Temporal lobe epilepsy is a disorder whose precise cause is often unknown. In it, a kind of "storm" of electrical activity develops in the temporal lobe and spreads throughout the brain, where it can cause any of a wide variety of symptoms ranging from an "absent seizure" to altered behavior. Drugs and occasionally surgery can control and sometimes even cure the disease. Billy's particular case was consequential to a meningioma. Meningiomas are usually benign tumors that arise in the meninges, or membranes, and surround and protect the brain (dura mater, pia mater, and arachnoid mater). Such tumors cause problems by pressing on delicate structures in the brain as they grow; almost nothing in the brain responds well to pressure. Because they have well defined margins, surgeons can usually completely resect this class of tumor; the difficult cases arise when the location of the tumor makes it difficult to completely expose and visualize it. Meningiomas often recur, sometimes elsewhere, and therefore such patients are often followed by a neurologist for a period of time, and advised what symptoms require immediate attention.