Different Types of Syringomyelia and Their Management: Part I

Surgical Procedures Posterior Fossa Decompression There are many ways to perform posterior fossa decompression (PFD), although indications for each technique are not clear, and its application depends on clinical manifestations, radiologic findings, dynamics of cerebrospinal fluid (CSF) and especially, the surgeon’s preference. OccipitalCraniectomy.This is the simplest procedure, and it consists of performinganoccipital craniectomywide enough to allow for both decompression and maintenance of the posterior fossaneural elements. The extent of bone removal is very important, because performing a wide occipital window has a high risk of formation of a pseudomeningocele and the socalled cerebellar ptosis; in these cases, symptomsmaynot only recur but even become associated with other cerebellar manifestations. Themost recommendedaverage size for the craniectomy is approximately 2.5 to 3 cm on each side of the midline immediately below the inionup to the foramenmagnumand, depending on the extension of cerebellar tonsillar herniation, it is usually associated with resection of the posterior arch of C1 and sometimes, the lamina of C2 (Figure 1). Most patients with type I Chiari malformation experience improvement in their symptomswith this simpleprocedure. This improvement is because pathologic analysis has shown an increase in collagen fibers, hyaline nodules, and calcification in thedural band of the craniovertebral junction, so bone removal promotes liberationof all these elements andallows restorationofCSF flow. However, if this procedure is chosen as the only treatment, it Different Types of Syringomyelia and Their Management: Part II