Which histologic findings are characteristic 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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Early in the disease, frontotemporal lobe dementia with motor neuron disease (FTD/MND) preferentially affects frontal and temporal lobes, the hypoglossal nucleus, and the spinal motor neurons. The later and terminal stages reveal histologic evidence of widespread cortical involvement. In the frontal and temporal lobes, microscopic changes include loss of pyramidal cells, spongiform neuropil change, and astrocytic gliosis.

Ubiquitinated, tau-negative inclusions are present within the frontal cortex and the dentate gyrus of the hippocampus. Pick cells (inflated neurons) and Pick bodies (ubiquitin and tau-positive intracellular inclusions) are absent. Betz cells in the precentral gyrus usually are affected.

In approximately 50% of patients, neuronal loss and pigmentary incontinence in the substantia nigra and other pigmented brainstem neurons occur, even in patients without clinically overt parkinsonism. There can be marked hypoglossal and spinal motor neuron degeneration (although this is not essential for patients to progress to an anarthric state) and ubiquitinated tau-negative inclusions in the spinal neurons.

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