PMC8204668_01
Preoperative pure tone audiogram revealing normal hearing thresholds in both ears
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F1
She had normal hearing on pure audiogram (Figure 1 (Fig. 1)) and normal ventilation of her middle ears on tympanogram (Figure 2 (Fig. 2)). 
The preoperative tympanogram shows type A curve bilaterally.
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F2
She had normal hearing on pure audiogram (Figure 1 (Fig. 1)) and normal ventilation of her middle ears on tympanogram (Figure 2 (Fig. 2)). 
CT scan showing the right high jugular bulb, dehiscent sigmoid plate with sigmoid sinus herniation into the mastoid (yellow star)
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F3
It also showed dehiscence of right sigmoid plate with herniation of the lateral aspect of the transverse and sigmoid venous sinuses into the mastoid complex (Figure 3 (Fig. 3)). 
An example of intraoperative view of left cortical mastoidectomy showing sigmoid sinus (1). The patient is positioned supine with head turned to right. The patient is undergoing left lateral temporal bone resection, total parotidectomy, mandible resection, left neck dissection and reconstruction for malignancy. The left internal jugular vein has been ligated in the upper neck (2). The external auditory canal has been excised along with removal of the tympanic membrane and middle ear contents followed by obliteration of the middle ear with fat and gel foam (3). The glenoid or mandibular fossa can be seen clearly (4).
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F4
An example of intra-operative appearance of the cortical mastoidectomy and sigmoid sinus is shown in Figure 4 (Fig. 4). 
Postoperative pure-tone audiogram confirming normal hearing levels in both ears
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F5
At three-month follow-up the haemotympanum had resolved and her hearing had returned back to normal (Figure 5 (Fig. 5)).