Cavernous Sinus: An irregularly shaped venous space in the dura mater at either side of the sphenoid bone.Cavernous Sinus Thrombosis: Formation or presence of a blood clot (THROMBUS) in the CAVERNOUS SINUS of the brain. Infections of the paranasal sinuses and adjacent structures, CRANIOCEREBRAL TRAUMA, and THROMBOPHILIA are associated conditions. Clinical manifestations include dysfunction of cranial nerves III, IV, V, and VI, marked periorbital swelling, chemosis, fever, and visual loss. (From Adams et al., Principles of Neurology, 6th ed, p711)Sphenoid Sinus: One of the paired air spaces located in the body of the SPHENOID BONE behind the ETHMOID BONE in the middle of the skull. Sphenoid sinus communicates with the posterosuperior part of NASAL CAVITY on the same side.Cranial Sinuses: Large endothelium-lined venous channels situated between the two layers of DURA MATER, the endosteal and the meningeal layers. They are devoid of valves and are parts of the venous system of dura mater. Major cranial sinuses include a postero-superior group (such as superior sagittal, inferior sagittal, straight, transverse, and occipital) and an antero-inferior group (such as cavernous, petrosal, and basilar plexus).Abducens Nerve Diseases: Diseases of the sixth cranial (abducens) nerve or its nucleus in the pons. The nerve may be injured along its course in the pons, intracranially as it travels along the base of the brain, in the cavernous sinus, or at the level of superior orbital fissure or orbit. Dysfunction of the nerve causes lateral rectus muscle weakness, resulting in horizontal diplopia that is maximal when the affected eye is abducted and ESOTROPIA. Common conditions associated with nerve injury include INTRACRANIAL HYPERTENSION; CRANIOCEREBRAL TRAUMA; ISCHEMIA; and INFRATENTORIAL NEOPLASMS.Carotid-Cavernous Sinus Fistula: An acquired or spontaneous abnormality in which there is communication between CAVERNOUS SINUS, a venous structure, and the CAROTID ARTERIES. It is often associated with HEAD TRAUMA, specifically basilar skull fractures (SKULL FRACTURE, BASILAR). Clinical signs often include VISION DISORDERS and INTRACRANIAL HYPERTENSION.Central Nervous System Vascular Malformations: Congenital, inherited, or acquired abnormalities involving ARTERIES; VEINS; or venous sinuses in the BRAIN; SPINAL CORD; and MENINGES.Cranial Nerves: Twelve pairs of nerves that carry general afferent, visceral afferent, special afferent, somatic efferent, and autonomic efferent fibers.Ophthalmoplegia: Paralysis of one or more of the ocular muscles due to disorders of the eye muscles, neuromuscular junction, supporting soft tissue, tendons, or innervation to the muscles.Sinus Thrombosis, Intracranial: Formation or presence of a blood clot (THROMBUS) in the CRANIAL SINUSES, large endothelium-lined venous channels situated within the SKULL. Intracranial sinuses, also called cranial venous sinuses, include the superior sagittal, cavernous, lateral, petrous sinuses, and many others. Cranial sinus thrombosis can lead to severe HEADACHE; SEIZURE; and other neurological defects.Cranial Fossa, Middle: The compartment containing the anterior extremities and half the inferior surface of the temporal lobes (TEMPORAL LOBE) of the cerebral hemispheres. Lying posterior and inferior to the anterior cranial fossa (CRANIAL FOSSA, ANTERIOR), it is formed by part of the TEMPORAL BONE and SPHENOID BONE. It is separated from the posterior cranial fossa (CRANIAL FOSSA, POSTERIOR) by crests formed by the superior borders of the petrous parts of the temporal bones.Sphenoid Bone: An irregular unpaired bone situated at the SKULL BASE and wedged between the frontal, temporal, and occipital bones (FRONTAL BONE; TEMPORAL BONE; OCCIPITAL BONE). Sphenoid bone consists of a median body and three pairs of processes resembling a bat with spread wings. The body is hollowed out in its inferior to form two large cavities (SPHENOID SINUS).Dura Mater: The outermost of the three MENINGES, a fibrous membrane of connective tissue that covers the brain and the spinal cord.Cerebral Veins: Veins draining the cerebrum.Maxillary Sinus: The air space located in the body of the MAXILLARY BONE near each cheek. Each maxillary sinus communicates with the middle passage (meatus) of the NASAL CAVITY on