Also known as 'nerve deafness', sensorineural hearing loss is a term used to refer to trauma in the inner ear. This trauma can cause damage to either the cochlea (as in sensory hearing loss) or the acoustic nerve (as in neural hearing loss). Together, these conditions are termed 'sensorineural' and they pose a particularly tricky problem for medical professionals trying to treat patients suffering with it.
As you probably know already, the inner ear is incredible delicate, with thousands of hair-like nerves playing an important role in the function of hearing. If these are damaged then complete hearing loss can be instant, although for some people it's gradual but permanent. Nerves carry information to and from the brain, both about what they are sensing and also what the brain would like the tissue/muscle/organ that they're linked to, to do. The sensorineural nerves are not so much functional nerves, but messenger ones instead, constantly relaying information to the brain about what they are hearing. If they become damaged, however, the individual's ear is still picking up sounds, but there's no way to get that information to the brain. This means there's no information about sound that can be processed once it gets there and the person is effectively deaf.
It's lucky that humans have evolved a pair of ears on either side of the head, because if the nerves within one become damaged beyond repair then we still have hearing in the other. Trauma often occurs from water pressure damage, in which case one side of the head is often facing the surface but the damaged side is not. This kind of condition could have been life threatening thousands of years ago when we lived amongst predators, but today we would generally only miss snatches of conversation, perhaps train announcements or anything that goes on while we sleep on the ear that we can hear from. Basically, partial hearing loss today is not life threatening and in fact, neither is total hearing loss. Those who experience sensorineural hearing loss or nerve deafness will most likely be referred to a speech therapist or a teacher of ASL (American Sign Language) so that they have a new avenue of communication.
Unfortunately for patients suffering with sensorineural hearing loss, the condition is usually incurable, meaning that patients will never recover hearing in the ear affected again. However, patients are often lucky that sensorineural hearing loss is very rare in both ears. So while they may have 0% hearing in one ear, their right ear will most likely take over and may even become more effective than it was before. Some sufferers may find that their other senses become more keen, such as smell and touch to compensate for the loss of hearing.
If you are experiencing sensorineural hearing loss symptoms then you should visit a medical professional for their opinion immediately. You may be referred to a hearing specialist to see if there are any hearing aids or implants that would help your condition and you may require nerve tests on other areas of your body to check you are not suffering from a specific nerve disorder.