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Does attempt at hearing preservation microsurgery of vestibular schwannoma affect postoperative tinnitus?

Chovanec M, Zvěřina E, Profant O, Balogová Z, Kluh J, Syka J, Lisý J, Merunka I, Skřivan J, Betka J - Biomed Res Int (2015)

Bottom Line: Preservation of cochlear nerve but loss of preoperative hearing emerged as the main factor for tinnitus persistence and new onset tinnitus.Decrease of THI scores was observed postoperatively.Our results underscore the importance of proper pre- and intraoperative decision making about attempt at hearing preservation versus potential for tinnitus elimination/risk of new onset of tinnitus.

View Article: PubMed Central - PubMed

Affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, 1st Faculty of Medicine, Charles University, University Hospital Motol, V Úvalu 84, 150 06 Prague 5, Czech Republic.

ABSTRACT

Background: The aim of this study was to analyze the effect of vestibular schwannoma microsurgery via the retrosigmoid-transmeatal approach with special reference to the postoperative tinnitus outcome.

Material and methods: A prospective study was performed in 89 consecutive patients with unilateral vestibular schwannoma indicated for microsurgery. Patient and tumor related parameters, pre- and postoperative hearing level, intraoperative findings, and hearing and tinnitus handicap inventory scores were analyzed.

Results: Cochlear nerve integrity was achieved in 44% corresponding to preservation of preoperatively serviceable hearing in 47% and useful hearing in 21%. Main prognostic factors of hearing preservation were grade/size of tumor, preoperative hearing level, intraoperative neuromonitoring, tumor consistency, and adhesion to neurovascular structures. Microsurgery led to elimination of tinnitus in 66% but also new-onset of the symptom in 14% of cases. Preservation of useful hearing and neurectomy of the eighth cranial nerve were main prognostic factors of tinnitus elimination. Preservation of cochlear nerve but loss of preoperative hearing emerged as the main factor for tinnitus persistence and new onset tinnitus. Decrease of THI scores was observed postoperatively.

Conclusions: Our results underscore the importance of proper pre- and intraoperative decision making about attempt at hearing preservation versus potential for tinnitus elimination/risk of new onset of tinnitus.

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Related in: MedlinePlus

Steps of vestibular schwannoma removal via retrosigmoid-transmeatal approach (left side). (a) Tumor exposure in the cerebellopontine angle, (b) early opening of the internal auditory canal with debulking of tumor, (c) identification of CN VIII, (d) transection of vestibular nerves, (e) dissection of tumor from brainstem, (f) identification and dissection of CN VII from tumor, (g) removed tumor, and (h) endoscopic control of radicality of tumor removal in the fundus of internal auditory canal (asterisk: tumor; arrow: debulked cisternal and meatal portion of tumor; double arrowhead: arteriole on the surface of the CN VIII delineating vestibular and cochlear portion of the nerve; V: CN V, VII: CN VII, VIII: CN VIII, and IX-XI: CNs IX-XI; CN: cochlear nerve; VN: vestibular nerves; la: labyrinthine artery; spv: superior petrosal vein; hc: horizontal crest; vc: vertical crest).
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fig1: Steps of vestibular schwannoma removal via retrosigmoid-transmeatal approach (left side). (a) Tumor exposure in the cerebellopontine angle, (b) early opening of the internal auditory canal with debulking of tumor, (c) identification of CN VIII, (d) transection of vestibular nerves, (e) dissection of tumor from brainstem, (f) identification and dissection of CN VII from tumor, (g) removed tumor, and (h) endoscopic control of radicality of tumor removal in the fundus of internal auditory canal (asterisk: tumor; arrow: debulked cisternal and meatal portion of tumor; double arrowhead: arteriole on the surface of the CN VIII delineating vestibular and cochlear portion of the nerve; V: CN V, VII: CN VII, VIII: CN VIII, and IX-XI: CNs IX-XI; CN: cochlear nerve; VN: vestibular nerves; la: labyrinthine artery; spv: superior petrosal vein; hc: horizontal crest; vc: vertical crest).

