Gentamicin Treatment Prior to Schwannoma Surgery - Residual Function

Gentamicin Treatment Prior to Vestibular Schwannoma Surgery in Patients With Definite Remaining Vestibular Function

The purpose of the study is to determine whether vestibular and postural compensation following schwannoma surgery is improved by ablating remaining vestibular function prior to surgery, through gentamicin injections in the middle ear.

The residual function of the vestibular system before surgery differs considerably between patients, due to extent and influence of tumor growth, resulting in varying spectra of post-surgery illness as well as vestibular symptoms. An acute unilateral vestibular deafferentation (uVD) (if significant vestibular function remains prior to surgery) invariably results in severe nausea and vertigo. The nausea/vertigo induced by surgery and sudden uVD both can impede vestibular compensation processes and in extension, also the need for rehabilitation. The vestibular PREHAB protocol was developed in order to address this problem and to ensure an enhanced and sufficient rehabilitation. The protocol encompass treating patients that have measurable vestibular function before surgery with intratympanic gentamicin injections, thus producing gradually a uVD over a period of 3-4 weeks, whilst performing daily vestibular exercises before and after the gentamicin treatment. Through this procedure the sensory trauma is separated from the surgical trauma, making it possible for vestibular compensation to ensue as the vestibular function gradually decline from gentamicin toxicity, unencumbered by any depression of central nervous function that might result from schwannoma surgery or the acute stages of an uVD.

Inclusion Criteria:

• diagnosed with vestibular schwannoma and surgical treatment is advised
• remaining vestibular function

Exclusion Criteria:

• impaired decision making
• no remaining vestibular function
• signs of central nervous dysfunction
• neurofibromatosis
• Patients are advised not to participate in the gentamicin arm but encouraged to participate in the 'non-gentamicin' arm:
• when hearing is better than 30decibel (dB) i pure tone average (500, 1000, 2000, 3000/4000 Hz) and speech discrimination better than 70% -when the neurosurgeon aim at hearing preservation surgery and do not want to risk gentamicin- associated hearing loss