Progressive dysarthria: definition and clinical follow-up

Progressive dysarthria is a common sign of sever- al degenerative disorders of the central nervous system; it may also be a distinct nosographic entity. We identified nine patients in which progressive dysarthria remained the sole neurological sign for at least 2 years after onset. At least a year after hospital admission, the following diagnoses were made: two cases of corticobasal degeneration, one of fron- totemporal dementia, one of primary progressive aphasia, one of motor neuron disease (MND)-dementia, one of ALS, and one of ALS-aphasia. In the remaining two patients pro- gressive dysarthria remained the only neurological sign at latest examination. We conclude that in most cases progres- sive dysarthria is the presenting sign of an established neu- rodegenerative disease (generally degenerative dementia or motor neuron disease), although the possibility that progres- sive dysarthria is a distinct entity cannot be excluded. To clarify this issue, studies (probably multicenter) on more patients with longer clinical follow-up and pathological con- firmation are required. Progressive dysarthria may be a sign of several neurodegen- erative diseases, but has been described as a unique disorder in a few cases (1, 2). We retrospectively examined all patients admitted to our department over a 5-year period in which progressive dysarthria was the only sign for at least 2 years following onset. The patients were followed for at least a year following admission. We therefore excluded acute- onset cases, those associated with other neurological signs from onset, and those in whom dysarthria was due to periph- eral lesions (flaccid dysarthria) or cerebral lesions confirmed by imaging. We identified nine patients (six women, three men) com- plying with these criteria. On admission the mean age of these nine patients was 65.2±13.7 years (range 30-75 years) and mean duration of dysarthria 3.2±1.3 years (range 2-6 years). At first examination all had tongue hypomobility and dysprosody, and all but two had by then developed other neurological signs. These were bradykinesia, rigidity, and anomic language in two patients; mental decay (including aphasia, hemispatial neglect, and alien limb), behavioral alteration, and pseudobulbar signs in one patient; motor aphasia in another patient; and a combination of tongue hypotrophy, behavioral modification (mostly apathy), tongue and vocal tremor, hyperreflexia, and aphasia in three other patients. In spite of the additional signs in these seven patients the diagnoses were unclear at first examination. At latest follow-up, at least a year after admission, two