Agraphia: An Uncommon Presentation of a Stroke

An acquired difficulty in the ability to write is commonly seen in association with disorders of language, but in contrast to a selective difficulty with reading, its occurrence as an isolated sign of brain damage has been questioned. The act of writing involves "the symbols of symbols" and in view of its complexity might, therefore, be expected to be more vulnerable to insult than either speaking or reading. Most people who have isolated agraphia have survived a stroke or serious head injury but occasionally it can be the first sign of a progressive disease like a brain tumour or dementia.

A number of cases of pure agraphia due to focal lesions in the central nervous system have been reported and on the basis of analysis of spontaneous and copied script, several distinct types described. For example, after a stroke in the peri-Sylvian region of the left temporal lobe, paragraphias (the writing of a different letter or word from that which is intended), omission of vowels and consonants, transposition of letters and syllables, and inappropriate word repetition can occur. In aphasic agraphia of this type, the copying of script is relatively conserved. Left hemisphere damage at the foot of the second frontal gyrus (Exner’s area) may also lead to an isolated difficulty in the copying of simple words and symbols that is both phonological and lexical.

An inability to copy words or respect the margins and lines of the page is also seen after small left parietal lobe strokes along with poorly-formed, often illegible graphemes (the individual letters or groups of letters, which represent individual speech sounds and that make up a word). These calligraphic problems can occur without any difficulty in gripping the pen and in the absence of limb dyspraxia.

Gerstmann syndrome is an uncommon tetrad of agraphia, an inability to name and distinguish one finger from another, difficulties with arithmetic, and right-left disorientation of the hands, usually seen with a small lesion restricted to the left angular gyrus of the left inferior parietal lobe, close to the second occipital convolution. Some cases also have additional difficulty drawing and copying objects but there is no associated language impairment. The writing difficulty is characterised by an inability to copy letters to dictation. Writing is often slow, and there may be confusion between the letters b and p and the letters d and q, substitutions due to top-bottom letter reversals, and some letter omissions in long words. A disturbance of transforming visuospatial mental images has been suggested as the cause.

Damage to the right parietal lobe can affect the visual-spatial component of writing too. There may be an abnormally wide left margin, and examination of the handwriting may reveal extra strokes or loops so that letter n may be written as m or an extra vowel is added to a word. The writing may also be characterised by an upward slope of the script as it progresses to the right of the page. Spontaneous writing, writing to dictation, and copying may all be affected. Stimuli on the left side of the body are neglected and there is left-right sensory inattention.

These reported differences between frontal, temporal, and parietal lobe agraphia may be of some clinical value in localising the site of the lesion but there are many overlapping and outlying cases and pure agraphia has also been associated with basal ganglia and corpus callosum damage.

The overall findings from neurological reports are consistent with the view that writing relies on a distributed neuroanatomical network that links component linguistic elements with some aspects of visuomotor activity.

Many authors prefer writing over speaking as their primary means of communication, so the loss of the ability to write and read after a stroke may come as a particularly cruel blow, even when strength and coordination in the writing hand and spoken speech are unaffected. Initial guidance from language and occupational therapists including the use of copying and anagram exercises is helpful but persistent self-practise is the secret of restorative success with improvement often continuing over several years.