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Table of Contents    
Year : 2017  |  Volume : 65  |  Issue : 4  |  Page : 878-880

Gas in the venous sinus: An incidental finding

1 Department of Neurology, Rajagiri Hospital, Aluva, Kochi, Kerala, India
2 Department of Internal Medicine, VPS Lakeshore Hospital, Kochi, Kerala, India

Date of Web Publication5-Jul-2017

Correspondence Address:
Muhammed J. A Jalal
Department of Internal Medicine, VPS Lakeshore Hospital, Maradu, Kochi - 682 040, Kerala
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/neuroindia.NI_1036_16

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How to cite this article:
Alif M, Jalal MJ, Vijayakumar N, Chacko J, Kuruttukulam G. Gas in the venous sinus: An incidental finding. Neurol India 2017;65:878-80

How to cite this URL:
Alif M, Jalal MJ, Vijayakumar N, Chacko J, Kuruttukulam G. Gas in the venous sinus: An incidental finding. Neurol India [serial online] 2017 [cited 2020 Jan 21];65:878-80. Available from:


Brain imaging with free air in the cavernous sinus is seen in patients with septic thrombosis,[1] skull fractures,[2] and barotrauma.[3] Penetrating craniocerebral trauma also shows free air in the dural sinuses.[4] Air in the venous sinuses is a rare incidental finding in a healthy individual.

A 46-year old female patient, without any co-morbidities, presented with a history of sudden onset giddiness followed by a fall and loss of consciousness for <30 minutes. There was no history of head trauma, cranial surgery, or recent rhinosinusitis. On examination, she was afebrile, conscious, and oriented. Her neurologic examination, including cranial nerves, motor power, and gait, was normal. Systemic examination was unremarkable. Computed tomography (CT) of the brain showed a normal brain parenchyma. However, it showed air foci within bilateral cavernous sinuses [Figure 1]. Small foci of air were also noted within the bilateral internal jugular veins, neck veins, intraspinal veins in the region of the craniovertebral (CV) junction, as well as right superior ophthalmic veins [Figure 2] and [Figure 3]. There was no evidence of skull fractures. Her other blood investigations were normal. She was absolutely asymptomatic and was discharged. A repeat CT of the brain after 10 days showed resolution of the air from the cavernous sinus and other veins [Figure 4].
Figure 1: CT brain showing air foci within the bilateral cavernous sinuses. Small foci of air is also noted in the right superior ophthalmic veins

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Figure 2: CT brain showing small foci of air within the bilateral internal jugular veins and other neck veins. Air foci is also noted within the intraspinal veins in the region of the CV junction

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Figure 3: CT head showing air foci within the intraspinal veins in the region of the CV junction

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Figure 4: Repeat CT brain after 10 days showing resolution of gas in the sinuses

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Intravenous-induced pneumocephalus should be considered in the evaluation of unexplained pneumocephalus if: (1) the history and physical examination are inconsistent with infection in the head and neck area, craniofacial trauma, barotrauma, or recent cranial surgery; (2) patients do not have the classic symptoms of tension pneumocephalus; and, (3) the pattern of air observed on head CT follows the cranial venous anatomical distribution.

As part of evaluation, brain imaging in our patient showed air foci within the bilateral cavernous sinuses, right superior ophthalmic veins, bilateral internal jugular veins, and other neck veins. Air foci were also noted within the intraspinal veins in the region of CV junction. Small quantities of intracranial or intravascular air are rapidly reabsorbed by the body. As the bubbles disappeared on the follow-up scan, it supported their identification as free air. Free air in the cavernous sinus can be a potential neurological or neurosurgical emergency. It may also be a sign of cavernous sinus thrombosis due to gas forming organisms.[1]

Our patient was healthy and she did not have any comorbidities; therefore, infection was ruled out as an explanation for air in her venous sinuses. She denied a history of trauma and recent rhinosinusitis. Free air cannot reach the cavernous sinus from an arterial source after traversing through the cerebral circulation.

Our explanation for free air in the venous sinuses of our patient is through the intravenous access. Frequently, small air bubbles are not removed completely from the tubing before starting the intravenous lines.

