PMC3326941_01
Pre-operative imaging. (a) CT shows a single hypodense lesion in the left temporal lobe with mild mass effect. (b) Plain skull radiograph demonstrating a bubble air. (c) Axial and coronal CT with bone window shows the close relationship of pneumocephalus with a highly pneumatized temporal bone. (d) Coronal FLAIR MR shows the pneumocele in the left inferior and middle temporal gyrus and post-gadolinium T1-weighted axial MR shows no pathological enhancement
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F1
The computed tomography (CT) showed a hypodense space-occupying lesion (-1000 Hounsfield units) compatible with air in the white matter of the left temporal lobe, of approximately 4 cm diameter [Figure 1a]. Similar findings were found on plain radiographs of the skull [Figure 1b]. A high-resolution CT using a bone algorithm demonstrated a close relationship of the air bubble with air cells of the mastoid, which were highly pneumatized [Figure 1c]. Magnetic resonance (MR) showed the large intraparenchymal pneumocephalus in the white matter of the left inferior and middle temporal gyrus with minimal perilesional edema [Figure 1d].
Operative findings. Extradural subtemporal approach to the tegmen tympani area showed a 5-mm bone defect (blue arrow) in close relationship with an adjacent dural defect (red arrow), through which cerebrospinal fluid leak was observed. Other smaller bony defects of about 2 mm (green arrow) were also found, but without any relationship with dural hole
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F2
Later, an extradural approach to the tegmen tympani showed a 5-mm bone defect in close relationship with an underlying dural hole, through which output of cerebrospinal fluid was observed [Video 1 and Figure 2].
Postoperative imaging. (a) Axial CT and (b) axial post-gadolinium T1-weighted MR show a total resolution of the pneumocephalus
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F3
The follow-up examination 1 month later revealed normal speech and absence of pneumocephalus on CT and MR [Figure 3].