Purpose: Case reports and a review of literature of the coexistence of motor neuron disease (MND) and frontotemporal dementia (FTD).
Case report: All three patients demonstrated generalized lower motor neuron signs and very few upper motor neuron signs. In the level of patterns of cognitive impairments, neuropsychological studies do not distinguish between patients with onset of weakness from bulbar palsy and patients with onset of weakness from limbs. All patients of FTD had their onset of MND or amyotrophic lateral sclerosis symptoms within a two-year interval which is similar to previous reports. FTD combined with MND may shorten the survival to less than three years shorter than cases with FTD only. Respiratory failure occurred one to two years after onset of the behavioral symptoms in all patients.
Conclusion: We reported three patients of FTD with MND to remind clinicians that these two disorders may occur together on the same patient and that these two disorders may belong to one broad spectrum neurodegenerative disease.
Keywords: motor neuron disease, amyotrophic lateral sclerosis, frontotemporal dementia, frontotemporal lobar degeneration.