[Intradural spinal arachnoid cyst associated with Noonan's syndrome]

Intradural spinal arachnoid cysts are collections of liquid similar to CSF, caused by a disorder of the arachnoid trabeculae. Noonan s syndrome is a condition involving multiple malformations, with autosomal dominant inheritance, variable penetration and expression and a phenotype similar to that of Turner s syndrome. We describe the case of a girl with Noonan s syndrome who presented with progressive scoliosis and signs and symptoms of a disorder of the spine related to an intradural spinal arachnoid cyst.

A four year old girl with no significant previous clinical history was seen for slow growth (in size and weight), progressive scoliosis and urinary sphincter dysfunction. On physical examination there were features of polymalformation compatible with Noonan s syndrome and thoracic scoliosis. In view of this a spinal MR study was done. This showed an intradural arachnoid cyst from segment T4 to T11, with displacement and spinal narrowing which required a cyst-peritoneal shunt.

Intradural spinal arachnoid cysts are collections of liquid produced due to arachnoid trabeculae. Noonan s syndrome is a condition involving multiple malformations with a phenotype which is very similar to that of Turner s syndrome. It is linked to alterations of tissue elastin which favor the appearance of arachnoid cysts. Arachnoid cysts are an uncommon cause of spinal compression and/or progressive scoliosis. Although this association has not been described previously, in the case of a patient with Noonan s syndrome, with clinical features of a spinal disorder and/or progressive scoliosis, the presence of a spinal arachnoid cyst should be considered.