Clinical features, etiological spectrum, and outcomes of neurological patients initially presenting with psychiatric symptoms.

Background: Neurological disorders can manifest with psychiatric symptoms as the initial presentation (PSIP), leading to diagnostic challenges and delayed treatment. Data on this patient population remain limited. Methods: We conducted a retrospective cohort study of patients admitted to a tertiary neurology department between 2019 and 2023 with PSIP. A structured screening protocol using predefined behavioral keywords was applied, followed by independent case review by two neurologists and a psychiatrist to confirm eligibility. Final diagnoses were adjudicated by consensus using contemporary diagnostic criteria. Poor outcome was defined as modified Rankin Scale score >2 at discharge. Multivariable logistic regression was used to identify independent predictors of poor outcome, and a risk score was developed based on these factors. Results: Of 16,473 screened admissions, 76 patients (mean age 55.8 ± 18.2 years; 42.1% female) met inclusion criteria. Most patients presented with acute-onset (92.1%) non-specific behavioral disturbance (63.2%), and nearly one-third (31.6%) had isolated psychiatric symptoms without any accompanying neurological signs. The leading etiologies were CNS infections (55.3%), predominantly viral encephalitis (40.8%), followed by cerebrovascular diseases (14.5%) and autoimmune encephalitis (13.2%). Poor outcome occurred in 32 patients (42.1%). Independent predictors of poor outcome were hyponatremia on admission (OR, 3.9; 95% CI, 1.3-11.8), viral encephalitis etiology (OR, 3.1; 95% CI, 1.1-8.7), and ICU admission (OR, 4.8; 95% CI, 1.3-17.6). A risk score combining these three factors effectively stratified patients (AUC 0.88; 95% CI, 0.80-0.96), with poor outcome rates ranging from 7.1% (score 0) to 100% (score 3). Subgroup analyses revealed that among viral encephalitis patients, those with PSIP had significantly higher rates of hyponatremia (41.9% vs. 15.2%, Conclusion: PSIP represents a critical clinical situation in which underlying neurological disorders, particularly viral encephalitis and autoimmune encephalitis are common. Hyponatremia serves as a readily available diagnostic clue and independent predictor of poor prognosis. The absence of neurological signs does not exclude serious underlying pathology. However, these findings are derived from a single tertiary center with a modest sample size and require validation in broader populations. Early comprehensive evaluation, including CSF analysis and neuroimaging, is essential to improve outcomes in this diagnostically challenging population.