What is the role imaging studies in the workup of frontotemporal lobe dementia with motor neuron disease (FTD/MND)?

Updated: Apr 11, 2017
  • Author: Jasvinder Chawla, MD, MBA; Chief Editor: Jasvinder Chawla, MD, MBA  more...
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Answer

Computed tomography (CT) scanning in patients with frontotemporal lobe dementia with motor neuron disease (FTD/MND) may show mild, generalized cerebral atrophy or asymmetrical frontotemporal atrophy.

Because it provides greater resolution than CT scanning does, magnetic resonance imaging (MRI) may reveal selective frontal and anterior temporal atrophy that cannot be appreciated on CT scanning.

Single-photon emission CT (SPECT) scanning often demonstrates reduced blood flow in an asymmetrical, frontotemporal pattern.

In a recent study, it has been shown that loss of gray matter volume in motor and extramotor regions of only ALS patients with FTD and not of ALS patients without FTD suggests distinct sites of predominant pathology. This may also provide some ideas about disease onset. Brain volumetric measures supplemented by histopathological correlations and other neuroimaging techniques, such as diffusion tensor imaging, may provide insight into ALS pathophysiology. [21]

A study reported that glucose hypometabolism on positron emission tomography (PET) scans in patients with dementia associated with MND affected only the frontal lobes, sparing the temporal lobes. [22] This contrasted with frontotemporal dementia, in which glucose hypometabolism is seen in the frontal lobes and temporal lobes. In Alzheimer disease, PET scans may reveal glucose hypometabolism in the parietal and temporal regions bilaterally.

Boyajian et al recommended magnetoencephalography (MEG) as a powerful new tool for researching the contribution of cortical dysfunction to motor disability, which can characterize the disease process. [23]


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