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Transcanal surgical excision of an intracochlear schwannoma
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American Journal of Otolaryngology–Head and Neck Medicine and Surgery 33 (2012) 779 – 781 www.elsevier.com/locate/amjoto
Transcanal surgical excision of an intracochlear schwannoma Andy F. Zhu, BS, Brian J. McKinnon, MD, MBA⁎ Department of Otolaryngology-Head and Neck Surgery, Georgia Health Sciences University, Augusta, GA, USA Received 13 July 2012
Abstract
An intracochlear schwannoma is a rare cause of sensorineural hearing loss, which is little discussed in the literature. This case report details the presentation of a patient with a sensorineural hearing loss due to an intracochlear schwannoma. The patient was initially managed conservatively; however, as her symptoms and serial imaging indicated progression, the lesion was surgically resected via a transcanal/transotic approach. Diagnosis and management of this unusual schwannoma are reviewed. © 2012 Elsevier Inc. All rights reserved.
1. Introduction Although uncommon in and of themselves, schwannomas are the most common tumor to cause sensorineural hearing loss. Schwannomas are derived from Schwann cells of the vestibulocochlear nerve (cranial nerve VIII), most often arising at the transition of central myelin to peripheral myelin near the medial opening of the internal auditory canal [1]. Rarely, these tumors may originate at the terminal end of the nerve including the vestibule, semicircular canal, or cochlea. This case presentation reports sensorineural hearing loss attributed to an intracochlear schwannoma as the cause of hearing loss, which was surgically resected via a transcanal/transotic approach. 2. Case report A 34-year-old African American female presented to the clinic with a 5-week history of decreased hearing and tinnitus in the right ear. The patient denied any trauma or exposure to loud noise. Physical examination was noncontributory, and facial nerve function was normal bilaterally. A hearing test performed showed decreased hearing in the right ear. A magnetic resonance imaging (MRI) with and without contrast demonstrated a focal region of enhancement 1.1 × 2.6 mm within the medial turn of the right cochlea. No extra⁎ Corresponding author. Department of Otolaryngology-Head & Neck Surgery, Georgia Health Sciences University, 1120 15th Street, BP-4121, Augusta, GA 30912. Tel.: +1 706 721 6100; fax: +1 706 721 0112. E-mail address: [email protected] (B.J. McKinnon). 0196-0709/$ – see front matter © 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.amjoto.2012.07.007
axial fluid collection, intraparenchymal hemorrhage, mass, or mass effect was identified. These findings were felt to be consistent with a small cochlear schwannoma. The patient was placed on hydrochlorothiazide and a low-salt diet with marked improvement in symptoms. The patient was followed up over the next 2 years with serial MRIs, which showed no expansion of the enhancement. The patient presented to the clinic 3 years post diagnosis of a right intracochlear schwannoma with a 4-day history of dizziness after cleaning her ears. The patient stated that the room felt like it was spinning and also complained of nausea. The patient was prescribed meclizine, and a repeat MRI was performed. The MRI demonstrated a lesion measuring 4.8 × 0.9 mm indicating growth of the tumor (Fig. 1). There was no apparent extension through the modiolus into the apex of the internal auditory canal. Because of the progression of the lesion, an elective excision was planned. A transcanal/transotic approach was used to achieve removal of the schwannoma. A wide tympanometal flap was raised, and the incus, stapes, short head of the malleus, and chorda tympani were removed to allow sufficient access to the cochlea. The facial nerve was identified and preserved. A wide cochleostomy was made from the oval window niche to the round window, and the otic capsule was sequentially exteriorized from the basal and apical turn, exposing the schwannoma. The schwannoma was noted to extend medially necessitating the resection of the modiolus. An abdominal fat graft was used to reconstruct the cochleostomy defect, covered with DuraSeal, and the tympanometal flap was repositioned back into place. The patient's initial postoperative course was unremarkable;
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A.F. Zhu, B.J. McKinnon / American Journal of Otolaryngology–Head and Neck Medicine and Surgery 33 (2012) 779–781
Fig. 1. The right cochlea enhancement is a signature finding of an intracochlear schwannoma.
