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Pneumocephalus After Lumbar Epidural Steroid Injection: A Case Report and Review of the Literature

Verdun, Aubrey V. MD; Cohen, Steven P. MD; Williams, Bryan S. MD; Hurley, Robert W. MD, PhD

doi: 10.1213/XAA.0000000000000055
Case Reports: Case Report

Pneumocephalus may occur after inadvertent injection of air into the subarachnoid space while performing epidural anesthesia using a loss-of-resistance technique with air in the syringe. We report a case of pneumocephalus after an interlaminar epidural steroid injection using the loss-of-resistance to air technique. In this report, we examine the etiology, the expected course of symptoms, and resolution, as well as treatment, of pneumocephalus following a systematic literature review.

From the *Department of Pain Medicine, Walter Reed National Military Medical Center, Bethesda; Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University, Baltimore; Department of Anesthesiology, Kaiser Permanente, Gaithersburg, Maryland; and §Department of Anesthesiology, University of Florida, Gainesville, Florida.

Accepted for publication January 17, 2014.

Funding: Division of Pain Medicine.

The authors declare no conflicts of interest.

Address correspondence to Robert W. Hurley, MD, PhD, Department of Anesthesiology, Division of Pain Medicine, University of Florida, 1600 SW Archer Rd., Rm M-500, Gainesville, FL 32607. Address e-mail to

Epidural steroid injections are a mainstay in the treatment of radicular pain. These procedures have a low incidence of adverse events and may provide symptomatic pain relief for patients with extremity pain due to a herniated disk, chemical irritation of a nerve root, foraminal stenosis, and central canal stenosis.1 Pneumocephalus is an uncommon complication that can occur after dural puncture.2 Prompt recognition, treatment, and patient reassurance are essential components of successful management. We report a case of pneumocephalus occurring after an inadvertent dural puncture during an interlaminar lumbar epidural steroid injection for bilateral lower extremity pain related to spinal pathology. Patient consent was not obtained; however, consent to publish the patient information was obtained from the University of Florida IRB after review of the manuscript.

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A male patient in his late 70s presented with complaints of bilateral lower extremity pain. His symptoms were consistent with the findings on magnetic resonance imaging including central spinal stenosis from the ligamentum flavum hypertrophy of T11 through S1 and radiculopathy from a herniated nucleus pulposus at L4-L5 contacting the descending L5 and S1 nerve roots. His body mass index was within the normal range. He was referred to the pain clinic for conservative management, including lumbar epidural steroid injections. The patient had previously received 2 interlaminar epidural injections separated by 3 months with good relief of his symptoms.

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With the patient in the prone position, the L4-L5 interlaminar space was identified under fluoroscopy, and an 18-gauge Tuohy needle was advanced into the ligamentum flavum under an anterior–posterior fluoroscopic view. The needle was advanced through the ligament into the epidural space under lateral fluoroscopy using intermittent verification for “loss-of-resistance” (LOR) with an air-filled (approximately 4 mL) glass syringe. After the LOR to 1 to 2 mL air, cerebrospinal fluid was noted in the syringe, and it was concluded that a dural puncture had occurred. The needle was withdrawn, repositioned, and advanced approximately 1 cm cephalad within the same interspace. Epidural entrance was confirmed with LOR to air (2–3 mL). Cerebrospinal fluid was not present at the needle hub or on aspiration. Next, a mixture of 0.25% bupivacaine (1 mL) and 80 mg (2 mL) of particulate methylprednisolone was injected into the epidural space. The extension tubing was cleared of medication with saline injection. The needle was restyleted and removed. After the procedure, the patient walked accompanied by the resident physician to the recovery room. Although the procedure was initially well tolerated, within 15 minutes the patient began to complain of nausea and vomited repeatedly. After the first bout of emesis, the patient reported a severe headache and visual disturbances. The headache was sharp and nonpositional in nature, described as “the worst headache of my life.” The patient had no mental status changes, hemodynamic instability, respiratory depression or cranial nerve pathology. Supplemental oxygen was administered via nasal cannula and IV access was obtained and the patient received antiemetics (ondansetron 4 mg IV), analgesics (fentanyl 100 μg IV), and a fluid bolus of 500 mL normal saline. The differential diagnosis included intracranial hemorrhage, pneumocephalus, subarachnoid hemorrhage, subdural hematoma, and postdural puncture headache (PDPH), and the patient was immediately taken to the computed tomography (CT) suite. The imaging revealed air in the subarachnoid space surrounding the rostral extent of the cervical spinal cord and within the third and lateral ventricles, with no signs of uncal herniation, or epidural, subdural, subarachnoid, or intraparenchymal bleeding, thereby confirming the diagnosis of pneumocephalus (column 1; Fig. 1, A–D). On returning from the CT scan, the patient continued to complain of severe headache and nausea refractory to medications, including fentanyl, ondansetron, metoclopramide, and promethazine. After reviewing the images and lack of symptom resolution, the patient was admitted for observation and management. He was maintained in a head-down (10°) supine position, was given supplemental oxygen to breathe via facemask, and was given maintenance IV fluids until symptom resolution. Eighteen hours after the procedure, the patient’s headache and nausea resolved. A repeat CT scan at that time revealed a modest reduction in the air in the ventricles (column 2; Fig. 1, A–C) and absence of air in the subarachnoid space around the rostral spinal cord (Fig. 1D). The patient was discharged 24 hours after the procedure with complete resolution of pneumocephalus-related symptoms. Of note, his initial presenting pain symptoms of radiculopathy were also reduced. Two weeks after admission, the patient (at his request) had another CT scan of his head for monitoring purposes. These images revealed resolution of intracranial and intrathecal air (column 3; Fig. 1, A–D). He returned to the pain clinic 12 weeks later for a repeat interlaminar lumbar epidural steroid injection that was performed without complication.

