High Spinal Block After Intrathecal Mepivacaine in Ankylosing Spondylitis During Total Hip Arthroplasty: A Case Report

Ankylosing spondylitis (AS) complicates anesthetic management due to altered spinal anatomy and potential airway difficulties. Neuraxial anesthesia is feasible but technically challenging, with potentially variable drug distribution. High spinal block reports in AS remain limited. This report describes the case of a 58-year-old male patient with AS who underwent elective total hip arthroplasty under spinal anesthesia (3.5 mL 2% isobaric mepivacaine). An initial T11 sensory block rapidly progressed cephalad to C6 within minutes, causing upper extremity weakness, bradycardia, and hypotension. Concern for impending total spinal anesthesia prompted conversion to general anesthesia for airway and hemodynamic control. The patient recovered fully without neurologic deficits. This case illustrates the potential for unpredictable intrathecal anesthetic spread in AS despite standard dosing. Careful monitoring, minimal sedation, and immediate readiness for advanced airway management are crucial during neuraxial anesthesia in patients with AS.