loading...| Preferred Name |
Microcephaly |
| Synonyms |
Reduced head circumference Small skull Decreased size of head Abnormally small skull small cranium Decreased circumference of cranium Small head circumference Decreased size of skull Small head Abnormally small cranium small calvarium Abnormally small head Decreased size of cranium |
| Definitions |
Head circumference below 2 standard deviations below the mean for age and gender. Head circumference is measured from just above the glabella (the most prominent point on the frontal bone above the root of the nose) to the most posterior prominent point of the occipital bone using a tape measure. Some standard charts are organized by centiles, others by standard deviations. It is important to add an indication of how far below the normal standard the head circumference is if an accurate assessment of this can be made. Microcephaly is an absolute term. The term relative microcephaly can be used when the head size centile is less than the centile for height, for example, head size at the 3rd centile with height at the 75% for age and sex. On prenatal ultrasound, microcephaly is diagnosed if the head circumference or the biparietal diameter is more than three standard deviations below the mean. Microcephaly is divided into primary microcephaly, which is present at birth, and secondary microcephaly, which develops postnatally. The crucial difference between these groupings is that primary microcephaly is usually a static developmental anomaly, whereas secondary microcephaly indicates a progressive neurodegenerative condition |
| ID |
http://purl.obolibrary.org/obo/HP_0000252 |
| comment |
Head circumference is measured from just above the glabella (the most prominent point on the frontal bone above the root of the nose) to the most posterior prominent point of the occipital bone using a tape measure. Some standard charts are organized by centiles, others by standard deviations. It is important to add an indication of how far below the normal standard the head circumference is if an accurate assessment of this can be made. Microcephaly is an absolute term. The term relative microcephaly can be used when the head size centile is less than the centile for height, for example, head size at the 3rd centile with height at the 75% for age and sex. On prenatal ultrasound, microcephaly is diagnosed if the head circumference or the biparietal diameter is more than three standard deviations below the mean. Microcephaly is divided into primary microcephaly, which is present at birth, and secondary microcephaly, which develops postnatally. The crucial difference between these groupings is that primary microcephaly is usually a static developmental anomaly, whereas secondary microcephaly indicates a progressive neurodegenerative condition |
| database_cross_reference |
SNOMEDCT_US:271611007 UMLS:C4551563 Fyler:4310 MeSH:D008831 UMLS:C0025958 |
| definition |
Head circumference below 2 standard deviations below the mean for age and gender. |
| has_alternative_id |
HP:0005485 HP:0005497 HP:0001366 HP:0005489 |
| has_broad_synonym |
Small skull Decreased size of head Small head Abnormally small head |
| has_exact_synonym |
Reduced head circumference Abnormally small skull small cranium Decreased circumference of cranium Small head circumference Decreased size of skull Abnormally small cranium small calvarium Decreased size of cranium |
| id |
HP:0000252 |
| in_subset | |
| label |
Microcephaly |
| notation |
HP:0000252 |
| prefLabel |
Microcephaly |
| subClassOf |