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Unruptured translabyrinthine meningocele without CSF otorrhea
International Journal of Pediatric Otorhinolaryngology 78 (2014) 567–570
Contents lists available at ScienceDirect
International Journal of Pediatric Otorhinolaryngology journal homepage: www.elsevier.com/locate/ijporl
Case Report
Unruptured translabyrinthine meningocele without CSF otorrhea Won Kyoung Kong a, Chang Ho Lee a,*, Yoo Eunhye b, Seung-Ho Shin a a b
Department of Otolaryngology-Head & Neck Surgery, 59 Yatap-ro, Bundang-gu, Seongnam-si, Gyeonggi-do 463-712, Republic of Korea Department of Radiology, CHA Bundang Medical Center, CHA University, 59 Yatap-ro, Bundang-gu, Seongnam-si, Gyeonggi-do 463-712, Republic of Korea
A R T I C L E I N F O
A B S T R A C T
Article history: Received 20 August 2013 Received in revised form 27 December 2013 Accepted 29 December 2013 Available online 10 January 2014
Labyrinthine meningocele can be classified into translabyrinthine and perilabyrinthine type. We describe a case of rare unruptured translabyrinthine meningocele (TLM). It is rare to encounter an unruptured TLM because it is usually diagnosed after rupture as a labyrinthine fistula, cerebral spinal fluid otorrhea, and subsequent meningitis. We provide for the first time an intraoperative photo and video of a case of an unruptured TLM that developed through an inner ear malformation in a single-side deaf child, which was preoperatively misdiagnosed as congenital cholesteatoma in preoperative temporal bone computed tomography. TLM without CSF otorrhea in an unruptured state merit attention because of its importance during the workup of congenital cholesteatoma or cochlear implantation in spite of its rarity of reports. ß 2014 Elsevier Ireland Ltd. All rights reserved.
Keywords: Labyrinthine meningocele Congenital malformation CSF otorrhea
1. Introduction Labyrinthine meningocele is a rare disease formed by an arachnoid membrane that herniates through defects close to the labyrinth, which can be misdiagnosed during the differential diagnosis of the middle ear lesion. We present a case of translabyrinthine meningocele (TLM) that was preoperatively misdiagnosed as congenital cholesteatoma. 2. Case. Translabyrinthine meningocele with a vestibulocochlear malformation presenting as deafness and a middle ear mass A 7-year-old girl visited our otology clinic to receive surgical treatment for congenital cholesteatoma. She had a history of facial nerve paralysis at 2 years old and a brief seizure attack 2 years ago. The otomicroscopic and otoendoscopic findings suggested a round mass under the intact tympanic membrane in the posterosuperior quadrant, suggesting congenital cholesteatoma. However, she had a complete loss of hearing (deafness) or sensorineural hearing loss (SNHL), which was not a finding of congenital cholesteatoma that could be diagnosed during conductive hearing loss. Although she did not complain of dizziness, she showed no response to caloric stimulation of her left ear.
* Corresponding author at: Department of Otolaryngology-Head & Neck Surgery, CHA Bundang Medical Center, CHA University, 351 Yatap-dong, Bundang-gu, Seongnam-si, Gyeonggi-do 463-712, Republic of Korea. Tel.: +82 31 780 5340; fax: +82 31 780 5347. E-mail address: [email protected] (C.H. Lee). 0165-5876/$ – see front matter ß 2014 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijporl.2013.12.034
A high-resolution computed tomographic (CT) examination (1.3 mm-thick sections, Discovery CT750 HD, U.K) through the temporal bone in the axial and coronal planes revealed a dysplastic cochlea without separate apical and second turns and the absence of a normal modiolus; short, abnormal lateral and posterior semicircular ducts; and a broad connection with a large vestibule (Fig. 2). These features correlated with Mondini’s dysplasia or incomplete partition type I (IP-I) cystic cochleovestibular malformation acongenital cholesteatomaording to the classification described by Sennaroglu and Saatci [1]. The opening between the cochlea and the deep internal auditory canal (IAC) revealed a possible connection between the cerebrospinal fluid and the labyrinthine fluid. There was additionally an oval soft tissue mass in the middle ear that was compatible with the otoendoscopic finding of a round mass under the tympanic membrane. The incudostapedial joint was destroyed with an intact malleus and incus, which was consistent with congenital cholesteatoma abutting the incudostapedial joint. There was neither any fluid collection nor facial canal enlargement suggestive of cerebrospinal fluid otorrhea. The congenital malformation of the inner ear and middle ear mass did not seem to be connected in the axial section, whereas there was a suspected connection in the coronal section. Exploratory tympanotomy was performed under general anesthesia via an endaural incision to confirm the diagnosis, check the CSF otorrhea and remove the middle ear mass if it was congenital cholesteatoma. After a Koener flap and tympanomeatal flap elevation, a thin membrane-walled middle ear cyst was found behind the malleus handle in the area of the oval window. It was not congenital cholesteatoma, and the arachnoid membrane-like
568
W.K. Kong et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 567–570
Fig. 1. Translabyrinthine meningocele. F/7 years. Intraoperative photo of after tympanomeatal flap elevation. A pulsatile left middle ear cyst covered with a thin, partially transparent arachnoid membrane and filled with clear fluid was found and intraoperatively diagnosed as translabyrinthine meningocele. The meningocele was protected using a perichondrium graft from the conchal cartilage.