the same side.Sella Turcica: A bony prominence situated on the upper surface of the body of the sphenoid bone. It houses the PITUITARY GLAND.Oculomotor Nerve Diseases: Diseases of the oculomotor nerve or nucleus that result in weakness or paralysis of the superior rectus, inferior rectus, medial rectus, inferior oblique, or levator palpebrae muscles, or impaired parasympathetic innervation to the pupil. With a complete oculomotor palsy, the eyelid will be paralyzed, the eye will be in an abducted and inferior position, and the pupil will be markedly dilated. Commonly associated conditions include neoplasms, CRANIOCEREBRAL TRAUMA, ischemia (especially in association with DIABETES MELLITUS), and aneurysmal compression. (From Adams et al., Principles of Neurology, 6th ed, p270)Paranasal Sinuses: Air-filled spaces located within the bones around the NASAL CAVITY. They are extensions of the nasal cavity and lined by the ciliated NASAL MUCOSA. Each sinus is named for the cranial bone in which it is located, such as the ETHMOID SINUS; the FRONTAL SINUS; the MAXILLARY SINUS; and the SPHENOID SINUS.Arteriovenous Fistula: An abnormal direct communication between an artery and a vein without passing through the CAPILLARIES. An A-V fistula usually leads to the formation of a dilated sac-like connection, arteriovenous aneurysm. The locations and size of the shunts determine the degree of effects on the cardiovascular functions such as BLOOD PRESSURE and HEART RATE.Sinus of Valsalva: The dilatation of the aortic wall behind each of the cusps of the aortic valve.Paranasal Sinus Neoplasms: Tumors or cancer of the PARANASAL SINUSES.Embolization, Therapeutic: A method of hemostasis utilizing various agents such as Gelfoam, silastic, metal, glass, or plastic pellets, autologous clot, fat, and muscle as emboli. It has been used in the treatment of spinal cord and INTRACRANIAL ARTERIOVENOUS MALFORMATIONS, renal arteriovenous fistulas, gastrointestinal bleeding, epistaxis, hypersplenism, certain highly vascular tumors, traumatic rupture of blood vessels, and control of operative hemorrhage.Carotid Sinus: The dilated portion of the common carotid artery at its bifurcation into external and internal carotids. It contains baroreceptors which, when stimulated, cause slowing of the heart, vasodilatation, and a fall in blood pressure.Skull Base Neoplasms: Neoplasms of the base of the skull specifically, differentiated from neoplasms of unspecified sites or bones of the skull (SKULL NEOPLASMS).Cerebral Angiography: Radiography of the vascular system of the brain after injection of a contrast medium.Pituitary Neoplasms: Neoplasms which arise from or metastasize to the PITUITARY GLAND. The majority of pituitary neoplasms are adenomas, which are divided into non-secreting and secreting forms. Hormone producing forms are further classified by the type of hormone they secrete. Pituitary adenomas may also be characterized by their staining properties (see ADENOMA, BASOPHIL; ADENOMA, ACIDOPHIL; and ADENOMA, CHROMOPHOBE). Pituitary tumors may compress adjacent structures, including the HYPOTHALAMUS, several CRANIAL NERVES, and the OPTIC CHIASM. Chiasmal compression may result in bitemporal HEMIANOPSIA.Neurosurgical Procedures: Surgery performed on the nervous system or its parts.Frontal Sinus: One of the paired, but seldom symmetrical, air spaces located between the inner and outer compact layers of the FRONTAL BONE in the forehead.Paranasal Sinus Diseases: Diseases affecting or involving the PARANASAL SINUSES and generally manifesting as inflammation, abscesses, cysts, or tumors.Maxillary Sinus Neoplasms: Tumors or cancer of the MAXILLARY SINUS. They represent the majority of paranasal neoplasms.Exophthalmos: Abnormal protrusion of both eyes; may be caused by endocrine gland malfunction, malignancy, injury, or paralysis of the extrinsic muscles of the eye.Cranial Nerve Diseases: Disorders of one or more of the twelve cranial nerves. With the exception of the optic and olfactory nerves, this includes disorders of the brain stem nuclei from which the cranial nerves originate or terminate.Carotid Artery, Internal: Branch of the common carotid artery which supplies the anterior part of the brain, the eye and its appendages, the forehead and nose.Trochlear Nerve: