Abstract
The temporal bone is a complex anatomical structure and so preoperatively computed tomography (CT) of the temporal bone is important for choice of the surgical procedure. In this study, evaluation of the surgical difficulty to conduct transmastoid atticotomy with the coronary cut of CT temporal bone. Additional, attic pathology intraoperative is evaluated. The current research is a retrospective study of 79 patients with chronic suppurative otitis media (safe type) with the preoperative opacity of the attic in CT temporal bone. The researcher correlates difficulty to do transmastoid attictomy with the distance in mm between the roof of external audiatory canal (EAC) and tegmen with ruler directly in the coronary cut of CT temporal bone at the the level of internal auditory canal (IAC). The researcher also compares attic pathology intraoperative with preoperative CT attic opacity. In group of surgically difficulty average distance between the superior wall of EAC and tegmen on preoperative CT at the level of IAC is 2–5 mm while distance in easily surgical approach is from 6 to 10 mm. 68.4%(54/79) of cases had pathology in attic in the form of granulation tissue in 50 cases and glue in 4 cases. Preoperative CT temporal bone is very important to detect atticotomy approach either transmastoid or transcanal, through measuring the distance in mm between the roof of EAC and tegmen with ruler directly in the coronal cut of CT temporal bone at the level of internal auditory canal. The opacity of the attic in Preoperative CT does not mean that there is a pathology in the attic.
Keywords: Attic, CT temporal bone, Atticotomy
Introduction
The temporal bone is considered a complex anatomical structure that contains the middle ear and its ossicles as well as the inner ear [1].
Due to its complex anatomical structure, collecting information about the anatomy of temporal bone was necessary for surgery [2].
Computed high resolution tomography (CT) scanning allowed preoperative imaging of the anatomy of the temporal bone, showed the extent of disease and also it is playing an important role for the choice of the surgical procedure [3, 4].
In the current study, correlation of surgical difficulty to perform transmastoid atticotomy with the distance between the roof of the external auditory canal and the tegmen was performed in the coronary cut of CT temporal bone. Comparison of the attic pathology intraoperative was done with the preoperative CT attic opacity.
Patients and Methods
The current research is a retrospective randomized study which was conducted in El Minia University Hospital from April 2014 to April 2016. The study included 79 patients with chronic suppurative otitis media, safe type. All patients had opacity in the attic in the preoperative CT temporal bone. The patients had no history of previous otological procedures. Cortical mastoidectomy and cartilage tympanoplasty had been performed for all patients. Cortical mastoidectomy was performed with exposure of the antrum (Figs. 1, 2, 3 and 4).
Fig. 1.
Coronal cut CT temporal bone shows small distance 1 mm (red line) between the superior wall of EAC and tegmen
Fig. 2.
Operative picture shows small attic with difficulty to perform complete transmastoid atticotomy
Fig. 3.
Coronal cut CT temporal bone shows large distance 7 mm (red line) between the superior wall of EAC and the tegmen
Fig. 4.
Operative picture shows a large attic with easy to perform complete transmastoid atticotomy, with exposure of head of malleus and incus
The researcher, then, drilled in space between the roof of the external auditory canal and the tegmen tympani (bone covering middle cranial fossa).
Towards the root of zygoma to expose attic (see the head of malleus and incus) and remove any granulation tissue (if found). If it difficult to expose attic as the distance between tegmen tympani and roof of the external auditory canal is small, so if we proceed we will make trauma to dura or roof of EAC. So transcanal atticotomy had been done, as the scutum had been drilled down to expose the attic. Tragal cartilage tympanoplasty was done. In cases of transcanal atticotomy, cartilage graft was used to repair attic.
In this study researcher measure in mm the distance between the roof of EAC and tegmen with ruler directly in the coronary cut of CT temporal bone at the level of the internal auditory canal.
The study was conducted according to the Declaration of Helsinki and was approved by El Minia faculty of Medicine institutional review board.
Statistical Analysis
All data were collected and analyzed using SPSS 20 software.
Results
Out of the 79 patients in this study, 38 males and 41 females were in the age range of 15–45 years (with average 23.89 ± 7.45). 49 patients represented surgical difficulty to reach the attic through transmastoid route. 30 patients represented easy surgery to access the attic transmastoid. In the group of surgically difficulty average distance between the superior wall of EAC and the tegmen on preoperative CT at level of IAC was 2–5 mm while the distance in the easily surgical approach was from 6 to 10 mm. Granulation tissue was found in the attic in 50 patients intraoperative and glue was found in 4 patients while 25 patients had no pathology in the attic in spite of opacity seen preoperative (Table 1).
Table 1.
The table shows the statistically significant difference between surgical difficulty group and group with no difficulty
| Surgical difficulty N = 49 | No difficulty N = 30 | P value | |
|---|---|---|---|
| Mean ± SD | Mean ± SD | ||
| Distance from EAC to tegmen | 3.73 ± 1.05 | 7.17 ± 1.14 | < 0.001* |
Discussion
Chronic otitis media (COM) is a condition commonly seen in patients attending the reseaecher’s ENT clinics and the global burden of illness is about 65–330 million individuals [5]. The attic can be involved by granulation tissue in chronic suppurative otitis media (safe type) so there is need to explore the attic through atticotomy. Atticotomy can be done transmastoid or transcanal [6]. Attictomy is conducted by removal of the lateral epitympanic wall. The roof of the attic is middle cranial fossa (tegmen tympania). Low hanging dura may be at risk of injury during surgery [7]. Preoperative c.t petrous is controversial; some perform it in certain cases such as complicated CSOM, suspicion of congenital anomalies’, previous otological procedure [8]. Pereira et al. conducted a study on 30 patients of chronic suppurative otitis media and correlated findings from preoperative C.T. (distance from sigmoid sinus to external auditory canal and distance from meninges of temporal bone) and surgical difficulty during mastoidectomy. They measured the height of meninges by measure the distance from it to a line that ended at the upper edge of the petrous bone. If this distance was 7 mm or more, they found surgical difficulties [9]. In the current study, the distance between EAC and tegmen was measured and if it turned to be less than or equal to 5 mm, it was difficult to approach the attic through transmastoid route and if the proceeding trauma will happen to the dura or roof of EAC, so transcanal atticottomy was performed. Many surgeons believe that the volume of the attic and mastoid were reduced due to sclerosis. Lee et al. conducted a study on 37 patients with unilateral chronic suppurative otitis media. They found that reduction of the volume of pneumatization of mastoid bone in the healthy site than diseased site this is due to sclerosis of bone more than shrinkage in the mastoid bone. So relations of surgical landmarks in temporal bone did not change [10].
Preoperative CT opacity of the attic does not mean there is a pathology in the attic. In the current study, 68.4% (54/79) of cases had pathology intraoperative in the attic in the form of granulation tissue in 50 cases and glue in 4 cases. Amongst the cases examined, there were 25 cases with no pathology in the attic intraoperative and it is believed that mucopurulent discharge in the attic was responsible for preoperative opacity in it. Tatlipinar et al. conducted a study on 50 patients with chronic suppurattive otitis media and found that only 26% (13/50) of cases had pathology in the attic during surgery, despite the existence of opacity of the attic in preoperative CT [11].
Conclusion
Preoperative CT temporal bone is very important to detect atticotomy approach, through measuring the distance in mm between the roof of EAC and tegmen with ruler directly in the coronal cut of CT temporal bone at the level of internal auditory canal. The opacity of the attic in Preoperative CT does not mean that there is pathology in the attic.
Compliance with Ethical Standards
Conflict of interest
Authors declare that there was no conflict of interest.
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