however, the patient was briefly admitted 10 days later for a community acquired pneumonia that resolved uneventfully. The resected lesion's histologic features included random proliferation of spindle-shaped cells with tapering nuclei and bland nuclear morphology with a fine fibrillary background. Immunohistochemisty showed positivity for S-100 and negativity for neurofilament. These findings were morphologically consistent with a Schwann cell neoplasm. 3. Discussion Schwannomas are benign, slow-growing nerve sheath tumors derived from Schwann cells and can arise anywhere along the vestibulocochlear nerve. Tumors that originate in the vestibule, cochlea, and semicircular canals are termed intralabyrinthine schwannomas, and there have been only 137 reported cases [2]. Cochlear schwannomas can be further divided into 3 subdivisions: confined to the cochlea, confined to the internal auditory canal, or involvement of both structures. Schwannomas confined solely to the cochlea are extremely rare. Two retrospective reviews detailed only 17 patients combined [3,4]. Anatomical localization of a tumor is essential and dictates the therapeutic approach. Surgical resection of a classical Internal Auditory Canal schwannoma is aimed at preservation of hearing, whereas hearing preservation is not an outcome of intracochlear schwannoma resection [2]. Patients with intracochlear schwannomas can present with a variety of symptoms, with sensorineural hearing loss as the most common presenting complaint, tinnitus as the second most common, and vertigo as the third [2,4,5]. Diagnosis of intracochlear schwannoma is made with T1and T2-weighted MRI sequences with gadolinium enhancement [5]. The tumor will enhance on T1-weighted sequences
with gadolinium and appear hypointense on T2-weighted sequences [4]. Management depends on the severity of the symptoms and the progression of the tumor. Nonoperative management involves serial MRIs to monitor tumor growth while treating symptoms with medication, hearing aids, and vestibular therapy. Surgical management is indicated for intractable vertigo, extension of tumor into cerebellopontine angle or middle ear, evidence of tumor growth, or uncertainty regarding pathological diagnosis [6]. Although surgical resection results in loss of hearing, monaural pseudostereophonic hearing can be achieved with current hearing technology, improving patients' quality of life [5]. This patient presented with a chief complaint of hearing loss and tinnitus. MRI revealed an intracochlear schwannoma. The patient was managed conservatively with serial MRIs, medical therapy, and close follow-up, and responded well. The recurrence of symptoms 3 years post diagnosis with MRI demonstrating tumor expansion led to consideration of surgical resection. Owing to the tumors location, a transcanal/transotic approach achieved total gross resection. At 6-month follow-up, the patient described occasional light-headedness but an overall improvement of her symptoms. Audiogram showed profound hearing loss in the right ear, and hearing aid options were presented to the patient.
4. Conclusion Cochlear schwannoma, although rare, should be considered in any patient who presents with unilateral hearing loss, with MRI as the diagnostic test of choice. Both conservative and surgical management should be considered in management plans.
A.F. Zhu, B.J. McKinnon / American Journal of Otolaryngology–Head and Neck Medicine and Surgery 33 (2012) 779–781
References [1] Johnson J, Lalwani AK. Chapter 61. Vestibular Schwannoma (Acoustic Neuroma). In: Lalwani AK, ed. CURRENT Diagnosis & Treatment in Otolaryngology–Head & Neck Surgery, 3rd ed. New York: McGrawHill; 2012, http://www.accessmedicine.com/content.aspx? aID=55772548. Accessed January 21, 2012. [2] Salzman KL, Childs AM, Davidson HC, et al. Intralabyrinthine schwannomas: imaging diagnosis and classification. Am J Neuroradiol 2012;33(1):104-9.
781
[3] Jiang ZY, Kutz JW, Roland PS, et al. Intracochlear schwannomas confined to the otic capsule. Otol Neurotol 2011;32:1175-9. [4] Grayeli AB, Fond C, Kalamarides M, et al. Diagnosis and management of intracochlear schwannomas. Otol Neurotol 2007;28(7):951-7. [5] Jia H, Marzin A, Dubreuil C, et al. Intralabyrinthine schwannomas: symptoms and managements. Auris Nasus Larynx 2008;35: 131-6. [6] Kennedy RJ, Shelton C, Salzman KL, et al. Intralabyrinthine schwannomas: diagnosis, management, and a new classification system. Otol Neurotol 2004;25:160-7.
