What exactly are alternative therapies for neurological disease?

Alternative treatmen. This depends on what neurological disease you are referring to. There are many neurological disease, and many of which have different alternative treatments.
Ask your neurologist. Most "alternative" therapies are nothing but useless scams. Some are very harmful. Don't be a sucker.
Alternative therapy. Depending on the neurologic condition, there are many alternative treatments. Dietary management, herbal preparations, vitamins, meditation, exercises minerals, among others. Before relying on any of these, you should check with your doctor or neurologist.