Volume 6, Issue 4 , Pages 165-167, December 2011
Posterior cranial fossa extension of congenital cholesteatoma in children: Report of two cases
Article Outline
Abstract
Objectives: To present the results of surgical treatment and long term follow-up of two cases of congenital cholesteatoma in young children extending into the posterior cranial fossa. Method: A retrospective review of 264 children, surgically treated for cholesteatoma of the temporal bone between 1999 and 2008 was performed. The presenting symptoms, tympanic membrane findings, surgical findings, methods, and results were investigated retrospectively. Results: 30 cases satisfied the criteria of congenital cholesteatoma. Two patients presented radiological and surgical evidence of extension of the cholesteatoma in the posterior cranial fossa. Post-operative air-bone gap changes were not significant. No recurrence is observed to date. Conclusion: Congenital cholesteatoma is a different disease entity from acquired cholesteatomas, no previous otorrhea episodes are described and the tympanic membrane appears to be intact; the first symptom is usually hearing loss, but in very young children, one side hearing loss may be misdiagnosed, therefore CC may have severe intracranial complications as onset symptomatology. Pre-operative CT imaging is useful for the evaluation of the extension of the disease and planning the appropriate surgical technique.
Keywords: Congenital cholesteatoma, Posterior cranial fossa extension
1. Introduction
Congenital cholesteatoma (CC) is used to define an epidermoid cyst of the temporal bone, characterized by a silent slow growing and serious intracranial complication. Congenital cholesteatoma of the middle ear was first described by House in 1953 [1]. Later Derlacki and Clemisin in 1965 [2] have established the following points in defining congenital cholesteatoma of the tympanum and mastoid: (1) development of the cholesteatoma behind an intact tympanic membrane, (2) absence of previous history of aural infections, and (3) no demonstrable connection of the cholesteatoma with the external auditory canal. In 1986 Levenson [3] revised the criteria by adding that previous bouts of otitis media or effusion should not be exclusion criteria of CC. Cholesteatomas, congenital and acquired, have an incidence of 3–6 per 100,000 [4]. The incidence of CC has been estimated at 0.12 per 100,000 [5], even though the number is thought to be on the rise [6]. This increase is generally attributed to enhanced physician awareness and to improved imaging techniques that confirm clinical diagnosis. Several theories have been proposed for the pathophysiology of CC but the theory of epithelial rests from faulty embryogenesis is today the most widely accepted. The symptoms depend on the location and extensiveness of the lesion and are usually manifested as conductive hearing loss; the most common presentation is an asymptomatic white mass medial to an intact tympanic membrane usually located in the anterior superior quadrant, less commonly in the posterior superior quadrant [7,8]. Early diagnosis of CC is important to reduce complications and surgical risks. Numerous complications resulting from chronic otitis media and cholesteatoma have been reviewed in the literature. Fisch reported that approximately 1.2% of patients who suffer from cholesteatoma will develop intracranial complications [9]. Whereas the sequelae of infectious intracranial complication have been well documented in the literature [10,11], little has been written about intracranial posterior fossa extension of congenital middle ear cholesteatoma in children.
This report reviews the patient characteristics, operative treatment and long term follow-up of two children affected by congenital cholesteatoma with a posterior cranial fossa involvement treated at the E.N.T. Department of the Pediatric Hospital Bambino Gesù (Rome).
2. Materials and methods
A retrospective review of the medical records of 264 children surgically treated for cholesteatoma of the temporal bone between 1999 and 2008 was completed. Out of 264 cholesteatomas, 30 cases satisfied the criteria for congenital cholesteatoma suggested by Levenson. Two patients had surgically documented evidence of congenital cholesteatoma extending into the posterior cranial fossa. A complete otological history was obtained including hearing loss and vertigo. Otomicroscopy, head and neck examination, neurological and audiological examination and pre-operative imaging of the temporal bone, which included computed tomography and/or magnetic resonance imaging, were performed. The operative reports were reviewed and the sites of cholesteatoma involvement and the surgical approach were evaluated. The extent of clinical follow-up for these two patients is 5 and 3 years.
3. Case 1
A 3-year-old boy was admitted to the Otolaryngology Department for recurrent adenoiditis and snoring. No history of otorrhea or otalgia was referred. Otomicroscopic examination of the left ear showed a white mass behind the posterior superior quadrant of an intact tympanic membrane. The CT scan showed a low density soft tissue involving the middle ear, attic and mastoid; a wide erosion of the mastoid air cells opening in the posterior cranial fossa was evidentiated (Fig. 1). The pre-operative audiologic data showed an air-bone conduction gap of 40
db on the three frequencies tested (250, 1000 and 4000Hz). At surgical exploration, the intracranial extension of cholesteatoma was extradural, infact compression but not disruption of the dura of the posterior cranial fossa was noted. The incus was eroded and the malleus surrounded by granulation tissue. The surgical management required complete intra-operative dissection of the matrix of cholesteatoma; a canal wall down tympanoplasty with ossiculoplasty with hydroxylapatite partial ossicular reconstruction prosthesis were performed. The endocranial bony dehiscence was closed with a piece allogenic cartilage coated by autologous temporalis fascia. Extrusion of the cartilage was noted after 2 years of follow-up and the bony dehiscence remained covered by fibrotic tissue. At the same time a CT scan imaging was performed showing no recurrence and/or other complications (Fig. 2). The post-operative pure tone audiometry showed a 25dB air-bone gap.