thin wall of the cyst and clear fluid contents of the middle ear mass led to a diagnosis of temporal bone meningocele. The diagnosis of meningocele was made intraoperatively (Fig. 1; the operation video is also provided in the supplemental material.). The oval window and stapes located in the center of mass in the coronal section of the temporal bone CT scan indicated that the meningocele belonged to the translabyrinthine type. Extreme
care was taken to avoid rupturing the meningocele, and it was not aspirated because of the risk of immediate profuse CSF otorrhea and later meningitis that would require subtotal petrosectomy (neurotologic surgery and closure of the external auditory canal). It was confirmed that there was no CSF leakage in the middle ear, and the meningocele was not ruptured and showed no surgical trauma. The unruptured meningocele was covered with perichondrium and cartilage composite graft obtained from conchal cartilage to protect it from later trauma and to prevent CSF leakage (Fig. 2). Postoperatively, the child did not present any vertigo, headache or signs of CSF otorrhea. Postoperative otoendoscopy was submitted in the supplemental video. A one-month postoperative T2-weighted magnetic resonance (MR) (Siemens, Erlangen, Germany, 3.0T) (Fig. 3) revealed a less than 5-mm (slightly decreased size) known meningocele within the left middle ear cavity (asterisk) connected to the cystic semicircular canal, as well as vestibular dysplasia and cochlea dysplasia (white arrowhead). The IAC and the vestibulocochlear malformation did not show a direct connection, but the true IAC of the Y-shaped IAC (white arrow) was observed connecting the inner ear cavity with the peripontine cistern. A pediatric neurosurgeon was consulted to perform transmastoid removal of the meningocele, but regular follow-up was planned instead of impending surgical treatment. Parental education focused on the possibility of meningitis or cerebrospinal fluid otorrhea, which could be potentially life threatening and require subtotal petrosectomy. 3. Discussion Our case was not present with CSF otorrhea, but the classification of temporal bone meningocele generally follows the classification of CSF otorrhea [2]. Spontaneous CSF otorrhea is a rare but potentially life-threatening condition with two different subtypes: (1) translabyrinthe type in children with inner ear malformation and SNHL, and (2) perilabyrinthine type in adults with meningoencephaloceles [3]. Reported cases include 80 cases of childhood-type translabyrinthine fistula by 2002 [4], 57 cases of
Fig. 2. (a) Axial high-resolution CT images reveal an oval soft tissue mass (asterisk) in the middle ear near the oval window that was caudal to the inner ear malformation (black arrow), indicating a cystic cochleovestibular malformation incomplete partition type I (IP-I) and a geniculate ganglion opening of the facial nerve (short white arrow). The Yshaped internal auditory canal (long white arrow) was observed. The incudostapedial joint was destroyed with an intact malleus and incus, which was consistent with congenital cholesteatoma abutting the incudostapedial joint. There was neither any fluid collection nor facial canal enlargement suggestive of cerebrospinal fluid otorrhea. (b) Coronal high-resolution CT images show a 7 mm 4 mm 3 mm opacification (short white arrow) in the left mesotympanum posterior to the malleus and anterior to the incus abutting the incudostapedial joint and cochlear promontory, of which the first differential diagnosis was congenital cholesteatoma arising from the incudostapedial joint. The internal auditory canal is connected to the vestibule (black arrow) and narrowed (long white arrow). The posterior semicircular canal dysplasia is connected to a translabyrinthine meningocele (long black arrow).