American Journal of Otolaryngology–Head and Neck Medicine and Surgery 33 (2012) 779 – 781 www.elsevier.com/locate/amjoto
Transcanal surgical excision of an intracochlear schwannoma Andy F. Zhu, BS, Brian J. McKinnon, MD, MBA⁎ Department of Otolaryngology-Head and Neck Surgery, Georgia Health Sciences University, Augusta, GA, USA Received 13 July 2012
Abstract
An intracochlear schwannoma is a rare cause of sensorineural hearing loss, which is little discussed in the literature. This case report details the presentation of a patient with a sensorineural hearing loss due to an intracochlear schwannoma. The patient was initially managed conservatively; however, as her symptoms and serial imaging indicated progression, the lesion was surgically resected via a transcanal/transotic approach. Diagnosis and management of this unusual schwannoma are reviewed. © 2012 Elsevier Inc. All rights reserved.
1. Introduction Although uncommon in and of themselves, schwannomas are the most common tumor to cause sensorineural hearing loss. Schwannomas are derived from Schwann cells of the vestibulocochlear nerve (cranial nerve VIII), most often arising at the transition of central myelin to peripheral myelin near the medial opening of the internal auditory canal [1]. Rarely, these tumors may originate at the terminal end of the nerve including the vestibule, semicircular canal, or cochlea. This case presentation reports sensorineural hearing loss attributed to an intracochlear schwannoma as the cause of hearing loss, which was surgically resected via a transcanal/transotic approach. 2. Case report A 34-year-old African American female presented to the clinic with a 5-week history of decreased hearing and tinnitus in the right ear. The patient denied any trauma or exposure to loud noise. Physical examination was noncontributory, and facial nerve function was normal bilaterally. A hearing test performed showed decreased hearing in the right ear. A magnetic resonance imaging (MRI) with and without contrast demonstrated a focal region of enhancement 1.1 × 2.6 mm within the medial turn of the right cochlea. No extra⁎ Corresponding author. Department of Otolaryngology-Head & Neck Surgery, Georgia Health Sciences University, 1120 15th Street, BP-4121, Augusta, GA 30912. Tel.: +1 706 721 6100; fax: +1 706 721 0112. E-mail address: [email protected] (B.J. McKinnon). 0196-0709/$ – see front matter © 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.amjoto.2012.07.007
axial fluid collection, intraparenchymal hemorrhage, mass, or mass effect was identified. These findings were felt to be consistent with a small cochlear schwannoma. The patient was placed on hydrochlorothiazide and a low-salt diet with marked improvement in symptoms. The patient was followed up over the next 2 years with serial MRIs, which showed no expansion of the enhancement. The patient presented to the clinic 3 years post diagnosis of a right intracochlear schwannoma with a 4-day history of dizziness after cleaning her ears. The patient stated that the room felt like it was spinning and also complained of nausea. The patient was prescribed meclizine, and a repeat MRI was performed. The MRI demonstrated a lesion measuring 4.8 × 0.9 mm indicating growth of the tumor (Fig. 1). There was no apparent extension through the modiolus into the apex of the internal auditory canal. Because of the progression of the lesion, an elective excision was planned. A transcanal/transotic approach was used to achieve removal of the schwannoma. A wide tympanometal flap was raised, and the incus, stapes, short head of the malleus, and chorda tympani were removed to allow sufficient access to the cochlea. The facial nerve was identified and preserved. A wide cochleostomy was made from the oval window niche to the round window, and the otic capsule was sequentially exteriorized from the basal and apical turn, exposing the schwannoma. The schwannoma was noted to extend medially necessitating the resection of the modiolus. An abdominal fat graft was used to reconstruct the cochleostomy defect, covered with DuraSeal, and the tympanometal flap was repositioned back into place. The patient's initial postoperative course was unremarkable;
780
A.F. Zhu, B.J. McKinnon / American Journal of Otolaryngology–Head and Neck Medicine and Surgery 33 (2012) 779–781
Fig. 1. The right cochlea enhancement is a signature finding of an intracochlear schwannoma.
