A unilateral sudden loss of function generates intense and frightening symptoms urging patients to see a doctor. Generally, the symptoms and signs of the deficit are so obvious that doctors make the diagnosis quickly. The situation is quite different if the deficit is gradual and affects both sides. To better understand the difficulties faced by patients suffering from total bilateral vestibular loss, 19 subjects were interviewed in a semistructured talk. The discussion focused on five main topics: (1) symptoms, (2) the medical trajectory from the earliest symptoms to the diagnosis, (3) the prescribed treatments, (4) the impact of the disease on work, and (5) the impact on social functioning and recreational activities. The symptoms reported by patients are insidious, and they may suggest a neurological deficit or a cardiocirculatory or psychiatric disorder. The diagnosis is often made after several consultations with several doctors from different specialties. When the diagnosis is made, all kinds of treatment are undertaken, in particular vestibular rehabilitation. Indeed, most physicians believe that it can promote central compensation processes, even though it has been demonstrated that vestibular exercises are ineffective in most of these patients. Two thirds of our subjects were obliged to modify or even stop their professional activities due the bilateral vestibular loss. In some patients, the disability is such that they almost constantly require the presence of their spouse. In conclusion, the symptoms of bilateral vestibular loss are sometimes misleading. They are often not recognized by doctors. The deficit has an obvious impact on patients' social functioning and professional activities.

The quality of life of patients suffering from a bilateral vestibular loss is severely altered. Patients mainly complain of oscillopsia, imbalance, and spatial disorientation. Up to now, there is no efficient treatment. Some teams around the world are working on the development of a vestibular implant for the restoration of the vestibular function based on the concept similar to that of a cochlear implant, stimulating the neural vestibular pathways through electrical pulses. There are different potential stimulation sites of the vestibular system, all raising the major concern about a potential hearing loss in the implanted ear. As this implant does not exist yet, patients cannot be informed of the risk of hearing loss due to the surgical intervention versus the benefits brought by the vestibular prosthesis. In order to better inform future vestibular implant candidates, we need to evaluate the handicap of patients with an actual unilateral hearing loss, and to compare it to the way that patients suffering from a bilateral vestibular loss perceive a potential unilateral hearing loss. For this, we used the HHIA questionnaire (Hearing Handicap Inventory for Adults) on 3 groups of participants, i.e. patients with a unilateral hearing loss, patients suffering from a bilateral vestibular loss but having normal hearing, and healthy subjects. The scores reported by patients with a unilateral hearing loss were much lower than those of the other 2 groups, indicating that people whose hearing is normal overstate the disability related to a unilateral hearing loss. Patients to whom a vestibular implant is proposed in order to correct their balance disorders may use this information to decide whether or not to choose an operation.