W.K. Kong et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 567–570
569
Fig. 3. Postoperative T2 MR. The known meningocele (less than 5 mm) within the left middle ear cavity (asterisk) was observed. The fluid signal intensity of the enlarged inner ear structure (cystic semicircular canal – vestibular dysplasia and cochlea dysplasia) (white arrowhead) on MR is similar to that of the cerebrospinal fluid. The true internal auditory canal (white arrow) of the Y-shaped IAC was observed and connects the inner ear cavity with the peripontine cistern.
perilabyrinthine fistula, and 9 cases of fallopian canal meningocele with CSF leakage [5]. If we exclude CSF otorrhea through a tegmen defect, which encompass typical postsurgical or postinfectious series, congenital abnormalities of the temporal bone are a much rarer cause of CSF fistulas and should be suspected in cases of recurrent meningitis in the absence of an inciting event [6]. The greatest clinical difference between the two types of labyrinthine
meningocele is the presence of deafness or sensorineural hearing loss in the absence of CSF otorrhea. There is usually no sensorineural hearing in perilabyrinthine meningocele and it is frequently asymptomatic unlike TLM. In contrast, congenital TLM usually features congenital deafness, and radiological imaging of TLM reveals a profound labyrinthine deformity in 85% of patients, especially cystic
570
W.K. Kong et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 567–570
cochleovestibular malformation, which is commonly known as Mondini’s dysplasia. Abnormal communication exists between the subarachnoid and perilymphatic spaces because the internal auditory canal can extend into the vestibule through a deficiency in the lamina cribrosa, a thin bony layer separating the apex of the IAC from the vestibule [6]. The abnormal communication between CSF and perilymph could lead to increased pressure within the vestibule and the development of CSF otorrhea through the oval window, the round window or, rarely, a fissure on the promontory. Our photo and video indicate unruptured TLM that has bulged out of the oval window was pulsatile and covered with arachnoid membrane. A temporal bone meningocele can be covered with dura or arachnoid membrane, but our photo suggests TLM is covered with arachnoid membrane to be able to herniate through the microscopic structure of the labyrinth [7]. The average age of meningitis and CSF otorrhea through the stapes footplate in cases of congenital cochlea malformation found during exploratory tympanotomy was 4–6.4 years [8], indicating early rupture of thin arachnoid membrane that would precede CSF otorrhea. The location of the TLM was most frequently in the central portion of the stapes footplate, followed by the anterior portion of the stapes [7], thus the temporal bone CT finding in Fig. 2 showing a middle ear mass surrounding the stapes in a vestibulocochlear malformation might be a clue to TLM rather than congenital cholesteatoma. But it is not possible to reliably differentiate meningocele from congenital cholesteatoma with temporal bone CT, and the differentiation between a meningocele and a cholesteatoma may be made using MR. Thus SNHL or vestibulocochlear malformation during the workup of congenital choelsteatoma might warrant preoperative temporal bone MR. On the other hand, the incidence of presumed congenital choelsteatoma during evaluation of bilateral SNHL for cochlear implant was reported as 0.25% (2/794), which might be unruptured TLM that would require completely different surgical approach for cochlear implantation [9]. A meningocele will have the same characteristics as CSF, low signal intensity in T1-weighted and high intensity in the T2weighted images, whereas cholesteatoma will appear as a low to intermediate signal in the T1-weighted images and a highintensity signal in the T2-weighted images. When an adult-type meningocele with tegmen erosion is observed, a meningocele or brain herniation is usually considered as a differential diagnosis of the temporal bone mass, and a temporal bone MR is usually obtained [10]. However, the current radiological diagnosis of choice is temporal bone CT in children with a middle ear mass or congenital SNHL, which