Brain herniation into the middle ear cavity: MR imaging

Imagerie des otites chroniques de l’adulte

Chronic otitis media (COM) can be divided into two subtypes: COM with cholesteatoma (including precholesteatomatous states) is an aggressive form of otitis. Surgical treatment is mandatory because of the risk for labyrinthine or cerebromeningeal complications. CT is very important in the preoperative work-up (extension of cholesteatoma, anatomic variants). In patients who have undergone middle ear surgery, CT and presently MRI play an increasing role in the detection of recurrent or relapsing cholesteatoma. COM without cholesteatoma does not have an osteolytic potential, but may leave auditive sequelae that in selected cases may warrant surgical treatment to improve hearing. CT is useful in the etiological work-up of patients with severe hypoacusis. CT also plays an important role in cases of surgical failure, to detect a dislocation of the ossiculoplasty or impairment of the middle ear caused by fluid effusion. The objective of this paper is to specify the indications, the results and the limits of pre- and postoperative imaging in COM.

Transmastoid Repair of Minor Skull Base Defects with Flexible Hydroxyapatite Sheets

This prospective open pilot study was designed to assess the suitability of flexible composite sheets of polymer and hydroxyapatite (HA) for the reconstruction of limited lateral skull base defects through a conservative transmastoid approach.Seven patients with a petrous bone dehiscence less than 3 cm in diameter, either iatrogenic or caused by chronic otitis media or temporal bone trauma, underwent a mastoidectomy. The defect was repaired with the new material and a connective tissue graft. All bone defects were detected by computed tomography (CT) of the temporal bone except one that was found at surgery in an asymptomatic patient.Outcome was evaluated in terms of anatomical integrity of the tegmina, absence of cerebrospinal fluid leaks, side effects, and extrusion and complication rates. None of the patients suffered from immediate side effects related to the implant or the operation. With a minimum follow-up of 18 months (maximum, 62 months), neither extrusion nor a foreign body reaction occurred. Postoperative CT confirmed a satisfactory anatomic contour. Although the number of patients is limited, these preliminary results are encouraging and indicate a need for further clinical trials with a material that allows a minimally invasive approach to selected skull base defects.

CT scanning of middle ear cholesteatoma: what does the surgeon want to know?

The history of surgery for middle ear cholesteatoma is of an evolution of techniques to meet the challenges of inaccessible disease and of post-operative cavity management. The concept has traditionally been of exploration guided by awareness and anticipation of all, possibly asymptomatic, complications. Modern imaging reliably demonstrates surgical anatomy, dictating the ideal approach, forewarns of complications and may reveal the extent of disease. An apparent resistance amongst otologists to universal CT scanning prior to mastoidectomy contrasts with the enthusiasm of skull base surgeons or rhinologists for appropriate imaging.

[Spontaneous middle ear meningoencephalic herniation. 2 case reports]

Two cases of idiopathic brain herniation into the middle ear without previous surgery are reported. Brain herniation is an unusual pathology, usually related to middle ear surgery. The idiopathic appearance of this disease is the secondly most frequent cause. Its origin is believed to be related to a congenital defect of tegmen timpani. Two elements, both rare, are emphazised: the spontaneous bilateral presentation in one of the cases, and the CSF leak as an initial symptom. We present a review of the literature, describing epidemiology results and the main accepted etiology theories. We discuss the diagnosis and treatment methods: magnetic resonance imaging and surgery.

[Post-surgical and post-infectious meningoencephalic herniation in the middle ear]

Meningoencephalic hernia of the middle ear, due to the advent of antibiotics, the surgical microscope, and the new surgical techniques for the treatment of chronic otitis media, is an infrequent pathology in the presents days. The goal of this paper is to present four cases of meningoencephalic hernia of the middle ear, three of then postsurgical and the remaining of inflammatory origin. Diagnosis, treatment and complications are discussed. Meningoencephalic hernia of the middle ear is usually asymptomatic and diagnosis is accidental. Immediate surgical treatment is indicated in order to avoid the potential complications of this disease. Transmastoid approach has been used for three cases and a middle cranial fossa approach was used in the fourth patient.

