16770
So far , there have been no standardised morphometric measurements of the paediatric MPS IVA cervical spine to evaluate whether there is pre - existing spinal stenosis predisposing to compressive myelopathy or whether this is purely an acquired process secondary to instability and compression .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None