Neurologic Diseases: Arachnoid Brain Cyst

Arachnoid Brain Cyst is nothing but an arachnoid cyst occurring intracranially (within the skull cavity); but since it can occur in the spine as well sometimes this term may be preferred to distinguish it from the one that develops in the spine.

Neurologist & Neurosugeon are the specialists generally involved in the care of patients with Arachnoid Brain Cyst.

Arachnoid cysts are cystic (cavity like) structures developing from the arachnoid membrane of the meninges. Meninges are the protective coverings of brain & spinal cord and there are 3 layers from out side to inside; dura, arachnoid and pia matter.

The above cysts have a wall composed arachnoid cells and collagen connective tissue fibers. They contain CSF (cerebrospinal fluid) unless there are any complications like bleeding, infection etc.

The intracranial arachnoid cysts can occur almost anywhere on the surface of the brain and their size varies from few millimeter to several centimeters. Some of the preferred location include middle cranial fossa, sylvian fissure etc.

Majority of these cysts are congenital in nature (present at birth) although some of them may be secondary to traumas, infections etc. The congenital cysts do not generally manifest at a very young age, rather around adolescent or young adult age.

The natural course of them is generally to remain silent and of the same size throughout life. So when they are found on CT or MRI they are conservatively treated on most occasions rather than surgically. However for whatever reason sometimes the size might increase causing pressure effect in the adjacent brain; also complications like bleeding in to the cyst or infection of the cyst can occur and complicate the picture. Then a surgical treatment may be required.

Remember majority of the patients do not have any symptoms attributable to these cysts and they are diagnosed incidentally. But when symptoms occur they include (may vary from patient to patient);

• Headache (usually unilateral)
• Seizures
• Focal extremity weakness
• Dizziness
• Numbness of one sided limbs etc.

• CT or MRI of the brain

There is no medication to treat the Arachnoid Brain cyst and the treatment has to be surgical. As pointed above asymptomatic cysts are left like that since surgical approach carries some risk.

There are various surgical procedures and the type of surgery generally depends upon the size and location of the cyst. Such procedures include excision or resection, aspiration, shunt placement, drainage of the cyst etc.

Patients are also treated symptomatically; headache with pain killers, seizures with seizure mediations etc.