I stood behind my seated mother, with a hand on her shoulder.

"What is it?" Mom asked. "A stroke? For God's sake, Cliff is only thirty-nine. He's too young for a stroke."

"A stroke can happen at any age," said Dr. Thanh. "But, although technically this was a form of stroke, it's not what you're thinking of."

"What then?"

"Your husband has a kind of congenital lesion we call an AVM: an arteriovenous malformation. It's a tangle of arteries and veins with no interposing capillaries — normally, capillaries provide resistance, slowing down the blood-flow rate. In cases like this, the vessels have very thin walls, and so are prone to bursting.

And when they do, blood pours through the brain in a torrent. In the form of AVM your husband has — called Katerinsky's syndrome — the vessels can rupture in a cascade sequence, going off like fire hoses."

"But Cliff never mentioned…"

"No, no. He probably didn't know. An MRI would have shown it, but most people don't have routine MRIs until they turn forty."

"Damn it," said my mother — who almost never swore. "We would have paid for the test! We—"

Dr. Thanh glanced up at me, then looked into my mother's eyes. "Mrs. Sullivan, believe me, it wouldn't have made any difference. Your husband's condition is inoperable. AVMs in general affect only one in a thousand people, and Katerinsky's affects only one in a thousand of those with AVMs. The sad truth is that the principal form of diagnosis for Katerinsky's is autopsy. Your husband is actually one of the lucky ones."

I looked over at my father, in the bed, a tube up his nose, another in his arm, his hair matted, his mouth hanging open.

"So, he's going to be okay, then?" said my mother. "He's going to get better?"

Dr. Thanh sounded truly sad. "No, he's not. When the blood vessels ruptured, the adjacent parts of his brain were destroyed by the jet of blood pounding into the tissue. He's…"