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Incidence, radiographical features, and proposed mechanism for pneumocephalus from intravenous injection of air.

Tran P, Reed EJ, Hahn F, Lambrecht JE, McClay JC, Omojola MF - West J Emerg Med (2010)

Bottom Line: These cases are characterized clinically by the absence of signs and symptoms of pathologic pneumocephalus and radiographically by the distribution of air densities along the cranial venous system on head CTs.Idiopathic and presumed IV-induced pneumocephalus could be considered in the workup of ED patients with unexplained intracranial air on head CT if there are no findings of pathological causes for the pneumocephalus on history and physical examination and if the head CTs show a characteristic distribution of air limited to the cranial venous system.Knowledge of this clinical entity in the evaluation of ED patients with unexplained pneumocephalus can lead to more efficient emergency care and less patient anxiety.

View Article: PubMed Central - PubMed

Affiliation: University of Nebraska Medical Center, Department of Emergency Medicine, Omaha, NE.

ABSTRACT

Background: Pneumocephalus typically implies a traumatic breach in the meningeal layer or an intracranial gas-producing infection. Unexplained pneumocephalus on a head computed tomography (CT) in an emergency setting often compels emergency physicians to undertake aggressive evaluation and consultation.

Methods: In this paper, we report three cases of pneumocephalus that appear to result from retrograde injection of air through an intravenous (IV) catheter. We also performed a retrospective study to determine the incidence of presumed IV-induced pneumocephalus and etiologies of pneumocephalus in our emergency department (ED) population.

Results: The incidence of idiopathic and presumed IV-induced pneumocephalus was 0.034% among all head CTs ordered in the ED and 4.88% among cases of pneumocephalus seen in the ED. These cases are characterized clinically by the absence of signs and symptoms of pathologic pneumocephalus and radiographically by the distribution of air densities along the cranial venous system on head CTs.

Conclusion: Idiopathic and presumed IV-induced pneumocephalus could be considered in the workup of ED patients with unexplained intracranial air on head CT if there are no findings of pathological causes for the pneumocephalus on history and physical examination and if the head CTs show a characteristic distribution of air limited to the cranial venous system. Knowledge of this clinical entity in the evaluation of ED patients with unexplained pneumocephalus can lead to more efficient emergency care and less patient anxiety.

No MeSH data available.


Related in: MedlinePlus

Axial (A), coronal (B) and sagittal (C) computed tomography reformatted views of soft tissue of the neck, showing contrast flow cephalad into the left internal (white arrowheads) and external jugular veins (black arrowheads) during a left upper extremity contrast injection for a head and neck computed tomography angiogram (white arrowheads: internal jugular, black arrowheads: external jugular).
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f5-wjem-11-180: Axial (A), coronal (B) and sagittal (C) computed tomography reformatted views of soft tissue of the neck, showing contrast flow cephalad into the left internal (white arrowheads) and external jugular veins (black arrowheads) during a left upper extremity contrast injection for a head and neck computed tomography angiogram (white arrowheads: internal jugular, black arrowheads: external jugular).

Mentions: Having considered the standard causes for pneumocephalus, the consensus among the neurosurgical and neuroradiological consultants was that these three cases of idiopathic pneumocephalus occurred as a result of the injection of air into the IV. While infusion from a peripheral IV site in the upper extremities normally travels through the axillary, subclavian, and brachiocephalic veins to empty into the superior vena cava (SVC), the infusion can also flow cephalad through the internal/external jugular veins to the cranial venous system under certain clinical situations (Valsalva maneuvers as in coughing, stenotic brachiocephalic vein, partially obstructed SVC, or low flow state as in heart failure). We have documented CT images of retrograde flow of contrast dye from a peripheral IV site into the internal and external jugular venous system (Figure 5). Since air is lighter than blood, which in turn is lighter than contrast, under similar clinical situations, air bubbles can flow retrograde up through the jugular veins with less difficulty than contrast dye, especially in patients who are in a reclining position (due to the buoyancy force). Once in the jugular veins, air continues its ascension in those patients who are in reclining position to accumulate in the highest areas of the head: the orbital veins, cavernous sinuses, frontal venous system, petrosal sinuses, and the superficial temporal veins. This is what we observed in Figures 1–3.


