Objective: To verify the presence of the sedimentation sign in patients with lumbar spinal stenosis (LSS) in comparison to those without LSS. Methods: Retrospective, cross-sectional and descriptive study. Review of the imaging processes of patients with LSS operated between January 1, 2008 and December 31, 2009, comparing with patients without LSS observed in outpatient consultations. Patients were divided into two groups: group I had 34 patients with a diagnosis of LSS. Diagnostic criteria: existence of low back pain and/or neurogenic claudication and/or radiculopathy, associated with an anteroposterior canal diameter of less than 10 mm. Group II had 40 patients observed in outpatient consultations for low back pain without clinical LSS. The canal diameter was measured and the presence of the sedimentation sign between D12 and S1 was verified. Results: A positive sedimentation sign was identified in 31 of the 34 patients in group I (91.2%); only below the stenosis in two of these 31 patients. The sign was not observed in the patients in group II. A statistically significant correlation was observed between the variables "canal diameter" and "presence of sedimentation sign" (p < 0.01) in the group of patients with lumbar spinal stenosis. Conclusion: The diagnosis of LSS is not always easy due to the frequent dissonance between the clinical and imaging findings. The sedimentation sign is positive in patients with LSS between L1 and L5 and can be a valid sign to complement the diagnosis of LSS.Keywords: Lumbar; Roots; Diagnosis; Magnetic resonance spectroscopy; Sedimentation. RESUMO

BackgroundPrevious studies have suggested that the study condition of an item influences how the item is encoded. However, it is still unclear whether subsequent source memory effects are dependent upon stimulus content when the item and context are unitized. The present fMRI study investigated the effect of encoding activity sensitive to stimulus content in source memory via unitization. In the scanner, participants were instructed to integrate a study item, an object in either a word or a picture form, with perceptual context into a single image.ResultsSubsequent source memory effects independent of stimulus content were identified in the left lateral frontal and parietal regions, bilateral fusiform areas, and the left perirhinal cortex extending to the anterior hippocampus. Content-dependent subsequent source memory effects were found only with words in the left medial frontal lobe, the ventral visual stream, and bilateral parahippocampal regions. Further, neural activity for source memory with words extensively overlapped with the region where pictures were preferentially processed than words, including the left mid-occipital cortex and the right parahippocampal cortex.ConclusionsThese results indicate that words that were accurately remembered with correct contextual information were processed more like pictures mediated by integrated imagery operation, compared to words that were recognized with incorrect context. In contrast, such processing did not discriminate subsequent source memory with pictures. Taken together, these findings suggest that unitization supports source memory for both words and pictures and that the requirement of the study task interacts with the nature of stimulus content in unitized source encoding.

BackgroundIt is vital to select and process relevant information while restraining irrelevant information for successful retrieval. When multiple streams of information are concurrently present, the ability to overcome distraction is very crucial for processing relevant information. Despite its significance, the neural mechanism of successful memory formation under distraction remains unclear, especially with memory for associations. The present fMRI study investigated the effect of distraction due to irrelevant stimuli in source memory.MethodsIn the MR scanner, participants studied an item and perceptual context with no distractor, a letter-distractor, or a word-distractor. Following the study phase, a source recognition test was administered in which participants were instructed to judge the study status of the test items and context of studied items. Participants’ encoding activity was back-sorted by later source recognition to find the influence of distractors in subsequent memory effects.ResultsSource memory with distractors recruited greater encoding activity in the left dorsolateral prefrontal cortex, and the bilateral inferior temporal gyrus/fusiform cortex, along with the left posterior hippocampus. However, enhanced activity in the left anterior ventrolateral prefrontal cortex and the left parahippocampal cortex predicted successful source memory regardless of the presence of a distractor.ConclusionsThese findings of subsequent memory effects suggest that strong binding of the item-context associations, as well as resistance to interference, may have greater premium in the formation of successful source memory of pictures under distraction. Further, attentional selection to the relevant target seems to play a major role in contextual binding under distraction by enhancing the viability of memory representations from interference effects of distractors.Electronic supplementary materialThe online version of this article (doi:10.1186/1744-9081-10-40) contains supplementary material, which is available to authorized users.

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