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.

vestibular schwannoma, acoustic neuroma, cerebellopontine angle tumour, gentamicin, rehabilitation, postural balance

Installation of gentamicin in the middle ear 6 weeks prior to surgery + rehabilitation exercises before and after both treatment and surgery. Rehabilitation exercises are not considered to be an intervention since their benign impact on vestibular/postural compensation is well documented, and exclusion from exercises would not be approved by the ethical board.

Rehabilitation exercises before and after surgery. Rehabilitation exercises are not considered to be an intervention since their benign impact on vestibular/postural compensation is well documented, and exclusion from exercises would not be approved by the ethical board.

Intratympanic installation of gentamicin 2-4 times depending on the efficacy of vestibular deafferentation

Measuring hearing levels (pure tone hearing and speech discrimination) before and after gentamicin treatment to determine possible detrimental effect on hearing

Daily Measures of cortisol in the saliva after surgery during the time patients are admitted to the hospital

Measure of level of impact of dizziness in daily life, measured with Dizziness Handicap Inventory (DHI)

Measure of level of anxiety and depression after surgery, enquiry with Hospital Anxiety and Depression Scale (HADS)

Measure of level of impact of dizziness in daily life, measured with Dizziness Handicap Inventory (DHI)

Measure of level of impact of dizziness in daily life, measured with Dizziness Handicap Inventory (DHI)

To measure spontaneous nystagmus after surgery and its direction as a sign of vestibular deafferentation or central nervous damage

Day 1 after surgery and for duration of either spontaneous nystagmus or hospital stay (up to 2 weeks)

Vestibular function tests, v-HIT, calorics and otolith tests to determine compensation and function after gentamicin treatment

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

Magnusson M, Padoan S. Delayed onset of ototoxic effects of gentamicin in treatment of Meniere's disease. Rationale for extremely low dose therapy. Acta Otolaryngol. 1991;111(4):671-6. doi: 10.3109/00016489109138398.

Tjernstrom F, Fransson PA, Kahlon B, Karlberg M, Lindberg S, Siesjo P, Magnusson M. Vestibular PREHAB and gentamicin before schwannoma surgery may improve long-term postural function. J Neurol Neurosurg Psychiatry. 2009 Nov;80(11):1254-60. doi: 10.1136/jnnp.2008.170878. Epub 2009 Jul 1.

Magnusson M, Kahlon B, Karlberg M, Lindberg S, Siesjo P, Tjernstrom F. Vestibular "PREHAB". Ann N Y Acad Sci. 2009 May;1164:257-62. doi: 10.1111/j.1749-6632.2009.03778.x.

Magnusson M, Karlberg M, Tjernstrom F. 'PREHAB': Vestibular prehabilitation to ameliorate the effect of a sudden vestibular loss. NeuroRehabilitation. 2011;29(2):153-6. doi: 10.3233/NRE-2011-0689.

Magnusson M, Kahlon B, Karlberg M, Lindberg S, Siesjo P. Preoperative vestibular ablation with gentamicin and vestibular 'prehab' enhance postoperative recovery after surgery for pontine angle tumours--first report. Acta Otolaryngol. 2007 Dec;127(12):1236-40. doi: 10.1080/00016480701663433.

Postema RJ, Kingma CM, Wit HP, Albers FW, Van Der Laan BF. Intratympanic gentamicin therapy for control of vertigo in unilateral Menire's disease: a prospective, double-blind, randomized, placebo-controlled trial. Acta Otolaryngol. 2008 Aug;128(8):876-80. doi: 10.1080/00016480701762458.