Impaired articulatory ability resulting from defects in the peripheral motor nerves or in the speech musculature WordNet 3.0 & Open English WordNet

Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phonemes. Wikipedia

Disglosia Wikidata

Difficulty in articulating words due to disturbance in the form or function of the structures that modulate voice into speech; one of the first indicative symptoms of myasthenia gravis, brought about by an autoimmune response to acetylcholine receptors. Wiktionary

Difficulty in articulating. Wiktionary (translation)