European Journal of Radiology 48 (2003) 171 /174 www.elsevier.com/locate/ejrad
Transverse sinus air after cranial trauma Mutlu Cihangiroglu a,*, Huseyin Ozdemir a, Omer Kalender a, Faik Ozveren b, Adnan Kabaalioglu c a Department of Radiology, Fırat University School of Medicine, Elazig, Turkey Department of Neurosurgery, Fırat University School of Medicine, Elazig, Turkey c Department of Radiology, Akdeniz University School of Medicine, Antalya, Turkey b
Received 9 October 2002; received in revised form 24 December 2002; accepted 30 December 2002
Abstract Air in vascular compartments has been rarely reported. We report a case in whom air within transverse sinus and sinus confluence through ruptured superior sagittal sinus (SSS) due to fractures of parietal and frontal bones was disclosed by computed tomography (CT). Although air in transverse sinus has been reported rarely this could be the first case with air in transverse sinus through the SSS after cranial trauma. # 2003 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Intravascular air; Transverse sinus; Cranial trauma; Computed tomography
1. Introduction Pneumocephalus is a common entity usually encountered in cranial trauma, barotrauma, tumors, infections, some surgical interventions, e.g after craniotomy, craniofacial reconstruction, posterior fossa operations in the sitting position, some interventional prosedures such as lumbar puncture and insertion of arterial or venous catheters, nitrous oxide anesthesia, air supply with mask, congenital cranium defects [1 /9]. We report a case in whom air within transverse sinus and sinus confluence through ruptured superior sagittal sinus (SSS) was disclosed by computed tomography (CT) and disappeared within 2 days.
2. Case report A 23-year-old male patient who sustained cranial trauma after falling down, was admitted to the emergency service. Initially, the patient only had confusion and no other abnormal neurological finding. CT was
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[email protected] (M. Cihangiroglu).
performed 2 h after the trauma and showed multiple depressed fractures at the level of left side of the vertex including left parietal and frontal bone and multiple scattered cortical contusions in the left frontal lobe (Figs. 1 and 2). On the bone window, multiple fractures were seen in the left side of the frontal bone, and linear fracture in the left parietal bone through the right side of the occipital bone. In addition, nasal fracture was also seen at the lower levels. Adjacent to the multiple frontal fractures, air was seen beneath the scalp and probably in the epidural space. Lower slices disclosed air at the level of the right transverse sinus and the sinus confluence (Fig. 3). The localization of the air was parallel configuration to the transverse sinus. At the level and just above of the transverse sinus, intracranial structures or calvarium and meningial spaces were unremarkable. There was no relationship between the level of fractures and localization of the air. Densitometric measurement confirmed the air which varied between /254 and / 325 HU. The patient was operated on for decompression of the bone fractures of the scalp. During the operation, two separate transections of the SSS were seen, and then repaired by duraplasty and holding-up of depression fractures. Follow-up CT examination 2 days later showed that air in transverse sinus disappeared whereas
0720-048X/02/$ - see front matter # 2003 Elsevier Science Ireland Ltd. All rights reserved. doi:10.1016/S0720-048X(03)00011-1
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Fig. 1. Axial CT scan in the bone window at the level of the vertex shows multiple separated fractures in frontal and left parietal bone. One of the fragment of the bone is seen at the intracerebral localization.
Fig. 3. On axial CT scan, parenchymal (a) and bone windows, (b) show air in the transverse sinus (arrows).
Fig. 2. Axial CT scan discloses multiple cortical contusions (arrows) with presumed intraparenchymal or epidural air (small arrows).
air in sinus confluence had persisted (Fig. 4). After 6 days, air in the sinus confluence also disappeared (Fig. 4). All the radiological and other findings including those documented at operation and disappearance of the air within in a few days later confirmed that the air was within transverse sinus and sinus confluence. The patient was discharged uneventfully.
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3. Discussion
Fig. 4. (a) Follow-up CT examination 2 days later demonstrates that no longer air exists in the transverse sinus, (b) whereas air in the sinus confluence still exists (arrow).
Intracranial air may localize within intravascular, intraventricular, intradural, epidural, subdural, subarachnoid or intraparenchymal areas [4]. Several classifications of pneumocephalus according to localization have been reported previously [10,11]. Briggs described pneumocephalus in two forms; extracerebral or intracerebral. The former represents air collected in the subdural, epidural, subarachnoid, intravascular and ventricular spaces [11]. In the literature, air in vascular compartments (superior sagittal, straight sinus and cavernous sinus) has been reported [2,3,5 /7,12,13]. Rao et al. reported that a patient sustained a head injury involving the right temporal bone fracture extending in the mastoid air cells [12]. A localized collection of air was seen along the posterior border of the brain in the transverse and confluence sinuses. One week later, air in the venous sinuses was no longer visible on the control CT [12]. In this patient, air could have entered the transverse sinus from the mastoid air cells through the mastoid process after fracture. However, in our case, air entered the transvers sinus via SSS through frontal bone fracture. To explain intravascular air after trauma, several hypotheses have been suggested [9,10]. One of them is that fractures cause a defect of dura and arachnoid and, therefore, the difference between intracranial pressure and atmospheric pressure could cause absorption of air through fracture line, and then check-valve mechanism entraps air [9]. Although intravascular air could not be demonstrated by angiography or magnetic resonance venography due to the patient’s status, in the present case radiological and operation findings confirmed that the air was intravascular. In addition above, dura and SSS were ruptured in two separate localizations which were confirmed by surgery. The explanation of air in the transverse sinus could be due to separate ruptures of SSS. While proximal transection of SSS was origin of the blood extravasation, at the distal transection localization, the air could have entered into the SSS due to decreased venous pressure. Afterwards, the air probably migrated into the transverse sinus due to head position or decreases of venous pressure. The detection of intravascular air in a patient with cranial trauma could be dependent on the timing of the imaging. Rubinstein et al. proposed that gas collection could migrate faster in larger vessel compared with smaller vessels, and persist longer in smaller vessels. He also emphasized that the persistence of intravascular air could depend on the position of the patient when the emboli entered the venous system, and the patient’s anatomical variations. They found that the air in the jugular vein persisted 4.5 min [6]. On the other hand, in the present case, 2 h after the event, the air migrated into the transverse sinus, and then disappeared within 2 days.
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This may show that the air in sinus confluence as a medium sized vessel persisted at least 2 days. This finding may not support Rubinstein’s explanation. We may speculate that the persistence of the gas collection in vascular component could depend on more vessel configuration and patient’s head position rather than size. Since anatomically, the SSS usually is contiguous with the right transverse sinus, this could explain why air was seen in right transverse sinus. Briggs reported 33 patients with traumatic pneumocephalus and emphasized that majority of the cases with intracerebral pneumocephalus required surgical intervention since the intracerebral air caused elevation of intracranial pressure [11]. On the other hand, extracerebral pneumocephalus is a benign condition, only requiring surgical intervention when complicated by meningitis or CSF fistulas. The intravascular air is delineated as an extracerebral pneumocephalus and should be evaluated with a similar approach. In conclusion, the detection of the air in the vessel could be related to not only timing and patient position but also to the vessel configuration.
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