Award Article: Have we forgotten what tics are?

Sara Schaefer:
Alright, so let's start with the background. What prompted you to do this study and what were you hoping to add to the literature?

Tamara Pringsheim:
I think the main motivation was that we started seeing a lot of young people with functional tic like behaviors during the pandemic, and I was getting many, many referrals to my clinic.

And these functional tic like behaviors look nothing like tics to me and it perplexed me. Why do people think these are tics? Because the behaviors that we were seeing were so different from my patients with tics. And I remember when I first became interested in Tourette syndrome in medical school, in my case, I started reading the articles written by the Shapiros who were a husband and wife team of psychiatrists in New York City. And , they were publishing articles in the seventies and eighties and they did these in-depth phenomenological descriptions of the symptoms their patients had. And I said, well, maybe we need to get back to this.

Maybe neurologists aren't seeing a lot of patients with tics anymore. And maybe just this modern reappraisal of what are the most common tics that we see is needed. So that was the motivation. Another was when we started seeing these functional tic like behaviors, some people started questioning that many of the patients that we're presenting were assigned female at birth.

And most of our patients with Tourette syndrome are male. So some people were saying, well, maybe girls look different than boys who have tics. And we have had a bias, like our view of Tourette syndrome is unfairly biased towards boys since, three quarters of the patients are boys.

So, I thought this was fair. And so I said, well, I have the data. I've been running this tic disorder registry at my university. We got started in 2016 and we had accumulated hundreds of patients over several years. So I said we've been collecting this data prospectively.

We do it the same way on every child that we see. So this is really a chance to look at these questions.

[00:03:13] Sara Schaefer:
Certainly legitimate questions we've seen over and over in medicine that when you zoom out on demographics outside of males generally, that you might find different ways that people present.

So I applaud you for recognizing that. So let's talk about how you went about your study.

[00:03:33] Tamara Pringsheim:
Yeah, so as I was mentioning, we have a Calgary Child Tic Disorders Registry. And so every child that we see, we invite to participate in our registry at their first clinical visit. And we have, I'd say very good participation in the registry with the majority of people signing on. During the registration visit we record basic demographic information the diagnosis the medications, the age of onset.

We systematically screen and diagnose comorbid disorders, and we perform the Yale Global tic Severity Scale. This is the gold standard instrument for measuring tic severity, and it includes a tic inventory. So the first few pages of the instrument are just a list of simple motor and simple vocal tics and complex motor and complex vocal tics.

And you're supposed to ask the patient, what are the different tics you've had in the past week? And you simply, check them off. And then there are ratings of number, frequency, intensity, complexity, and interference, and then impairment. And so we collect all this information at the first clinical visit.

We have three other visits, a six month visit, a twelve month visit, and then another visit when the patient turns eighteen. So for this study, we use the baseline data. So these were all children presenting for their first visit with a specialist for a question of a tic disorder. And so that was our methodology.

We looked at the Yale inventories and severity, and we looked at influencing factors of age, sex, and comorbidity on these symptoms.

[00:05:28] Sara Schaefer:
Can you summarize the results for us? And also I was wondering if you were surprised by any of the results. And if you feel like the results are representative of tics in general in the population.

[00:05:43] Tamara Pringsheim:
So, I guess I wasn't really surprised by any of the results because this is what I do every day. I run a tic disorders clinic. I've seen thousands of children with tics. But, the mean age of onset was six. The mean age of the first visit was ten, and there were no differences in age of onset or age of clinical presentation between the girls and the boys that we saw. I mean, we had 75% of our participants were boys. But we still had, I'd say, a decent number of girls to make a comparison with. The predominant areas affected, or the most common area to have tics were the eyes and the face.

And there was a preponderance of simple tics. And the most common vocal tics were throat clearing, sniffing, and coughing. And again, this is my everyday practice. So I wasn't surprised. I knew this from my experiences in those common complex vocal tic was the repetition of syllables and coprolalia was uncommon.

At the first clinical visits, only about 5% of kids had coprolalia at their first visit. We could, we did a side-by-side comparison in terms of our girls presenting with different tics than boys. There were a couple differences, but I don't really think that they were very clinically significant.

So girls had a little bit more nose wrinkling and shoulder shrugging and grunting than boys. But, I didn't think that this was really important. Girls interestingly had a very small difference in motor tic severity. The scores, it was barely statistically significant, the difference but it seemed consistent and that frequency and intensity were higher.

And tic related impairment was higher in girls, not by a lot. Just a couple points. But there was a small difference there. Tic severity also was influenced by comorbidity, which again, is not surprising. I think that all these children have neurodevelopmental disorders and this is a greater burden of pathology.