Fig. 1.
Pre-operative CT scan showing cholesteatoma eroding the left posterior cranial fossa.
Fig. 2.
Post-operative CT scan showing the surgical closure of the left posterior fossa defect.
4. Case 2
A 4-year-old boy was admitted at the Otolaryngology Department for sleep apnea. The clinical examination revealed at the otomicroscopic evaluation of the left ear an endo-tympanic cholesteatoma bulging the posterior superior quadrant of an intact eardrum. No history of otorrhea was detected. The CT scan revealed a soft tissue density lesion involving the middle ear and the mastoid region with a large bony erosion of the posterior cranial fossa (Fig. 3). The audiological pre-operative evaluation (pure tone audiometry) showed a mono lateral conductive hearing loss with an average air-bone gap of 50dB on the three frequencies tested (250, 1000 and 4000Hz). At surgery, the intracranial extension into the posterior cranial fossa was noted through the retrofacial air cells. The cholesteatoma was extradural without disruption of the dura. All three ossicles were eroded, but the stapes footplate remained intact. The patient underwent a canal wall down mastoidectomy for removal of the cholesteatoma and a tympanoplasty with ossiculoplasty using hydroxylapatite total ossicular reconstruction prosthesis. The bony defect of the posterior fossa was reconstructed only with dura and temporalis autologous fascia. To date the extension of follow-up is 3 years and no recidivism has showed. The post-operative pure tone audiometry showed a 35dB air-bone gap in the operated ear.
Fig. 3.
Pre-operative CT scan showed a low density soft tissue involving the middle ear with erosion of the mastoid air cells in the posterior cranial fossa.
5. Discussion
Congenital cholesteatoma is a nonmalignant, slowly progressive, destructive middle ear disease because of the presence of keratinizing stratified squamous epithelium in the middle ear cleft. In contrast to acquired cholesteatomas, CC presents without otorrhea and the tympanic membrane appears to be intact. The first symptom is usually hearing loss, but this is not referred from young children. The cause of CC remains controversial. Of the several theories explaining the origin of congenital cholesteatoma the most commonly accepted is the epithelial rest theory proposed by Teed in 1936 [12] based on observation of an epidermal structure found in a 5-month human fetus in the upper mesotympanum, medial to the malleus neck. This epithelial thickening usually involutes to become normal endothelium, however, if it does not CC may result. In 1986, Michaels identified a similar structure, a nest of squamous cells in the anterior superior lateral wall of the tympanic cavity in fetal middle ears at between 10 and 33 weeks’ gestation [13]. He termed this structure the epidermoid formation. In our experience of CC, the 80% of children had anterior superior quadrant cholesteatoma which seems to validate Michaels’ theory; on the contrary in the two cases reported in this article a posterior superior quadrant involvement, with a posterior direction of spread, was observed. CC of the middle ear is often staged by its location and relationship with surrounding structures. Recently, two staging systems for CC of the middle ear have been suggested. The first proposed by Potsic in 2002, suggests the following stages [14]:
The second classification proposed by Nelson in 2002 suggests the classification of CC into three categories [15]:
The growth of the congenital cholesteatoma presented in this article extended posteriorly along the superior mesotympanum involving the incudostapedial joint, stapes superstructures and eroded the mastoid air cells into the posterior cranial fossa. The extra mastoid extension, not reported in the exposed classification below, required a different surgical planning of treatment and a different prognosis. The progressive growth of the CC from the attic into the antrum and then into the mastoid follows the overall pattern of enlargement of other categories of middle ear cholesteatomas. However, there is one significant difference: the mastoid of very young children with CC tends to be well pneumatized with few, but large, air cells. It is structurally different from the fully developed normal mastoid of older children and sclerotic, poorly pneumatized mastoids of children with chronic otitis media. The smaller and more open architecture of the developing mastoid is facilitates the rapid spread of the CC. Although the air cell septa may be so vulnerable to osteolysis, the otic capsule appears to be resistant and spared by the CC. The extension around the labyrinth into the petrous apex cells and in the posterior cranial fossa may nevertheless occur. The complications of the two reported cases have rarely been described, but they well document how CC in children can silently evolve towards severe life-threatening complications. This may happen with no advice of the true extension of the lesion because the more common complications that we are used to observe in acquired cholesteatomas, such as vertigo, sensorineural hearing loss or facial palsy are rare in CC. The very young age and the poor clinical history explain such surprising findings. Otolaryngologist must be aware of this rare but dangerous condition, in order to achieve an early diagnosis and a thorough pre-operative assessment.
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PII: S1871-4048(10)00050-X
doi:10.1016/j.pedex.2010.06.005
© 2010 Elsevier Ireland Ltd. All rights reserved.
Volume 6, Issue 4 , Pages 165-167, December 2011