carries the risk that silent TLM isolated in the mesotympanum might be confused with congenital cholesteatoma in temporal bone CT without temporal bone MR, as occurred in this case. Temporal bone MR for congenital cholesteatoma is usually reserved for petrous apex lesions, although the recent trend toward favoring an initial temporal bone MR is emerging. Other rare middle ear masses under normal tympanic membranes include paraganglioma, ectopic carotid artery, and facial nerve schwannoma, which can be readily differentiated preoperatively from congenital cholesteatoma using temporal bone CT [11]. Surgical intervention for unruptured meningocele carries a risk of iatrogenic CSF otorrhea or meningitis in a previously asymptomatic child, and the temporal bone CT finding of TLM is worth noting. It is important to undertake the risk of surgery on TLM only when the symptoms clearly indicate the presence of this lesion [12]. Although herniation of the arachnoid membrane through a
temporal bone defect may be congenital, a CSF leakage occurs when dynamic factors produce a rent in the arachnoid membrane [12]. It might be possible to manage meningocele without CSF otorrhea conservatively because an incomplete partition deformity is not associated with a heightened risk of CSF leakage compared to a common cavity deformity [13]. The oval window packing or plugging the vestibule with muscle was also reported in a case of meningitis with oval window fistula [8]. However, if the patient develops CSF otorrhea and meningitis, which is a potentially life-threatening complication, aggressive surgical repair of the leak using subtotal petrosectomy or middle fossa craniotomy will be required. Verbal consent was obtained from the parents on the publication of this case. 4. Conclusions Translabyrinthine meningocele without CSF otorrhea in an unruptured state merit attention because of its importance during the workup of congenital cholesteatoma or cochlear implantation in spite of its rarity of reports. Financial disclosure There was no financial and material support for this research and work. Conflict of interest None. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.ijporl.2013.12.034. References [1] L. Sennaroglu, I. Saatci, Unpartitioned versus incompletely partitioned cochleae: radiologic differentiation, Otol. Neurotol. 25 (2004) 520–529 (discussion 529). [2] B.G. Gray, R.A. Willinsky, J.A. Rutka, C.H. Tator, Spontaneous meningocele, a rare middle ear mass, Am. J. Neuroradiol. 16 (1995) 203–207. [3] M.D. Graham, L.B. Lundy, Dural herniation and cerebrospinal fluid leaks, in: D.E. Brackmann, C. Shelton, M.A. Arriaga (Eds.), Otologic Surgery, W.B. Saunders, 2001, p. p219. [4] J.P. Windfuhr, K. Sesterhenn, Spontaneous defects of the lateral skull base. 2. Etiology and review of the literature, HNO 50 (2002) 441–463. [5] S. Mong, A.N. Goldberg, L.R. Lustig, Fallopian canal meningocele: report of two cases, Otol. Neurotol. 30 (2009) 525–528. [6] L.V. Romo, J.W. Casselman, C.D. Robson, Temporal bone: congenital anomalies, in: P.M. Som, H.D. Curtin (Eds.), Head and Neck Imaging, Mosby Elsevier, 2011 , pp. 1097–1166. [7] C. Herther, R.A. Schindler, Mondini’s dysplasia with recurrent meningitis, Laryngoscope 95 (1985) 655–658. [8] S.C. Parisier, E.A. Birken, Recurrent meningitis secondary to idiopathic oval window CSF leak, Laryngoscope 86 (1976) 1503–1515. [9] J. Chung, S.L. Cushing, A.L. James, K.A. Gordon, B.C. Papsin, Congenital cholesteatoma and cochlear implantation: implications for management, Cochlear Implants Int. 14 (2013) 32–35. [10] K.R. Moore, N.J. Fischbein, H.R. Harnsberger, C. Shelton, C.M. Glastonbury, D.K. White, et al., Petrous apex cephaloceles, Am. J. Neuroradiol. 22 (2001) 1867–1871. [11] Y. Robert, S. Carcasset, N. Rocourt, C. Hennequin, F. Dubrulle, L. Lemaitre, Congenital cholesteatoma of the temporal bone: MR findings and comparison with CT, Am. J. Neuroradiol. 16 (1995) 755–761. [12] N. Brown, K. Grundfast, A. Jabre, C. Megerian, B. O’malley, S. Rosenberg, Diagnosis and management of spontaneous cerebrospinal fluid-middle ear effusion and otorrhea, Laryngoscope 114 (2004) 800–805. [13] P.D. Phelps, A. King, L. Michaels, Cochlear dysplasia and meningitis, Am. J. Otol. 15 (1994) 551–557.