Incidence, radiographical features, and proposed mechanism for pneumocephalus from intravenous injection of air.

Tran P, Reed EJ, Hahn F, Lambrecht JE, McClay JC, Omojola MF - West J Emerg Med (2010)

Axial (A), coronal (B) and sagittal (C) computed tomography reformatted views of soft tissue of the neck, showing contrast flow cephalad into the left internal (white arrowheads) and external jugular veins (black arrowheads) during a left upper extremity contrast injection for a head and neck computed tomography angiogram (white arrowheads: internal jugular, black arrowheads: external jugular).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2908654&req=5

f5-wjem-11-180: Axial (A), coronal (B) and sagittal (C) computed tomography reformatted views of soft tissue of the neck, showing contrast flow cephalad into the left internal (white arrowheads) and external jugular veins (black arrowheads) during a left upper extremity contrast injection for a head and neck computed tomography angiogram (white arrowheads: internal jugular, black arrowheads: external jugular).
Mentions: Having considered the standard causes for pneumocephalus, the consensus among the neurosurgical and neuroradiological consultants was that these three cases of idiopathic pneumocephalus occurred as a result of the injection of air into the IV. While infusion from a peripheral IV site in the upper extremities normally travels through the axillary, subclavian, and brachiocephalic veins to empty into the superior vena cava (SVC), the infusion can also flow cephalad through the internal/external jugular veins to the cranial venous system under certain clinical situations (Valsalva maneuvers as in coughing, stenotic brachiocephalic vein, partially obstructed SVC, or low flow state as in heart failure). We have documented CT images of retrograde flow of contrast dye from a peripheral IV site into the internal and external jugular venous system (Figure 5). Since air is lighter than blood, which in turn is lighter than contrast, under similar clinical situations, air bubbles can flow retrograde up through the jugular veins with less difficulty than contrast dye, especially in patients who are in a reclining position (due to the buoyancy force). Once in the jugular veins, air continues its ascension in those patients who are in reclining position to accumulate in the highest areas of the head: the orbital veins, cavernous sinuses, frontal venous system, petrosal sinuses, and the superficial temporal veins. This is what we observed in Figures 1–3.

Bottom Line: These cases are characterized clinically by the absence of signs and symptoms of pathologic pneumocephalus and radiographically by the distribution of air densities along the cranial venous system on head CTs.Idiopathic and presumed IV-induced pneumocephalus could be considered in the workup of ED patients with unexplained intracranial air on head CT if there are no findings of pathological causes for the pneumocephalus on history and physical examination and if the head CTs show a characteristic distribution of air limited to the cranial venous system.Knowledge of this clinical entity in the evaluation of ED patients with unexplained pneumocephalus can lead to more efficient emergency care and less patient anxiety.

View Article: PubMed Central - PubMed

Affiliation: University of Nebraska Medical Center, Department of Emergency Medicine, Omaha, NE.

ABSTRACT

Background: Pneumocephalus typically implies a traumatic breach in the meningeal layer or an intracranial gas-producing infection. Unexplained pneumocephalus on a head computed tomography (CT) in an emergency setting often compels emergency physicians to undertake aggressive evaluation and consultation.

Methods: In this paper, we report three cases of pneumocephalus that appear to result from retrograde injection of air through an intravenous (IV) catheter. We also performed a retrospective study to determine the incidence of presumed IV-induced pneumocephalus and etiologies of pneumocephalus in our emergency department (ED) population.

Results: The incidence of idiopathic and presumed IV-induced pneumocephalus was 0.034% among all head CTs ordered in the ED and 4.88% among cases of pneumocephalus seen in the ED. These cases are characterized clinically by the absence of signs and symptoms of pathologic pneumocephalus and radiographically by the distribution of air densities along the cranial venous system on head CTs.

Conclusion: Idiopathic and presumed IV-induced pneumocephalus could be considered in the workup of ED patients with unexplained intracranial air on head CT if there are no findings of pathological causes for the pneumocephalus on history and physical examination and if the head CTs show a characteristic distribution of air limited to the cranial venous system. Knowledge of this clinical entity in the evaluation of ED patients with unexplained pneumocephalus can lead to more efficient emergency care and less patient anxiety.

No MeSH data available.


Related in: MedlinePlus