Case Presentation: We present an unusual case of a previously healthy patient presenting with a demyelinating polyneuropathy, which was determined to be the initial presentation of systemic lupus erythematosus (SLE).This was a 36 year-old female with an unremarkable past medical history who presented with leg weakness that progressively spread to her arms with associated tingling sensation and numbness of her thighs. She had been diagnosed 2 weeks prior with Bell’s Palsy, for which she was given steroids, with consequent symptomatic improvement. Vital signs were significant for sinus tachycardia. Initial neurologic exam was remarkable for facial weakness on the left side, marked ataxia, 4/5 strength bilaterally in the upper and lower extremities, with preserved deep tendon reflexes. Initial lab work was unremarkable and COVID-19 PCR was negative. Cerebrospinal fluid (CSF) showed clear fluid, opening pressure of 26, albuminocytologic dissociation (CSF protein 204 mg/dL, WBC 18/uL) with no evidence of meningitis, Lyme antibody, syphilis, or crypotococcal antigen. CSF cytology was negative for malignant cells. Computed tomography revealed paratracheal, clavicular, and bilateral axillary lymphadenopathy. MRI of the head and cervical/thoracic/lumbar spine showed increased signal in the cauda equina concerning for Guillain-Barre syndrome (GBS) versus lymphoma with leptomeningeal spread. Biopsy of a right axillary lymph node was negative for malignancy. Connective tissue disorder workup showed significantly positive titers for anti-nuclear antibody (ANA) and double stranded DNA (dsDNA). Complement levels were also low, with C3 of 43 mg/dL and C4 of 12 mg/dL, suggestive of SLE. Nerve conduction study showed severely prolonged F-wave with minimal latencies suggestive of an early polyradiculoneuropathy such as acute inflammatory demyelinating polyneuropathy (AIDP). Given the abrupt onset of neurologic symptoms and positive dsDNA with low complement levels, neurologic lupus was suspected as the underlying cause. She was initiated on pulse steroids and cyclophosphamide, with improvement in her symptoms and was discharged to rehabilitation, with complete resolution of symptoms two months later.

Discussion: SLE is a connective tissue disorder that can affect any organ system. Neuropsychiatric SLE can affect either the central or the peripheral nervous system. AIDP, a variant of GBS that affects motor and sensory fibers, has rarely been associated with SLE. It is an immune-mediated disease that affects peripheral motor neurons, usually following viral illness. Ours is an unusual case of a young female who presented with progressive upper and lower extremity weakness and was diagnosed with AIDP in the setting of new diagnosis of SLE and no evidence of a recent viral illness.AIDP is usually a self-limited disease and in severe cases patients need IVIG and plasmapheresis [1]. On the contrary, in the setting of SLE, the AIDP is driven by sustained antibody production from connective tissue disease and require treatment of the underlying disease process for resolution [2,3].

Conclusions: Understanding the variety of unusual presentations of SLE allows for its timely diagnosis in those situations. In this patient, high titers of ANA and anti-dsDNA, low complement, and high protein in CSF established the diagnosis of neurologic lupus. Treatment with pulse dose of steroids followed by cyclophosphamide quickly led to a resolution of the symptoms.