PAIN MEDICINE: Case Report
Cervical epidural steroid injection is a fairly well accepted therapeutic modality used in the management of cervical radicular pain. Complications are rare and occur mostly when the dura has been accidentally punctured. We recently encountered a case of pneumocephalus after cervical epidural steroid injection.
A 53-yr-old otherwise healthy man with a history of cervical radiculopathy had received one cervical epidural steroid injection for the management of his symptoms 3 wk before this attempt. He had a vasovagal episode with his first injection, which provided minimal benefit. The patient was placed in the sitting position, and IV access was secured. By using the “hanging drop” technique, the epidural space was identified very easily at the level of C6-7 (1). After injection of 1 mL of a mixture composed of 80 mg of triamcinolone diacetate and normal saline (6 mL total volume) through a 20-gauge Weiss needle, the patient complained of pain in his shoulder and then moved abruptly. The injection was completed after rechecking for the proper position of the needle in the epidural space with loss of resistance to 1 mL of saline. The pain in his shoulder resolved quickly and did not recur with a slower rate of injection. However, after completion of the procedure, the patient experienced a severe headache. He was placed in the decubitus position and given IV fluids, and he remained hemodynamically stable. He then received 50 mg IV meperidine. This was repeated twice, but the onset of nausea limited the administration of additional opioid. The patient also received lorazepam and chlorpromazine and was subsequently transferred to the inpatient neurology service. His neurologic examination was normal but, because of an unremitting headache, he underwent a computed tomography of the head without contrast. This study revealed air in the subarachnoid space, specifically in the basal cisterns. Pneumocephalus was thought to be the etiology of his headache. He was treated with analgesics. Over the next few days, the headache, nausea, and vomiting resolved completely. The patient experienced no sequelae from pneumocephalus but did not return to the pain clinic for further management of his cervical radicular pain.
Headache can be caused by pneumocephalus or dural puncture after spinal or epidural anesthesia. The onset is often immediate with pneumocephalus. In contrast, headaches related to dural puncture typically manifest 1–3 days after the procedure (2). Pneumocephalus causes a headache that is aggravated by any motion and is not relieved with lying down, as is characteristic of postdural puncture headache (3,4). A severe headache can arise from a volume of air as little as two milliliters (5). The air is reabsorbed after two days, and the headache usually resolves five days after the dural puncture (3,4).
Our patient required only minute amounts of subarachnoid air to develop very dramatic symptoms, which abated in the expected time course. Pneumocephalus has been associated mainly with the loss of resistance to air (2). The frequency of intracranial air after lumbar epidural placement is uncommon, with one case report per year (6). The hanging drop technique obviates the active injection of air, and therefore, the complication of pneumocephalus should be rare.
However, this method is probably not entirely specific for identification of the epidural space. Placement of the needle into epidural blood vessels can give rise to false-positive results. Venous air embolism may shortly ensue with significant cardiopulmonary embarrassment (7). The column of saline inside the needle may also be aspirated into the subarachnoid space at the cervical level. In the sitting position, the pressures in the ventricles and basal cisterns are subatmospheric (7). During inspiration, negative intrathoracic pressure may easily decrease cervical subarachnoid pressure below atmospheric pressure, which would permit a small quantity of air to enter (8).
The basis of the hanging drop technique relies on artifactual initial negative pressure related to bulging of the flavum with subsequent recoil (9). At the cervical level, the ligamentum flavum is thin, making loss of resistance subtle (10). Also, the possibility of a false loss of resistance between the interspinous ligament and ligamentum flavum is increased in the cervical region. The distance from the ligamentum flavum to the dura at the cervical region is approximately one-half that of the lumbar spine (11). A smaller margin of error, coupled with a more mobile region of the spine, can allow the needle to advance ever so slightly just before or during injection. Air that fills the needle after proper identification of the epidural space by using the above method may now be pushed intrathecally when the syringe of medication is attached.
During cervical epidural placement, therefore, the patient must remain immobile, and the needle must be stabilized. Careful attachment of extension tubing with prior aspiration may help to minimize subarachnoid air injection.
1. Bromage PR. The “hanging-drop” sign. Anaesthesia 1953; 8: 237–41.
2. Saberski LR, Kondamuri S, Osinubi OYO. Identification of the epidural space: is loss of resistance to air a safe technique? A review of the complications related to the use of air. Reg Anesth 1997; 22: 3–15.
3. Wolfson B, Siker E, Gray G. Post-pneumoencephalography headache. Anaesthesia 1970; 25: 328–38.
4. Katz JA, Lukin R, Bridenbaugh PO, Gunzenhauser L. Subdural intracranial air: an unusual cause of headache after epidural steroid injection. Anesthesiology 1991; 74: 615–7.
5. Roderick L, Moore DC, Artru AA. Pneumocephalus with headache during spinal anesthesia. Anesthesiology 1985; 62: 690–2.
6. Scott DB. Identification of the epidural space: loss of resistance to air or saline? Reg Anesth 1997; 22: 1–2.
7. Jackson KE, Rauck RL. Suspected venous air embolism during epidural anesthesia. Anesthesiology 1991; 74: 190–1.
8. Lee JA, Atkinson RS. Sir Robert Macintosh’s lumbar puncture and spinal analgesia intradural and extradural. New York: Churchill Livingstone Inc, 1979: 76.
9. Zarzur E. Genesis of the ‘true’ negative pressure in the lumbar epidural space. Anaesthesia 1984; 39: 1101–4.
10. Waldman SD, Winnie AP. Interventional pain management. Philadelphia: WB Saunders Co, 1996: 276–7.
11. Reynolds AF, Roberts PA, Pollay M, et al. Quantitative anatomy of the thoracolumbar epidural space. Neurosurgery 1985; 17: 905–7.