Enrique Pena

Seton Spine and Scoliosis Center, Austin, Texas, United States

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Publications (6)14.24 Total impact

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    ABSTRACT: Walking limitations caused by neurogenic claudication (NC) are typically assessed with self-reported measures, although objective evaluation of walking using motorized treadmill test (MTT) or self-paced walking test (SPWT) has periodically appeared in the lumbar spinal stenosis (LSS) literature. This study compared the validity and responsiveness of MTT and SPWT for assessing walking ability before and after common treatments for NC. Prospective observational cohort study. Fifty adults were recruited from an urban spine center if they had LSS and substantial walking limitations from NC and were scheduled to undergo surgery (20%) or conservative treatment (80%). Walking times, distances, and speeds along with the characteristics of NC symptoms were recorded for MTT and SPWT. Self-reported measures included back and leg pain intensity assessed with 0 to 10 numeric pain scales, disability assessed with Oswestry Disability Index, walking ability assessed with estimated walking times and distances, and NC symptoms assessed with the subscales from the Spinal Stenosis Questionnaires. Motorized treadmill test used a level track, and SPWT was conducted in a rectangular hallway. Walking speeds were self-selected, and test end points were NC, fatigue, or completion of the 30-minute test protocol. Results from MTT and SPWT were compared with each other and self-reported measures. Internal responsiveness was assessed by comparing changes in the initial results with the posttreatment results and external responsiveness by comparing walking test results that improved with those that did not improve by self-reported criteria. Mean age of the participants was 68 years, and 58% were male. Neurogenic claudication included leg pain (88%) and buttock(s) pain (12%). Five participants could not safely perform MTT. Walking speeds were faster and distances were greater with SPWT, although the results from both tests correlated with each other and self-reported measures. Of the participants, 72% reported improvement after treatment, which was confirmed by significant mean differences in self-reported measures. Motorized treadmill test results did not demonstrate internal responsiveness to change in clinical status after treatment but SPWT results did, with increased mean walking times (6 minutes) and distances (387 m). When responsiveness was assessed against external criterion, both SPWT and MTT demonstrated substantial divergence with self-reported changes in clinical status and alternative outcome measures. Both MTT and SPWT can quantify walking abilities in NC. As outcome tools, SPWT demonstrated better internal responsiveness than MTT, but neither test demonstrated adequate external responsiveness. Neither test should be considered as a meaningful substitution for disease-specific measures of function.
    The spine journal: official journal of the North American Spine Society 12/2011; 12(2):101-9. · 2.90 Impact Factor
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    ABSTRACT: To determine whether older adults (aged ≥ 60) experience less improvement in disability and pain with nonsurgical treatment of lumbar disk herniation (LDH) than younger adults (< 60). Prospective longitudinal comparative cohort study. Outpatient specialty spine clinic. One hundred thirty-three consecutive patients with radicular pain and magnetic resonance-confirmed acute LDH (89 younger, 44 older). Nonsurgical treatment customized for the individual patient. Patient-reported disability on the Oswestry Disability Index (ODI), leg pain intensity, and back pain intensity were recorded at baseline and 1, 3, and 6 months. The primary outcome was the ODI change score at 6 months. Secondary longitudinal analyses examined rates of change over the follow-up period. Older adults demonstrated improvements in ODI (range 0-100) and pain intensity (range 0-10) with nonsurgical treatment that were not significantly different from those seen in younger adults at 6 month follow-up, with or without adjustment for potential confounders. Adjusted mean improvement in older and younger adults were 31 versus 33 (P = .63) for ODI, 4.5 versus 4.5 (P = .99) for leg pain, and 2.4 versus 2.7 for back pain (P = .69). A greater amount of the total improvement in leg pain and back pain in older adults was noted in the first month of follow-up than in younger adults. These preliminary findings suggest that the outcomes of LDH with nonsurgical treatment were not worse in older adults (≥ 60) than in younger adults (< 60). Future research is warranted to examine nonsurgical treatment for LDH in older adults.
    Journal of the American Geriatrics Society 03/2011; 59(3):423-9. · 4.22 Impact Factor
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    ABSTRACT: Cross-sectional study with prospective recruitment. OBJECTIVE.: To determine the accuracy of the physical examination for the diagnosis of midlumbar nerve root impingement (L2, L3, or L4), low lumbar nerve root impingement (L5 or S1) and level-specific lumbar nerve root impingement on magnetic resonance imaging, using individual tests and combinations of tests. The sensitivity and specificity of the physical examination for the localization of nerve root impingement has not been previously studied. Sensitivities, specificities, and likelihood ratios (LRs) were calculated for the ability of individual tests and test combinations to predict the presence or absence of nerve root impingement at midlumbar, low lumbar, and specific nerve root levels. LRs ≥5.0 indicate moderate to large changes from pre-test probability of nerve root impingement to post-test probability. For the diagnosis of midlumbar impingement, the femoral stretch