Introduction: Cerebral air embolism is a known but rare complication of pulmonary arteriovenous malformation (AVM) during or after hemoptysis. This report describes the first case of cerebral air embolism as a result of pulmonary AVM with neurological manifestations, which was successfully treated with hyperbaric oxygen.
Case Presentation: A 17 year old healthy male was referred to our neurology service for evaluation with a history of transient neurologic complaints. He described several, five to ten minute, episodes over the last three months. Episodes would often start with scant hemoptysis, followed by a generalized numbness and tingling and weakness of the right side. Because the episodes would resolve by the time he was medically evaluated, he was told that he was suffering from anxiety and was prescribed anxiolytics. He was referred to the pulmonary clinic after the neurologic work-up was negative.
The physical examination and pulmonary function tests were normal. Review of an old CXR showed prominent tight pulmonary artery with a left-sided infiltrate. On repeat chest X-ray the infiltrate had cleared but a prominent nodule was revealed. We entertained the diagnosis of AVMs with clearing hemorrhage. CT of the chest demonstrated three distinct masses with differential CT numbers during contrast administration consistent with AVM's. A magnetic resonance angiograph of cerebral circulation was performed and was without evidence of CNS AVMs. The patient underwent fight heart catheterization, which confirmed the three large AVMs seen on CT, as well as, multiple small ones. Coil embolization was planned. The patient developed another episode of lost consciousness and became decerebrate. On arrival to our institution, the patient was stable, sedated and ventilated. Physical examination revealed pupils of 4 mm bilaterally with oculocephalic reflex present, fixed, downward gaze and was decerebrate. The CT of the head was normal. At this time, after consultation with neurology and neurosurgery, the ICU team postulated, by exclusion, that the most likely etiology was air embolism. In an effort to reduce the air embolus and salvage CNS function, the patient underwent hyperbaric oxygen therapy, descended to 3 ATA per US Navy treatment table 6 on 100% oxygen. After the treatment protocol of three days the posturing activity stopped. However, his right-to-left shunt worsened and oxygenation deteriorated. He underwent arterial coil embolization of three AVMs and increased his PaO2 from 66 to 447 mm Hg on 100% oxygen. Slowly his neurological examination returned and he was extubated.
Discussion: Pulmonary vascular malformations are either acquired or congenital. Hereditary hemorrhagic telangiectasia or Rendu-Osler-Weber disease is a familial disorder transmitted as an autosomal dominant trait of high penetrance. Our patient had a grandmother and a brother who had recurrent nosebleeds and found to have AVM's. Direct communication between branches of the pulmonary artery and vein are thought to be the most common abnormalities of the pulmonary circulation. Such communications causes right-to-left shunt in which mixed venous blood cannot be oxygenated. The majority of patients are asymptomatic but the most common symptom in symptomatic patients is dyspnea and the second most common symptom is hemoptysis. Up to 30% of symptomatic patients with pulmonary AVM's have neurological manifestations. These may range from headache, tinnitus and seizures to transient paresthesia and hemiplegia. Air embolism is a known complication of pulmonary AVM's, diving related injury and penetrating lung injury. In the past many authors have suggested the possibility of air embolism from entrance of air into the circulation through a defect in the wall of AVM, particularly during or after hemoptysis.
Conclusion: Air embolisln is a known complication of pulmonary AVM's. There should be a high index of suspicion when the patient presents with neurological symptoms after hemoptysis. Early recognition and timely treatment with hyperbaric oxygen may result in better outcome.
References
[1] Roman G, Fisher M, Perl DP, et al. Neurological manifestations of hereditary hemorrhagic telangiectasia. Ann Neurol 1978; 4:130-144
[2] Halpern P, et al. Arterial air embolism after penetrating lung injury. Critical Care Medicine, May 1983; 11(5):392-393
[3] NOAA Diving Manual--October 1991
[4] Textbook of respiratory medicine (edited by) John F. Murray, Jay A. Nadel--2nd ed. Chapter 55. W.B. Saunders Co, Philadelphia, PA 1994
R. B. Ramaswamy, A. R. O'Brien-Ladner--University of Kansas Medical Center, Kansas City, KS
COPYRIGHT 1999 American College of Chest Physicians
COPYRIGHT 2000 Gale Group
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