Neuro-Syphilis Initially Presenting as Non-convulsive Status Epilepticus: A Case Report

Background: Neurosyphilis is a renowned "great imitator" in clinical practice. While it can cause seizures, its presentation as non-convulsive status epilepticus (NCSE) is exceptionally rare and diagnostically challenging. Case presentation: A 67-year-old female with a history of prior cerebral infarction presented acutely with recurrent episodes of impaired consciousness and conjugate eye deviation, without convulsive limb movements. Critically, her consciousness did not fully normalize between episodes. Neurological examination revealed stupor, mixed aphasia, bilateral miotic pupils with absent light reflexes, and bilateral Babinski signs. Neuroimaging (MRI) showed findings suggestive of prior infarcts and possible hydrocephalus. Long-term video-EEG monitoring revealed epileptiform discharges over the left temporo-occipital region, fulfilling diagnostic criteria for NCSE. Serological and cerebrospinal fluid (CSF) analysis confirmed active neurosyphilis (positive serum and CSF RPR). The patient was diagnosed with neurosyphilis presenting as NCSE, alongside syphilitic encephalitis and general paresis. Treatment with benzathine penicillin G and levetiracetam led to significant improvement in consciousness and cessation of seizure activity. Conclusion: This case underscores that neurosyphilis must be considered in the differential diagnosis of NCSE, especially in patients with stroke-like symptoms but with contraindications to thrombolysis. Early CSF analysis and syphilis serology are critical for accurate diagnosis and timely initiation of antibiotic therapy, which can prevent permanent neurological damage. It emphasizes the importance of considering infectious etiologies in cases of unexplained altered mental status and seizures.