatively.³⁰ From a surgical standpoint, repeated surgeries are linked to poor outcomes, with success rates as low as 5% after a fourth surgery.³¹

Postoperatively, PSPS Type 2 can occur from progression of preexisting degenerative changes, new spine pathology, or trauma to adjacent structures. Altered biomechanics may accelerate degenerative changes in the adjacent intervertebral discs, facets, and sacroiliac joints.³² Epidural fibrosis may cause nerve root tethering or compression, leading to axial or radicular pain.³³ Concurrent myofascial pain can occur from intraoperative muscle trauma or compensatory postural changes.

What pharmacologic options are available for PSPS?

Pharmacologic options for PSPS Type 2 include oral/systemic agents (e.g., NSAIDs, muscle relaxants, antidepressants, gabapentinoids, opioids) and intrathecal drug delivery (e.g., opioids, local anesthetics, clonidine, ziconotide). Oral agents are generally less effective for refractory PSPS Type 2, with intrathecal therapy and neuromodulation reserved for severe, treatment-resistant cases due to procedural risks and adverse events. There is a lack of direct comparative data and long-term safety data for intrathecal therapies.

Below is a summary table of pharmacologic options, their routes, indications, evidence, and key findings.

When should you consider spinal cord stimulation, peripheral nerve stimulation, dorsal root ganglion stimulation, and other neuromodulation modalities for PSPS Type 2?

Neuromodulation modalities such as spinal cord stimulation (SCS), peripheral nerve stimulation (PNS), and dorsal root ganglion stimulation (DRG-S) should be considered for PSPS Type 2 when conservative treatments (e.g., medications, physical therapy, interventional procedures) have failed to provide meaningful relief, and the patient has persistent, disabling neuropathic pain. Careful patient selection, including psychological evaluation and a successful trial (≥50% pain relief), is essential before permanent implantation.^39-41

SCS is the most established neuromodulation technique for PSPS Type 2, especially for patients with predominant leg pain. SCS is supported by high-level evidence showing superior pain relief, improved function, and reduced opioid use compared to conventional medical management or reoperation.^30-42 Evolving SCS technologies such as high-frequency, burst, and multicolumn SCS have yielded improved outcomes for both leg and back pain.^{34, 40, 41, 43} However, SCS is less effective for predominant low back pain, and device-related complications occur in up to 30% of patients.^{34, 39, 41}

PNS should be considered for patients with refractory low back pain who do not respond to SCS. The American Society of Pain and Neuroscience notes emerging evidence for PNS, particularly subcutaneous field stimulation, with significant improvements in pain and quality of life in PSPS Type 2 patients.⁴⁴ PNS may be added to SCS in select cases.⁴³

DRG-S is indicated for focal pain syndromes or as salvage therapy after failed SCS. DRG-S has demonstrated substantial pain reduction and functional improvement in PSPS Type 2, including cases with prior failed SCS.^{41, 45} Safety data are comparable to SCS, though lead migration and device complications may be more frequent.^{39, 46}

Other interventional options, such as epidural adhesiolysis, have grade A evidence for short-term benefit, while epidural injections have grade C evidence. Most other modalities have poor or inconclusive evidence for PSPS Type 2.⁴⁷

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