Contents lists available at ScienceDirect
International Journal of Pediatric Otorhinolaryngology journal homepage: www.elsevier.com/locate/ijporl
Case Report
Unruptured translabyrinthine meningocele without CSF otorrhea Won Kyoung Kong a, Chang Ho Lee a,*, Yoo Eunhye b, Seung-Ho Shin a a b
Department of Otolaryngology-Head & Neck Surgery, 59 Yatap-ro, Bundang-gu, Seongnam-si, Gyeonggi-do 463-712, Republic of Korea Department of Radiology, CHA Bundang Medical Center, CHA University, 59 Yatap-ro, Bundang-gu, Seongnam-si, Gyeonggi-do 463-712, Republic of Korea
A R T I C L E I N F O
A B S T R A C T
Article history: Received 20 August 2013 Received in revised form 27 December 2013 Accepted 29 December 2013 Available online 10 January 2014
Labyrinthine meningocele can be classified into translabyrinthine and perilabyrinthine type. We describe a case of rare unruptured translabyrinthine meningocele (TLM). It is rare to encounter an unruptured TLM because it is usually diagnosed after rupture as a labyrinthine fistula, cerebral spinal fluid otorrhea, and subsequent meningitis. We provide for the first time an intraoperative photo and video of a case of an unruptured TLM that developed through an inner ear malformation in a single-side deaf child, which was preoperatively misdiagnosed as congenital cholesteatoma in preoperative temporal bone computed tomography. TLM without CSF otorrhea in an unruptured state merit attention because of its importance during the workup of congenital cholesteatoma or cochlear implantation in spite of its rarity of reports. ß 2014 Elsevier Ireland Ltd. All rights reserved.
Keywords: Labyrinthine meningocele Congenital malformation CSF otorrhea
1. Introduction Labyrinthine meningocele is a rare disease formed by an arachnoid membrane that herniates through defects close to the labyrinth, which can be misdiagnosed during the differential diagnosis of the middle ear lesion. We present a case of translabyrinthine meningocele (TLM) that was preoperatively misdiagnosed as congenital cholesteatoma. 2. Case. Translabyrinthine meningocele with a vestibulocochlear malformation presenting as deafness and a middle ear mass A 7-year-old girl visited our otology clinic to receive surgical treatment for congenital cholesteatoma. She had a history of facial nerve paralysis at 2 years old and a brief seizure attack 2 years ago. The otomicroscopic and otoendoscopic findings suggested a round mass under the intact tympanic membrane in the posterosuperior quadrant, suggesting congenital cholesteatoma. However, she had a complete loss of hearing (deafness) or sensorineural hearing loss (SNHL), which was not a finding of congenital cholesteatoma that could be diagnosed during conductive hearing loss. Although she did not complain of dizziness, she showed no response to caloric stimulation of her left ear.
* Corresponding author at: Department of Otolaryngology-Head & Neck Surgery, CHA Bundang Medical Center, CHA University, 351 Yatap-dong, Bundang-gu, Seongnam-si, Gyeonggi-do 463-712, Republic of Korea. Tel.: +82 31 780 5340; fax: +82 31 780 5347. E-mail address: [email protected] (C.H. Lee). 0165-5876/$ – see front matter ß 2014 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijporl.2013.12.034
A high-resolution computed tomographic (CT) examination (1.3 mm-thick sections, Discovery CT750 HD, U.K) through the temporal bone in the axial and coronal planes revealed a dysplastic cochlea without separate apical and second turns and the absence of a normal modiolus; short, abnormal lateral and posterior semicircular ducts; and a broad connection with a large vestibule (Fig. 2). These features correlated with Mondini’s dysplasia or incomplete partition type I (IP-I) cystic cochleovestibular malformation acongenital cholesteatomaording to the classification described by Sennaroglu and Saatci [1]. The opening between the cochlea and the deep internal auditory canal (IAC) revealed a possible connection between the cerebrospinal fluid and the labyrinthine fluid. There was additionally an oval soft tissue mass in the middle ear that was compatible with the otoendoscopic finding of a round mass under the tympanic membrane. The incudostapedial joint was destroyed with an intact malleus and incus, which was consistent with congenital cholesteatoma abutting the incudostapedial joint. There was neither any fluid collection nor facial canal enlargement suggestive of cerebrospinal fluid otorrhea. The congenital malformation of the inner ear and middle ear mass did not seem to be connected in the axial section, whereas there was a suspected connection in the coronal section. Exploratory tympanotomy was performed under general anesthesia via an endaural incision to confirm the diagnosis, check the CSF otorrhea and remove the middle ear mass if it was congenital cholesteatoma. After a Koener flap and tympanomeatal flap elevation, a thin membrane-walled middle ear cyst was found behind the malleus handle in the area of the oval window. It was not congenital cholesteatoma, and the arachnoid membrane-like
568
W.K. Kong et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 567–570
Fig. 1. Translabyrinthine meningocele. F/7 years. Intraoperative photo of after tympanomeatal flap elevation. A pulsatile left middle ear cyst covered with a thin, partially transparent arachnoid membrane and filled with clear fluid was found and intraoperatively diagnosed as translabyrinthine meningocele. The meningocele was protected using a perichondrium graft from the conchal cartilage.
