Edema:  An excessive accumulation of fluid in cells, tissues, or body cavities.
Electroencephalography (EEG):  The study of the electrical currents set up by brain actions; the record made is called an electroencephalogram.
Electromyography (EMG):  A method of recording the electrical currents generated in a muscle during its contraction.
Encephalocele:  The herniation of brain meninges through a skull defect.
Endarterectomy:  The removal of fatty or cholesterol plaques and calcified deposits from the internal wall of an artery. More about carotid occlusive disease.
Endoscope:  A thin, telescope-like instrument. A video camera attached to the endoscope records images a surgeon can view on a monitor. Specially designed surgical tools enable a surgeon to operate through small incision(s). See illustration at right.
Endovascular:  Inside a blood vessel, especially a minimally invasive catheter-based approach for the treatment of central nervous system disorders (for example, a cerebral aneurysm).
Ependyma:  The membrane that lines the cerebral ventricles of the brain and central canal of the spinal cord.
Ependymoma:  A growth in the brain or spinal cord arising from ependymal tissue.
Epidural (extradural):  Immediately outside the dura mater.
Epidural hematoma:  A blood clot between the dura mater and the inside of the skull.
Epilepsy:  A disorder characterized by abnormal electrical discharges in the brain, causing abnormal sensation, movement or level of consciousness. More about epilepsy in adults and epilepsy in children.

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