The Case Files

Abstract

A 41-year-old woman with a past medical history of chronic low back pain and migraines presented with a headache. She had had a L4-L5 epidural steroid injection performed for her chronic lower back pain, but complained of a headache immediately after the procedure. The headache was in the front of her head and associated with photophobia. She stated that she had multiple epidural steroid injections in the past with no prior post-procedure headache. She denied neck pain, vision changes, extremity numbness, or extremity weakness. The patient had a temperature of 98.1°F, a pulse of 76 bpm, a blood pressure of 99/63 mm Hg, a respiratory rate of 16 bpm, and an oxygen saturation of 99% on room air. She was alert and oriented. Her speech was fluent, her cranial nerves were intact, and she had full strength in all extremities. She had normal sensation to dull and light touch in all extremity dermatomes, and her neurologic examination was nonfocal. She also had full range of motion of her neck with no meningismus.FigureFigureA head CT was obtained, and showed pneumocephalus ventral to the pons and medulla. Pneumocephalus was also present throughout the posterior fossa. She received IV Toradol, Valium, Benadryl, and opiate pain medication with only minimal symptom relief. The patient was evaluated by neurosurgery based on the amount of pneumocephalus present on the CT scan. They recommended inpatient observation and symptom control. The patient was placed supine, and provided with supplemental oxygen and pain medications as needed. After three days, her symptoms had significantly improved, and she was able to be discharged from the hospital. Headache is a frequently encountered chief complaint in the emergency department. Migraine, subarachnoid hemorrhage, dural venous sinus thrombosis, meningitis, subdural hematoma, epidural hematoma, and carotid artery dissection are all diagnoses that every emergency medicine physician must consider when evaluating a patient presenting with headache. Headaches can be the result of procedures, most commonly lumbar punctures. Cephalgia may also result from epidural puncture from injection or anesthesia. At times, pneumocephalus may result from accidental puncture of the dura mater during a procedure. Post-procedural pneumocephalus is not a frequently encountered diagnosis, and it rarely makes the differential diagnosis of headache in the emergency department.FigureFigurePneumocephalus is the accumulation of intracranial air. (Clin Neurol Neurosurg 2009;111[3]:309.) There are multiple etiologies of pneumocephalus, the most common being trauma. Other etiologies include craniotomy, injection of air during a procedure, placement of VP shunts, CSF-pleural fistula, nasopharyngeal cancer with invasion of the skull base, nasal sinus surgery with perforation of the skull base, and otogenic causes. Injection of air can occur from accidental dural puncture during epidural anesthesia, during a blood patch procedure, epidural saline infusions, or spinal anesthesia. (Can J Neurol Sci 2002;29[3]:278.) Pneumocephalus can cause a severe headache, and no direct correlation exists between the amount of air and the presence or severity of the headache. (Can J Neurol Sci 2002;29[3]:278.) It has also been shown that increasing the amount of inspired air oxygen concentration decreases the amount of time needed to absorb intracranial air, decreasing the duration of the patient's headache. This study showed that the duration of absorption of 50 ml of air decreased from 5.8 to 1.9 weeks by 40% FiO2 from 1.9 to 0.6 weeks on room air and 100% FiO2, respectively. (Anesthesiology 1996;84[2]:442.) Several diagnoses should be added to the headache differential diagnosis in the case of a patient receiving recent epidural spinal injections. Post-procedural headache or low-pressure headache, as well as pneumocephalus, should be added to the differential. The patient can be easily placed on a face mask to expedite air resorption, and can be provided symptom control as needed. This patient was successfully managed using supplemental oxygen and analgesia.