Long-term effectiveness of epidural steroid injections after new episodes of low back pain in older adults

BACKGROUND

There is limited research on the long-term effectiveness of epidural steroid injections (ESI) in older adults despite the high prevalence of back and leg pain in this age group. We tested the hypotheses that older adults undergoing ESI, compared to patients not receiving ESI: 1) have worse pain, disability and quality of life ("outcomes") pre-ESI, 2) have improved outcomes after ESI, and 3) have improved outcomes due to a specific ESI effect.

METHODS

We prospectively studied patients ≥65 years old presenting to primary care with new episodes of back pain in three US healthcare systems (BOLD registry). Outcomes were leg and back pain intensity, disability and quality of life, assessed at baseline and 3-, 6-, 12- and 24-month follow-ups. We categorized participants as: 1) ESI within 6 months from the index visit (n=295); 2) no ESI within 6 months (n=4,809); 3) no ESI within 6 months, propensity-score matched to group 1 (n=483). We analyzed the data using linear regression and Generalized Estimating Equations.

RESULTS

Pain intensity, disability and quality of life at baseline were significantly worse at baseline in ESI patients (group 1) than in group 2. The improvement from baseline to 24 months in all outcomes was statistically significant for group 1. However, no statistically significant differences were observed between outcome trajectories for the propensity-score matched groups 1 and 3.

CONCLUSIONS

Older adults treated with ESI have long-term improvement. However, the improvement is unlikely the result of a specific ESI effect.

Lumbar Spinal Stenosis Severity by CT or MRI Does Not Predict Response to Epidural Corticosteroid versus Lidocaine Injections

BACKGROUND AND PURPOSE

Epidural steroid injections may offer little-to-no short-term benefit in the overall population of patients with symptomatic spinal stenosis compared with lidocaine alone. We investigated whether imaging could identify subgroups of patients who might benefit most.

MATERIALS AND METHODS

A secondary analysis of the Lumbar Epidural Steroid Injections for Spinal Stenosis prospective, double-blind trial was performed, and patients were randomized to receive an epidural injection of lidocaine with or without corticosteroids. Patients (n = 350) were evaluated for qualitative and quantitative MR imaging or CT measures of lumbar spinal stenosis. The primary clinical end points were the Roland-Morris Disability Questionnaire and the leg pain numeric rating scale at 3 weeks following injection. ANCOVA was used to assess the significance of interaction terms between imaging measures of spinal stenosis and injectate type on clinical improvement.

RESULTS

There was no difference in the improvement of disability or leg pain scores at 3 weeks between patients injected with epidural lidocaine alone compared with corticosteroid and lidocaine when accounting for the primary imaging measures of qualitative spinal stenosis assessment (interaction coefficients for disability score, -0.1; 95% CI, -1.3 to 1.2; P = .90; and for the leg pain score, 0.1; 95% CI, -0.6 to 0.8; P = .81) or the quantitative minimum thecal sac cross-sectional area (interaction coefficients for disability score, 0.01; 95% CI, -0.01 to 0.03; P = .40; and for the leg pain score, 0.01; 95% CI, -0.01 to 0.03; P = .33).

CONCLUSIONS

Imaging measures of spinal stenosis are not associated with differential clinical responses following epidural corticosteroid injection.

Changes in Pain Sensitivity and Pain Modulation During Oral Opioid Treatment: The Impact of Negative Affect

OBJECTIVE

Opioids are frequently prescribed for chronic low back pain (CLBP), but there are broad individual differences in the benefits and risks of opioid therapy, including the development opioid-induced hyperalgesia. This study examined quantitative sensory testing (QST) data among a group of CLBP patients undergoing sustained oral opioid treatment. We investigated whether individual differences in psychological characteristics were related to opioid-induced changes in pain perception and pain modulation.

DESIGN

The six-month, open-label trial evaluated patients with low to high levels of negative affect (e.g., symptoms of distress, depression and anxiety); participants underwent QST at baseline (prior to initiating treatment) and during oral opioid treatment.

