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ECR 2016 / C-0658
Imaging of the complications of middle ear surgery : how do I keep my favorite surgeon away from jail?
This poster is published under an open license. Please read the disclaimer for further details.
Congress: ECR 2016
Poster No.: C-0658
Type: Educational Exhibit
Keywords: Inflammation, Infection, Congenital, Diagnostic procedure, MR, CT, Head and neck, Emergency, Ear / Nose / Throat
Authors: A. Venkatasamy1, M. D. A. Cavalcanti1, M. Eliezer2, F. Veillon3; 1Strasbourg/FR, 2paris/FR, 3Strasbourg Cedex/FR
DOI:10.1594/ecr2016/C-0658

Findings and procedure details

 

1)   Imaging of the complications of middle ear surgery and their clinical setting

 

·      Facial nerve lesions

 

 A major complication of middle ear surgery, and especially cholesteatoma surgery, is a lesion to the facial nerve, especially to its tympanic and mastoid portions, leading to facial nerve palsy.

 

Fig. 2: VII 3 lesions during middle ear surgery (2 different patients sagittal and axial CT, red) compared to normal VII 3 at the same levels of sections (in green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

 

Fig. 3: VII 2 section during surgery (red) on CT (curved reconstruction in the VII 2 - VII 3 axis) compared to normal VII 2 at the same level of section (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

·      Meningoencephalocele

 

Meningoencephalocele is a brain herniation in the middle ear, associated with cerebrospinal fluid leakage, commonly developing on a tegmen breach. Patients are at high risk of meningitis.

 

 

Fig. 4: Meningo-encephalocele (red image) compared to a normal tegmen (green image), coronal HRT2 wi MRI
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

2)   How do I prevent these with my preoperative imaging?

 

·      By describing the facial nerve position compared to it’s usual course

 

 VII-2 above the oval window: in case of a lowered VII-2, where the nerve is located below the OW, the surgeon is constrained even is the nerve remain distant.

 

Fig. 5: Lowered VII2 on the footplate (red) on coronal non enhanced CT compared to normal image (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015
Fig. 6: Lowered VII2 canal on the stapes (red) on non enhanced coronal CT compared to normal image (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

Dehiscent VII-2 canal with or without inferior herniation of the nerve

 

Fig. 7: Dehiscent canal with or without inferior herniation of the nerve (red) on non enhanced coronal CT compared to normal image (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

 VII-3 position at the level of the round window : anterior location of the VII-3 ?

 

Fig. 8: Anteriorized VII 3 (red) on non enhanced coronal CT compared to normal VII 3 (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

·      By describing the position of the sinus sigmoid

 

Fig. 9: Position of the sinus sigmoid on axial non enhanced CT : procident (red) versus normal (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

·      By describing the position of the tegmen

 

A lowered tegmen is of higher risk of postoperative meningocele.

 

Fig. 10: Height of the tegmen on coronal non enhanced CT: lowered tegmen (red) versus normal tegmen (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

·      By describing any osteomatous otitis in the middle ear

 

Osteomatous otitis is a state of chronic inflammation accompanied by bony excressences in the middle or the outer ear. Theses cases are difficult to treat surgically as the vital middle ear structures : VII-2, lateral semicircular canal, or even the cholesteatoma itself may be hidden.

 

 

Fig. 11: Osteomatous otitis masking VII2 and lateral semicircular canal (red), axial CT, compared to normal image at the same level of section
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

 

 

 

 

3)   Imaging of the complications of stapes surgery and their clinical setting

 

 

 

Stapes surgery is in most cases performed for as a treatment for otosclerosis. It’s major complications may concern the middle ear, the inner ear or the oval window.

 

 

 

·      The middle ear

 

 Displacement of the piston

 

The displacement of the prosthesis is the most common cause of surgical failure. It often occurs after a minor trauma or may be related to a fibrous retraction of the graft on the oval window. In the majority of cases, the medial part of the piston is displaced, with the ring still attached to the long process of the incus but it’s foot displaced on the oval window. The displacement is best seen on a CT with MPR along the axis of the prosthesis. In fewer cases, the loop of the piston can also be desinserted form the long process of the incus. Rarely, a complete luxation of the piston is observed.

 

 

Fig. 12: Complete luxation of the prosthesis (red) on coronal CT compared to normally positionned prosthesis (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

Erosion of the long process of the incus

 

Erosions of the long process of the incus (LPI) can occur with any type of prosthesis but seems to be less frequent with Teflon prosthesis. CT can show abnormally short LPI, better seen on MPR reconstructions, associated with a displacement of the prosthesis.

