Update from Mr S on the CT scan of his Brain

In the big tub of mail I picked up yesterday there was a referral from my primary care physician for an MRI because the CT scan showed a small cyst in the posterior fossa region of my arachnoid tissue. The MRI order is for a “Differentiation b/w craniopharyngioma”.

Meninges: Three distinct connective tissue membranes called meninges (dura, arachnoid, and pia mater ),enclose and protect the central nervous system.

Arachnoid: Internal to the dura mater is a thin meninge called arachnoid mater. The arachnoid space is a relatively large space that contains the cerebrospinal fluid. That membrane is called arachnoid because the cobweblike trabeculae crossing the subarachnoid to become continuous with the pia mater.

Craniopharyngioma is a histologically benign, extra-axial, slow-growing tumor that predominately involves the sella and suprasellar space. Despite its histologic appearance, craniopharyngiomas occasionally behave like malignant tumors, they can metastasize, and patients can have severe symptoms that usually require surgery and/or radiation therapy.

Clinical Details: Arachnoid cysts often are an incidental finding on imaging, and patients usually are asymptomatic even if the cyst is quite large. The most common associated clinical features include headache, calvarial bulging, intracranial hypertension, craniomegaly, developmental delay, visual loss, precocious puberty, and seizures, with focal neurologic signs occurring less frequently.[Note from Tina: Mr S has most certainly been experiencing an uptick in headaches and vision problems.] Arachnoid cysts are known to rupture into the subdural space or undergo intracystic hemorrhage. MRI is the diagnostic procedure of choice because of its ability to demonstrate the exact location, extent, and relationship of the arachnoid cyst to the spinal cord. http://www.emedicine.com/RADIO/topic48.htm

“The posterior fossa is a common site of benign intracranial cysts.”

Intracranial arachnoid cysts: treatment alternatives and outcome in a series of 25 patients