Presentation
New onset headache and disequilibrium
Patient Data
There is a 6 x 8 x 10 cm large extra-axial fluid signal arachnoid cyst at the left frontotemporal region causing marked pressure on adjacent brain parenchyma and effacement of adjacent gyri as well as midline shift measuring about 1 cm to the right side. Subdural hygroma adjacent to the left cerebral hemisphere measuring about 3 cm thickness is also seen in keeping with a ruptured arachnoid cyst.
Case Discussion
Most arachnoid cysts are asymptomatic throughout life. Symptoms are produced when arachnoid cysts are large or complicated by subdural hygroma or intracystic hemorrhage.
It is worth noting that small cysts, because they constrain CSF, prevent it from flowing with cardiac pulsations, are therefore usually brighter than "normal" CSF. Large cysts, however, like this one can have turbulent flow within them as they are deformed during systole and thus have volume loss.