Back Pain as a Clue to Spinal Cord Involvement in Sjögren's Syndrome: An Uncommon Case

Sjögren's syndrome (SS) is an autoimmune disease with systemic manifestations. Neurological manifestations of SS include vasculitis, dorsal ganglionitis, demyelination, myelitis, myeloradiculitis, meningoencephalitis, cognitive dysfunction, and autonomic dysfunction mediated by antibodies. We present a case of a 65-year-old woman with a significant medical history of rheumatoid arthritis and secondary Sjögren's syndrome, diagnosed 20 years prior, and treated non-Hodgkin lymphoma. She presented to the emergency department with progressive lower back pain, radiating to the lower limbs for the past five months, along with sensory loss, weakness in the lower limbs, urinary retention, fecal incontinence, and recurrent fever. On examination, she had grade 4 paraparesis predominantly in the proximal muscles, with suspended thermoalgesic sensation from D6-11 and areas of allodynia in L5-S1, abolished deep tendon reflexes in the lower limbs, and absent bilateral plantar reflexes. MRI revealed a longitudinally extensive spinal cord lesion (from D4 to the conus medullaris) with T2 hyperintensity, contrast enhancement, and meningeal and cauda equina root thickening. Lumbar puncture showed lymphocytosis, hypoglycorrhachia, and hyperproteinorrachia, suggestive of lymphocytic meningitis. Microbiology, immunophenotyping, anti-aquaporin-4 antibodies, angiotensin-converting enzyme (ACE), calcium, and urinary calcium levels were normal. Meningeal biopsy at D10 showed an unspecific mononuclear inflammatory process. She received pulses of methylprednisolone but continued to experience paraparesis, fever, asthenia, and new vertebral joint arthritis/synovitis at L4-L5, leading to the initiation of cyclophosphamide treatment with progressive improvement. Sjögren's syndrome has a wide range of manifestations and can involve multiple systems. Spinal cord involvement is rare and presents diagnostic dilemmas between infectious causes, other autoimmune diseases, and neuromyelitis optica spectrum disorders.