The 4th cranial nerve. The trochlear nerve carries the motor innervation of the superior oblique muscles of the eye.Hemangioma, Cavernous, Central Nervous System: A vascular anomaly composed of a collection of large, thin walled tortuous VEINS that can occur in any part of the central nervous system but lack intervening nervous tissue. Familial occurrence is common and has been associated with a number of genes mapped to 7q, 7p and 3q. Clinical features include SEIZURES; HEADACHE; STROKE; and progressive neurological deficit.Coronary Sinus: A short vein that collects about two thirds of the venous blood from the MYOCARDIUM and drains into the RIGHT ATRIUM. Coronary sinus, normally located between the LEFT ATRIUM and LEFT VENTRICLE on the posterior surface of the heart, can serve as an anatomical reference for cardiac procedures.Trigeminal Nerve Diseases: Diseases of the trigeminal nerve or its nuclei, which are located in the pons and medulla. The nerve is composed of three divisions: ophthalmic, maxillary, and mandibular, which provide sensory innervation to structures of the face, sinuses, and portions of the cranial vault. The mandibular nerve also innervates muscles of mastication. Clinical features include loss of facial and intra-oral sensation and weakness of jaw closure. Common conditions affecting the nerve include brain stem ischemia, INFRATENTORIAL NEOPLASMS, and TRIGEMINAL NEURALGIA.Meningeal Arteries: Arteries which supply the dura mater.Orbit: Bony cavity that holds the eyeball and its associated tissues and appendages.Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.Orbital Diseases: Diseases of the bony orbit and contents except the eyeball.Skull Base: The inferior region of the skull consisting of an internal (cerebral), and an external (basilar) surface.Central Nervous System Cysts: Congenital or acquired cysts of the brain, spinal cord, or meninges which may remain stable in size or undergo progressive enlargement.Hemangioma, Cavernous: A vascular anomaly that is a collection of tortuous BLOOD VESSELS and connective tissue. This tumor-like mass with the large vascular space is filled with blood and usually appears as a strawberry-like lesion in the subcutaneous areas of the face, extremities, or other regions of the body including the central nervous system.Horner Syndrome: A syndrome associated with defective sympathetic innervation to one side of the face, including the eye. Clinical features include MIOSIS; mild BLEPHAROPTOSIS; and hemifacial ANHIDROSIS (decreased sweating)(see HYPOHIDROSIS). Lesions of the BRAIN STEM; cervical SPINAL CORD; first thoracic nerve root; apex of the LUNG; CAROTID ARTERY; CAVERNOUS SINUS; and apex of the ORBIT may cause this condition. (From Miller et al., Clinical Neuro-Ophthalmology, 4th ed, pp500-11)Petrous Bone: The dense rock-like part of temporal bone that contains the INNER EAR. Petrous bone is located at the base of the skull. Sometimes it is combined with the MASTOID PROCESS and called petromastoid part of temporal bone.Sphenoid Sinusitis: Inflammation of the NASAL MUCOSA in the SPHENOID SINUS. Isolated sphenoid sinusitis is uncommon. It usually occurs in conjunction with other paranasal sinusitis.Diplopia: A visual symptom in which a single object is perceived by the visual cortex as two objects rather than one. Disorders associated with this condition include REFRACTIVE ERRORS; STRABISMUS; OCULOMOTOR NERVE DISEASES; TROCHLEAR NERVE DISEASES; ABDUCENS NERVE DISEASES; and diseases of the BRAIN STEM and OCCIPITAL LOBE.Cranial Nerve Neoplasms: Benign and malignant neoplasms that arise from one or more of the twelve cranial nerves.Abducens Nerve: The 6th cranial nerve which originates in the ABDUCENS NUCLEUS of the PONS and sends motor fibers to the lateral rectus muscles of the EYE. Damage to the nerve or its nucleus disrupts horizontal eye movement control.Sick Sinus Syndrome: A condition caused by dysfunctions related to the SINOATRIAL NODE including impulse generation (CARDIAC SINUS ARREST) and impulse conduction (SINOATRIAL EXIT BLOCK). It is characterized by persistent BRADYCARDIA, chronic ATRIAL FIBRILLATION, and failure to resume sinus rhythm following CARDIOVERSION. This syndrome can be congenital or acquired, particularly after surgical correction for heart