Brainstem atrophy is linked to extrapyramidal symptoms in frontotemporal dementia

Patients with frontotemporal dementia with extrapyramidal symptoms show brainstem atrophy and reduced metabolism in certain areas of the brain much more often than patients without extrapyramidal symptoms, according to a new study from the University of Eastern Finland. This observation may facilitate the differential diagnosis in frontotemporal dementia. The findings were published in Journal of Neurology.

Frontotemporal dementia, FTD, is an umbrella term for degenerative brain diseases that affect behavior and cognition. Sometimes FTD is accompanied by extrapyramidal symptoms, such as those of Parkinson’s disease, which makes it difficult to diagnose FTD. However, the new study now shows that accurate imaging and analysis of the brain can help distinguish between FTD and other diseases that cause extrapyramidal symptoms.

Extrapyramidal symptoms refer to involuntary movements, usually tremors, sluggishness, stiffness, loss of facial expressions, and automatic movements, such as arm swinging when walking. They are often associated with extrapyramidal disorders such as Parkinson’s disease and atypical parkinsonism. Examples of atypical parkinsonism include progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). They share disease mechanisms with frontotemporal dementia, which is why they are today considered part of the same disease spectrum. Frontotemporal dementia is traditionally divided into two main categories: the more common variant with behavioral changes as an early symptom, and the rarer primary progressive aphasia (PPA) with speech-related problems as an early symptom.

Neurodegeneration associated with progressive memory impairment is usually imaged in two ways: magnetic resonance imaging of the brain provides precise information about brain structures and volumes of different parts of the brain, while positron emission tomography, or PET scan, provides information about metabolism in different areas of the brain. Degeneration of brain tissue is often preceded by slow or absent metabolism.

The researchers analyzed medical records from Kuopio University Hospital of a total of 139 patients with frontotemporal dementia, PSP or CBD, focusing in particular on their diagnosis and the presence of extrapyramidal symptoms. MRI and PET images of the patients were analyzed using automated analysis software.

The researchers found that patients with extrapyramidal symptoms also had atrophy of the basal ganglia in the midbrain and brainstem. Looking only at patients with frontotemporal dementia, it was found that patients with extrapyramidal symptoms experienced brainstem atrophy significantly more often than patients without extrapyramidal symptoms. Additionally, PET image analyzes showed reduced metabolism in the superior cerebellar peduncle and frontal lobes in patients with extrapyramidal symptoms.

The study showed, for the first time, that significant structural and metabolic differences can be detected in the brains of frontotemporal dementia patients with extrapyramidal symptoms, compared to patients without these symptoms.

“If our results are confirmed in other cohorts, they could be used in early diagnosis to distinguish between frontotemporal dementia and Parkinson’s disease, for example. These results will also allow us to better understand the mechanisms of these diseases”, explains doctoral researcher Sami Heikkinen, the main author of the article.

“Although treatment for these diseases is symptomatic at this time, early and accurate diagnosis is an important step towards the development of disease-modifying treatments.”

The study was conducted in the Frontotemporal Lobar Degeneration and Early Dementia Research Group, led by Adjunct Professor Eino Solje.

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