test (FST), crossed FST, medial ankle pinprick sensation, and patellar reflex testing demonstrated LRs ≥5.0 (LR ∞). LRs ≥5.0 were observed with the combinations of FST and either patellar reflex testing (LR 7.0; 95% confidence interval [CI] 2.3-21) or the sit-to-stand test (LR ∞). For the diagnosis of low lumbar impingement, the Achilles reflex test demonstrated an LR ≥5.0 (LR 7.1; 95% CI 0.96-53); test combinations did not increase LRs. For the diagnosis of level-specific impingement, LRs ≥5.0 were observed for anterior thigh sensation at L2 (LR 13; 95% CI 1.8-87); FST at L3 (LR 5.7; 95% CI 2.3-4.4); patellar reflex testing (LR 7.7; 95% CI 1.7-35), medial ankle sensation (LR ∞), or crossed FST (LR 13; 95% CI 1.8-87) at L4; and hip abductor strength at L5 (LR 11; 95% CI 1.3-84). Test combinations increased LRs for level-specific root impingement at the L4 level only. Individual physical examination tests may provide clinical information that substantially alters the likelihood that midlumbar impingement, low lumbar impingement, or level-specific impingement is present. Test combinations improve diagnostic accuracy for midlum-bar impingement.
    Spine 01/2011; 36(1):63-73. · 2.16 Impact Factor
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    ABSTRACT: An abstract is unavailable. This article is available as HTML full text and PDF.
    Spine Journal Meeting Abstracts. 09/2010;
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    ABSTRACT: No prior study has investigated the frequency of patient-identified inciting events in lumbar disc herniation (LDH) or their clinical significance. To examine the clinical frequency of patient-identified inciting events in LDH, and to identify associations between the presence of inciting events and the severity of the clinical presentation. Cross-sectional analysis of data from a cohort study with prospective recruitment, with retrospective data collection on inciting events. The setting was a hospital-based specialty spine clinic. One hundred fifty-four adults with lumbosacral radicular pain and LDH confirmed by magnetic resonance imaging. Self-report measures of disability measured by the Oswestry Disability Index (ODI), the visual analog scale (VAS) for leg pain, and the VAS for back pain. Dependent variables included the presence of a patient-identified inciting event, which were categorized as spontaneous onset, nonlifting physical activity, heavy lifting (>35 lbs), light lifting (<35 lbs), nonexertional occurrence, or physical trauma. We examined the association of an inciting event, or a lifting-related event, with each outcome, first using univariate analyses, and second using multivariate modeling, accounting for important adjustment variables. Sixty-two percent of LDH did not have a specific patient-identified event associated with onset of symptoms. Nonlifting activities were the most common inciting event, comprising 26% of all LDH. Heavy lifting (6.5%), light lifting (2%), nonexertional occurrences (2%), and physical trauma (1.3%) accounted for relatively small proportions of all LDH. Patient-identified inciting events were not significantly associated with a more severe clinical presentation in crude analyses. Spontaneous LDH was significantly associated with higher baseline ODI scores in multivariate analysis, although the magnitude of this effect was small. There were no significant associations (p< or =.05) between the presence of a lifting-associated event and the outcomes of ODI, VAS leg pain, or VAS back pain. The majority of LDH occurred without specific inciting events. A history of an inciting event was not significantly associated with a more severe clinical presentation. There was no significant association between the occurrence of a lifting-related event and the severity of the clinical presentation. This information may be useful in the counseling of patients recovering from acute LDH.
    The spine journal: official journal of the North American Spine Society 03/2010; 10(5):388-95. · 2.90 Impact Factor
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    ABSTRACT: Progressive resistance exercises (PRE) are prescribed to reverse the deconditioning associated with chronic back pain. The spine rehabilitation program has utilized 2 sets of progressive resistance exercises during each session, with increased resistance between sets, and with successive sessions. Exercise literature has challenged the need for multiple sets of resistance exercises, with a single set producing similar functional benefits. The authors studied whether completing 1 versus 2 sets of resistance exercises would affect strength, pain and disability outcomes in subjects with chronic low back pain (CLBP). The study randomly assigned subjects with CLBP to perform either 1 set or 2 sets of progressive resistance exercises during otherwise identical spine rehabilitation programs. The patient sample included 100 subjects (36 male patients, 64 female patients, mean age 46 years) with chronic back pain referred to spine rehabilitation. Primary outcomes were back strength and progressive isoinertial lifting evaluation (PILE) at discharge. Secondary outcomes were Oswestry disability (0-100) and pain scores (0-10). Exercises consisted of Cybex back extension, rotary torso, pull downs, and multi-hip; lifting of crates from floor-to-waist (lumbar) and waist-to-shoulder (cervical) heights. The maximum levels of exercises were determined using a four repetition to maximum protocol, and the PILE. At discharge, there was no significant difference in strength, disability or pain measures between subjects completing 1 versus 2 sets of resistance exercises. These findings suggest that there were no added benefits for completing a second set of resistance exercises during therapy sessions for patients with CLBP.
    European journal of physical and rehabilitation medicine 01/2009; 44(4):399-405. · 2.06 Impact Factor