Mentions: Details of the surgical technique were reported elsewhere [18]; thus, only critical steps are reviewed here. All surgeries were performed in supine position with head fixation in the 3-point Mayfield clamp. Facial nerve monitoring was used to identify and confirm the function of the facial nerve in all cases and continuous brainstem auditory evoked potentials (BAEP) for hearing monitoring were employed when applicable (12 cases) (NeMo NeuroMonitor, Inomed Medizintechnik GmbH). Craniotomy has been performed exposing the edges of the transverse and sigmoid sinuses. Opened mastoid air cells were closed with bone wax. Minimally invasive approach with craniotomy ≤2.5 cm was employed for small tumors (≤20 mm extrameatal extension). Dural incision has been done along the sinuses and lateral cerebellomedullary cistern was opened to allow egress of cerebrospinal fluid (CSF). Before dural incision, controlled hypotension and assisted hyperventilation to obtain a pCO2 of about 25 mm Hg and to lower the intracranial pressure to help spontaneous cerebellar retraction have been instituted. Bolus of corticoids at the same moment could be beneficial. Mannitol infusions and lumbar drainage were not needed. Thus, a minimal brain retraction was necessary. The intrameatal tumor portion was approached by removing the posterior wall of the IAC. Any dissection of the tumor from cranial nerves and vessels was performed after adequate tumor debulking (Figure 1). In case of preoperative hearing, we attempted its preservation. On the contrary in cases of preoperative deafness we did not attempt to preserve cochlear nerve. The same would be true for cases of obvious cochlear nerve injury during tumor dissection. Endoscopic technique (rod-lens Hopkins II endoscopes 4 mm lens with 0° and 30° and 70° viewing angle and length 18 cm, Clearview, Image 1 HD three-chip camera, KARL STORZ GmbH & Co.) with standard neurotological and neurosurgical instruments was used for monitoring of neurovascular anatomy in cerebellopontine angle (CPA), during dissection of the meatal portion of tumors, to assess radicality of resection and structures of labyrinth and for identification of potential pathways for CSF-leak formation. Multiple muscle pieces and fibrin glue have been used to plug the drilled IAC after tumor removal. Dura was closed with absorbable stitches. Pieces of muscle, fascia, and fibrin glue have been used to augment duraplasty. Previously removed bone and collected bony pate have been used for reconstruction of the skull at the end of the procedure.


Does attempt at hearing preservation microsurgery of vestibular schwannoma affect postoperative tinnitus?

Chovanec M, Zvěřina E, Profant O, Balogová Z, Kluh J, Syka J, Lisý J, Merunka I, Skřivan J, Betka J - Biomed Res Int (2015)

Steps of vestibular schwannoma removal via retrosigmoid-transmeatal approach (left side). (a) Tumor exposure in the cerebellopontine angle, (b) early opening of the internal auditory canal with debulking of tumor, (c) identification of CN VIII, (d) transection of vestibular nerves, (e) dissection of tumor from brainstem, (f) identification and dissection of CN VII from tumor, (g) removed tumor, and (h) endoscopic control of radicality of tumor removal in the fundus of internal auditory canal (asterisk: tumor; arrow: debulked cisternal and meatal portion of tumor; double arrowhead: arteriole on the surface of the CN VIII delineating vestibular and cochlear portion of the nerve; V: CN V, VII: CN VII, VIII: CN VIII, and IX-XI: CNs IX-XI; CN: cochlear nerve; VN: vestibular nerves; la: labyrinthine artery; spv: superior petrosal vein; hc: horizontal crest; vc: vertical crest).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4309247&req=5

