Treatment of vertigo after removal of a tumor of the balance and hearing nerve after neurosurgery, which damages or cuts the vestibular nerve (balance).

This trial explores the efficacy and safety of AM-125 in the treatment of acute vertigo. In this proof of concept trial patients experiencing vertigo after neurosurgery (vestibular schwannoma labyrinthectomy and vestibular neurectomy) will receive AM-125 or placebo. It evaluates the potential of AM-125 versus placebo in reducing the symptoms of vestibular dysfunction and accelerating vestibular compensation following neurosurgery.

Main Inclusion Criteria:

1. Scheduled for neurosurgery (vestibular schwannoma resection, labyrinthectomy or vestibular neurectomy).
2. Small to moderately large vestibular schwannoma (Koos grade I-III; Samii grade T1-T3b; ≤ 30 mm in diameter in cerebellopontine angle) that does not displace the brainstem, documented by magnetic resonance imaging not older than six months or Indication for labyrinthectomy or vestibular neurectomy.
3. Confirmed vestibular function on both sides.

Main Exclusion Criteria:

1. Prior radiotherapy (gammaknife, intensity modulated radiation therapy) irradiating the brain-stem with more than 4 Gy.
2. Any ongoing other peripheral vestibular disorder (e.g. Meniere's disease, benign paroxysmal vertigo, vestibular neuritis) or central vestibular disorder (e.g. vestibular migraine, central vertigo).
3. Vestibular rehabilitation therapy or presurgical gentamicin therapy (i.e. "pre-habilitation therapy") within the past three months prior neurosurgery.
4. Any clinically relevant nasal obstruction or pathology precluding effective and/or safe intranasal delivery.

For intranasal subjects, allocation is blinded. The oral arm is an open-label arm.