Sturge-Weber syndrome

Sturge-Weber syndrome is a congenital neurocutaneous disorder named after William Sturge and Frederick Weber, the first physicians to describe it.

Neurocutaneous because it affects the brain and the skin.

In fact, Sturge-Weber syndrome is also called encephalotrigeminal angiomatosis; encephalo- refers to the brain, trigeminal refers to the trigeminal or fifth cranial nerve, and angiomatosis refers to a vascular malformation.

That’s because in Sturge-Weber syndrome there are too many capillaries in the meninges covering the brain, as well as in some areas of the face that are innervated by the trigeminal nerve, like the forehead and upper eyelid.

Finally, in Sturge-Weber syndrome there’s often a congenital mark - a birthmark - called a port-wine stain.

When the embryo is one week old, it has two layers of cells: a dorsal or outer epiblast layer and a ventral or inner hypoblast layer.

During week 3 of development the embryo undergoes gastrulation where the cells in the epiblast layer form a three layered trilaminar disc with an ectoderm, mesoderm and endoderm layer.

The ectoderm is the dorsal most germ layer, and through a process called neurulation forms the neural tube.

From the neural tube, neural crest cells migrate to help form the central and peripheral nervous systems, as well as the cornea of the eyes and the epidermis layer of the fetal skin.

During week 6 of development, as the cephalic portion of the neural tube grows, a network of tiny blood vessels called a vascular plexus develops, to better supply that neural tissue.

There’s a gene called the GNAQ gene which codes for a guanine nucleotide-binding protein, and that protein is involved in development of the vascular plexus.

Normally, around week 9 of development, the GNAQ gene stops getting expressed, and that leads to regression of the vascular plexus.