Neurophysiological Testing is Useful for the Diagnosis and Treatment of Neuropsychiatric Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by multiorgan damage mediated by multiple autoantibodies. The nervous system is one of the target organs of SLE, presenting as neuropsychiatric SLE (NPSLE), which includes central nervous system (CNS) involvement, peripheral neuropathy, and psychiatric symptoms. These symptoms are not necessarily associated with systemic disease activity and are often challenging to diagnose. We report an 11-year-old girl presenting with persistent fever and mild headache. Based on clinical and laboratory findings, she was diagnosed with SLE complicated by antiphospholipid antibody syndrome. Brain magnetic resonance imaging revealed multiple small lesions in the bilateral deep white matter of the frontal lobes, with high signal intensity on diffusion-weighted imaging and low signal intensity on apparent diffusion coefficient maps, consistent with multiple cerebral infarcts. Although multiple cerebral infarcts were present in this case, no localized clinical symptoms corresponding to the infarct locations were observed, and the case did not meet the definition of NPSLE. Conversely, electroencephalography (EEG) revealed diffuse high-amplitude slow waves in the occipital region, and short-latency somatosensory evoked potentials (SSEPs) showed absence of the N20 component at C3' following right median nerve stimulation. These neurophysiological findings supported a comprehensive diagnosis of CNS NPSLE. These abnormalities gradually improved during immunosuppressive treatment. NPSLE represents one of the most challenging organ-specific manifestations to diagnose in pediatric SLE due to its complex and heterogeneous clinical presentation and the absence of standardized diagnostic screening methods. Unlike lupus nephritis, complement consumption is not necessarily involved in the pathogenesis of NPSLE. Therefore, NPSLE may remain undiagnosed unless clinically suspected. In this case, abnormal EEG findings and absence of the N20 component on SSEP suggested ischemic changes due to cerebrovascular disease, enabling a comprehensive diagnosis of CNS NPSLE. Neurophysiological testing proved useful for early diagnosis of NPSLE and evaluation of treatment efficacy.