Above: During repair of a teenager’s chest, a cryoprobe numbs pain between the ribs by freezing nerves at -87 degrees Fahrenheit.

Some cold, hard facts: If the outside temperature is -30 degrees Fahrenheit (-34 degrees Celsius), people’s body temperature can drop to dangerous levels in minutes. If our body temp were to go below 70 degrees, we’d be in real trouble; normally, we’re around a cozy 98.6.

But the human body can withstand even colder temps from the inside. In fact, some doctors use “cryoanalgesia,” a fancy word for applying super-cold temperatures to numb pain. They can freeze nerve endings in an ice ball, keeping the brain’s signals from hitting the nerve. That’s called a nerve block, and the interruption can last several weeks to even months.

“How cold?” you might ask. Well, freezing the body’s nerves requires temperatures around -87 degrees Fahrenheit. Brrrrr.

People have been using cold to lessen pain since the time of Hippocrates in ancient Greece, around 460-377 BCE. Many centuries later, Napoleon’s soldiers had painless amputations performed on them at subzero temperatures in Russia.

Then in 1917, a German surgeon named Friedrich Trendelenburg froze the nerves of patients in one of the first instances of modern cryotherapy. Today, cryoanalgesia freezes tissue with tiny ice crystals, using chemicals like nitrous oxide delivered by a tiny needle, or “cryoprobe.”

Freezing nerve endings can give a person temporary pain relief without injury because it only freezes the very outside layer of a nerve while keeping the inside intact. This means the nerve can grow back because it retains the building-block layers to regenerate.

Cryoanalgesia is an exciting field for surgeons. It has been shown to be more effective during surgery than opioids and other pain medications that carry high risk, especially for kids and teens. And that’s just the tip of the iceberg!

Thanks to Pitt’s Stefan Scholz, an MD, PhD assistant professor of surgery and the director of minimally invasive surgery at UPMC Children’s Hospital of Pittsburgh, for his insights. Scholz’s professional interests include using the latest regional anesthesia methods to minimize pain after surgery for children and other super-cool stuff.

Read more from the Fall 2023 issue.