|ECR 2019 / C-1904|
|MR Neurography:an emerging modality in the evaluation of the lumbosacral plexus and sciatic lesions|
Magnetic resonance neurography (MRN) is the direct imaging of nerves in the body by optimizing selectivity for unique MRI water properties of nerves.It is high end application of MRI that requires special dedicated protocol,
targeting the nerve in question.
Clinical evaluation of peripheral neuropathies has traditionally relied on clinical examination and electro-diagnostic testing.
Recent developments in MR scanner and coil technology and the refinement of pulse sequences for increasing structural resolution have allowed imaging of fine details in healthy and diseased peripheral nerve.
MRN nicely depicts peripheral nerve anatomy and pathology, and studies have shown that MRN findings may substantially influence the management of patients with peripheral neuropathies.
MRN is an advanced technique , that its application helps proper pre operative planning , resulting in better surgical techniques with better results in terms of morbidity and function preservation. It helps proper assessment of the affected peripheral nerve , length of segment and exact location (Table 1) , It has an evolving role in the post operative assessment especially with developing functional techniques.Peripheral nerves are vulnerable to a large variety of diseases, which can be divided into three groups:
1. First group: It includes systemic diseases, such as ischemia, toxic, endocrine, vasculitis, and metabolic disorders as diabetes amyotrophy, amyloidosis, multifocal motor neuropathy, hereditary motor sensory neuropathies, acute and chronic demyelinating inflammatory neuropathies.
2. Second group: that includes local conditions such as nerve injury, plexopathy, adhesive neuropathy in failed tunnel cases perineural compressive lesions, and nerve sheath tumors.
3. Third group: It includes neuropathy attributed to functional anatomical changes, as repetitive exercise and habitual leg crossing, which can cause compressive neuropathy in functional compartment syndromes. This group is usually diagnosed on clinical basis.
Nerve injuries were traditionally classified according to the Seddon and Sunderland classification. It was published in 1942. There are three different types of nerve injuries are described in this classification system which are neurapraxia, axonotmesis and neurotmesis(Fig. 1).
The mildest type of injury, involve only the myelin sheath around the axon with resultant transient functional loss and are associated with an excellent prognosis(Fig. 2).
The axon suffers complete rupture resulting in wallerian degeneration of its distal segment; however, the supporting structures, including the perineurium and epineurium, remain intact.
The prognosis for recovery remains good, but time is required for axonal regeneration (≈ 1 mm per day)(Fig. 3).
The axon suffers complete rupture resulting in wallerian degeneration of its distal segment; however, the supporting structures, including the perineurium and epineurium, remain intact
The prognosis for recovery remains good, but time is required for axonal regeneration (≈ 1 mm per day).
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