FTD with motor neuron disease

In addition to the three subtypes of FTD, frontotemporal dementia can present in the context of motor disturbances as well. Three other disorders that commonly overlap with FTD are: corticobasal degeneration (CBD), progressive supranuclear palsy (PSP) and FTD with motor neuron disease (FTD-MND).

Traditionally, CBD was defined by the presence of asymmetric parkinsonism with dystonia, rigidity, limb apraxia and a “useless or alien” limb. Pathological examination demonstrates neuronal inclusions with tau present in astrocytes and neurons.

PSP has been described as a movement disorder associated with falls, ophthalmoplegia, axial rigidity and a frontal dementia. Like CBD, tau inclusions are seen postmortem. Recently, it has become evident that most patients with PNFA show PSP or CBD postmortem.

Patients with FTD-MND generally start with dementia symptoms, primarily behavioral changes such as disinhibition. Shortly after the onset of dementia, patients develop weakness and wasting of limb muscles. Typically, the respiratory complications of bulbar palsy are the cause of death, and patients live approximately 1.4 years after diagnosis.