Symbrachydactyly, as noted previously, https://congenitalhand.wustl.edu/2011/12/normal.html means “short, webbed fingers.” The use of this label is clearly appropriate for some children who (brace yourself for this truth) have short and webbed fingers (i.e., a syndactyly). The term symbrachydactyly has further meaning as it has implications for etiology (i.e., cause).
I believe symbrachydactyly occurs due to difficulties with the AER and the underlying mesoderm during development- please see previous description of limb development https://congenitalhand.wustl.edu/2012/10/limb-formation.html If the AER is lost, limb outgrowth stops and there is a deficient limb. The theory is that early loss (i.e., at 4-5 weeks of gestation) leads to a really short limb and later loss (i.e., at 6-7 weeks of gestation) leads to more subtle symbrachydactyly. The following children would be considered to have a severe symbrachyactyly– at least the way I consider it. We have shared our thoughts and experiences with this diagnosis in the Journal of Hand Surgery: http://www.ncbi.nlm.nih.gov/pubmed/17996776
|Nubbins of symbrachydactyly|
|Another example of severe symbrachydactyly|
The “nubbins” on the end of the arm likely represent some remnant from the cells from development (from the apical ectodermal ridge). The nubbins can be surprisingly well formed and often have fingernails. Some families preserve and value the nubbins while others feel that the nubbins get in the way and can be difficult to keep clean. When families request, the nubbins can be easily excised with a small surgery. The nubbins certainly do not grow and removal, therefore, is reasonable because function of the nubbins will not get better with age. I leave these decisions to the family.
Others believe severe symbrachydactyly really should be called a transverse arrest or congenital amputation of the limb. I don’t mind those terms but I happen to believe this is most likely a development issue (a malformation)- meaning that something went wrong during limb development, not after.
The above examples differ from less severe symbrachydactyly:
|Short finger type of symbrachydactyly– short, webbed fingers.|
|Another short finger symbrachydactyly|