CT-guided transthoracic lung biopsy is a minimally invasive and generally safe procedure that is used for the diagnosis of benign and malignant diseases that avoids the need for an exploratory thoracotomy. There have been many reports concerning various complications due to this procedure. The most frequent complication is pneumothorax, accounting for 27% of cases, followed by pulmonary hemorrhage (11%), and hemoptysis (7%) [1]. Systemic air embolism is a rare but potentially fatal complication, with a reported incidence of 0.06 to 0.21% [1–3].

Mansour et al. [4] listed three mechanisms whereby air can enter the systemic circulation during a needle lung biopsy. First, there is communication between the atmosphere and the pulmonary vein when the needle tip is placed within the pulmonary vein and the stylet has been removed. Second, when the needle passes through the lung parenchyma, a bronchovenous fistula may be created. There may be communication between intra-alveolar or intra-bronchial air and the pulmonary vein when the airway pressure is elevated, such as during a Valsalva maneuver, coughing, or positive pressure ventilation. Third, air in the pulmonary arterial circulation may reach pulmonary venous circulation by traversing the pulmonary microvasculature. Once in systemic circulation, an air embolus can lodge in any distal vessel, and the clinical presentation is similar to thromboembolic stroke syndrome or myocardial infarction, as has been previously reported [4–6]. The emboli tend to enter the vertebral artery through the brachiocephalic artery and descending thoracic aorta because the patient takes a prone position. The interesting feature of our case is that, to the best of our knowledge, this is the first report of a coexisting cerebellar and spinal cord infarction resulting from a transthoracic lung biopsy.

Regarding the available therapies for a systemic air embolism, the primary treatment involves supplying 100% oxygen, thereby promoting the replacement of nitrogen by oxygen and thus facilitating the resorption of the air. Positional therapy, such as the Trendelenburg position or right lateral decubitus, may be more helpful in cases of shock induced by a left ventricular air embolus before it causes an embolism in the brain [5, 7]. Because the volume of gas in an enclosed space is inversely proportional to the pressure exerted on it, hyperbaric oxygen therapy reduces the size of air bubbles and accelerates the dissolution of nitrogen by replacing it with oxygen. In patients with cerebral air embolisms, the prompt initiation of hyperbaric oxygen therapy decreases morbidity and mortality [8].

A recent study by Hiraki et al. [9] reported that the incidence of systemic air embolisms may be underestimated by missing systemic air in patients without cardiac or cerebral symptoms. Radiologists must be aware of this extremely rare but potentially fatal complication so that they may be able to provide accurate diagnosis and treatment. It should be suspected in patients who present any neurological symptoms during the procedure. Several considerations, such as: avoiding needle biopsies of cystic, cavitary, or bullous lung parenchymas; penetrating the least amount of traversing lung parenchyma by choosing an appropriate entrance site to reach the mass; and performing the procedure by means of CT guidance are recommended to decrease the risk of this complication [7].