fig1: Steps of vestibular schwannoma removal via retrosigmoid-transmeatal approach (left side). (a) Tumor exposure in the cerebellopontine angle, (b) early opening of the internal auditory canal with debulking of tumor, (c) identification of CN VIII, (d) transection of vestibular nerves, (e) dissection of tumor from brainstem, (f) identification and dissection of CN VII from tumor, (g) removed tumor, and (h) endoscopic control of radicality of tumor removal in the fundus of internal auditory canal (asterisk: tumor; arrow: debulked cisternal and meatal portion of tumor; double arrowhead: arteriole on the surface of the CN VIII delineating vestibular and cochlear portion of the nerve; V: CN V, VII: CN VII, VIII: CN VIII, and IX-XI: CNs IX-XI; CN: cochlear nerve; VN: vestibular nerves; la: labyrinthine artery; spv: superior petrosal vein; hc: horizontal crest; vc: vertical crest).
Mentions: Details of the surgical technique were reported elsewhere [18]; thus, only critical steps are reviewed here. All surgeries were performed in supine position with head fixation in the 3-point Mayfield clamp. Facial nerve monitoring was used to identify and confirm the function of the facial nerve in all cases and continuous brainstem auditory evoked potentials (BAEP) for hearing monitoring were employed when applicable (12 cases) (NeMo NeuroMonitor, Inomed Medizintechnik GmbH). Craniotomy has been performed exposing the edges of the transverse and sigmoid sinuses. Opened mastoid air cells were closed with bone wax. Minimally invasive approach with craniotomy ≤2.5 cm was employed for small tumors (≤20 mm extrameatal extension). Dural incision has been done along the sinuses and lateral cerebellomedullary cistern was opened to allow egress of cerebrospinal fluid (CSF). Before dural incision, controlled hypotension and assisted hyperventilation to obtain a pCO2 of about 25 mm Hg and to lower the intracranial pressure to help spontaneous cerebellar retraction have been instituted. Bolus of corticoids at the same moment could be beneficial. Mannitol infusions and lumbar drainage were not needed. Thus, a minimal brain retraction was necessary. The intrameatal tumor portion was approached by removing the posterior wall of the IAC. Any dissection of the tumor from cranial nerves and vessels was performed after adequate tumor debulking (Figure 1). In case of preoperative hearing, we attempted its preservation. On the contrary in cases of preoperative deafness we did not attempt to preserve cochlear nerve. The same would be true for cases of obvious cochlear nerve injury during tumor dissection. Endoscopic technique (rod-lens Hopkins II endoscopes 4 mm lens with 0° and 30° and 70° viewing angle and length 18 cm, Clearview, Image 1 HD three-chip camera, KARL STORZ GmbH & Co.) with standard neurotological and neurosurgical instruments was used for monitoring of neurovascular anatomy in cerebellopontine angle (CPA), during dissection of the meatal portion of tumors, to assess radicality of resection and structures of labyrinth and for identification of potential pathways for CSF-leak formation. Multiple muscle pieces and fibrin glue have been used to plug the drilled IAC after tumor removal. Dura was closed with absorbable stitches. Pieces of muscle, fascia, and fibrin glue have been used to augment duraplasty. Previously removed bone and collected bony pate have been used for reconstruction of the skull at the end of the procedure.

Bottom Line: Preservation of cochlear nerve but loss of preoperative hearing emerged as the main factor for tinnitus persistence and new onset tinnitus.Decrease of THI scores was observed postoperatively.Our results underscore the importance of proper pre- and intraoperative decision making about attempt at hearing preservation versus potential for tinnitus elimination/risk of new onset of tinnitus.

View Article: PubMed Central - PubMed

Affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, 1st Faculty of Medicine, Charles University, University Hospital Motol, V Úvalu 84, 150 06 Prague 5, Czech Republic.

ABSTRACT

Background: The aim of this study was to analyze the effect of vestibular schwannoma microsurgery via the retrosigmoid-transmeatal approach with special reference to the postoperative tinnitus outcome.

Material and methods: A prospective study was performed in 89 consecutive patients with unilateral vestibular schwannoma indicated for microsurgery. Patient and tumor related parameters, pre- and postoperative hearing level, intraoperative findings, and hearing and tinnitus handicap inventory scores were analyzed.

Results: Cochlear nerve integrity was achieved in 44% corresponding to preservation of preoperatively serviceable hearing in 47% and useful hearing in 21%. Main prognostic factors of hearing preservation were grade/size of tumor, preoperative hearing level, intraoperative neuromonitoring, tumor consistency, and adhesion to neurovascular structures. Microsurgery led to elimination of tinnitus in 66% but also new-onset of the symptom in 14% of cases. Preservation of useful hearing and neurectomy of the eighth cranial nerve were main prognostic factors of tinnitus elimination. Preservation of cochlear nerve but loss of preoperative hearing emerged as the main factor for tinnitus persistence and new onset tinnitus. Decrease of THI scores was observed postoperatively.

Conclusions: Our results underscore the importance of proper pre- and intraoperative decision making about attempt at hearing preservation versus potential for tinnitus elimination/risk of new onset of tinnitus.

Show MeSH
Related in: MedlinePlus