Figure 1

Figure 1

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Literature Review

Relevant keywords (“pneumocephalus,” “epidural,” “neuraxial,” “headache”) were used to design a search strategy of the published literature (“pneumocephalus” and “epidural” or “pneumocephalus” and “neuraxial” or “pneumocephalus” and “headache”). No language restrictions were applied to the search. The Medline (PubMed, 1919–2013) and Google Scholar (1919–2013) databases were used for the literature search. This yielded 2590 articles. Articles involving intentional injection of air into the neuraxis, intentional dura entry, surgical manipulation, medical causes, or idiopathic causes of pneumocephalus were excluded. These were reviewed by the author (RWH) resulting in 22 articles describing 26 cases of pneumocephalus after an inadvertent dural puncture during an epidural needle-based procedure (Table 1).

Table 1

Table 1

Treatment of symptomatic pneumocephalus described in the articles in the literature review included bed rest with the head of the bed lowered slightly, hemodynamic and volume support as needed, and symptomatic pain and nausea relief with medications. The addition of high-concentration oxygen therapy in an attempt to reduce the partial pressure of nitrogen in the blood hastening the systemic absorption of intraventricular nitrogen3 has been demonstrated to accelerate the resolution of intracranial air collections.4–6 More aggressive oxygen therapies such as hyperbaric oxygen therapy are unlikely to be needed and may result in an increased tension pneumocephalus.7–9

In the current case, the likely source of the pneumocephalus was the direct injection of air through the dural puncture with the LOR to air. Although the use of LOR to air technique is a common technique used for the identification of the epidural space,10–12 it has been associated with an increased risk of inadvertent dural puncture12–14 and an increased risk of headache and pneumocephalus if a dural puncture occurs.15 For instance, Aida et al.15 describe in a case series of 3730 patients receiving epidural injections for chronic pain that LOR with air was associated with significantly more frequent incidence of pneumocephalus (94%) than that after LOR to saline (0%). In the literature reviewed, headache associated with pneumocephalus after an epidural procedure when the LOR to air technique was used was reported in 22 cases, while in 3 cases the LOR technique was not reported and in 1 case the hanging drop technique was used (Table 1). Eleven cases reported nonpostural-related headaches, 2 cases reported postural headaches, and the remaining cases either did not report postural effects or were unclear in the positional dependence. In 5 cases, headache symptoms resolved before the resolution of the pneumocephalus, while there were no cases in which the symptoms lasted longer than the pneumocephalus. In 21 cases, imaging after the initial diagnostic CT scan was not obtained.

The literature describing pneumocephalus-related headache is inconsistent regarding time to onset, the duration and time to resolution of symptoms, and/or recommendations to avoid this complication. For example, symptom onset was highly variable from minutes after the LOR to hours to days (Table 1). Similarly, symptom resolution was also variable; however, patients with headaches resulting from inadvertent dural puncture as part of epidural catheter placement for labor analgesia or the treatment of PDPH appeared to have headaches for longer durations than those who had procedures for the treatment of pain or to provide surgical anesthesia. This may reflect misattribution of the etiology of the duration of headache to the pneumocephalus instead of the initial PDPH. This review also revealed a lack of clinical correlation between symptom onset, duration, and radiologically confirmed resolution of the intracranial and intrathecal air, the latter of which was quite variable ranging from hours to weeks (Table 1).16–18

Although the current literature review focuses on those reports published after the era during which pneumoencephalography was used as an imaging technique, there are similarities between the pneumoencephalogram literature and the current literature. In the former, the headache associated with pneumocephalus has a longer duration but still resolved before the resolution of the pneumocephalus,19 as in our case. The difference in duration may relate to the far larger volume of air injected for pneumoencephalography.20 The resolution of the pneumocephalus has been reported to be between 1 and 2 weeks after injecting a large volume (20–50 mL) of air.21

Although the critical volume of air necessary to produce symptoms related to pneumocephalus is unknown,22 asymptomatic pneumocephalus has been reported with as much as 50 mL air in the ventricles,19,23 while headache has been reported after the injection of 2 mL.24 There is likely a threshold-related volume; however, the headache symptoms may also relate to the abruptness of the distension of the meninges by the temporary displacement of the parenchyma.19,25

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First, trainees should be taught the LOR to saline technique; however, experienced providers trained using LOR to air need not change technique if they are uncomfortable using with LOR to saline.12 However, regardless of training, one should avoid the use of LOR to air after a known dural puncture.

Second, for those preferring the tactile feedback of LOR to air when performing an interlaminar epidural procedure in a patient in the prone position, we suggest an alternative. The use of a glass syringe filled with 1 to 2 mL saline and 1 to 2 mL air will provide the tactile feel of resistance preferred by some physicians26 and the saline will serve a protective role should accidental dural puncture occur.13 In the case of patients in the seated or lateral positions, training providers using saline-filled syringes might be preferable due to the lesser risk of pneumocephalus.13

Third, in the case of significant central canal stenosis from a herniated intervertebral disk, one might consider bilateral transforaminal injections or positioning the needle 1 interspace cephalad to avoid the additional risk of dural puncture from reduced epidural space.27–29

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Pneumocephalus-related headache is more likely to result from the LOR to air technique, be nonpostural, resolve in 24 to 48 hours, and resolve before resolution of the pneumocephalus. Subsequent studies of procedural-related headache should focus on clarification of symptom onset, quality, duration, and resolution of pneumocephalus-related headache compared to traditional PDPH. Pneumocephalus is necessary but likely not sufficient for the diagnosis of pneumocephalus-related headache and confusion, and PDPH can occur especially days following the post-dural puncture.

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