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Minimally Invasive Neurosurgical Approach to Preserve Hearing while Treating an Acoustic Neuroma
Acoustic neuroma, also known as vestibular schwannoma or schwannoma of the auditory nerve, originates from Schwann cells along the eighth cranial nerve. This type of tumor accounts for approximately 8% of all intracranial tumors. It predominantly occurs in the cerebellopontine angle region, comprising 80-90% of all tumors in this location.
Acoustic neuroma, also known as vestibular schwannoma or schwannoma of the auditory nerve, originates from Schwann cells along the eighth cranial nerve. This type of tumor accounts for approximately 8% of all intracranial tumors. It predominantly occurs in the cerebellopontine angle region, comprising 80-90% of all tumors in this location.
Case Presentation:
A patient presented with symptoms of dizziness, tinnitus, and a six-month history of left-sided hearing loss. Pure tone audiometry indicated a preservation of 70% hearing capability. The patient opted for tumor removal surgery with a specific request to preserve as much of the auditory and facial nerve function as possible.
Procedure:
A five-hour minimally invasive neurosurgical operation was performed. Throughout the surgery, continuous intraoperative nerve monitoring (IOM) was employed to ensure real-time monitoring of facial and auditory nerve functions.
Outcomes:
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Over 60% of the tumor was successfully excised.
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The internal auditory canal was opened up to create more space, accommodating both the auditory nerve and the remaining benign tumor, reducing the potential for further hearing degradation.
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The facial nerve function was preserved.
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Auditory nerve functionality was also maintained.
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The patient was discharged two days post-operation.
Postoperative MRI:
The MRI revealed that more than 60% of the tumor had been removed, and the auditory nerve remained intact. Over a year of follow-up appointments showed that the remaining 40% of the benign tumor had not grown. The patient did not require postoperative radiotherapy, and hearing levels remained stable, consistent with preoperative levels.
Future Treatment Plans:
MRI surveillance will monitor the growth of the remaining benign tumor. If needed, radiotherapy could be employed to treat any residual tumor growth.
Conclusion:
This case, over a year post-surgery, demonstrates that it is possible for individuals to coexist happily with a benign acoustic neuroma, with preserved quality of life and minimal impact on auditory functions.
Acoustic neuroma is a benign brain tumour arising from the acoustic nerve of hearing at brainstem.
Left: MRI in axial view revealed a 3.5 cm round shaped left acoustic neuroma compressing on brainstem.
Right: MRI in coronal view revealed a 3.5 cm round shaped left acoustic neuroma compressing on brainstem.
During surgery under microscope, the 3.5 cm round-shaped left acoustic neuroma compressing on cerebellum.
The 9-11th lower cranial nerves were just next to the tumour.
Using a nerve stimulation probe to detect the position of facial nerve during surgery in order to preserve its function.
The acoustic neuroma had been debulked at its inside and the outer tumour capsule was kept left behind to avoid the injury of acoustic nerve for hearing preservation.
Most of the tumour was removed and the cerebellum and brainstem were both well decompressed at the end of surgery.
MRI after surgery (upper row of 3) was compared with MRI before surgery ( the lower row of 3 ), showing that most of the tumour was excised, the brainstem, cranial nerves were well decompressed. Patient’s hearing and facial nerve function were both preserved.
Postoperative radiosurgery treatment with using Cyberknife is option, most patient’s small residual tumour can be observed by MRI in future, if there is no tumour growth and symptom, no treatment is necessary.