agraphia

n. inability to write as a result of a brain injury

Dysgraphia (or agraphia) is a deficiency in the ability to write, regardless of the ability to read, not due to intellectual impairment. People with dysgraphia often can write on some level, but often lack co-ordination, and may find other fine motor tasks such as tying shoes difficult. It often does not affect all fine motor skills. They can also lack basic spelling skills (having difficulties with p,q,b,d), and often will write the wrong word when trying to formulate thoughts (on paper). In childhood, the disorder generally emerges when they are first introduced to writing. They make inappropriately sized and spaced letters, or write wrong or misspelled words despite thorough instruction. Children with the disorder may have other learning disabilities; however, they usually have no social or other academic problems. Cases of dysgraphia in adults generally occur after some  neurological trauma or it might be diagnosed in a person with Tourette syndrome, ADHD or an autism spectrum disorder such as Asperger's. The DSM IV identifies dysgraphia as a "Disorder of Written Expression" as "writing skills (that) ...are substantially below those expected given the person's ...age, measured intelligence, and age-appropriate education."
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Agraphia /agraph·ia/ impairment or loss of the ability to write.agraph´ic a·graph·i·a n. A form of aphasia characterized by loss of the ability to [more]Agraphia - Community and Resources

Noun
1. a loss of the ability to write or to express thoughts in writing because of a brain lesion
(synonym) anorthography, logagraphia
(hypernym) brain disorder, encephalopathy, brain disease

(n.)
The absence or loss of the power of expressing ideas by written signs. It is one form of aphasia.