Home Health Dyslexia and other learning difficulties
Whereas agnosia is a difficulty in sensing where the body is in space without using the eyes, visual-spatial deficit is a difficulty in direction sense when using the eyes. Agnosia may be thought of as a difficulty with ‘inner space’, visual-spatial deficit as difficulty with ‘outer space’.
Visual-spatial deficit will result in difficulties in tasks such as telling right from left and following a map. It is also a cause of clumsiness in complex actions such as tying shoe laces, drawing pictures, and catching a ball.
There are special tests that assess visual-spatial skills. These usually involve tasks such as copying and arranging shapes.
Although low tone is often given as a reason for a child’s clumsiness, it is probably not a common cause of clumsiness.
Tone (or muscular tone, as it is properly called) refers to the resistance that muscles give to being moved when they are relaxed. This is ascertained by the examiner when he or she moves the child’s limbs while the child keeps them as relaxed as possible. It should be distinguished from muscular weakness, which involves active contraction of the muscle by the child. Low tone, or ‘hypotonia’, signifies that the muscles give less resistance to passive movement, that is, they are floppier than normal.
The tone of the muscles is controlled by tiny ‘stretch receptors’ situated in their tendons. These in turn are controlled by the brain. Hypotonia is a common finding in children with clumsiness, but the cause is unknown.
Severe hypotonia can cause clumsiness, as it is difficult to control very floppy muscles, but mild hypotonia does not seem to be a problem. Many well-coordinated children have mild hypotonia, so it is difficult to accept that mild hypotonia on its own is a cause of clumsiness.
Many of the exercises to ‘strengthen tone’ are of questionable value. Exercises may increase the strength of the muscles, but probably have little effect on their tone.
Flat feet caused by low tone are often given as a cause of clumsiness. In the past, too much significance was given to flat feet. Flexible flat feet do not cause problems (high arches are more troublesome). As many as 10 per cent of normal school-age children have flat feet and these, like other low-tone manifestations, get better with time. Supports, special shoes, and exercises are of questionable value.
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