Neuroselective Sensory-Over-Motor Dissociation, Rapid Blockade Onset, and Hemodynamic Autoregulation With 10 μg Intrathecal Dexmedetomidine in High-Risk Orthopedic and Gynecological Surgery: An Observational Analytic Case Series

Background: Subarachnoid block gives dense blockade for orthopedic and gynecological surgery, but plain local anesthetics give brief analgesia. Intrathecal dexmedetomidine (DXM), a selective α₂-adrenergic agonist, prolongs block in low-risk patients. Data in high-risk patients are scarce. Objective: To describe block onset, regression, pain scores, and hemodynamic course after 10 μg of intrathecal DXM added to hyperbaric bupivacaine in four high-risk patients. Methods: Four consecutive women (29–73 years) were operated on at Dr. Saiful Anwar Regional General Hospital, Malang, Indonesia (Protocol: CMHC/EC/IRB/2026/0814). Each received 0.5% hyperbaric bupivacaine (15–20 mg) plus 10 μg DXM, by L4–L5 subarachnoid block (Cases 1–3) or combined spinal-epidural anesthesia (Case 4). Onset, hemodynamics, and Numerical Rating Scale (NRS) pain scores were recorded from T₀ to T₄. Results: All patients reached the target block (T6–T10). Sensory onset was ≤ 1 min and Modified Bromage 2 motor block appeared at 3 min; the published mean to Bromage 3 with 5 μg is 11.6 min. Motor inhibition lasted 300 min and analgesia 300–360 min (mean 330 ± 24.5 min), with NRS 0–2 in the first 4 h and 3–4 at 5–6 h. MAP was 70 mmHg in a post-stroke patient. A fall to 50/30 mmHg during bone curettage resolved with 1,000 mL crystalloid and ephedrine. Multimodal and neuraxial analgesia were also given. Conclusion: In four patients, 10 μg of intrathecal DXM was followed by rapid block onset and 5–6 h of analgesia, with no recorded respiratory depression. The series cannot establish effect or mechanism, so controlled studies are needed.