Amyotrophic Lateral Sclerosis (ALS) patients usually exhibit symptoms of brain damage related to their disease sub-type. Researchers have evidence that patients with bulbar-onset ALS have more extensive brain tissue loss. The results of this study could explain why some patients fare worse than others.
In their study, researchers from Hanyang University emphasised on the importance of the method used to assess the extent of brain damage. The tool used is critical in determining the progression of the disease and its prognosis; to determine whether the patterns of brain tissue loss in ALS patients differ. The Korea-based researchers examined 62 ALS patients: 48 with limb-onset ALS and 14 with bulbar-onset symptoms. It also included 57 healthy controls.
ALS is a rare motor neuron disease that affects the nerve cells responsible for controlling voluntary muscle movement: walking, talking, breathing, or chewing. The disease onset is characterised by symptoms such as muscle twitches, muscle cramps, muscle stiffness and tightness, slurred speech, and difficulty in chewing and swallowing. When the first symptoms affect the arms or legs, it is referred to as limb-onset ALS. Bulbar-onset ALS is first noticed as speech or swallowing problems.
The progressive and multi-system nature of bulbar-onset ALS makes it unpredictable. The condition of the patients deteriorates very fast because its symptoms mostly affect swallowing, speech and breathing. For instance, progressive loss of the ability to swallow makes eating a burden of survival and not pleasurable. Loss of speech and communication isolates the patients.
ALS has been identified as a neurodegenerative disease that affects the genetic and molecular structures of motor neurons. Despite this knowledge, it is still not understood how the disease progresses. Therefore, no effective treatment or cure has been made available. However, there is a recent discovery of genes linking ALS with dementia. The understanding that ALS affects multiple systems demystifies the fact that ALS affects more than the motor neuron system.
The scientists used a brain imaging technique known as voxel-based morphometry to measure volume in various brain regions. They also evaluated the patient’s ALS Functional Rating Scale-Revised (ALSFRS-R) scores, against forced vital capacity, and disease duration. All the ALS patients showed significant brain tissue loss as compared to the controls.
However, a comparison among ALS patients found that limb-onset patients had significant brain damage in the regions associated with movement. Bulbar-onset ALS patients had extensive brain tissue loss in both gray and white matter areas, regardless of the duration of illness. They also manifested more damage in movement related areas compared to limb-onset patients.
The damage in the gray matter in the participants from the bulbar-onset group was linked to ALSFRS-R scores while the FVC was associated with damage to the deeper brains structures.
The findings of this study support earlier studies that observed that the disease progression in bulbar-onset patients was most aggressive. The team concluded: “VBM analysis of gray and white matter atrophy in ALS can provide a basis for predicting ALS progression and prognosis.”