Clarence B. Watridge, MD, remembers learning in medical school when brain surgery was so likely to result in death that the hair shaved from the scalp prior to the scalp opening was saved for use by the undertaker—just in case.

 

“Much has been known about the anatomy of the brain for centuries,” said Watridge, chairman of Semmes-Murphey Neuro Institute in Memphis, and a neurosurgeon at Semmes Murphy and Baptist Memorial Hospital-Memphis. “Brain physiology and function have been correlated with anatomy for a long time, so many areas are considered ‘eloquent,’ meaning surgical manipulation of certain areas will result in neurologic deficits. Much remains to be learned about brain function, connections, ‘plasticity,’ and recovery.”

 

Initial brain surgeries were performed based on localization of where the pathology was—based on the presenting symptoms and neurologic abnormalities on examination, matching those with known anatomy, physiology, and function, Watridge said.

 

“This required the surgeon to make a large opening in the scalp and skull to inspect the brain,” he explained. “In many instances, the surface of the brain renders a hint of underlying pathology, but many times the brain surface appears completely normal. Diagnostic studies that were developed, such as pneumoencephalography and arteriography, could indicate the presence of a mass in one of the compartments of the skull but no information of the nature of that mass.”

 

In the 1970s, computerized tomography (CT) was developed, allowing the measurement of different densities within the skull.

 

“Densities of structures measured by CT are measured in Hounsfield Units,” said Watridge. “Brain has a specific density, as does spinal fluid, calcium, acute blood, chronic liquefied blood. CT enabled surgeons and radiologists to predict what many abnormalities inside the head and brain were likely to be, and assist in the localization. Even though the CT accurately localized the abnormalities on each scan or slice, the angle of the ‘gantry’ (the plane of the CT x-ray beam) during the scan was important to consider when determining how far forward or back an abnormality may be. Early in the utilization of CT, it was common to place the opening in the scalp and skull in a location the surgeon thought was directly over the pathology, but wasn’t.”

 

Magnetic Resonance Imaging (MRI) was developed in the 1980s. The imaging method employs a magnetic field—not an X-Ray—that aligns the protons of cells that take on a certain intensity.

 

“Structures in the brain have certain intensities and the length of exposure to the magnetic field can make structures have different intensities,” noted Watridge. “For instance, a T2-weighted scan makes spinal fluid appear bright, whereas a T1-weighted scan makes the spinal fluid appear dark. Because MRI protocols include axial, coronal, and sagittal images, localization of brain abnormalities gives the surgeon a more accurate determination of where an abnormality is located.”

 

In the 1990s, computer specialists and physicians developed a surgical planning technique combining the images of scans (CT and MRI) with operating instruments, resulting in surgical navigation.

 

“Surgical navigation involves loading digitized imaging data into a computer, registration of head surface anatomy into the computer, and utilizing instruments to navigate to surgical targets,” said Watridge. “This allows precise localization to the millimeter size. Biopsies can be performed through small cranial openings, catheters can be placed in precise locations, and surgical resection of tumors can be aided. The planning of the surgical approach takes into context the eloquent areas of the brain, and minimizes the likelihood of irreversible injury. Smaller openings can be performed as the surgeon has more confidence the opening is precisely where it needs to be to deal with the pathology.”

 

Watridge studied medicine on an Armed Forces Health Professions Scholarship at the University of Tennessee Center for the Health Sciences (UTCHS) in Memphis, where classmates recognized his talents by presenting him with the Most Promising Physician Award. He spent time during his residency training in neurosurgery at Frenchay Hospital in Bristol, England, before returning to Memphis. In 1985, he joined the Semmes-Murphey Clinic, where he now serves as chair, and the UT Department of Neurosurgery faculty, where he is associate professor. Former president of the Southern Neurosurgical Society, Tennessee Neurosurgical Society, and Memphis Medical Society, and currently a board member of the American Association of Neurological Surgeons and on the Board of Governors for the American College of Surgeons, Watridge’s special areas of interest include cerebrovascular disease, brain tumor surgery, tic douloureux and hemifacial spasm, and degenerative cervical spine disease. A principal investigator at the Memphis site for the Carotid Occlusion Surgery Study (COSS), Watridge’s research interests also include co-investigating an artificial cervical disc trial, and participating in an asymptomatic carotid artery surgery trial, brain tumor therapies, and the North American Symptomatic Carotid Endarterectomy Trial (NASCET).

 

“Of course, all this progress comes with a price,” said Watridge. “Computers and scanning devices continue to develop and improve and get faster. All these technologies have to be paid for by the institution. Upgrades are the rule and not the exception. Is this progress worth the price? Maybe this cannot be established in dollars and cents, but the safety and accuracy with which brain surgery can be accomplished today is tremendously better than it was even 20 years ago.”