Can an MRI of the tongue give a first clue to amyotrophic lateral sclerosis (ALS), a serious and debilitating degenerative disease? In any case, this is the hypothesis of a team of Australian researchers.
Their work, recently published in the journal Computers in Biology and Medicineshow that an MRI examination could identify discreet but revealing muscular signs very early on.
The tongue, a mirror of the motor nervous system
These University of Queensland researchers have developed a method combining magnetic resonance imaging (MRI) and artificial intelligence (AI) to measure the size and shape of tongue muscles.
“Our tongue is made up of eight interconnected muscles, each with a different role. But in people with motor neuron disease (like ALS or Charcot disease), these muscles gradually weaken and waste away.”explains Dr. Thomas Shaw, lead author of the study.
By comparing more than 200 MRIs of patients with or without ALS, the team found that the volume of the tongue is significantly reduced in patients. This marker could not only help detect the disease earlier, but also give an indication of the speed of its progression:
“People with lower lingual volume have a worse prognosis”specifies the researcher.
© The University of Queensland.
ALS, signs that are often discreet at first
In practice, Charcot disease often begins with subtle symptoms, sometimes ignored for several months. Neurologist Dr Wilfrid Casseron described these first signs in a previous article:
“Patients often notice asymmetrical muscle weakness, first in one arm or one leg. It is sometimes accompanied by muscle atrophy and fasciculations, these small twitches under the skin, like moving worms.”
These involuntary contractions often worry patients, but the doctor points out that they are not always synonymous with ALS: “Many people consult after reading on the Internet that fasciculations can suggest Charcot’s disease, but in the majority of cases, there are other, benign causes.”
In the spinal form, the symptoms first affect the limbs: loss of strength, stiffness or on the contrary softness, then progressive extension to other regions of the body. In 30% of cases, the disease begins in the bulbar sphere, that is to say the mouth, throat and tongue.
“The first manifestations are then difficulties in swallowing, chewing or articulating, sometimes with a changed voice or hypersalivation” explains Dr. Casseron. “This is what we call paralytic dysarthria: the disorders are persistent and worsen, they are never transient.”
And a diagnosis that takes time
Today, confirming ALS takes on average almost a year after the first symptoms. Diagnosis is mainly based on clinical examination and neurological tests.“The neurologist most often prescribes an electromyogram, a brain and spinal cord MRI, as well as a blood test to rule out other possible causes,” explained Dr. Casseron.
A genetic test may also be offered when there is a family history. But the first signs are often diffuse or confused with other pathologies (such as compression of the spinal cord), many cases go unnoticed for several months.
What an MRI of the tongue would change
This is precisely where Dr. Shaw’s approach could be game-changing. By detecting lingual muscle atrophy before the appearance of clinical symptoms, targeted MRI could direct patients more quickly towards a diagnosis and appropriate treatment.
“More importantly, this measurement could tell us about the life expectancy of people with ALS and allow for more rapid inclusion in clinical trials”underlines the Australian researcher.
For her colleague, Dr. Brooke-Mai Whelan, speech therapist, this method also opens the way to concrete strategies to improve quality of life: “Understanding which tongue muscles atrophy first will help us adapt speech exercises and preserve communication for as long as possible.”
Towards a new neurological screening tool?
Still in the validation phase, this MRI measurement technique could become a new non-invasive tool in the arsenal of neurological diagnosis. And not just for ALS: researchers are already considering its application to other diseases affecting speech or swallowing, such as Parkinson’s disease or certain forms of dementia.
The tongue, often neglected in medical protocols, could thus become a valuable sentinel of the brain and motor nerves. A simple review to save vital time.