Radio Surgical Ablation of Acoustic Neuromas: A Unique Treatment Modality for an Elderly Woman

This is the authors' abstract. We don't add key points for this paper.

To the Editor: Acoustic neuromas (ANs) are tumors of the tissues covering nerves (the Schwann cell). They are often benign, and the eighth cranial nerve is most commonly affected. Variability in growth and progression of symptoms make their management challenging. This is a report on the case of a 66-year-old woman with an AN who was successfully treated using gamma knife ablation. A 66-year-old woman presented to the clinic with a complaint of right-side facial numbness, tingling, right-side hearing loss, abnormal taste sensation, and an unsteady gait that started after treatment for a dental abscess and extraction of her right upper molar. A course of antibiotics was not successful in alleviating her symptoms. Her past medical history included asthma, obstructive sleep apnea on continuous positive airway pressure therapy, and basal cell carcinoma treated with Mohs excision. She had no limitations in her functional status or cognition, and her physical examination was benign. Magnetic resonance imaging of the brain without contrast showed a 1.8- by 1.3-cm mass of the right internal auditory canal through the porus acusticus into the cerebellopontine angle cistern with associated mild brain stem compression (Figure 1). Computed tomography of the neck from February 2008 showed no mass, favoring a diagnosis of AN. Audiometric testing showed mild to moderate high-frequency sensorineural hearing loss in the right ear. The neurosurgeons discussed the advantages and disadvantages of conservative management, radiosurgery, and surgical intervention. She opted for the radiosurgical approach, which required no admission to the hospital. Two months later, the tumor size remained stable, with diminished facial pain and tingling and improved gait and hearing. AN, also known as vestibular schwannoma, has an incidence of 19 per million per year.1 ANs are usually slow growing, with symptoms and signs that vary depending on the size and location of the tumor. One study enrolled 114 individuals and found that hearing loss was the main symptom, with tinnitus being the most-frequent associated symptom.2 Other associated symptoms include pressure sensation in the ears, dizziness, imbalance, and facial disorders (pain, paresthesias, numbness, weakness, twitching). Variability in the growth and progression of symptoms can make the decision about the mode of management challenging. The majority of tumors grow, and a small portion regress. There are three management approaches—surgical intervention, radiosurgical intervention, and observation.3 Observation (wait and see) has been used for slow-growing, stable, and regressing tumors, although studies suggest poorer outcomes because even small tumor growth results in diminished hearing and decreased facial nerve preservation.4, 5 Surgical removal has long been considered the criterion standard of management. Tumor size and surgeon experience are the two main factors to be considered with surgical intervention,6 which is invasive and may be complicated by blood loss, pain, postprocedure infection, and damage to surrounding structures. Specific to AN surgery is the risk of cerebrospinal fluid leaks, meningitis, cranial nerve palsy, disordered vestibular compensation, intracranial hemorrhage, postprocedure headaches, and mortality.6 Radiosurgical intervention uses image guidance and radiation directed precisely at the lesion. Delivery methods are gamma knife (as in this case), linear accelerators, and proton beam and heavy-charged particles. Radiation leads to disruption in cell deoxyribonucleic acid, which results in permanent cancer cell damage and death. This procedure is less invasive than surgery and is preferred in individuals with high anesthetic risk and may therefore be preferred in elderly adults.7 Complications include cranial nerve dysfunction and radiation-associated inflammation, but dose-adjusted radiosurgery shows preservation of hearing and fewer episodes of cranial nerve dysfunction than surgery.8 There is the added benefit of reducing the need for hospitalization, maintaining functionality, and hearing improvement,9 as was the case for this woman. In conclusion, when considering AN management in an older adult, radiosurgical intervention is less invasive, reduces the need for hospitalization, and shortens the recovery period. There may be the added benefit of fewer complications. Conflict of Interest: The authors declare no competing interests. Author Contributions: Preparation of this manuscript was a collaborative effort of Jasmine Brathwaite and Priya Mendiratta. Sponsor's Role: None.