Please confirm that an ethics committee approval has been applied for or granted: Not relevant (see information at the bottom of this page)

Background and Aims Pneumorrhachis is a rare complication of epidural analgesia and is most often asymptomatic. It can cause permanent deficit and differential diagnosis can be challenging, so clinicians should be aware of this entity.

Results A 74 year old woman was admitted to elective total knee replacement surgery. A L3/L4 spinal block using a paramedian approach was achieved after 2 attempts with a 25G quincke needle. An epidural catheter was placed with loss of resistance (LOR) to saline through L3/L4 intervertebral place, by single attempt. The procedure was uneventful and the sensitive and motor block reversed in the PACU. Before the transference to the ward, an epidural DIB was initiated with 0,1% ropivacaine, 5 mL/h. 4 hours later, the anesthesiologist was called for a bilateral sensitive and motor block up to T10 and urinary retention. After neurologist’s assessment and DIB clamping, an MRI revealed intradural and extradural air collections, in locations compatible with the deficits presented. The patient was transferred to the hyperbaric medicine center with oxygen inhalation via a non- rebreather mask. Upon arrival, the deficits had completely reversed and it was decided to do 12 hours of normobaric oxygen therapy. Patient was discharged by 6th post-operative day and no other complications was observed.

Conclusions Pneumorrachis after an epidural technique with LOR to saline is rare. Our most plausible hypothesis was that air could have been entrapped in the DIB. It usually gets reabsorbed spontaneously1. Nonoperative treatment includes hyperbaric oxygen therapy, which can lead to reabsorption of trapped air.