Inferior gluteal neuropathy or inferior gluteal nerve injury can be the result of nerve compression or traction injury of the inferior gluteal nerve.
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Epidemiology
Inferior gluteal nerve neuropathy like superior gluteal nerve neuropathy is rather uncommon and often associated with iatrogenic injury 1.
Diagnosis
The diagnosis might be made by a combination of clinical symptoms and abnormal electrodiagnostic testing. Isolated denervation changes of the gluteus maximus on imaging can further support the diagnosis. Lumbosacral radiculopathy, plexopathy and sciatic neuropathy should be ruled out 1.
Clinical presentation
Clinical presentation includes weakness in leg extension and muscle atrophy of the gluteus maximus 1,2.
Electrophysiologic studies of the gluteus maximus should be abnormal 1.
Pathology
The inferior gluteal nerve is formed by the L5-S2 nerve roots supplying motor innervation to the gluteus maximus muscle. It exits the pelvis through the greater sciatic foramen below the piriformis muscle and turns backwards splitting into branches entering the gluteus maximus 2,3.
Aetiology
Potential causes of superior gluteal nerve injury include the following 1-3:
- iatrogenic injury
- hip surgery (total hip replacement, posterior access)
- intramuscular injections
- acute traumatic injury
- chronic compression
- osteophytes
- fracture-related bony outgrowth or heterotopic ossifications
- tumours
- sciatic hernia
Radiographic features
MRI
Due to its small size visualisation of inferior gluteal nerve abnormalities might be difficult. The nerve can be seen while exiting the pelvis on coronal images and then on axial planes deep to the gluteus maximus. Denervation changes affect the gluteus maximus and include muscle oedema, muscle atrophy and fatty degeneration 2,3.
Radiology report
The radiology report should include a description of the following:
- the appearance of the inferior gluteal nerve
- denervation changes
- aetiology of nerve compression
Treatment and prognosis
Like superior gluteal nerve entrapment, the treatment will depend on the aetiology and include conservative measures including physiotherapy, stretching local anaesthetics and non-steroidal anti-inflammatory drugs. Surgery might be necessary for the removal of space-occupying lesions and involves decompression and neurolysis.
Differential diagnosis
The differential diagnosis of sacral neuropathy includes 1-3:
- lumbar spinal canal stenosis
- L5 or S1 radiculopathy
- lumbosacral plexopathy
- sciatic neuropathy
- piriformis syndrome