Synonyms:
Idiopathic Lumbosacral plexitis a.k.a. lumbosacral plexitis a.k.a. idiopathic neuralgic amyotrophy a.k.a. Lumbosacral plexopathy
Diagnosis:
The diagnosis is based on clinical features, electrophysiological findings and exclusion of competing causes.
Clinical features:
Lumbosacral distribution of pain followed by weakness
See lumbosacral plexopathy
Findings on investigations:
+EMG
- Localises the lesion to the lumbar/sacral plexus
- Localises the lesion (short head of biceps femoris, above or below the fibula)
- Paraspinal muscles (no denervation, distinguishes this from radiculopathy)
Other tests:
- CSF: protein high
- ESR: may be high
Pathology, nerve biopsy:
Multifocal loss of axons
Inflammation, lymphocytic of endoneurial and epineurial vessels
Immunohistochemistry: CLA for lymphocytes
Investigations to consider: also see lumbosacral plexopathy
X-ray: fibula fracture
EMG/NCS
HIV testing
ESR, CRP, ANA screen, ENA panel (anti- dsDNA, anti-Sm, anti-RNP, SSA, SSB, anti-Jo-1, antitopoisomerase ‘formerly anti Scl-70’, antinucleolar, anticentromere), ANCA (c-ANCA, p-ANCA), Complement C3, C4 and CH50
CT abdomen and pelvis: rule out retroperitoneal hematoma or tumor
Treatment:
Consider:
- Intravenous immunoglobulin IVIg
- Plasmapheresis
- Corticosteroids