Accidental Dural Puncture

Accidental dural puncture is unintended penetration of the dura and arachnoid by an epidural needle (or catheter), causing cerebrospinal fluid leak. It is the main cause of severe post-dural puncture headache.

Epidemiology. It happens in about 0.5% to 2% of obstetric epidurals (0.2% to 3% in different series), less often in non-obstetric practice. Headache follows in 50% to 80% when a large epidural needle is used.

Risk factors. Inexperience, obesity, difficult anatomy (scoliosis, previous spinal surgery), sudden patient movement, loss of resistance with air, previous puncture and pregnancy.

Pathophysiology.

A 16 to 18 gauge needle leaves a large dural hole. Fluid loss continues (up to 4 mL/min), reducing intracranial pressure and causing headache.

Free flow of cerebrospinal fluid through the needle, or a sudden warm fluid returning via the catheter. Later: positional headache, neck stiffness and nausea, hearing disturbance or visual blurring.

Red flags.

• Unexpected high or patchy block (catheter in subdural or subarachnoid space).
• Severe headache with focal signs or seizures.

Confirm by free flow of clear fluid with glucose test positive (glucose over 0.3 mmol/L) and warm temperature, and recognise a catheter that aspirates fluid. Document the event and inform the patient.

Differential diagnosis.

• Epidural vein puncture.
• Saline from loss of resistance technique.
• Subdural placement.

Choose one of two options at the time of puncture.

• Resite the epidural at an adjacent level, with careful dosing in small increments (test dose, aspiration, slow top up).
• Place the catheter intrathecally (spinal catheter), labelled clearly, with only anaesthetists giving doses of 1 to 2 mL of 0.25% bupivacaine incrementally. Leave in place for 24 hours or less to promote closure, though evidence for reducing headache is mixed.

Prophylactic epidural blood patch is not routinely needed. Follow up daily for headache.

• Caffeine and simple analgesia: paracetamol 1 g orally every 6 hours (maximum 4 g daily), ibuprofen 400 mg every 8 hours (maximum 1.2 g daily), caffeine 300 mg orally once or twice daily (maximum 900 mg daily); monitor sedation and symptoms; reduce paracetamol with hepatic impairment or under 50 kg; avoid ibuprofen in peptic ulcer and renal impairment.

In labour, avoid prolonged pushing if possible. If headache develops, offer an epidural blood patch of 15 to 20 mL after failed conservative treatment.

Monitoring. Daily headache review for 5 days, including after discharge.

Referral and escalation. Senior anaesthetic help. Neurology if atypical features.