A teacher claims he has developed a stammer since overcoming the coronavirus.
Not everyone who fights off the infection returns to a clean bill of health, with tens of thousands of people in the UK alone enduring complications known as long COVID.
While the majority report fatigue, palpitations or even organ damage, Patrick Thornton from Houston in Texas started struggling to speak at the end of September 2020.
The maths teacher, 40, had a relatively mild case of the coronavirus itself, developing a sore throat, headaches and slight breathing difficulties.
After initially losing his voice, Thornton thought he was on the mend until his mother phoned on 25 September.
The teacher’s words reportedly came out jumbled, not “feeling right in his mouth”.
While the thought of returning to work was “terrifying”, Thornton’s speech had improved enough for him to go back to the classroom in December and he stressed “there’s light at the end” of the “rocky road”.
Thornton is thought to have had the coronavirus in mid-August.
More than a month later, his mother rang, remarking on how his lost voice was starting to return. The teacher was not convinced, however.
“I realised some of the words didn’t feel right in my mouth, you know?” he told Scientific American.
“I got my voice back, but it broke my mouth.”
By November, Thornton was enduring low energy, chest pain, headaches and an elevated heart rate like he was being “chased by a tiger”.
With his stammer – also referred to as a stutter – worsening, doctors reportedly insisted it was just a sign of stress.
By December, Thornton’s speech and energy levels had improved enough for him to return to work.
“It’s been a rocky road, but there’s light at the end,” he said.
Watch: How coronavirus could affect the brain
Can coronavirus cause a stammer?
With the coronavirus only identified at the end of 2019, and long COVID a newer phenomenon still, expert understanding of the infection and its complications is still growing.
The fact patients commonly lose their sense of smell and taste while infected with the coronavirus demonstrates it can affect the brain to some extent.
When it comes to stammers specifically, evidence is fairly limited.
Dr Soo-Eun Chang from the University of Michigan researches stammers and “speech motor control”.
She claims stress and anxiety do not cause the speech defect, but may worsen it.
A stammer’s onset is said to lie in the brain’s complex circuits that co-ordinate the nerve cell connections required when talking.
Dr Chang has reportedly seen an increase in stammers during the pandemic, however, this has largely been in people who had the speech problem as a child.
The coronavirus may also be causing relatively mild stammers to worsen, she added.
Although unclear, the infection could trigger an inflammatory response that affects the efficiency of the brain’s nerve networks.
Stammers aside, severe cases of the infection have been shown to impact the brain.
Scientists from the US National Institute of Neurological Disorders and Stroke previously reported signs of stroke-like brain damage in some coronavirus victims.
The 1918 pandemic left some patients enduring viral encephalitis, brain swelling that can occur if an infection enters the central nervous system.
Some survivors went on to develop viral Parkinsonism, defined as symptoms similar to Parkinson’s disease, like shaking and stiff movements.
Previous University College London research also found a “higher than expected number of [coronavirus] patients with stroke”, which was put down to the infection making blood “stickier”.
Experts have previously said “time will tell” how the coronavirus affects the brain, with some degree of complications being “very likely” but rare.
While research is ongoing, the virus may enter the brain directly via the olfactory nerve in the nasal passages or through blood vessels.
The excessive release of immune-fighting proteins, known as a cytokine storm, may also lead to inflammation that affects the brain.
Dr William Banks from the University of Washington claims cytokines can cross the blood brain barrier, leading to symptoms like depression.
In November, scientists from the University of Oxford reported coronavirus patients face more than double the risk of developing anxiety, insomnia or even dementia as those who have overcome flu.
Watch: What is long COVID?