Robert Louis, MD, has Partnered with Find a Top Doc. Robert Louis, MD, a fellowship-trained Orange County Neurosurgeon, is the Director of the Skull Base and Pituitary Tumor Program at Hoag Memorial Hospital in Orange County, California. Dr. Louis has particular expertise in endoscopic and minimally invasive treatment of benign and malignant ...Contact Us‧Neurosurgery‧Neurologic Conditions‧Procedures‧Patient Resources‧Brain and Skull Base Tumors.