P-025 - Unintentional Extradural Pneumocephalus: A Unique Case Report of Post-Procedural Headache After Lumbar Epidural Steroid Injection

Abstract Title: Unintentional Extradural Pneumocephalus: A Unique Case Report of Post-Procedural Headache After Lumbar Epidural Steroid Injection

Background: Pneumocephalus is a rare complication of lumbar epidural injections which initially manifests as rapid onset headache with associated nausea, vomiting, and cranial nerve palsies. Most cases of pneumocephalus after an epidural occur secondary to an accidental dural puncture which allows air to enter into the subdural or subarachnoid space. The incidence of unintentional dural puncture from epidural anesthesia is 0.06%. The incidence of pneumocephalus from epidural anesthesia has not been well documented. There are two primary mechanisms behind the development of pneumocephalus. The ball-valve theory suggests a dural puncture creates a one-way valve which traps air into the cranium. The inverted bottle theory postulates a cerebrospinal fluid leak creates a vacuum effect, drawing air into the intracranial space. Based on our literature search, most cases of pneumocephalus that occur after an epidural injection are secondary to inadvertent dural punctures.

Purpose/Objectives: We present a rare case of a 57-year-old male with chronic low back pain status post spinal cord stimulator implant who presented for a routine lumbar epidural injection. The L5-S1 vertebrae were identified under fluoroscopic guidance. A 20 gauge 3.5 inch epidural Tuohy needle was directed to the L5-S1 interlaminar space where 2 cc of air was used for loss of resistance. Aspiration was negative for any blood or cerebrospinal fluid. Epidural space was confirmed with contrast and medication was administered. Shortly after the procedure, the patient reported symptoms of headache and nausea. He presented the next day to the special procedures unit and underwent a blood patch procedure which failed to improve his headache. He was subsequently admitted to the inpatient observation unit due to worsening headache and nausea.


Methods: Patient: 57-year-old male with complex medical history including prior spinal cord stimulator implant.

Setting: Outpatient pain clinic with subsequent admission to inpatient observation unit.

Consent: Patient provided verbal and written consent to use of de-identified patient information and images for medical research.


Results: CT of his head confirmed a small volume of intracranial air. CT of the lumbar was consistent with a small amount of air within the epidural space at L5 and did not comment on a CSF leak or dural tear. High flow oxygen and analgesics were administered. CTA of his head obtained five days later was negative for acute intracranial pathology and the patient was subsequently discharged home.

Conclusions/Implications for future research and/or clinical care: This represents a unique case of pneumocephalus localized to the extradural space. It is imperative for providers to recognize the nuances between post dural puncture headache and pneumocephalus as treatment options differ. Use of alternative media such as saline for identifying the epidural space may pose less risk for patients undergoing epidural anesthesia. Further research is needed to evaluate the risks and benefits of utilizing different loss of resistance techniques.


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