6.1 Introduction

The clinical presentation of sporadic vestibular schwannoma (VS)—a spontaneous disease without the evidence of an underlying genetic syndrome, in particular neurofibromatosis type 2—is relatively homogenous, with a small number of dominant symptomatologies accompanied by several uncommon variants or anecdotal exceptions. Symptoms of VS occur either as a direct result of their involvement of the vestibulocochlear system or from compression of adjacent structures—including the facial nerve, trigeminal nerve, cerebellum, brainstem, or fourth ventricle. Notably, the fraction of diagnoses made incidentally has grown markedly in recent history, attributable to the growing availability of high-resolution magnetic resonance imaging (MRI) technology, and the rise in the use of this imaging modality for surveillance in unrelated disease such as headache.

6.2 Vestibulocochlear Presentations

Overwhelmingly, unilateral sensorineural hearing loss dominates the landscape of VS clinical presentation, most often occurring with a characteristic high-frequency loss (Fig. 6‑1 ). In several large cohorts documenting the natural history of these tumors, subjective hearing deficits have been reported from 26 up to 95% of patients—with equal or higher rates detected on audiometric testing.s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur Unilateral tinnitus represents the second most common cochlear symptom, occurring in 12 to 60% of patients, and frequently accompanied by a nonspecific sense of aural fullness.s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur In spite of this, delay in identification of an underlying VS in patients with auditory symptoms is common, with mean time to diagnosis averaging 3.7 to 7.6 years after symptom onset in these same series.

By contrast, sudden hearing loss is an uncommon presentation of VS, accounting for 2 to 7% of patients, with waxing and waning symptoms indicating intermittent cochlear dysfunction occurring less frequently still.s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur When approached from the perspective of clinical assessment in sudden sensorineural hearing loss, discovery of an underlying VS is rare, accounting for less than 5% of all patients.s. Literatur Nevertheless, where present, sudden hearing loss may benefit from corticosteroid therapy—either via a short oral course or intratympanic injection—although the results of relevant clinical trials have been equivocal, and not specifically designed or powered to look at the VS subpopulation.s. Literatur ^,​ s. Literatur

As with cochlear nerve symptoms, vestibular dysfunction is prominent in the clinical presentation of VS, typically precipitating symptoms of dizziness, imbalance, or gait unsteadiness, whereas spells of true vertigo are less common. Clinical complaints invoking the vestibular system arise in 14 to 61% of VS patients; as with hearing loss, formal testing on asymptomatic individuals often discloses a degree of dysfunction that is either clinically insignificant or that the patient is able to unconsciously compensate.s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur Where vestibulopathies were parsed in detail and reported independently, gait disturbance was noted in approximately 40%, although the fraction attributable to concomitant brainstem compression is difficult to establish definitively.s. Literatur ^,​ s. Literatur ^,​ s. Literatur Frequently, vestibulopathy in VS is complex, with one in three patients reporting multiple concomitant symptoms.s. Literatur

6.3 Trigeminal Facial Presentations

After hearing loss and vestibulopathy, craniofacial sensory changes localizing to the trigeminal nerve represent the next most common group of presenting symptoms. Numbness predominates, affecting 7 to 49% of all patients in at least one distribution, with a preponderance of V2 symptoms.s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur Less commonly, involvement of the ipsilateral nerve may induce trigeminal neuralgia or paresthesia, which occur in approximately 1 to 3% of patients and share the same preference for a V2 distribution.s. Literatur ^,​ s. Literatur ^,​ s. Literatur In these patients, tumors can present with classic trigeminal neuralgia symptoms, a specific unrelated complaint such as otalgia, or a nonspecific facial pain syndrome.s. Literatur ^,​ s. Literatur Very rarely, contralateral facial pain has been documented, with symptomatic resolution following removal of the tumor.s. Literatur In the vast majority of cases involving trigeminal symptoms, diagnostic delays are less significant than in the setting of hearing loss, with most patients reporting symptoms over 0.6 to 1.3 years prior to diagnosis.s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur Motor trigeminal symptoms are infrequently reported, but in one large study, mastication disorders were observed in 3% of patients, and the ipsilateral corneal reflex was noted to be absent in 15%.s. Literatur

Facial nerve symptoms are uncommon but by no means unheard of; however, the presence of a facial nerve paresis at diagnosis should significantly raise the index of suspicion for a primary facial nerve tumor or malignancy. Notwithstanding, several large series report a limited incidence of facial weakness or hemifacial spasm in patients with confirmed eighth nerve tumors, with an overall incidence of 1 to 4%.s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur Hemifacial spasm and taste disturbance are less common still, occurring in less than 1 to 4% of patients at primary presentation in larger series, with rare case reports documenting hemifacial spasm as the primary presenting symptom—including one instance of ipsilateral hearing loss and contralateral hemifacial spasm, which resolved following tumor resection.s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur ^,​ s. Literatur Diagnostic delays in patients with isolated facial nerve symptoms are slightly more pronounced than those with trigeminal symptoms, typically leading to the identification of a VS within 2 years. Of note, although the majority of these symptoms occurred in patients with simultaneous hearing loss, the observed results are preserved in cohorts with normal hearing—studies in patients without a hearing deficit revealed that most patients presented with vestibular, trigeminal, and facial neuropathies, in that order.s. Literatur