Acoustic neuromas are the most common type of tumor in the region of the internal auditory canal with a higher prevalence in females than in males . Our study found the same trend, with a larger prevalence of ANs in women (n = 59.1%) than in men (n = 40.9%). Dizziness is a shared complaint among patients presenting to primary care physicians, accounting for 30% of people suffering at different points . Dizziness is divided into four subtypes: vertigo, disequilibrium, presyncope, and psychological dizziness. Vertigo is a sensation of rotation or movement of one's self or of one's surroundings in any place, and vertigo is classified as peripheral or central. In AN patients, vertigo strongly influences quality of life. The true incidence of vertigo in the AN patient population is controversial, from 10%--70%[12–14]. In our practice, vertigo is present in 41% of patients at baseline. When these patients consult in the neurology department, they are commonly first diagnosed with peripheral vestibular vertigo, such as benign paroxysmal positional vertigo, Meniere’s disease, or persistent postural-perceptual dizziness. As they arise from the vestibular nerve, ANs can grow into the internal auditory canal and impinge on the eighth cranial nerve, cerebellum, or pons. Furthermore, ANs can cause secondary hydrocephalus and vestibular changes, which can result in vertiginous episodes. However, we found that it is difficult to observe or detect vestibular abnormalities. The average lag time for diagnosis is 37.25 months. A previous study suggested that tumor size may be associated with the severity of vertigo. Because ANs grow slowly and undergo sensory substitution, there is adequate time for the occurrence of vestibular compensation and adjustment. In addition, some have argued that the symptom of dizziness is related to patient age [16, 17]. Nilsen.et.al explained that central compensation leads to a slight decrease in dizziness over time in patients with diagnosed AN and counteracts the effects of aging. It is vital to detect vestibular dysfunction at the early stage of AN. In patients with non-specific vertigo, unexplained unilateral VHIT and VEMP asymmetry should alert neurologists to perform imaging.
Headache is among the most common causes in patients seeking medical attention in neurology departments. Headache resulting from acoustic neuromas generally belongs to the category of secondary headache. To date, most studies have focused on headaches after surgery, including microsurgical resection and retrosigmoid craniotomy[19–21]. Patients with postoperative headache syndrome appear to be directly associated with the presence of occipital nerve damage and occipital nerve excision can provide relief. Despite the connection between headache in patients with ANs and substantial physical and emotional burdens, this condition remains unnoticed. One study discovered that the prevalence of headache in patients was surprisingly 60%, with varying degrees of headache before treatment, and 19% recorded a positive history of migraine. RyzenHman and colleagues suggested that headache was the second most common symptom in 17.6% of patients with small tumors. In our study, headache was also the second most common neurological symptom in AN patents who consulted in the neurology department. Acoustic neuromas generally do not cause headaches until they are large enough to compress the fifth cranial nerve or until they cause obstructive hydrocephalus resulting from fourth ventricle effacement. Mechanisms of headache include increased intracranial pressure, venous outflow obstruction, and pain associated with dura sensitivity or meningeal vasculature as well as intracranial sensory nerves such as the trigeminal nerve, facial nerve, glossopharyngeal nerve, and vagus nerve.. Another explanation for headache caused by small ANs is dural traction within the internal auditory canal. In addition, occipital neuralgia is a type of headache that is partly related to a peripheral nerve-mediated mechanism. In terms of neuroanatomical observations of the trigeminal system, C2 and C3 projections are to the ventral posteromedial nucleus rather than to the ventral posterolateral nucleus, leading to headaches with occipital origin extending to the V1 distribution. The condition is often misdiagnosed as migraine, trigeminal neuralgia, or tension headache due to the different potential presentations of ANs; for example, there have been 5 cases where patients report that they were misdiagnosed with migraine, 1 case was tension headache.
Imaging is a crucial tool in the evaluation, treatment and management of patients with ANs, including magnetic resonance imaging (MRI) imaging and computerized tomography (CT). A previous study suggested that if the hearing threshold is worse than 70 dB, patient management should directly proceed to CT. However, MRI with gadolinium enhancement is now widely accepted as the 'gold standard' inspection for acoustic neuromas because it is superior for identifying soft-tissue structures, whereas CT can provide resolution of bone structures and detect moderate-large ANs. A further advantage of using MRI as the primary screening procedure is its ability to identify small tumors.T1-weighted sequences of mucoceles reveal hypointensity of the mass, whereas T2-weighted sequences show equal intensity or hyperintensity with significant enhancement. Some MRIs reveal a high signal intensity on both T1-weighted sequences and T2-weighted sequences because of the associated bleeding. Enhanced MRI scans show the most uneven patchy enhancement and ipsilateral auditory nerve thickening and strengthening, which are characteristics of neoplastic processes. Therefore, MRI was the best diagnostic and detection method in our cohort study.
Three treatment options are available for AN patients: observation, radiotherapy (RT) and microsurgery (MS) via hearing preservation retrosigmoid or middle fossa approach or trans-labyrinthine approach. The choice of treatment depends on several criteria such as age, comorbidity, tumor size and location, hearing status, expected treatment outcomes and complications, and patient preference. For small ANs, especially in elderly patients, the “wait and see” controlling method has been advised.The appropriate and proactive option for patients who hope for hearing preservation is microsurgery  or rehabilitation with translabyrinthine surgery and hearing aids. Multi-option management for small ANs has been found to be an effective strategy in terms of hearing outcomes.
We recognize some limitations of this study. First, our study is a retrospective data analysis. All relevant information was documented from electronic medical records. Second, the investigation lacked complete information about the exact neurological outcomes because the patients were discharged from the Department of Otolaryngology or Neurosurgery, and they did not have a routine neurological examination. Furthermore, the follow-up time was not long enough to obtain the terminal outcomes, and some patients who underwent the “wait-and-see” did not continue follow-up to identify the delayed treatment.