2402 Zebras, not horses: an atypical case of neurosarcoidosis

Objectives Sarcoidosis isolated to peripheral nerves and/or muscles is rare.^{1 2} Clinical suspicion typically occurs when there are other systemic manifestations present. This case is an example of neurosarcoidosis presenting similarly to Guillain-Barré Syndrome. It also emphasises the significant impact nerve and muscle biopsies can have on diagnosis and management.

Case A previously well 64-year-old male presented with a severe symmetric, ascending weakness and numbness of all limbs with associated areflexia progressing over two weeks and culminating in an inability to walk. His presentation was of a severe subacute onset polyneuropathy and Guillaine-Barre syndrome was therefore suspected. Tests for autoimmune, infectious, malignant, and nutritional causes were negative. Cerebrospinal fluid showed a protein level of 2100 mg/L, white cell count of 45 x10⁶/L, 99% of which were mononuclear. MRI of the brain and spine showed no nerve root enhancement or other relevant abnormality. Nerve conduction studies and electromyography demonstrated a severe axonal polyneuropathy with active denervation. The patient continued to deteriorate despite two courses of intravenous immunoglobulin and a sural nerve and vastus lateralis muscle biopsy was therefore performed. Both the nerve and muscle biopsies showed noncaseating granulomatous inflammation consistent with neurosarcoidosis. An FDG-PET scan did not show sarcoidosis involving other organs.

Conclusions This case shows that sarcoidosis can be limited to just the nerves and muscles without clear systemic manifestations. It also provides a case for neurosarcoidosis to be considered as a differential in future presentations of subacute onset polyneuropathy.

References

1. Kidd DP. Neurosarcoidosis: clinical manifestations, investigation and treatment. Practical Neurology. 2020;20(3):199. doi:10.1136/practneurol-2019-002349

2. Cohen Aubart F, Abbara S, Maisonobe T, et al. Symptomatic muscular sarcoidosis. Neurology – Neuroimmunology Neuroinflammation. 2018;5(3):e452. doi:10.1212/NXI.0000000000000452