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Background Aneurysmal subarachnoid haemorrhage (SAH) is a life-threatening condition with high morbidity. Delayed cerebral ischaemia (DCI) significantly contributes to secondary injury and poor outcomes. While perfusion CT (CTP) aids DCI detection, multimodal neuromonitoring—including brain tissue oxygenation (PtiO 2) and cerebral microdialysis—offers superior temporal resolution. Its value in guiding treatment remains underexplored.Methods This prospective cohort study included SAH patients monitored with multimodal neuromonitoring at RWTH Aachen University Hospital (2014–2020). DCI was diagnosed with neuromonitoring abnormalities and confirmed by CTP. First-line treatment involved induced hypertension, with endovascular rescue treatment for refractory cases. Physiological data were time-aligned to treatment onset and aggregated into hourly summaries. Binomial logistic regression identified predictors of favourable 1-year outcome (modified Rankin Scale 0–3).Results Of 56 patients with confirmed DCI, correctly placed probes and available outcome data, 22 (39.3%) achieved favourable outcome. These patients showed greater post-treatment reductions in pressure reactivity index (PRx) and lactate-to-pyruvate ratio (LPR). In multivariable analysis, greater PRx reduction was significantly associated with favourable outcome (OR 0.023, 95% CI 0.001 to 0.394, p=0.009), translating to a 46.5% increase in odds per 0.1-unit decrease. Greater LPR reductions were also predictive (OR 0.950, 95% CI 0.904 to 0.998, p=0.042), with a 5-unit drop linked to a 29.3% increase in odds. Although PtiO2 ₂ improved post-treatment, it was not associated with outcome.Conclusion PRx and LPR reflect meaningful physiological responses to DCI treatment and are associated with 1-year outcomes. Multimodal neuromonitoring may support not only diagnosis but also treatment monitoring and decision-making in unconscious SAH patients.Trial registration number German Clinical Trial Registry (DRKS00030505).