however, the patient was briefly admitted 10 days later for a community acquired pneumonia that resolved uneventfully. The resected lesion's histologic features included random proliferation of spindle-shaped cells with tapering nuclei and bland nuclear morphology with a fine fibrillary background. Immunohistochemisty showed positivity for S-100 and negativity for neurofilament. These findings were morphologically consistent with a Schwann cell neoplasm. 3. Discussion Schwannomas are benign, slow-growing nerve sheath tumors derived from Schwann cells and can arise anywhere along the vestibulocochlear nerve. Tumors that originate in the vestibule, cochlea, and semicircular canals are termed intralabyrinthine schwannomas, and there have been only 137 reported cases [2]. Cochlear schwannomas can be further divided into 3 subdivisions: confined to the cochlea, confined to the internal auditory canal, or involvement of both structures. Schwannomas confined solely to the cochlea are extremely rare. Two retrospective reviews detailed only 17 patients combined [3,4]. Anatomical localization of a tumor is essential and dictates the therapeutic approach. Surgical resection of a classical Internal Auditory Canal schwannoma is aimed at preservation of hearing, whereas hearing preservation is not an outcome of intracochlear schwannoma resection [2]. Patients with intracochlear schwannomas can present with a variety of symptoms, with sensorineural hearing loss as the most common presenting complaint, tinnitus as the second most common, and vertigo as the third [2,4,5]. Diagnosis of intracochlear schwannoma is made with T1and T2-weighted MRI sequences with gadolinium enhancement [5]. The tumor will enhance on T1-weighted sequences
with gadolinium and appear hypointense on T2-weighted sequences [4]. Management depends on the severity of the symptoms and the progression of the tumor. Nonoperative management involves serial MRIs to monitor tumor growth while treating symptoms with medication, hearing aids, and vestibular therapy. Surgical management is indicated for intractable vertigo, extension of tumor into cerebellopontine angle or middle ear, evidence of tumor growth, or uncertainty regarding pathological diagnosis [6]. Although surgical resection results in loss of hearing, monaural pseudostereophonic hearing can be achieved with current hearing technology, improving patients' quality of life [5]. This patient presented with a chief complaint of hearing loss and tinnitus. MRI revealed an intracochlear schwannoma. The patient was managed conservatively with serial MRIs, medical therapy, and close follow-up, and responded well. The recurrence of symptoms 3 years post diagnosis with MRI demonstrating tumor expansion led to consideration of surgical resection. Owing to the tumors location, a transcanal/transotic approach achieved total gross resection. At 6-month follow-up, the patient described occasional light-headedness but an overall improvement of her symptoms. Audiogram showed profound hearing loss in the right ear, and hearing aid options were presented to the patient.
4. Conclusion Cochlear schwannoma, although rare, should be considered in any patient who presents with unilateral hearing loss, with MRI as the diagnostic test of choice. Both conservative and surgical management should be considered in management plans.
A.F. Zhu, B.J. McKinnon / American Journal of Otolaryngology–Head and Neck Medicine and Surgery 33 (2012) 779–781
References [1] Johnson J, Lalwani AK. Chapter 61. Vestibular Schwannoma (Acoustic Neuroma). In: Lalwani AK, ed. CURRENT Diagnosis & Treatment in Otolaryngology–Head & Neck Surgery, 3rd ed. New York: McGrawHill; 2012, http://www.accessmedicine.com/content.aspx? aID=55772548. Accessed January 21, 2012. [2] Salzman KL, Childs AM, Davidson HC, et al. Intralabyrinthine schwannomas: imaging diagnosis and classification. Am J Neuroradiol 2012;33(1):104-9.
781
[3] Jiang ZY, Kutz JW, Roland PS, et al. Intracochlear schwannomas confined to the otic capsule. Otol Neurotol 2011;32:1175-9. [4] Grayeli AB, Fond C, Kalamarides M, et al. Diagnosis and management of intracochlear schwannomas. Otol Neurotol 2007;28(7):951-7. [5] Jia H, Marzin A, Dubreuil C, et al. Intralabyrinthine schwannomas: symptoms and managements. Auris Nasus Larynx 2008;35: 131-6. [6] Kennedy RJ, Shelton C, Salzman KL, et al. Intralabyrinthine schwannomas: diagnosis, management, and a new classification system. Otol Neurotol 2004;25:160-7.