 

Fig. 13: Erosion of the long process of the incus, coronal CT
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

 

·      The oval window

 

 Perilymph fistula on a venous graft leakage

 

Perilymph fistula is due to a perilymphic fluid leakage through the oval window. It is suspected in patients presenting with vertigo, tinnitus, fluctuating hearing loss, in the early days after the procedure.

 

Fig. 14: Suspicion of perilymphatic fistula on coronal CT (red) versus normal image (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015
Fig. 15: Coronal HRT2 wi MRI confirms the diagnosis of perilymphatic fistula (red) versus normal side (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

Hemorrhage after a wound to a persistent stapedial artery

 

The persistence of a stapedial artery (PSA) is a rare congenital vascular anomaly, with persistent stapedial artery arising from the genu of the petrous internal carotid artery, ascending in the cochlear promontory, passing through the stapes before entering the tympanic segment of the cranial nerve VII. It becomes the middle meningeal artery intracranially. This PSA is of high risk of lesion during stapes surgery.

 

Fig. 16: Example of a persistent stapedial artery on non enhanced CT
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

Granuloma forming in the oval window

 

Inflammatory postoperative granulation tissue may develop as a reaction to foreign material, organizing at the foot of the prosthesis. Patients present cochleovestibular symptoms after 2-3 weeks. CT shows non-specific tissular mass in the oval window around the shaft of the prosthesis. On MR it appears as a focal hypersignal on T2 weighted images, enhancing after contrast injection.

 

Fig. 17: Granuloma of the oval window (red) on coronal CT, versus normal image (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

 

·      The inner ear

 

Pneumolabyrinth

 

In the early 1 to 3 days after the surgery, the CT may show the presence of a bubble at the end of the prosthesis or in the vestibular cavity. Air may be difficult to see in case of metallic artifacts due to the prosthesis.

 

Fig. 18: Pneumolabyrinth on non enhanced coronal CT (red) versus normal image (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

Displacement of the piston in the vestibule

 

A penetration of more than 1mm of the tip of the prosthesis in the vestibule is considered pathological in patient presenting with vertigo, tinnitus or sensorineural hearing loss. A non pathological protrusion may be seen in patients without any suspicion of labyrinthic complications: it may be explained by the absence of injury to the membranous labyrinth despite a bulging tip of the prosthesis in the vestibule. Presence of symptoms suggestive of labyrinthic complications is required for the diagnosis.

 

Fig. 19: Displacement of the piston in the vestibule > 1mm on non enhanced coronal CT (red) versus normally positionned piston (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

Intravestibular granuloma

 

Intravestibular granuloma may present with cochleovestibular symptoms, 2 to 3 weeks after the surgery. CT shows non specific tissular mass in the oval window niche wrapped around the shaft of the prosthesis. On MR it appears as a focal hypersignal on T2 WI, enhancing after injection on T1WI.

 

 

 

Fig. 20: Intravestibular granuloma on coronal HRT2 wi MRI (red) versus normal image (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

 

Labyrinthitis

 

Labyrithitis is a rare but severe complication of surgery. CT is non specific but MR shows a decrease in the normally hyperintense signal of the perilymph on T2 weighted images, associated with an extensive enhancement post contrast of the labyrinth. Other complications such as sinus thrombosis, temporal abscess or meningitis might be associated.

 

Fig. 21: Infectious labyrinthitis on axial T1 post-contrast MRI (red) versus normal image (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

 Cophosis on Gusher ear

 

The Gusher ear associates absent cochlear partition and modiolus with “corkscrew” appearance, with bulbous lateral aspect of the internal carotid artery. The inability to define the clinical diagnosis prior to surgery and the absence of pathognomonic signs complicate the diagnosis of Gusher, especially when associated with otosclerosis. A sudden exist of cerebrospinal fluid can occur during stapes surgery on a Gusher ear, causing post operative cophosis.

 

 

Fig. 22: Gusher ear axial non enhanced CT and axial HRT2 wi MRI (red) versus normal image (green) : notice the presence of the modiolus on the normal side.
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

4)   What should the radiologist tell the surgeon before the stapes surgery?

 

 

 

·      The position of the facial nerve

 

·      A stenosis or a congenital hypoplasia of the OW

 

Fig. 23: Stenosis of the oval window on coronal non enhanced CT (red) versus normal oval window (>1.5mm) (green)
References: Department of Radiology 1, Strasbourg University Hospital, Strasbourg University, France 2015

 

·      The persistence of a stapedial artery

 

·      Associated inner ear malformations

 

              Dehiscence of the anterior semicircular canal

 

              Gusher ear

 

              Malformed inner ear

 

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