So they have more severe symptoms.

[00:08:03] Sara Schaefer:
One thing that I found fascinating that you brought up in the article was, How the frequency of tics in different body regions may relate to the somatotopic map in the brain. Can you talk a little bit more about that? I've just never thought about that before.

[00:08:19] Tamara Pringsheim:
Well, it's been demonstrated in other people's work as well. Christos Ganos, colleague from Berlin has also examine the somatotopic distribution in tics, showing that it's the cranial and cervical regions that are most commonly affected. And we know that those areas have the greatest cortical representation.

So face, cranial region, and then hands. And I think it makes sense that those parts of our body where there's more gray matter dedicated to their movement and we have more intricate control of those movements, that we would have more tics. When I think about the part of our body that we move the most, it's our eyes.

Right, probably, I mean, that's what I'm assuming it's our eyes, our eyes are constantly moving and so it doesn't surprise me that the most common places people have tics are their eyes as well.

[00:09:20] Sara Schaefer:
Now you said that one of the things that prompted you to do this study originally was this explosion of functional tic like behaviors, the so-called quote unquote TikTok tics, right?

That we've all, heard about over the last few years, and then you bring it back in the article to how your data might help to distinguish between functional tic like behaviors or primary tic disorders. Can you talk a little bit more about that?

[00:09:49] Tamara Pringsheim:
Yeah. So we just submitted another paper where you see the graphs on the prevalence of motor tics by type and location, the prevalence of phonic tics by type and you see the distribution of the simple tics and the complex tics on those pages.

Again, sort of reinforcing the fact that the 10 most common motor tics are all simple. And so we have a nice population of patients with functional tic like behaviors that we've produced similar graphs for and here the situation is the reverse the top 10 tics are not all simple.

There are some simple in there. In functional tic like behaviors the most common simple tic is a head jerk. It's a head jerk like this. I know you can't see what I'm doing. But it's a head tic where the neck is sort of forcefully extended and the chin comes up in the air.

And that was really characteristic. And there was a lot of complex behaviors. So a lot of self-injurious behaviors like hitting oneself in the chest, hitting oneself in the head. A lot of words that were being repeated phrases. And if you compare the bars side by side, the difference, it's striking that it's such a departure from the phenomenology that we see in Tourette syndrome.

It's a highly sensationalized version of what people might think Tourette syndrome is, but in reality is not.

[00:11:29] Sara Schaefer:
And final point, can you speak a little bit to the lack of rostral caudal progression in functional tic like behaviors as opposed to primary tic disorders?

Yeah, so typically , when I first see a child who's five or six , I'd say in at least half of cases, the first tic the child has is blinking.

And often they get taken to the eye doctor. I hear the story. Oh yeah, we took him to the optometrist. We thought the eyes were dry and we tried drops and then after a few months it went away. And then a few months later he started like wrinkling his nose or he started opening his mouth really wide.

Or started looking the eyes in one direction. And then, over a period of time, the tics can sort of migrate to involve the neck and the arms, but usually sort of the last places that they go are the trunk or the lower limbs. And so we see this rostral caudal progression in tics over time in people.

In the functional tic like behaviors we didn't see that. So in Tourette syndrome tics creep in insidiously. They come in and then they wane, and then they come back again and they change but it's over months or years. Like you saw that most people had their onset at six, but they didn't come and see the specialist until they were ten.

Because it was just so slow and waxing and waning. So parents weren't alarmed. But with the functional tic like behaviors, it was these symptoms started explosively overnight. Patients tell me, yeah, I woke up one day and I started throwing things or hitting myself in the chest and they developed 10 different tics all on the same day, which were large and explosive.

Didn't start with the face just one day had 10 different tics. All being large, dramatic movements or complex phrases, and we really don't see that in people with Tourette syndrome.

Great, is there anything else that you wanna add or any next steps that you have in mind?

[00:13:34] Tamara Pringsheim:
Well, I have an adult tic registry as well. It's a combined effort with the Sorbonne University in Paris. And so we have a collection of adult patients who we are studying prospectively, also looking at their tic phenomenology. it's very similar to the tic phenomenology in children. There are some subtle differences, so that's something that we're working on.

I wanna acknowledge my fellow Christelle Neles who is the first author on this paper who did all the digging through the data and all the analyses. I wish she was here to join this conversation with us. But she couldn't come to the meeting this year. But I just wanna acknowledge all the hard work and effort that she made on this project.

[00:14:21] Sara Schaefer:
Absolutely. And congratulations to everybody on the paper.

[00:14:24] Tamara Pringsheim:
Thank you.