Inclusion Criteria:

- ≥ 18 years of age, but ≤70 years of age;

- IIEF EF Domain*1 score ≥ 22;

- be able to effectively communicate with study personnel;

- be considered by the physician to be available for subsequent visits;

- be willing to comply with all aspects of the treatment and evaluation schedule over a
24 month duration;

- sign and date an IRB-approved written informed consent prior to initiation of any
study procedures, including screening procedures; and

- require radical prostatectomy.

Exclusion Criteria:

- prior surgery in the last 6 months which could affect sexual function;

- history of Peyronie's disease;

- significant neurological disorder (i.e. multiple sclerosis, peripheral neuropathy);

- treatment for major psychiatric disorders;

- history of penile implant or prosthesis;

- history of diabetic neuropathy;

- life expectancy of less than two years;

- concurrently involved in another investigational study;

- uncontrolled hypertension with systolic BP >200mmHg or diastolic BP >115mmHg is
present at screening;

- currently receiving or planned treatment with chemotherapy or radiation therapy;

- diagnosis of bony metastasis;

- known allergy or severe intolerance to PDE-5 inhibitors; or

- cardiac pacing equipment or other electro-mechanical devices which preclude the use
of CaverMap™ neurostimulator.