Figure 1
Unenhanced CT exaination of internal auditory meati
Unenhanced CT of internal auditory meati demonstrating previous right sided mastoid surgery and left sided cholesteatoma.
Sigmoid sinus diverticulum
SectionNeuroradiology
Case TypeClinical Cases
AuthorsMacdonald K, Farboud A, Favill E
Connected authors
45 years, female
Clinical History
The patient presented with symptoms and signs suggestive of a left sided cholesteatoma. Non contrast CT examination was requested to evaluate anatomy prior to a proposed left sided radical mastoidectomy.
Imaging Findings
Non contrast CT examination of the internal auditory meati demonstrated previous right sided mastoid surgery (Fig. 1). On the left side, there is considerable bony sclerosis and complete infilling of all the mastoid air cells by soft tissue/fluid density material. There is evidence of ossicular dislocation. Laterally, some of the aerated mastoid is in continuation with the posterior cranial fossa with a possible breech in the cranial vault at this location (Fig. 2,3).
Contrast enhanced CT examination carried out for further characterisation of the possible breech in the cranial vault revealed an intact temporal periosteum over a highly lateralised and protruding sigmoid sinus. This represented a diverticulum of the sigmoid sinus extending into the mastoid portion of the temporal bone (Fig. 3,4).
Contrast enhanced CT examination carried out for further characterisation of the possible breech in the cranial vault revealed an intact temporal periosteum over a highly lateralised and protruding sigmoid sinus. This represented a diverticulum of the sigmoid sinus extending into the mastoid portion of the temporal bone (Fig. 3,4).
Discussion
Sigmoid sinus diverticuli are rare variations usually picked up inconsequently on intracranial imaging. They represent an outpouching of the sinus, most commonly, into the mastoid portion of the temporal bone [1].
From a clinical point of view these are important for the radiologist to highlight. Due to the abnormal position of the diverticuli in the mastoid, there is increased risk of laceration during mastoidectomy [2].
Interestingly, there have been recent publications suggesting a link between pulsatile tinnitus and sigmoid sinus diverticuli. In the studies reviewed, obliteration of the diverticulum resulted in symptom resolution with the authors subsequently advocating thorough radiological investigation of all patients with pulsatile tinnitus [3, 4].
The diagnosis of sigmoid sinus diverticuli can be made using contrast enhanced CT examination. For further characterisation, angiography can be carried out and this is usually required prior and following obliteration of the sinus diverticulum.
CT examination of the internal auditory meati is necessary before mastoidectomy to minimise complications associated with aberrant anatomy.
From a clinical point of view these are important for the radiologist to highlight. Due to the abnormal position of the diverticuli in the mastoid, there is increased risk of laceration during mastoidectomy [2].
Interestingly, there have been recent publications suggesting a link between pulsatile tinnitus and sigmoid sinus diverticuli. In the studies reviewed, obliteration of the diverticulum resulted in symptom resolution with the authors subsequently advocating thorough radiological investigation of all patients with pulsatile tinnitus [3, 4].
The diagnosis of sigmoid sinus diverticuli can be made using contrast enhanced CT examination. For further characterisation, angiography can be carried out and this is usually required prior and following obliteration of the sinus diverticulum.
CT examination of the internal auditory meati is necessary before mastoidectomy to minimise complications associated with aberrant anatomy.
Differential Diagnosis List
Sigmoid sinus diverticulum
Bulging sigmoid sinus
Dehiscent jugular bulb
Sinus pericranii
Final Diagnosis
Sigmoid sinus diverticulum
References
[1] Eisenman DJ (2011) Sinus wall reconstruction for sigmoid sinus diverticulum and dehiscence: a standardized surgical procedure for a range of radiographic findings. Otol Neurotol 32(7):1116-9 (PMID: 21799456)
[2] Beek E, Pameijer F (2009) Temporal bone-pathology. http://www.radiologyassistant.nl/en/49c62abe0880e#p49c69c065e6f5
[3] Otto KJ, hudgins PA, Abdelkafy W, Mattox DE (2007) Sigmoid sinus diverticulum: a new surgical approach to the correction of pulsatile tinnitus. Otol Neurotol 28(1): 48-53 (PMID: 17195746)
[4] Sanchez TG (2002) A new therapeutic procedure for treatment of objective venous pulsatile tinnitus. Int Tinnitus J 8(1):54-7 (PMID: 14763237)
Case information
| URL: | https://eurorad.org/case/10278 |
| DOI: | 10.1594/EURORAD/CASE.10278 |
| ISSN: | 1563-4086 |
Figure 2
Unenhanced CT examination of internal auditory meati
Unenhanced CT of internal auditory meati demonstrating continuation of the aerated mastoid with the posterior cranial fossa on the left. Possible breach in the cranial vault at this location.
Figure 3
Unenhanced CT of internal auditory meati
Unenhanced CT of internal auditory meati demonstrating continuation of the aerated mastoid with the posterior cranial fossa on the left. Possible breach in the cranial vault at this location.
Figure 4
Enhanced CT examination
Enhanced CT of the internal auditory meati demonstrating a left sided sigmoid sinus diverticulum with no breach in the cranial vault.
Figure 5
Enhanced CT examination
Enhanced CT of the internal auditory meati demonstrating a left sided sigmoid sinus diverticulum with no breach in the cranial vault.
Unenhanced CT exaination of internal auditory meati
Unenhanced CT of internal auditory meati demonstrating previous right sided mastoid surgery and left sided cholesteatoma.
Department of radiology, Glan Clwyd Hospital, Bodelwyddan, Wales
Department of radiology, Glan Clwyd Hospital, Bodelwyddan, Wales
Unenhanced CT examination of internal auditory meati
Unenhanced CT of internal auditory meati demonstrating continuation of the aerated mastoid with the posterior cranial fossa on the left. Possible breach in the cranial vault at this location.
Department of radiology, Glan Clwyd Hospital, Bodelwyddan, Wales
Department of radiology, Glan Clwyd Hospital, Bodelwyddan, Wales
Unenhanced CT of internal auditory meati
Unenhanced CT of internal auditory meati demonstrating continuation of the aerated mastoid with the posterior cranial fossa on the left. Possible breach in the cranial vault at this location.
Department of radiology, Glan Clwyd Hospital, Bodelwyddan, Wales
Department of radiology, Glan Clwyd Hospital, Bodelwyddan, Wales
Enhanced CT examination
Enhanced CT of the internal auditory meati demonstrating a left sided sigmoid sinus diverticulum with no breach in the cranial vault.
Department of radiology, Glan Clwyd Hospital, Bodelwddan, Wales
Department of radiology, Glan Clwyd Hospital, Bodelwddan, Wales
Enhanced CT examination
Enhanced CT of the internal auditory meati demonstrating a left sided sigmoid sinus diverticulum with no breach in the cranial vault.
Department of Radiology, Glan Clwyd Hospital, Bodelwyddan, Wales
Department of Radiology, Glan Clwyd Hospital, Bodelwyddan, Wales