hydrocephalus obstructive hydrocephalus DOID:14159 ICD10CM:G91.1 ICD9CM:331.4 MESH:D006849 NCI:C116347 SNOMEDCT_US_2016_03_01:230746009 SNOMEDCT_US_2016_03_01:82346000 UMLS_CUI:C0549423 disease_ontology