Pneumocephalus with Intense Headache and Unilateral Pupillary Dilatation After Accidental Dural Puncture During Epidural Anesthesia for Cesarean Section

The loss of resistance technique (LOR) using either an air- or saline-filled syringe is widely used to identify the epidural space. Recently, the use of air has been criticized because of its potential risks ^[1,2]. We report a case of sudden bifrontal headache and unilateral pupillary dilation after an accidental dural puncture during the performance of epidural anesthesia using the LOR to air technique.

Case Report

A healthy, 27-yr-old woman (156 cm, 74 kg) was scheduled for elective cesarean section at term because of podalic presentation of the fetus. The course of pregnancy had been uneventful, and there were no contraindications to regional anesthesia. With the consent of the patient, epidural anesthesia was chosen. With the patient in the sitting position, the back was prepared and draped in an aseptic fashion, and 2% lidocaine was infiltrated for skin analgesia at the L3-4 interspace. An 18-gauge Tuohy needle was introduced using the LOR to air technique. During the first attempt, an accidental dural puncture occurred with free flow of cerebrospinal fluid from the needle. Inadvertently, 5 mL of air was injected into the subarachnoid space. A second, successful epidural attempt was performed at the L2-3 interspace using the LOR to saline technique. An epidural catheter was introduced 3 cm into the epidural space, and a 2-mL test dose of 2% lidocaine was administered. Thereafter, the patient was positioned supine with left uterine displacement. Incremental doses of carbonated 2% lidocaine were administered until a sensory level of T4 was reached. A total volume of 15 mL was needed. Suddenly, approximately 15 min after the accidental dural puncture, the patient complained of severe bifrontal headache. The arterial pressure decreased from 108/70 mm Hg to 74/45 mm Hg, and the patient reported respiratory difficulty. Lactated Ringer's solution 1000 mL, two doses of ephedrine 10 mg IV, and oxygen via a face mask were administered. No signs of total spinal anesthesia were observed. The patient was able to cough and phonate, and the strength of her upper extremities was normal. The sensory level of the block remained on T4. Peripheral oxygen saturation did not decrease, and the blood pressure promptly returned to normal levels. Because the patient's discomfort persisted, the decision to proceed with general anesthesia was made. A rapid-sequence induction with thiopental 400 mg and succinylcholine 75 mg IV was performed. For the maintenance of anesthesia, only isoflurane in oxygen was used. During general anesthesia, the patient's arterial pressure, heart rate, and oxygen saturation remained normal, but a left-sided unilateral pupillary dilation was observed. The cesarean section was performed without difficulty, and a live infant (3850 g) was delivered in good condition with Apgar scores of 9 and 10 at 1 and 5 min, respectively. The duration of the surgery was 50 min, and the patient's emergence from anesthesia was uneventful, with immediate return of spontaneous respiration. After tracheal extubation, the patient continued to complain of severe headache although she was conscious and lucid. In the recovery room, a thorough neurological examination was normal, except for the left-sided pupillary dilation. Headache and pupillary dilation resolved in 3 h. A computed tomography brain scan was performed 7 h after the accidental dural puncture and demonstrated subarachnoid (including intraventricular) air, especially in the anterior part of the interpeduncular cistern (Figure 1), where the oculomotor nerve runs between the posterior cerebral and superior cerebellar arteries to penetrate to the orbit through the superior orbital fissure. Surprisingly, the patient showed no signs of postdural puncture headache, and she was discharged from the hospital after 6 days-the usual length of stay after cesarean section in Switzerland. At the time of discharge, the patient was in good general condition and free from any neurological sequelae.

Figure 1: Computed tomography scan of the brain. The air bubble located in the interpeduncular cistern is indicated by an arrow.

Discussion

Various complications have been attributed to the use of air for identification of the epidural space: compression of the cauda equina ^[3], pneumocephalus ^[4-6], air embolism ^[7-10], cervical emphysema ^[11], and increased incidence of dural puncture ^[12]. There are also reports of unblocked segments caused by epidural air, resulting in insufficient analgesia in parturients ^[13,14]. In a study on 3730 patients who received an epidural blockade for acute or chronic pain, Aide et al. ^[15] showed that, after an accidental dural puncture, the incidence of headache was significantly higher when LOR to air instead of LOR to saline was used. Apparently, the likelihood of complications depends on the amount of air injected, and the effects of subarachnoid or subdural air are quite distinct from those of epidural air. In our case, the amount of air used to identify the epidural space was obviously larger than needed, and, unfortunately, it was accidentally injected into the subarachnoid space before the flow of cerebrospinal fluid was noticed.

With the advent of computed tomography and magnetic resonance imaging, pneumocephalograms are rarely, if ever, performed today. The symptoms of pneumocephalus described in old textbooks of neuroradiology ^[16] in connection with intracranial pneumography include severe frontal headache, paresthesias, restlessness, apprehension, vegetative symptoms, and changes in blood pressure. It has been suggested that hypotension and collapse respond promptly to cardiovascular stimulants and oxygen ^[16]. The specific symptoms depend on the intracranial distribution of the air, whereas the duration and severity of the symptoms are related to the amount of air. To relieve symptoms, supine position, aggressive hydration, caffeine, analgesics, and oxygen therapy are recommended ^[16].

In our patient, the headache was associated with pupillary dilation. This was probably secondary to direct pressure on the oculomotor nerve, caused by an air bubble. With slow reabsorption of the air, symptoms disappeared progressively. However, if nitrous oxide had been used during general anesthesia, the volume of air could have increased, with deleterious effects. It has been suggested that nitrous oxide should not be used after identification of the epidural space with LOR to air ^[5,17].

The LOR to saline technique offers many benefits compared with the LOR to air technique. Although this case report may not support the total abandonment of the LOR to air technique, it does suggest that when this technique is chosen, the amount of air should be minimized. In addition, the LOR to air technique should not be used after an accidental dural puncture.