thin wall of the cyst and clear fluid contents of the middle ear mass led to a diagnosis of temporal bone meningocele. The diagnosis of meningocele was made intraoperatively (Fig. 1; the operation video is also provided in the supplemental material.). The oval window and stapes located in the center of mass in the coronal section of the temporal bone CT scan indicated that the meningocele belonged to the translabyrinthine type. Extreme
care was taken to avoid rupturing the meningocele, and it was not aspirated because of the risk of immediate profuse CSF otorrhea and later meningitis that would require subtotal petrosectomy (neurotologic surgery and closure of the external auditory canal). It was confirmed that there was no CSF leakage in the middle ear, and the meningocele was not ruptured and showed no surgical trauma. The unruptured meningocele was covered with perichondrium and cartilage composite graft obtained from conchal cartilage to protect it from later trauma and to prevent CSF leakage (Fig. 2). Postoperatively, the child did not present any vertigo, headache or signs of CSF otorrhea. Postoperative otoendoscopy was submitted in the supplemental video. A one-month postoperative T2-weighted magnetic resonance (MR) (Siemens, Erlangen, Germany, 3.0T) (Fig. 3) revealed a less than 5-mm (slightly decreased size) known meningocele within the left middle ear cavity (asterisk) connected to the cystic semicircular canal, as well as vestibular dysplasia and cochlea dysplasia (white arrowhead). The IAC and the vestibulocochlear malformation did not show a direct connection, but the true IAC of the Y-shaped IAC (white arrow) was observed connecting the inner ear cavity with the peripontine cistern. A pediatric neurosurgeon was consulted to perform transmastoid removal of the meningocele, but regular follow-up was planned instead of impending surgical treatment. Parental education focused on the possibility of meningitis or cerebrospinal fluid otorrhea, which could be potentially life threatening and require subtotal petrosectomy. 3. Discussion Our case was not present with CSF otorrhea, but the classification of temporal bone meningocele generally follows the classification of CSF otorrhea [2]. Spontaneous CSF otorrhea is a rare but potentially life-threatening condition with two different subtypes: (1) translabyrinthe type in children with inner ear malformation and SNHL, and (2) perilabyrinthine type in adults with meningoencephaloceles [3]. Reported cases include 80 cases of childhood-type translabyrinthine fistula by 2002 [4], 57 cases of
Fig. 2. (a) Axial high-resolution CT images reveal an oval soft tissue mass (asterisk) in the middle ear near the oval window that was caudal to the inner ear malformation (black arrow), indicating a cystic cochleovestibular malformation incomplete partition type I (IP-I) and a geniculate ganglion opening of the facial nerve (short white arrow). The Yshaped internal auditory canal (long white arrow) was observed. The incudostapedial joint was destroyed with an intact malleus and incus, which was consistent with congenital cholesteatoma abutting the incudostapedial joint. There was neither any fluid collection nor facial canal enlargement suggestive of cerebrospinal fluid otorrhea. (b) Coronal high-resolution CT images show a 7 mm 4 mm 3 mm opacification (short white arrow) in the left mesotympanum posterior to the malleus and anterior to the incus abutting the incudostapedial joint and cochlear promontory, of which the first differential diagnosis was congenital cholesteatoma arising from the incudostapedial joint. The internal auditory canal is connected to the vestibule (black arrow) and narrowed (long white arrow). The posterior semicircular canal dysplasia is connected to a translabyrinthine meningocele (long black arrow).
