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|LETTER TO EDITOR
|Year : 2017 | Volume
| Issue : 4 | Page : 878-880
Gas in the venous sinus: An incidental finding
Muhammed Alif1, Muhammed J. A Jalal2, Nimish Vijayakumar1, Jacob Chacko1, Gigy Kuruttukulam1
1 Department of Neurology, Rajagiri Hospital, Aluva, Kochi, Kerala, India
2 Department of Internal Medicine, VPS Lakeshore Hospital, Kochi, Kerala, India
|Date of Web Publication||5-Jul-2017|
Muhammed J. A Jalal
Department of Internal Medicine, VPS Lakeshore Hospital, Maradu, Kochi - 682 040, Kerala
Source of Support: None, Conflict of Interest: None
|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
Brain imaging with free air in the cavernous sinus is seen in patients with septic thrombosis, skull fractures, and barotrauma. Penetrating craniocerebral trauma also shows free air in the dural sinuses. 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.
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., 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. 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.,
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.,
Conservative medical management of pneumocephalus includes bed rest, head elevation, analgesia, avoidance of coughing, sneezing, nose blowing, or the Valsalva manoeuvre. 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.
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.
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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[Figure 1], [Figure 2], [Figure 3], [Figure 4]