Ventriculostomy: Surgical creation of an opening in a cerebral ventricle.Third Ventricle: A narrow cleft inferior to the CORPUS CALLOSUM, within the DIENCEPHALON, between the paired thalami. Its floor is formed by the HYPOTHALAMUS, its anterior wall by the lamina terminalis, and its roof by EPENDYMA. It communicates with the FOURTH VENTRICLE by the CEREBRAL AQUEDUCT, and with the LATERAL VENTRICLES by the interventricular foramina.Hydrocephalus: Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, INTRACRANIAL HYPERTENSION; HEADACHE; lethargy; URINARY INCONTINENCE; and ATAXIA.Neuroendoscopy: PROCEDURES that use NEUROENDOSCOPES for disease diagnosis and treatment. Neuroendoscopy, generally an integration of the neuroendoscope with a computer-assisted NEURONAVIGATION system, provides guidance in NEUROSURGICAL PROCEDURES.Cerebral Aqueduct: Narrow channel in the MESENCEPHALON that connects the third and fourth CEREBRAL VENTRICLES.Ultrasonic Surgical Procedures: The use of HIGH-ENERGY SHOCK WAVES, in the frequency range of 20-60 kHz, to cut through or remove tissue. The tissue fragmentation by ultrasonic surgical instruments is caused by mechanical effects not heat as with HIGH-INTENSITY FOCUSED ULTRASOUND ABLATION.Endoscopy: Procedures of applying ENDOSCOPES for disease diagnosis and treatment. Endoscopy involves passing an optical instrument through a small incision in the skin i.e., percutaneous; or through a natural orifice and along natural body pathways such as the digestive tract; and/or through an incision in the wall of a tubular structure or organ, i.e. transluminal, to examine or perform surgery on the interior parts of the body.Cerebrospinal Fluid Pressure: Manometric pressure of the CEREBROSPINAL FLUID as measured by lumbar, cerebroventricular, or cisternal puncture. Within the cranial cavity it is called INTRACRANIAL PRESSURE.Ventriculoperitoneal Shunt: Surgical creation of a communication between a cerebral ventricle and the peritoneum by means of a plastic tube to permit drainage of cerebrospinal fluid for relief of hydrocephalus. (From Dorland, 28th ed)Cerebrospinal Fluid Shunts: Tubes inserted to create communication between a cerebral ventricle and the internal jugular vein. Their emplacement permits draining of cerebrospinal fluid for relief of hydrocephalus or other condition leading to fluid accumulation in the ventricles.Cerebral Ventriculography: Radiography of the ventricular system of the brain after injection of air or other contrast medium directly into the cerebral ventricles. It is used also for x-ray computed tomography of the cerebral ventricles.Cerebral Ventricles: Four CSF-filled (see CEREBROSPINAL FLUID) cavities within the cerebral hemispheres (LATERAL VENTRICLES), in the midline (THIRD VENTRICLE) and within the PONS and MEDULLA OBLONGATA (FOURTH VENTRICLE).Neurosurgical Procedures: Surgery performed on the nervous system or its parts.Craniotomy: Any operation on the cranium or incision into the cranium. (Dorland, 28th ed)Headache: The symptom of PAIN in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of HEADACHE DISORDERS.Magnetic Resonance Imaging, Cine: A type of imaging technique used primarily in the field of cardiology. By coordinating the fast gradient-echo MRI sequence with retrospective ECG-gating, numerous short time frames evenly spaced in the cardiac cycle are produced. These images are laced together in a cinematic display so that wall motion of the ventricles, valve motion, and blood flow patterns in the heart and great vessels can be visualized.