As Blackhawks endure concussion plague, ‘symptom nonlinearity’ creates an extra challenge

BOSTON — Drake Caggiula got back to his feet, played the rest of a Sunday night game last month, enjoyed a day off Monday, then practiced Tuesday morning. He felt completely fine.

Then he boarded the Blackhawks’ flight to Las Vegas that Tuesday afternoon and everything went downhill.

“Little bit of depression, anxiety, headaches, and then just feeling like not myself,” he said.

Caggiula told team doctors and was soon diagnosed with a concussion, even though his symptoms were nothing like those he’d experienced with previous concussions — “vision issues and headaches, fogginess, forgetfulness,” he said — and didn’t arise until two days after the initial hit.

As the Hawks suffer through a scourge of concussions, with forwards Dylan Strome and Andrew Shaw also enduring head injuries in the nearly four weeks Caggiula has been out, diagnosing and treating them is especially difficult, given their unpredictability.

Yet that “symptom nonlinearity” — the official term used by Dr. Jeremy Alland, a sports medicine professor at Rush University — is nothing unusual.

“It’s actually not as infrequent as you may think,” Alland said. “When you think about injuring your ankle, a lot of times the injury happens, and then it follows a very linear timetable. You can usually tell people how long it’s going to take. . . . A lot of times with concussions, it can fluctuate and come on later, or it can feel like it’s gone and all of a sudden the symptoms come back.”

Despite the two seemingly fine days immediately after he was hit, Caggiula still isn’t fully back to normal. He was eligible to return from long-term injured reserve Thursday against the Bruins but wasn’t activated — although he’s expected to return soon.

Strome, too, experienced late-onset symptoms. After taking a hit against the Lightning on Nov. 21, he played Nov. 23 in Dallas, then took the morning skate back in Chicago on Nov. 26 before entering concussion protocol.

“I was having some headaches,” he said. “Wasn’t having too many other symptoms, so I was just trying to see if it would go away, but it started to get worse. So I just tried to get through it and took a few days off the ice.”

The similarities and differences between Caggiula’s and Strome’s experiences point to two other difficult aspects of concussions. First, many symptoms — like Strome’s headaches and Caggiula’s anxiety — are common in everyday life and don’t necessarily indicate a concussion.

“There’s no great diagnostic test,” Alland said. “I can’t just MRI a brain and say, ‘Look, it’s a concussion.’ We have all these forms . . . to be aids in trying to unmask symptoms that maybe the athlete isn’t able to speak about. But a lot of times, it’s a very subjective thing: You rely on the athletes communicating to you that they’re having symptoms that they don’t usually have.”

Secondly, the timing of when symptoms begin to show largely has no correlation with recovery time.

“There’s a lot of factors that go into whether it’s going to be a longer concussion, and the delayed onset would be not as high on the list as things like prior concussions, how long it’s taken in the past [and] how severe the symptoms are,” Alland said.

Caggiula’s and Strome’s cases exemplify this. Whereas Caggiula sat out his 11th consecutive game Thursday, Strome returned after missing just four, slotting back into his old spot between Alex DeBrincat and Patrick Kane and scoring a goal in the first period.

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Shaw hasn’t spoken with reporters since his concussion diagnosis was announced Monday — again, two days after his most recent game. But even if he did, he likely wouldn’t have a clue about when his symptoms will fade and he’ll be able to resume skating.

That’s the reality of this type of injury, which has proved fairly elusive to science — and often to players who don’t know they’re hurt. Strome and Caggiula said it took several days for them to even realize themselves what they were dealing with, despite consciously prioritizing their mental health.

“There’s other symptoms that other people feel, so you just talk to [the doctors], you tell them what you’re feeling, they ask you some questions, you answer them, they let you know what they think,” Strome said. “It’s mostly based on how you feel, to be honest.”

Caggiula has noticed that exercise and other activities that increase heart rate can trigger his symptoms. Alland confirmed that checks out medically.

“[While a player is recovering], you put them through these return-to-play steps . . . just to see if it brings back symptoms,” he said. “The same concept would be if [the symptoms are] minor, and you return to play or you fly on a plane or you don’t get good sleep one night, and then all of a sudden they’re more severe, more prominent.”

Caggiula and Strome will at least make full recoveries, despite their rough Novembers. Caggiula’s depression didn’t stick around; Strome’s headaches have faded away.

There has been progress toward understanding concussions. But there’s clearly still much to learn.

“It’s not easy — you obviously want to battle for your teammates and get out there,” Strome said. “But a head’s a pretty serious thing.”