ABSTRACT
This chapter provides a brief outline of the full clinical spectrum of motor neuron diseases each with different etiologies, presentations, prognoses and pathologies. The classic clinical presentation is that of combined upper and lower motor neuron weakness in the extremities and/or bulbar innervated musculature. Approximately 25% of all cases present in the bulbar-onset form: the initial problems are dysarthria and/or dysphagia. Rare cases present in overt respiratory failure from fulminant early involvement of the cervical and thoracic cord. Front temporal dementia is not a single entity but a heterogeneous group of neurodegenerative disorders where the cognitive domains most affected are those concerning behavior, personality, executive control and language. The underlying pathology is most notable for neuronal loss in the setting of widespread tau-positive neurofibrillary tangles within the cerebral cortex and spinal cord, thus establishing this disorder as one of the tauopathies.
