Ultrasound combined with electrodiagnosis improves lesion localization and outcome in posterior interosseous neuropathy.

INTRODUCTION: Posterior interosseous nerve (PIN) syndrome is a rare compression neuropathy. Electrodiagnostic studies (EDx) combined with neuromuscular ultrasound (US) enable precise lesion localization and may improve patient outcome. METHODS: In 4 patients with finger extension weakness, US was used to accurately localize concentric electromyographic (EMG) needle placement in PIN muscles and to visualize the lesion site. RESULTS: EMG with US guidance showed decreased recruitment with abnormal configuration in PIN muscles. Active denervation was not always observed. US scanning demonstrated larger PIN diameter in the affected arm. All patients had surgical intervention to confirm EDx and US findings and had improved outcome on follow-up. CONCLUSION: These cases demonstrate the benefits of augmenting EDx with US by guiding accurate electrode localization and providing diagnostic information about lesion location.

White matter hyperintensity burden and disability in older adults: is chronic pain a contributor?

OBJECTIVE: To primarily explore differences in global and regional white matter hyperintensities (WMH) in older adults with self-reported disabling and nondisabling chronic low back pain (CLBP) and to examine the association of WMH with gait speed in all participants with CLBP. To secondarily compare WMH of the participants with CLBP with the pain-free controls. DESIGN: A cross-sectional, case-control study. SETTING: University of Pittsburgh. PARTICIPANTS: Twenty-four community-dwelling older adults: 8 with self-reported disabling CLBP, 8 with nondisabling CLBP, and 8 were pain-free. Exclusions were psychiatric or neurologic disorders (either central or peripheral), substance abuse, opioid use, or diabetes mellitus. METHODS: All participants underwent structural brain magnetic resonance imaging, and all participants with CLBP underwent the 4-m walk test. MAIN OUTCOME MEASUREMENTS: All the participants were assessed for both global and regional WMH by using an automated localization and segmentation method, and gait speed of participants with CLBP. RESULTS: The disabled group demonstrated statistically significant regional WMH in a number of left hemispheric tracts: anterior thalamic radiation (P = .0391), lower cingulate (P = .0336), inferior longitudinal fasciculus (P = .0367), superior longitudinal fasciculus (P = .0011), and the superior longitudinal fasciculus branch to the temporal lobe (P = .0072). Also, there was a statistically significant negative association (rs = -0.57; P = .0225) between the left lower cingulate WMH and the gait speed in all the participants with CLBP. There was a statistical difference in global WMH burden (P = .0014) and nearly all regional tracts (both left and right hemispheres) when comparing CLBP with pain-free participants. CONCLUSIONS: Our findings suggest that WMH is associated with, and hence, may be accelerated by chronic pain manifesting as perceived disability, given the self-reported disabled CLBP patients had the greatest burden, and the pain free the least, and manifesting as measurable disability, given increasing WMH was associated with decreasing gait speed in all chronic pain participants.

Differences in brain structure and function in older adults with self-reported disabling and nondisabling chronic low back pain.

OBJECTIVE: The primary aim of this pilot study was to identify structural and functional brain differences in older adults with self-reported disabling chronic low back pain (CLBP) compared with those who reported nondisabling CLBP. DESIGN: Cross-sectional. PARTICIPANTS: Sixteen cognitively intact older adults, eight with disabling CLBP and eight with nondisabling CLBP. Exclusions were psychiatric or neurological disorders, substance abuse, opioid use, or diabetes mellitus. METHODS: Participants underwent: structural and functional brain MRI; neuropsychological assessment using the Repeatable Battery for the Assessment of Neuropsychological Status, Trail Making Tests A and B; and physical performance assessment using the Short Physical Performance Battery. RESULTS: In the disabled group, there was significantly lower white matter (WM) integrity (P < 0.05) of the splenium of the corpus callosum. This group also demonstrated activation of the right medial prefrontal cortex at rest whereas the nondisabled demonstrated activation of the left lateral prefrontal cortex. Combined groups analysis revealed a strong positive correlation (r(s) = 0.80, P < 0.0002) between WM integrity of the left centrum semiovale with gait-speed. Secondary analysis revealed a strong negative correlation between total months of CLBP and WM integrity of the SCC (r(s) = -0.59, P < 0.02). CONCLUSIONS: Brain structure and function is different in older adults with disabling CLBP compared with those with nondisabling CLBP. Deficits in brain morphology combining groups are associated with pain duration and poor physical function. Our findings suggest brain structure and function may play a key role in chronic pain related disability and may be important treatment targets.

Chronic pain is associated with brain volume loss in older adults: preliminary evidence.

OBJECTIVES: The primary aim of this pilot investigation was to identify structural brain differences in older adults with chronic low back pain (CLBP) as compared with pain-free individuals. DESIGN: Cross-sectional, case-control. PARTICIPANTS: Sixteen cognitively intact older adults, eight with CLBP and eight pain-free; excluded if with psychiatric or neurological disorders, substance abuse, opioid use, diabetes mellitus, and/or hypertension. METHODS: Brain magnetic resonance imaging (MRI) and tests of neuropsychological performance (digit span, digit symbol substitution, letter-number sequencing, trail making) were administered to all participants. Gray matter (GM), white matter (WM), cerebrospinal fluid, and corpus callosum (CC) volumes were measured as a percentage of total supratentorial intracranial volume. Voxel-based morphometry analysis of GM and WM assessed regional differences. RESULTS: Between-groups analysis revealed a non-significant trend toward decreased middle CC volume in the CLBP group (1.43E-03 +/- 2.67E-04, 1.63E-03 +/- 2.00E-04: P = 0.09). Regional analysis in the CLBP group demonstrated significantly decreased GM volume (P < 0.001) in the posterior parietal cortex and middle cingulate WM volume (P < 0.001) of the left hemisphere. CLBP participants performed significantly worse on digit span forward (P = 0.03). CONCLUSIONS: Older adults with CLBP have structural brain changes in the middle CC, middle cingulate WM, and the GM of the posterior parietal cortex as well as impaired attention and mental flexibility. Additional investigation is needed to corroborate and extend these findings and more clearly elucidate their relationship to physical function and the risk of disability.