Failed epidural analgesia in a parturient with advanced ankylosing spondylitis: a novel explanation

Ankylosing spondylitis (AS) is a chronic progressive multisystemic disease. Patients with AS present a specific set of anesthesia-related challenges, and the parturient with AS presents particular anesthetic considerations. We report our experience with a parturient with advanced AS and offer a novel explanation for the high incidence of epidural failures in this patient population.

We present the case of a 36-yr-old primigravida parturient with a very difficult airway and a history of severe AS. The initial treatment plan was to use a continuous epidural for labour analgesia. Despite two successful placements of lumbar epidural catheters, adequate rostral spread of local anesthesia to control her labour pain was never achieved via the epidural route. Thus, continuous spinal anesthesia was used, which provided effective labour analgesia in this patient.

We hypothesize that this patient's advanced calcified posterior longitudinal ligament caused a physical barrier to rostral spread of local anesthesia solution within her epidural space. This hypothesis is supported by a recent study highlighting the importance of this ligament in allowing adequate distribution of solution within the epidural space. In addition, the successful use of continuous spinal analgesia adds to the growing body of literature supporting the safety and efficacy of intrathecal catheters for labour analgesia in specific situations.