Neurological disorders are abnormal conditions of the nervous system (the brain and spinal cord). They may be caused by traumatic injury or disease, but they also may develop spontaneously. Neurological disorders have a variety of symptoms and can affect people in different ways. Treatment depends on the disorder, but usually includes medication or surgery.

The brain is protected by a layer of tissue called meninges. The meninges are composed of three layers — the dura mater, arachnoid mater, and pia mater — that surround the brain and spinal cord. The dura mater is a tough outer protective layer; the arachnoid mater is a finer inner layer; and the pia mater is closest to the brain itself. Between these two layers, there may be small pockets filled with cerebrospinal fluid (CSF). These spaces are called subarachnoid cisterns. Along with CSF, they help cushion and protect the brain.