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Lidocaine patch (5%) is no more potent than placebo in treating chronic back pain when tested in a randomised double blind placebo controlled brain imaging study.

Hashmi JA, Baliki MN, Huang L, Parks EL, Chanda ML, Schnitzer T, Apkarian AV - Mol Pain (2012)

Bottom Line: However, 50% patients in both the Lidocaine and placebo arms reported a greater than 50% decrease in pain suggesting a marked placebo effect.When tested against an untreated CBP group at similar time points, the patch treated subjects showed significantly greater decrease in pain compared to the untreated group (n = 15).These findings suggest that although the 5% Lidocaine is not better than placebo in its effectiveness for treating pain, the patch itself induces a potent placebo effect in a significant proportion of CBP patients.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois 60611, USA.

ABSTRACT

Background: The 5% Lidocaine patch is used for treating chronic neuropathic pain conditions such as chronic back pain (CBP), diabetic neuropathy and complex regional pain syndrome, but is effective in a variable proportion of patients. Our lab has reported that this treatment reduces CBP intensity and associated brain activations when tested in an open labelled preliminary study. Notably, effectiveness of the 5% Lidocaine patch has not been tested against placebo for treating CBP. In this study, effectiveness of the 5% Lidocaine patch was compared with placebo in 30 CBP patients in a randomised double-blind study where 15 patients received 5% Lidocaine patches and the remaining patients received placebo patches. Functional MRI was used to identify brain activity for fluctuations of spontaneous pain, at baseline and at two time points after start of treatment (6 hours and 2 weeks).

Results: There was no significant difference between the treatment groups in either pain intensity, sensory and affective qualities of pain or in pain related brain activation at any time point. However, 50% patients in both the Lidocaine and placebo arms reported a greater than 50% decrease in pain suggesting a marked placebo effect. When tested against an untreated CBP group at similar time points, the patch treated subjects showed significantly greater decrease in pain compared to the untreated group (n = 15).

Conclusions: These findings suggest that although the 5% Lidocaine is not better than placebo in its effectiveness for treating pain, the patch itself induces a potent placebo effect in a significant proportion of CBP patients.

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Related in: MedlinePlus

Different groupings for brain activity for spontaneous fluctuations of pain of CBP calculated for brain scans collected at baseline. Coordinates x = 8, y = 56, z = 20 for A-D (top row are sagittal, middle horizontal, and bottom coronal slices; middle and bottom rows: left side is left hemisphere). A. Whole-group average brain activity for rating spontaneous pain of CBP patients (n = 30 subjects). Brain activity was limited to medial prefrontal cortex (BA 9) and the genual anterior cingulate cortex (BA 32). B. Contrast between activity for rating spontaneous pain of CBP and rating length of a bar varying in time (control for visual, motor, and task demands; paired t-statistic n = 30 subjects) identifies the same brain activity as in A. C and D. Brain activity was similar between placebo (C) and lidocaine (D) treated groups for spontaneous pain of CBP at baseline (n = 15 subjects per group), and closely matched whole-group activity shown in activity and contrast maps were generated using random-effects statistics with z score ≫ 2.3 and cluster threshold p ≪ 0.01, corrected for multiple comparisons.
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Figure 2: Different groupings for brain activity for spontaneous fluctuations of pain of CBP calculated for brain scans collected at baseline. Coordinates x = 8, y = 56, z = 20 for A-D (top row are sagittal, middle horizontal, and bottom coronal slices; middle and bottom rows: left side is left hemisphere). A. Whole-group average brain activity for rating spontaneous pain of CBP patients (n = 30 subjects). Brain activity was limited to medial prefrontal cortex (BA 9) and the genual anterior cingulate cortex (BA 32). B. Contrast between activity for rating spontaneous pain of CBP and rating length of a bar varying in time (control for visual, motor, and task demands; paired t-statistic n = 30 subjects) identifies the same brain activity as in A. C and D. Brain activity was similar between placebo (C) and lidocaine (D) treated groups for spontaneous pain of CBP at baseline (n = 15 subjects per group), and closely matched whole-group activity shown in activity and contrast maps were generated using random-effects statistics with z score ≫ 2.3 and cluster threshold p ≪ 0.01, corrected for multiple comparisons.

Mentions: Average group activity map was generated for 30 CBP patients to determine brain regions reflecting spontaneous back pain. The spontaneous pain ratings correlated significantly with BOLD response in the medial prefrontal cortex, extending from the medial frontal pole to the genual anterior cingulate cortex (Figure 2A, Table 1). To correct for task related brain activity confounds we subtracted the visual rating activity maps from the pain rating activity maps (whole-brain paired t-test). The resultant map showed essentially the same pattern as the uncorrected map (Figure 2B) (opposite contrast was ). Furthermore, contrasting between the Lidocaine and the placebo treated groups (unpaired t-tests, n = 15 subjects per group) at baseline, at 6 hours, and at 2 weeks of treatment showed no significant brain activity. The mean activation maps for Lidocaine treated and placebo treated groups (n = 15 subjects per group) at baseline again showed spontaneous pain related statistically significant activation in the medial prefrontal and the genual anterior cingulate cortices (Figure 2C &2D). However, there was no significant mean activation at 6 hrs or at 2 weeks of treatment in either the Lidocaine treated group, or the placebo treated group. Overall, we observe a consistent brain activity at baseline for spontaneous pain of CBP. However, as back pain magnitude decreases with treatment the related brain activity also decreases in both groups.


