John McCain's 'blood clot' may explain his recent behavior

Senator John McCain recently had surgery to "remove a blood clot above his left eye," according to a CNN report.  CNN fortunately didn't have a chance to wade into its familiar territory of fake news because it had a practicing neurosurgeon, CNN chief medical correspondent Dr. Sanjay Gupta, on hand to discuss Senator McCain's surgery.

Despite the cheery description, "minimally invasive craniotomy," this was brain surgery, opening the skull and removing something from the senator's brain.  Nothing simple or minimal about this.  Otherwise, neurosurgeons wouldn't need many years of training.

Dr. Gupta is correct in calling what was removed from the senator's brain "an abnormality."  It could also be described as "a lesion" or "a mass."  Although news articles called it "a blood clot," it was sent to pathology to be reviewed under a microscope to see what was actually removed.

Typically, blood that is drained or removed from a body cavity is not examined under a microscope.  Such detailed analysis is used for a tissue diagnosis – meaning that there was likely something besides blood removed from the senator's brain.

Lots of possibilities.  A cyst.  A mass, meaning a growth or tumor.  Could be benign or malignant.  Could be primary to the brain or spread from somewhere else.

Senator McCain was diagnosed with cutaneous or skin melanoma in 2000.  One of his skin tumors penetrated a bit deeper into the skin, meaning higher risk of spread throughout his body.  But this was also 17 years ago.

His surgery and lymph node analysis found no evidence of spread.  Good news at the time.  But the old saying applies: "Absence of evidence is not evidence of absence."

Fast-forward to last month, when Senator McCain was questioning former FBI director James Comey at a Senate Intelligence Committee hearing.  As the Washington Post reported at the time, McCain "referred to 'President Comey,' and at times looked confused and frustrated with Comey's answers. Viewers clearly thought it was notable; Twitter announced it was the most-tweeted moment of the hearing."

Partisan questioning or an uninformed senator trying to sound smart in front of the TV cameras?  Or something more?

Senator's McCain recent surgery was just above his left eye, meaning the frontal lobe of his brain.  The brain is incredibly complex, and each portion has specific purposes.  What does the frontal lobe do?

The frontal lobe is responsible for higher functions of the brain – personality, thought process, problem-solving, and conscience, as well as socially acceptable responses.  In other words, these are the specifically human aspects of behavior, as opposed to lower brain functions such as the "fight or flight" response.

A lesion in the frontal lobe could certainly be responsible for behavioral changes, such as McCain's "bizarre questioning of Comey," as described by the Washington Post.

Whether the senator just had a blood clot pressing on his brain or whether he had a tumor, melanoma, or otherwise remains unknown.  I am an eye surgeon, not a neurosurgeon, and I am not the senator's physician.  But given the speculation by reporters and journalists who know little about medicine, I wanted to provide another, hopefully more educated and useful analysis of the senator's situation.

I wish Senator McCain and his family the best under these challenging circumstances.

Brian C Joondeph, M.D., MPS is a Denver-based physician and writer.  Follow him on Facebook, LinkedIn, and Twitter.

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