W.K. Kong et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 567–570
569
Fig. 3. Postoperative T2 MR. The known meningocele (less than 5 mm) within the left middle ear cavity (asterisk) was observed. The fluid signal intensity of the enlarged inner ear structure (cystic semicircular canal – vestibular dysplasia and cochlea dysplasia) (white arrowhead) on MR is similar to that of the cerebrospinal fluid. The true internal auditory canal (white arrow) of the Y-shaped IAC was observed and connects the inner ear cavity with the peripontine cistern.
perilabyrinthine fistula, and 9 cases of fallopian canal meningocele with CSF leakage [5]. If we exclude CSF otorrhea through a tegmen defect, which encompass typical postsurgical or postinfectious series, congenital abnormalities of the temporal bone are a much rarer cause of CSF fistulas and should be suspected in cases of recurrent meningitis in the absence of an inciting event [6]. The greatest clinical difference between the two types of labyrinthine
meningocele is the presence of deafness or sensorineural hearing loss in the absence of CSF otorrhea. There is usually no sensorineural hearing in perilabyrinthine meningocele and it is frequently asymptomatic unlike TLM. In contrast, congenital TLM usually features congenital deafness, and radiological imaging of TLM reveals a profound labyrinthine deformity in 85% of patients, especially cystic
570
W.K. Kong et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 567–570
cochleovestibular malformation, which is commonly known as Mondini’s dysplasia. Abnormal communication exists between the subarachnoid and perilymphatic spaces because the internal auditory canal can extend into the vestibule through a deficiency in the lamina cribrosa, a thin bony layer separating the apex of the IAC from the vestibule [6]. The abnormal communication between CSF and perilymph could lead to increased pressure within the vestibule and the development of CSF otorrhea through the oval window, the round window or, rarely, a fissure on the promontory. Our photo and video indicate unruptured TLM that has bulged out of the oval window was pulsatile and covered with arachnoid membrane. A temporal bone meningocele can be covered with dura or arachnoid membrane, but our photo suggests TLM is covered with arachnoid membrane to be able to herniate through the microscopic structure of the labyrinth [7]. The average age of meningitis and CSF otorrhea through the stapes footplate in cases of congenital cochlea malformation found during exploratory tympanotomy was 4–6.4 years [8], indicating early rupture of thin arachnoid membrane that would precede CSF otorrhea. The location of the TLM was most frequently in the central portion of the stapes footplate, followed by the anterior portion of the stapes [7], thus the temporal bone CT finding in Fig. 2 showing a middle ear mass surrounding the stapes in a vestibulocochlear malformation might be a clue to TLM rather than congenital cholesteatoma. But it is not possible to reliably differentiate meningocele from congenital cholesteatoma with temporal bone CT, and the differentiation between a meningocele and a cholesteatoma may be made using MR. Thus SNHL or vestibulocochlear malformation during the workup of congenital choelsteatoma might warrant preoperative temporal bone MR. On the other hand, the incidence of presumed congenital choelsteatoma during evaluation of bilateral SNHL for cochlear implant was reported as 0.25% (2/794), which might be unruptured TLM that would require completely different surgical approach for cochlear implantation [9]. A meningocele will have the same characteristics as CSF, low signal intensity in T1-weighted and high intensity in the T2weighted images, whereas cholesteatoma will appear as a low to intermediate signal in the T1-weighted images and a highintensity signal in the T2-weighted images. When an adult-type meningocele with tegmen erosion is observed, a meningocele or brain herniation is usually considered as a differential diagnosis of the temporal bone mass, and a temporal bone MR is usually obtained [10]. However, the current radiological diagnosis of choice is temporal bone CT in children with a middle ear mass or congenital SNHL, which