Loss of Power of Speech.
This is a loss of the power of speaking[1], and is usually caused by a lesion in the brain — in the right side of the cerebrum[2]; or by injuries to certain nerve fibres. In most cases the patient is entirely conscious of his inability and strives to otherwise communicate his thoughts. Tumors, injuries and diseased conditions may be the provoking causes of lesions producing aphasia. The difficulty can be treated only by ascertaining the character and seat of the lesion. Temporary aphasia is sometimes met with in apoplexy, epilepsy, meningitis, hysteria and St. Vitus dance (chorea). Occasionally the intestinal irritation caused by worms or constipation may be transmitted and result in temporary aphasia.[3][1] Aphasia now refers to losing the ability to speak, read or write - "disturbances in the comprehension and expression of language".
[2] Prosodic language functions are generally found in the right hemisphere of the cerebrum, but vocabulary and definitions are more often found in the left hemisphere (though there is dependence on handedness).
[3] I couldn't find any evidence of an intestinal irritation resulting in temporary aphasia. Parkinson's disease can result in both aphasia and intestinal dysfunction.