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Sturge-Weber Syndrome

Sturge-Weber syndrome is a sporadic disorder. Sturge-Weber is classic because of the vascular port-wine nevus in the V-1 or V-2 trigeminal distribution with contralateral hemiparesis and seizures. Where do the seizures come from? They come from the cerebral cortex, as we keep saying. Another name for Sturge-Weber syndrome is leptomeningio-angiomatosis. So it’s really a vascular problem involving the pial membrane. Then when they begin to calcify of course.

They can develop glaucoma and there is a high incidence of mental retardation. Another radiologic picture; you see this less and less anymore. Fifteen years ago this was on every Boards because we did a lot of skull films. So calcified blood vessels leave a twin line. It looks like railroad track. So you’ll find that in books all the time, railroad track calcifications.

Anencephaly is relatively common. My medical school year, the very first delivery I did as a junior medical student in the heartland of Louisiana was an anencephalic child. It’s slightly less than 1:1,000 in the United States and the recurrence rate is 3-5%. As you know probably, it can be monitored with alpha fetoprotein. Then there are encephaloceles. These are herniations of meninges with or without brain parenchyma, usually through a bony defect. Three out of four are occipital, and in the Orient there is an association with hypertelorism and short stature, and frontal encephaloceles. This illustration is there in your handout on the right side, and what it is, is to schematically show that there are two types. One is called a meningocele.

The sensory findings have to do with the anatomy. We told you in the morning, neurologists tend to be very interested in anatomic correlations. These are patients in whom you will get a very distinctive sensory examination. You will find that they have some deficiency in sensation to pain or temperature and yet seem to be capable of perception of vibratory sense and, in an old enough and mature enough child, you may be able to test them for graphesthesia and so on. And you may wonder, how can this be possible? They can barely feel the hot or cold tuning fork, and yet they know the vibration. It has to do with the fact that this is the dorsal root ganglion on this side where pain temperature fibers enter the segment and they cross and go to the lateral spinal thalamic track. And then they ascend. So when there is a syrinx, which is shown in red here, you have an interruption.

Now we are going to disorders of cell division and migration. And here, before I go too far, let me just remind you of something from embryology. As the brain develops in early fetal stage, after the ventricular cavities are formed as you know there is a layer of cells there that are capable of cell division. These are the neuroblasts that divide in a highly orchestrated, controlled manner. When you think about the fact that we have billions of cells and each cell division doubles the number, one extra cycle or one cycle less would make a big difference. We would either end up with pinheads with very few neurons or with an enormous number of neurons. And in fact most of us end up with a relatively similar number of neurons. Because these are highly carefully controlled. After that, the cells migrate outward. So the cells begin their life near the ventricles but they have to reach the cerebral cortex for which they migrate along glial fibers with long processes. Like scaffolding. These are Bergmann’s glia.

Holoprosencephaly is a condition where you don’t have cerebral hemispheres. This is because the telencephalic vesicles never formed. Basically you end up with one cavity and there may be arrhinencephaly and there is cleft lip, again a midline defect. And these patients have severe mental retardation and motor deficits, seizures. Lissencephaly is another migrational error. It is often called by different names. Most commonly it would be called agyria. What happens here is it’s a disorder of sulcation, another term. The brain does not form, gyri and sulci. There are heterotopias in this condition, frequently, and the heterotopias.

Chiari malformations. Type I Chiari is one where there is herniation of the cerebellar tonsils. That’s a very classic type of description, many of you probably recall. Frequently Chiari’s are asymptomatic until later. Not everyone presents with major symptoms right away. Type II includes what’s said in type I, but there is an association of other anomalies. There is an elongation of caudal medulla, which is an important finding, and there is a kinking of the cervical medullary junction and type II always implies also a lumbosacral meningomyelocele.