Presentation
Gunshot wound to the pelvis, right buttock pain and worsening right foot pain, numbness, and tingling.
Patient Data
MRI after coil embolisation of the right internal iliac artery demonstrates haematoma in the right pelvis. There is mass effect on the lumbosacral plexus with anterior medial displacement of the nerve roots. Distal to the haematoma, the sciatic nerve demonstrates thickening and increased signal reflecting neuritis.
There is also a comminuted right iliac bone fracture secondary to the gunshot.
MRI of the same patient 4 months later shows resolution of the haematoma. MR neurography of the lumbosacral plexus demonstrates thickening and hyperintensity of the right sciatic nerve compared to the left, most pronounced distal to the greater sciatic foramen. Partial fibre discontinuity in this region is difficult to exclude.
Marked hyperintensity of the right superior gluteal nerve is also compatible with neuritis. Oedema in the right gluteus medias muscle may be due to traumatic injury and/or denervation.
Again, seen is a right iliac bone fracture.
Case Discussion
The sciatic nerve is the longest and widest single nerve in the body, arising from nerve roots L4-S3. Sciatic nerve injury and dysfunction is a common cause of lower extremity symptoms in clinical practice 1. MR neurography is a useful technique to show abnormalities of the sciatic nerve. Characteristics of the abnormal nerve include thickening (larger than adjacent artery), abrupt calibre change, increased signal on T2 weighted Imaging, or perineural oedema 2. Denervation myopathy can be seen with muscle oedema in the acute setting, or muscle atrophy and fatty infiltration in the chronic setting.
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