What term describes a nerve defect that results in the loss of speech?

The term that describes a nerve defect resulting in the loss of speech is aphasia. Aphasia is a communication disorder that affects a person's ability to process and produce language. It can occur due to damage in specific areas of the brain responsible for language, commonly as a result of a stroke or traumatic brain injury. Individuals with aphasia may have difficulty speaking, understanding speech, or both, depending on the type and severity of the disorder.

In contrast, dysarthria refers to difficulty in the physical production of speech due to muscle weakness, which impacts the clarity and articulation of speech, but does not affect language comprehension. Apraxia is a motor disorder that affects the ability to coordinate the movements necessary for speech, leading to challenges in the actual delivery rather than understanding or forming language. Alexia is a form of reading disorder, characterized by an inability to read despite being able to write and speak normally, focusing specifically on reading rather than speech production.