Lidocaine patch (5%) is no more potent than placebo in treating chronic back pain when tested in a randomised double blind placebo controlled brain imaging study.

Hashmi JA, Baliki MN, Huang L, Parks EL, Chanda ML, Schnitzer T, Apkarian AV - Mol Pain (2012)

Different groupings for brain activity for spontaneous fluctuations of pain of CBP calculated for brain scans collected at baseline. Coordinates x = 8, y = 56, z = 20 for A-D (top row are sagittal, middle horizontal, and bottom coronal slices; middle and bottom rows: left side is left hemisphere). A. Whole-group average brain activity for rating spontaneous pain of CBP patients (n = 30 subjects). Brain activity was limited to medial prefrontal cortex (BA 9) and the genual anterior cingulate cortex (BA 32). B. Contrast between activity for rating spontaneous pain of CBP and rating length of a bar varying in time (control for visual, motor, and task demands; paired t-statistic n = 30 subjects) identifies the same brain activity as in A. C and D. Brain activity was similar between placebo (C) and lidocaine (D) treated groups for spontaneous pain of CBP at baseline (n = 15 subjects per group), and closely matched whole-group activity shown in activity and contrast maps were generated using random-effects statistics with z score ≫ 2.3 and cluster threshold p ≪ 0.01, corrected for multiple comparisons.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475108&req=5

Figure 2: Different groupings for brain activity for spontaneous fluctuations of pain of CBP calculated for brain scans collected at baseline. Coordinates x = 8, y = 56, z = 20 for A-D (top row are sagittal, middle horizontal, and bottom coronal slices; middle and bottom rows: left side is left hemisphere). A. Whole-group average brain activity for rating spontaneous pain of CBP patients (n = 30 subjects). Brain activity was limited to medial prefrontal cortex (BA 9) and the genual anterior cingulate cortex (BA 32). B. Contrast between activity for rating spontaneous pain of CBP and rating length of a bar varying in time (control for visual, motor, and task demands; paired t-statistic n = 30 subjects) identifies the same brain activity as in A. C and D. Brain activity was similar between placebo (C) and lidocaine (D) treated groups for spontaneous pain of CBP at baseline (n = 15 subjects per group), and closely matched whole-group activity shown in activity and contrast maps were generated using random-effects statistics with z score ≫ 2.3 and cluster threshold p ≪ 0.01, corrected for multiple comparisons.
Mentions: Average group activity map was generated for 30 CBP patients to determine brain regions reflecting spontaneous back pain. The spontaneous pain ratings correlated significantly with BOLD response in the medial prefrontal cortex, extending from the medial frontal pole to the genual anterior cingulate cortex (Figure 2A, Table 1). To correct for task related brain activity confounds we subtracted the visual rating activity maps from the pain rating activity maps (whole-brain paired t-test). The resultant map showed essentially the same pattern as the uncorrected map (Figure 2B) (opposite contrast was ). Furthermore, contrasting between the Lidocaine and the placebo treated groups (unpaired t-tests, n = 15 subjects per group) at baseline, at 6 hours, and at 2 weeks of treatment showed no significant brain activity. The mean activation maps for Lidocaine treated and placebo treated groups (n = 15 subjects per group) at baseline again showed spontaneous pain related statistically significant activation in the medial prefrontal and the genual anterior cingulate cortices (Figure 2C &2D). However, there was no significant mean activation at 6 hrs or at 2 weeks of treatment in either the Lidocaine treated group, or the placebo treated group. Overall, we observe a consistent brain activity at baseline for spontaneous pain of CBP. However, as back pain magnitude decreases with treatment the related brain activity also decreases in both groups.

Bottom Line: However, 50% patients in both the Lidocaine and placebo arms reported a greater than 50% decrease in pain suggesting a marked placebo effect.When tested against an untreated CBP group at similar time points, the patch treated subjects showed significantly greater decrease in pain compared to the untreated group (n = 15).These findings suggest that although the 5% Lidocaine is not better than placebo in its effectiveness for treating pain, the patch itself induces a potent placebo effect in a significant proportion of CBP patients.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois 60611, USA.

ABSTRACT

Background: The 5% Lidocaine patch is used for treating chronic neuropathic pain conditions such as chronic back pain (CBP), diabetic neuropathy and complex regional pain syndrome, but is effective in a variable proportion of patients. Our lab has reported that this treatment reduces CBP intensity and associated brain activations when tested in an open labelled preliminary study. Notably, effectiveness of the 5% Lidocaine patch has not been tested against placebo for treating CBP. In this study, effectiveness of the 5% Lidocaine patch was compared with placebo in 30 CBP patients in a randomised double-blind study where 15 patients received 5% Lidocaine patches and the remaining patients received placebo patches. Functional MRI was used to identify brain activity for fluctuations of spontaneous pain, at baseline and at two time points after start of treatment (6 hours and 2 weeks).

Results: There was no significant difference between the treatment groups in either pain intensity, sensory and affective qualities of pain or in pain related brain activation at any time point. However, 50% patients in both the Lidocaine and placebo arms reported a greater than 50% decrease in pain suggesting a marked placebo effect. When tested against an untreated CBP group at similar time points, the patch treated subjects showed significantly greater decrease in pain compared to the untreated group (n = 15).

Conclusions: These findings suggest that although the 5% Lidocaine is not better than placebo in its effectiveness for treating pain, the patch itself induces a potent placebo effect in a significant proportion of CBP patients.

Show MeSH
Related in: MedlinePlus