Unfortunately, there is little published scientific literature that specifically addresses the impact of gentamicin poisoning on concentration or memory, although a very common complaint of gentamicin poisoning victims is a frustrating lack of concentration and ability to plan and carry out complex tasks, coupled with short-term memory loss.
According to the Vestibular Disorders Association, the cognitive and psychological symptoms of vestibular disorders can include:
Dr. Timothy Hain, a neurologist at Northwestern University in Chicago who has studied balance disorders and gentamicin ototoxity extensively, notes on his website:
Many people with bilateral vestibulopathy complain of a mild confusion or "brain fog", which is attributed to the increased attention needed to maintain balance and good vision, due to loss of vestibular input. Others call it "inability to multi-task". It is thought that in persons with bilateral vestibular loss, the ongoing extra effort needed to keep ones balance reduces the amount of attention that is available for other thinking tasks. Considerable evidence for this can be found in the recent literature (Andersson et al, 2003; Pellecchia, 2003; Redfern et al, 2003). Persons with other vestibular disorders often complain of difficulty concentrating and mental fatigue (Yardley et al. 1998). Complete web page here.
The references Dr. Timothy Hain cites:
Anderson G and others. Dual-Task study of cognitive and postural interference in patients with vestibular disorders. Otol Neurotol 24:289-293, 2003. Abstract
Pellechia GL. Postural sway increases with attentional demands of concurrent cognitive task. Gait and Posture 18(2003), 29-34 Abstract
Redfern MS and others, Cognitive influences in postural control of patients with unilateral vestibular loss. Gait and Posture, 2003, Abstract
Yardley L, Burgneay J, Nazareth I and Luxon L (1998). "Neuro-otological and psychiatric abnormalities in a community sample of people with dizziness: a blind, controlled investigation." J Neurol Neurosurg Psychiatry 65(5): 679-84. Abstract