Brain herniation and chronic otitis media: diagnosis and surgical management

Herniation of the brain into the middle ear is a rare, but potentially life-threatening complication of chronic otitis media. Fifty patients with a tegmen defect associated with chronic otitis media were operated on between 1985 and 1998. Among these 50, 15 patients presented brain herniation associated with the bony defect. Fourteen patients had undergone previous mastoid surgery for chronic otitis media. Neurological symptoms were encountered in five patients. In 10, magnetic resonance imaging (MRI) was performed before surgery, and a diagnosis of brain herniation could be made. The hernia was repaired in all patients using a middle fossa craniotomy, combined with a transmastoid approach in 11 cases where a large hernia, and/or inflammatory tissues were present in the mastoid. The herniated brain tissue was resected in all, and the dural and bony defects were closed with fascia and bone. No complication or recurrence occurred, during a mean follow-up of 2 years. In conclusion, the occurrence of severe neurological complications as a consequence of brain herniation emphasizes the necessity for recognition and appropriate management of this disease. Computerized tomography (CT) scanning allows the suspicion of brain herniation, but a definitive diagnosis can best be established with an MRI study. The hernia should be repaired using a middle fossa craniotomy, combined with a transmastoid approach in one or two stages, when necessary.

Imaging of temporal bone brain hernias: atypical appearances on magnetic resonance imaging

Brain tissue with or without its dural covering may protrude into the temporal bone through a defect in the tegmen tympani. Infection or granulation tissue, with or without cholesteatoma may make diagnosis difficult. While computed tomography (CT) may demonstrate a bony defect, it is difficult to distinguish between herniated brain, cholesteatoma or granulation tissue. Magnetic resonance imaging (MRI) clearly demonstrates healthy herniated brain tissue, but ischaemic or necrotic elements may mimic other lesions. We present a series of five patients with brain hernia, highlighting the spectrum of preoperative radiological appearances, and some of the difficulties encountered in interpreting these images. MRI demonstrated herniation of healthy brain in two patients but in three, showed irregular soft tissue with signal characteristics consistent with cholesteatoma. Surgery in these three patients demonstrated necrotic brain with coexisting cholesteatoma in two. Brain hernias are often necrotic and may have morphological and signal characteristics similar to cholesteatoma with which they may coexist.

Temporal bone fractures

High-resolution technique is essential to the evolution of temporal bone fractures. Axial and coronal scan planes are optimal but may not be possible in acutely traumatized patients. A knowledge of normal temporal bone anatomy is important and can be obtained from standard texts, so it will not be considered in detail in this article. Classically, petrous temporal bone fractures have been classified as longitudinal, transverse, or mixed. Recent publications have emphasized the importance of describing fractures in terms of planes rather than lines. According to this concept, most temporal bone fractures are actually oblique, and true longitudinal fractures are rare. Petrous temporal bone fractures may be associated with cranial nerve or vascular injuries when the fracture extends to the skull base. This is particularly true of the oblique fracture, which characteristically extends anteromedially to the skull base through weak places in that area, thus avoiding the compact bone of the otic capsule surrounding the labyrinth. The most common associated injury is to the facial nerve in its geniculate or proximal tympanic segment. Transverse fractures frequently involve the labyrinth. A careful search for various types of ossicular dislocation should be performed in association with temporal bone fractures, because this may result in conductive hearing loss. The site of cerebrospinal fluid otorhinorrhea resulting from temporal bone fractures can usually be defined on plain high-resolution temporal bone images, but intrathecal contrast may be helpful. Temporal bone fractures caused by gunshot wounds are frequently complex and may be limited by metallic streak artifacts. Pediatric patients have different proportions of facial nerve injury and types of hearing loss as compared with adults.

The temporal bone. Contemporary diagnostic dilemmas

The entire topic of temporal bone imaging cannot be addressed in a single article. This article discusses the clinical areas in which there have been particularly important advances: inflammatory disease, sensorineural hearing deficit, pulsatile tinnitus, facial nerve dysfunction, and the postoperative temporal bone. The common thread linking those sections is an attempt to emphasize their pitfalls.

Meningoencephalic herniation into the middle ear: a report of 27 cases

Meningoencephalic herniation into the middle ear is a rare and potentially life-threatening condition that may require prompt surgical intervention. Preoperative diagnosis is based on a high index of suspicion. Sometimes, however, meningoencephalic herniation is discovered during surgery. High-resolution computed tomography and magnetic resonance imaging should be performed to confirm the diagnosis and to evaluate the extension of the herniated tissue. This article discusses the diagnostic approach, management strategy, and surgical technique used in 27 patients with meningoencephalic herniation. In an attempt to avoid infective complications, the authors used the middle cranial approach in patients with large herniations.

Postauricular cerebellar encephalocoele secondary to chronic suppurative otitis media and mastoid surgery

Cerebellar herniation into the mastoid through the posterior aspect of the temporal bone as a result of chronic suppurative otitis media and mastoid surgery is a rare event. A case is reported in which such a hernia presented subcutaneously behind the pinna; its repair is discussed.