carries the risk that silent TLM isolated in the mesotympanum might be confused with congenital cholesteatoma in temporal bone CT without temporal bone MR, as occurred in this case. Temporal bone MR for congenital cholesteatoma is usually reserved for petrous apex lesions, although the recent trend toward favoring an initial temporal bone MR is emerging. Other rare middle ear masses under normal tympanic membranes include paraganglioma, ectopic carotid artery, and facial nerve schwannoma, which can be readily differentiated preoperatively from congenital cholesteatoma using temporal bone CT [11]. Surgical intervention for unruptured meningocele carries a risk of iatrogenic CSF otorrhea or meningitis in a previously asymptomatic child, and the temporal bone CT finding of TLM is worth noting. It is important to undertake the risk of surgery on TLM only when the symptoms clearly indicate the presence of this lesion [12]. Although herniation of the arachnoid membrane through a
temporal bone defect may be congenital, a CSF leakage occurs when dynamic factors produce a rent in the arachnoid membrane [12]. It might be possible to manage meningocele without CSF otorrhea conservatively because an incomplete partition deformity is not associated with a heightened risk of CSF leakage compared to a common cavity deformity [13]. The oval window packing or plugging the vestibule with muscle was also reported in a case of meningitis with oval window fistula [8]. However, if the patient develops CSF otorrhea and meningitis, which is a potentially life-threatening complication, aggressive surgical repair of the leak using subtotal petrosectomy or middle fossa craniotomy will be required. Verbal consent was obtained from the parents on the publication of this case. 4. Conclusions Translabyrinthine meningocele without CSF otorrhea in an unruptured state merit attention because of its importance during the workup of congenital cholesteatoma or cochlear implantation in spite of its rarity of reports. Financial disclosure There was no financial and material support for this research and work. Conflict of interest None. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.ijporl.2013.12.034. References [1] L. Sennaroglu, I. Saatci, Unpartitioned versus incompletely partitioned cochleae: radiologic differentiation, Otol. Neurotol. 25 (2004) 520–529 (discussion 529). [2] B.G. Gray, R.A. Willinsky, J.A. Rutka, C.H. Tator, Spontaneous meningocele, a rare middle ear mass, Am. J. Neuroradiol. 16 (1995) 203–207. [3] M.D. Graham, L.B. Lundy, Dural herniation and cerebrospinal fluid leaks, in: D.E. Brackmann, C. Shelton, M.A. Arriaga (Eds.), Otologic Surgery, W.B. Saunders, 2001, p. p219. [4] J.P. Windfuhr, K. Sesterhenn, Spontaneous defects of the lateral skull base. 2. Etiology and review of the literature, HNO 50 (2002) 441–463. [5] S. Mong, A.N. Goldberg, L.R. Lustig, Fallopian canal meningocele: report of two cases, Otol. Neurotol. 30 (2009) 525–528. [6] L.V. Romo, J.W. Casselman, C.D. Robson, Temporal bone: congenital anomalies, in: P.M. Som, H.D. Curtin (Eds.), Head and Neck Imaging, Mosby Elsevier, 2011 , pp. 1097–1166. [7] C. Herther, R.A. Schindler, Mondini’s dysplasia with recurrent meningitis, Laryngoscope 95 (1985) 655–658. [8] S.C. Parisier, E.A. Birken, Recurrent meningitis secondary to idiopathic oval window CSF leak, Laryngoscope 86 (1976) 1503–1515. [9] J. Chung, S.L. Cushing, A.L. James, K.A. Gordon, B.C. Papsin, Congenital cholesteatoma and cochlear implantation: implications for management, Cochlear Implants Int. 14 (2013) 32–35. [10] K.R. Moore, N.J. Fischbein, H.R. Harnsberger, C. Shelton, C.M. Glastonbury, D.K. White, et al., Petrous apex cephaloceles, Am. J. Neuroradiol. 22 (2001) 1867–1871. [11] Y. Robert, S. Carcasset, N. Rocourt, C. Hennequin, F. Dubrulle, L. Lemaitre, Congenital cholesteatoma of the temporal bone: MR findings and comparison with CT, Am. J. Neuroradiol. 16 (1995) 755–761. [12] N. Brown, K. Grundfast, A. Jabre, C. Megerian, B. O’malley, S. Rosenberg, Diagnosis and management of spontaneous cerebrospinal fluid-middle ear effusion and otorrhea, Laryngoscope 114 (2004) 800–805. [13] P.D. Phelps, A. King, L. Michaels, Cochlear dysplasia and meningitis, Am. J. Otol. 15 (1994) 551–557.