My eldest son was diagnosed with this problem when he was 12 or 13, by a peadiatric specialist, but his school did not take any notice nor did they allow for it in his classes.
i have often wondered if i did not have the same or similar thing, as i look at numbers as just numbers, i cannot relate them to each other except as patterns. i am able to add up very quickley using tricks i picked up when i tried to resit my o level maths about 15 years ago.
My son is 28 this year and still has problems, recently he had to lay some loft insulation and waqs told to lay one thickness first and then the other thickness on top, but his boss just told him the mm measurements of thickness, and he was completely confused. he did the job the wrong way round which seems a silly thing but he says the use of the numbers threw him.