SETTING

A chronic pain management center.

PATIENTS

The 31 study participants had chronic discogenic back pain, with a pain intensity rating >3/10. Participants were divided into groups with high vs. low levels of Negative Affect (NA).

RESULTS

In the previously-published manuscript describing the clinical outcomes of the trial, high NA patients achieved only about half of the analgesic effect observed in the low NA group (Wasan AD, Michna E, Edwards RR, et al. Psychiatric comorbidity is associated prospectively with diminished opioid analgesia and increased opioid misuse in patients with chronic low back pain. Anesthesiology 2015;123:861-72). The QST findings reported here suggested that tolerance to experimental (cold pressor) pain and conditioned pain modulation tended to decrease in the high NA group over the course of opioid treatment, while temporal summation of mechanical pain declined in the low NA group.

CONCLUSIONS

These results reveal that while the low NA group seemed to exhibit a generally adaptive, analgesic pattern of changes during opioid management, the high NA group showed a pattern more consistent with opioid-induced hyperalgesic processes. A greater susceptibility to hyperalgesia-promoting changes in pain modulation among patients with high levels of distress may contribute to a lower degree of benefit from opioid treatment in high NA patients.

Spinal cord stimulation for chronic intractable angina pectoris: a unified theory on its mechanism

The use of spinal cord stimulation (SCS) for chronic intractable anginal pain was first described in 1987. Numerous studies have demonstrated its efficacy in improving exercise tolerance, decreasing frequency of anginal episodes, and prolonging time to electrocardiographic signs of ischemia. This review will examine the potential mechanisms of this antianginal effect and propose a unified hypothesis explaining it. The effect of SCS involves a mutual interaction of decreased pain, decreased sympathetic tone, and a likely redistribution of myocardial blood flow to ischemic regions. Spinal cord stimulation reduces the transmission of nociceptive impulse via the spinothalamic tract due to an enhanced release of gamma aminobutyric acid (GABA) from dorsal horn interneurons. Improvement of myocardial blood flow at the microvascular level has been demonstrated by positron emission tomography (PET). A decreased sympathetic tone has been shown by norepinephrine kinetics, tests of sympathetic reflexes, and the use of ganglionic blockers. We hypothesize that SCS exerts its beneficial effects by decreasing pain and decreasing sympathetic tone, the result of which is decreased myocardial oxygen consumption along with an improved myocardial microcirculatory blood flow.

Opioid therapy for chronic noncancer back pain. A randomized prospective study

STUDY DESIGN

A randomized, open, long-term, repeated-dose comparison of an anti-inflammatory drug and two opioid regimens in 36 patients with back pain.

OBJECTIVES

To examine the long-term safety and efficacy of chronic opioid therapy in a randomized trial of patients with back pain.

METHODS

All participants underwent a 4-week washout period of no opioid medication before being randomly assigned to one of three treatment regimens for 16 weeks: 1) naproxen only, 2) set-dose oxycodone, or 3) titrated-dose oxycodone and sustained-release morphine sulfate. All patients then were assigned to a titrated dose of opioids for 16 weeks and then gradually tapered off their medication for 12 weeks. Finally, all participants were monitored for a 1-month posttreatment washout period. Each patient was called once a week for a report on pain, activity, mood, medication, hours awake, and adverse effects and was monitored carefully for signs of abuse and noncompliance.

RESULTS

Weekly reports during the experimental phase showed the titrated-dose group to have less pain (P < 0.001) and less emotional distress (P < 0.001) than the other two groups. Both opioid groups were significantly different from the naproxen-only group. During the titration phase, patients also reported significantly less pain and improved mood. Few differences were found in activity or hours asleep, or between average pretreatment and posttreatment phone-interview and questionnaire variables. No adverse events occurred, and only one participant showed signs of abuse behavior.

CONCLUSIONS

The results suggest that opioid therapy has a positive effect on pain and mood but little effect on activity and sleep. Opioid therapy for chronic back pain was used without significant risk of abuse. However, tapered-off opioid treatment is palliative and without long-term benefit.