The lumbosacral plexus: Anatomy, clinical imaging, and proof-of-concept insights with ultra-high-field 7 Tesla MRI

The lumbosacral plexus is the human neural network that provides motor and sensory innervation to the pelvis and lower extremities. Injury to the lumbosacral plexus may result due to trauma, compression, diabetes, infection, inflammation, or demyelination. Patients may present with persistent or progressive pain, paresthesia, or paresis. A diagnosis can typically be established based on correlation of clinical history, physical examination, and electromyography. However, although conventional diagnostic modalities provide vital functional information pertaining to motor unit activity and muscle response, it is often challenging to localize lesions and identify specific structural or intrinsic causes of nerve injury. Magnetic resonance neurography harnesses high-resolution imaging to delineate pathology of the lumbosacral plexus and identify sources of nerve compression, fascicular thickening, and inflammation that may be implicated in peripheral neuropathy. In this narrative review, we detail the anatomy of the lumbosacral plexus, describe common and uncommon neuropathology, summarize our early-stage investigation of lumbosacral plexus imaging using ultra-high-field 7 Tesla MRI. In addition, we provide case examples from our institutions that illustrate the value of magnetic resonance neurography for diagnosing lumbosacral plexus pathology and developing individualized treatment strategies.