Spelling and Writing

This chapter discusses disorders related to spelling and writing. Spelling and writing are less well-practiced skills for most people than reading or even calculation. Even in the case of the highly educated individual, the ability to write may be only exercised rarely. The chapter presents a major distinction between disorders of the spelling process and disorders of writing. Spelling disorders have been broadly subdivided into two main types depending on the pattern of the patient's errors: (1) spelling that appears to be based on word-sound information and (2) spelling that is dependent on an established vocabulary of words. The linguistic or central spelling deficits reflect impairment in either a sound-based or a vocabulary-based spelling route. Disorders of spelling can be thought of as affecting one of two processes, both of which are available to the normal individual. One process is concerned with translating or transcoding between the sound of a word and a spelling, and the other process allows spelling from a stored vocabulary of known words. The disorders of writing may be viewed as a highly specific form of apraxia. However, they dissociate from other impairments of voluntary action and have been thought of as implicating a specific set of stored motor patterns for writing.