A method for using
high intensity focused ultrasound (HIFU) to treat neurological structures to achieve a desired therapeutic affect. Depending on the dosage of HIFU applied, it can have a reversible or irreversible effect on neural structures. For example, a relatively high
dose of HIFU can be used to permanently block
nerve function, to provide a non-invasive alternative to severing a nerve to treat severe
spasticity. Relatively lower doses of HIFU can be used to reversible a block
nerve function, to alleviate pain, to achieve an
anesthetic effect, or to achieve a cosmetic effect. Where sensory nerves are not necessary for voluntary function, but are involved in pain associated with tumors or
bone cancer, HIFU can be used to non-invasively destroy such sensory nerves to alleviate pain without drugs. Preferably,
ultrasound imaging synchronized to the HIFU therapy is used to provide real-time
ultrasound image guided HIFU therapy of neural structures.