Patients may see subtle disease signs years before ALS diagnosis
Pain, motor issues indicate disease may have earlier phase
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- Patients often experience subtle motor and sensory signs, including pain and walking difficulties, years before a formal ALS diagnosis.
- These early manifestations suggest ALS includes a prodromal phase marked by gradual motor neuron loss and neuromuscular changes.
- Recognizing these early symptoms may facilitate earlier detection and refine clinical diagnostic frameworks.
Some people with amyotrophic lateral sclerosis (ALS) experience subtle signs of the disease, such as pain and motor problems, in the years before they are diagnosed.
The findings add to growing evidence that ALS may have a prodromal phase, a period in which people start to experience biological changes indicative of disease, but these early signs are insufficient to support an ALS diagnosis.
Researchers noted that the distinction between the prodromal period and overt disease in ALS is not as clear as it is in other neurological disorders. Some of the early complaints reported by patients may actually reflect the first manifestations of ALS rather than a distinct prodromal stage.
Nonetheless, better recognition of early symptoms may help facilitate earlier detection of ALS, they said. “By providing evidence consistent with prodromal mild motor impairment … this study provides a foundation for refining clinical frameworks aimed at identifying ALS at earlier stages,” they wrote.
The study, “EARLY-ALS: a multicentre study on prodromal amyotrophic lateral sclerosis,” was published in eBioMedicine.
Gradual neuron loss
ALS is marked by the gradual loss of motor neurons, the nerve cells that control movement. That causes ALS symptoms such as muscle weakness result, which progressively affect the ability to move, speak, and breathe.
By the time these symptoms are sufficiently apparent to support an ALS diagnosis, however, substantial motor neuron loss may have already occurred. Identifying unspecific changes that occur during this period could help researchers better understand how the disease develops and potentially improve early detection.
In several neurological diseases, such as Parkinson’s, symptoms that are common in the prodromal period are well defined. However, not much is known about prodromal symptoms in ALS.
An international team led by scientists in Germany set out to understand these early signs of ALS. The researchers conducted a survey, which was answered by 475 people with ALS at 20 centers across Germany and Switzerland. Patients were asked about symptoms they had experienced during the 10 years before they started showing signs of ALS, as well as other health problems and medical care.
The team also surveyed 285 people without the disease, most of whom were spouses or family members of the ALS patients. The researchers then looked for symptoms that were significantly more common in people with ALS than in those without the disease.
When asked to describe notable changes they had experienced before the onset of ALS symptoms, 117 patients (25%) reported at least one complaint, compared with 15 people in the control group (5%).
Among the early changes reported by patients, most (57%) affected the neuromuscular system and included muscle weakness, muscle cramps, and difficulty walking. Sensory symptoms, particularly pain in the back and/or limbs, were also common among patients.
These complaints were not necessarily confined to the months immediately preceding ALS onset. On average, motor-related complaints were reported about one year before symptom onset, while sensory complaints were reported about two years beforehand.
However, when looking at non-motor symptoms, the researchers found that most of the symptoms that differed between the groups were actually reported more frequently by controls. Only one symptom — trembling in the arms of legs — was significantly more common among patients with ALS than controls.
Together, the findings suggest that early ALS-related changes may be predominantly motor-related, although the researchers noted that differences in symptom awareness and recall could have influenced the results.
“Many of these [motor] symptoms likely represent very early symptomatic disease rather than a clearly separable prodromal phase,” they said.
“We support the view that ALS may evolve along a continuum in which prodromal and early clinical manifestations partially overlap, making a clear distinction between these stages inherently challenging, particularly in retrospective designs,” the researchers wrote.
The researchers also examined healthcare use in the years preceding ALS symptom onset and found that ALS patients had more frequent visits to neurologists and speech therapists in the months and years before they were diagnosed than people without the disease.
“Our findings suggest that a subset of patients with ALS retrospectively report a prodromal phase during which neurological and/or speech therapy services were already engaged, highlighting potential opportunities for earlier recognition,” the scientists concluded.
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