In imaging diagnosis, redundant nerve roots of the cauda equina are characterized by the presence of elongated, enlarged and tortuous nerve roots in close relationship with a high-grade lumbar spinal canal stenosis. This is not an independent entity, but it is believed to be a consequence of the chronic compression at the level of the lumbar canal stenosis and thus may be part of the natural history of lumbar spinal stenosis. The present paper is aimed at reviewing the histopathological, electrophysiological and imaging findings, particularly at magnetic resonance imaging, as well as the clinical meaning of this entity. As the current assessment of canal stenosis and root compression is preferably performed by means of magnetic resonance imaging, this is the imaging method by which the condition is identified. The recognition of redundant nerve roots at magnetic resonance imaging is important, particularly to avoid misdiagnosing other conditions such as intradural arteriovenous malformations. The literature approaching the clinical relevance of the presence of redundant nerve roots is controversial. There are articles suggesting that the pathological changes of the nerve roots are irreversible at the moment of diagnosis and therefore neurological symptoms are less likely to improve with surgical decompression, but such concept is not a consensus.

Keywords: Cauda equina; Spinal stenosis; Spine; Magnetic resonance imaging.

Sagittal balance describes the optimal alignment of the spine in the sagittal plane, resulting from the interaction between the spine and lower limbs, via the pelvis. Understanding sagittal balance has gained importance, especially in the last decade, because sagittal imbalance correlates directly with disability and pain. Diseases that alter that balance cause sagittal malalignment and may trigger compensatory mechanisms. Certain radiographic parameters have been shown to be clinically relevant and to correlate with clinical scores in the evaluation of spinopelvic alignment. This article aims to provide a comprehensive review of the literature on the spinopelvic parameters that are most relevant in clinical practice, as well as to describe compensatory mechanisms of the pelvis and lower limbs.

Keywords: Spine; Pelvis; Radiography; Lordosis/diagnostic imaging; Kyphosis/diagnostic imaging; Spinal curvatures/diagnostic imaging; Postural balance.