Venous air emboli due to the injection of contrast material for chest and neck CT scans can result in intravenous or intracardiac air.[5],[6] In 1994, David Rubinstein and David Symonds identified air in the veins in the region of the clavicle, the internal jugular vein, and an anterior neck vein at the level of the hypopharynx in a supine patient who received intravenous contrast material for a neck CT scan.[7] They demonstrated three cases of retrograde flow of radioactive material into the jugular vein (in one case up to the transverse sinus) on brain flow studies. They documented both orthograde flow of intravenous air in the arm and retrograde flow of air from the radial artery to the subclavian artery.[8],[9]

Intravenous lines resulting in air emboli from the upper extremity to the neck have been reported earlier. Normally the air empties into the superior vena cava. However, rarely, it can pass into the jugular veins. The mechanism postulated is the upright position of the patient facilitating the movement of air into the jugular veins by buoyancy. This may be accelerated by performing the Valsalva manoeuvre during spontaneous acts such as coughing. Through the large. Through the large and vertical internal jugular veins and then the inferior petrosal sinus, air can reach the cavernous sinus and get trapped there. In our patient, the air bubbles seen in the bilateral internal jugular veins, and neck veins provide a clue to the mechanism of air in the cavernous sinus.[10],[11]

Conservative medical management of pneumocephalus includes bed rest, head elevation, analgesia, avoidance of coughing, sneezing, nose blowing, or the Valsalva manoeuvre.[12] Laxatives are used to decrease intra-abdominal pressure during bowel movements, and supplemental oxygen therapy hastens the absorption of pneumocephalus. The efficacy of hyperbaric oxygen therapy for treating pneumocephalus is not supported by literature.[12]

Hyperosmolar therapy with mannitol is recommended prior to surgical treatment. Pneumocephalus and cerebrospinal fluid leaks secondary to traumatic dural tears are usually self-limiting and do not require prophylactic antibiotics unless there are signs of infection. Definitive surgical treatment is indicated for significant intracranial hypertension, persistent craniodural leaks, or persistent pneumocephalus lasting for longer than 1 week. In these cases, prophylactic antibiotics are usually recommended, whether or not signs of infection are present, while the patient is waiting for the neurosurgical repair of the breech.[12]

Air within cerebral venous sinuses need not always be due to septic thrombosis, skull fractures, nose blowing, rhinosinusitis, or barotrauma. It can be iatrogenic through an intravenous access while intravenous medication or fluid is being injected. Our case emphasizes the relevance of removing air bubbles completely and judiciously before starting an intravenous access.

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There are no conflicts of interest.

  References Top

Curves JT, Creasy JL, Whaley RL, Scatliff JH. Air in the cavernous sinus: A new sign of septic cavernous sinus thrombosis. AJNR 1987;8:176-7.  Back to cited text no. 1
Bartynski WS, Wang AM. Cavernous sinus air in a patient with basilar skull fracture: CT identification. Comput Assist Tomogr 1988;12:141-2.  Back to cited text no. 2
Canavan L, Osborn RE. Dural sinus air without head trauma or surgery: CT demonstration. Comput Assist Tomogr 1991;15:526-7.  Back to cited text no. 3
Crone KR, Lee KS, Moody DL, Kelly DL Jr. Superior sagittal sinus air after penetrating craniocerebral trauma. Surg Neurol 1986;25:276-8.  Back to cited text no. 4
Woodring JH, Fried AM. Nonfatal venous air embolism after contrast enhanced CT. Radiology 1988; 167:405-7.  Back to cited text no. 5
Price DB, Nardi P, Teitcher J. Venous air embolization as a complication of pressure injection of contrast media: CT findings. J Comput Assist Tomogr 1987;2:294-5.  Back to cited text no. 6
Rubinstein D, Symonds D. Gas in the cavernous sinus. Am J Neuroradiol 1994;15:561-6.  Back to cited text no. 7
Lowenstein E, Little JW, Hing HL. Prevention of cerebral embolization from flushing radial-artery cannulas. N Engl J Med 1971;25:1414-5.  Back to cited text no. 8
Chang C, Dughi J, Shitabata P, Johnson G, Coel M, McNamara JJ. Air embolism and the radial arterial line. Crit Care Med 1988;16:141-3.  Back to cited text no. 9
Navarrete ML, Galindo J, Pellicer M. Cavernous sinus air bubble. Ear Nose Throat J 1990;69:771-2.  Back to cited text no. 10
Orrell RW, Guthrie JA, Lamb JT. Nose-blowing and CSF rhinorrhea. Lancet 1991;337:804.  Back to cited text no. 11
Tran P, Reed EJM, Hahn F, Lambrecht JE, McClay JC, Omojola MF. Incidence, radiographical features, and proposed mechanism for pneumocephalus from intravenous injection of air. Western J Emerg Med 2010;11:180-5.  Back to cited text no. 12


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]


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