defects.Ethmoid Sinus: The numerous (6-12) small thin-walled spaces or air cells in the ETHMOID BONE located between the eyes. These air cells form an ethmoidal labyrinth.Meningioma: A relatively common neoplasm of the CENTRAL NERVOUS SYSTEM that arises from arachnoidal cells. The majority are well differentiated vascular tumors which grow slowly and have a low potential to be invasive, although malignant subtypes occur. Meningiomas have a predilection to arise from the parasagittal region, cerebral convexity, sphenoidal ridge, olfactory groove, and SPINAL CANAL. (From DeVita et al., Cancer: Principles and Practice of Oncology, 5th ed, pp2056-7)Oculomotor Nerve: The 3d cranial nerve. The oculomotor nerve sends motor fibers to the levator muscles of the eyelid and to the superior rectus, inferior rectus, and inferior oblique muscles of the eye. It also sends parasympathetic efferents (via the ciliary ganglion) to the muscles controlling pupillary constriction and accommodation. The motor fibers originate in the oculomotor nuclei of the midbrain.Tomography, X-Ray Computed: Tomography using x-ray transmission and a computer algorithm to reconstruct the image.Tolosa-Hunt Syndrome: An idiopathic syndrome characterized by the formation of granulation tissue in the anterior cavernous sinus or superior orbital fissure, producing a painful ophthalmoplegia. (Adams et al., Principles of Neurology, 6th ed, p271)Microsurgery: The performance of surgical procedures with the aid of a microscope.Meningeal Neoplasms: Benign and malignant neoplastic processes that arise from or secondarily involve the meningeal coverings of the brain and spinal cord.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.Streptococcus constellatus: A species of gram-positive bacteria in the STREPTOCOCCUS MILLERI GROUP. It is commonly found in the oropharnyx flora and has a proclivity for abscess formation in the upper body and respiratory tract.Vascular Neoplasms: Neoplasms located in the vasculature system, such as ARTERIES and VEINS. They are differentiated from neoplasms of vascular tissue (NEOPLASMS, VASCULAR TISSUE), such as ANGIOFIBROMA or HEMANGIOMA.Craniotomy: Any operation on the cranium or incision into the cranium. (Dorland, 28th ed)Neuronavigation: Intraoperative computer-assisted 3D navigation and guidance system generally used in neurosurgery for tracking surgical tools and localize them with respect to the patient's 3D anatomy. The pre-operative diagnostic scan is used as a reference and is transferred onto the operative field during surgery.PolyvinylsAdenoma: A benign epithelial tumor with a glandular organization.Skull Neoplasms: Neoplasms of the bony part of the skull.Otorhinolaryngologic Surgical Procedures: Surgery performed on the ear and its parts, the nose and nasal cavity, or the throat, including surgery of the adenoids, tonsils, pharynx, and trachea.Intracranial Arteriovenous Malformations: Congenital vascular anomalies in the brain characterized by direct communication between an artery and a vein without passing through the CAPILLARIES. The locations and size of the shunts determine the symptoms including HEADACHES; SEIZURES; STROKE; INTRACRANIAL HEMORRHAGES; mass effect; and vascular steal effect.Orbital Neoplasms: Neoplasms of the bony orbit and contents except the eyeball.Tachycardia, Sinus: Simple rapid heartbeats caused by rapid discharge of impulses from the SINOATRIAL NODE, usually between 100 and 180 beats/min in adults. It is characterized by a gradual onset and termination. Sinus tachycardia is common in infants, young children, and adults during strenuous physical activities.Anatomy, Veterinary: The study of the anatomical structures of animals.Growth Hormone-Secreting Pituitary Adenoma: A pituitary tumor that secretes GROWTH HORMONE. In humans, excess HUMAN GROWTH HORMONE leads to ACROMEGALY.Intracranial Aneurysm: Abnormal outpouching in the wall of intracranial blood vessels. Most common are the saccular (berry) aneurysms located at branch points in CIRCLE OF WILLIS at the base of the brain. Vessel rupture results in SUBARACHNOID HEMORRHAGE or INTRACRANIAL HEMORRHAGES. Giant aneurysms (>2.5 cm in diameter) may compress adjacent structures, including the OCULOMOTOR NERVE. (From Adams et al., Principles of Neurology, 6th ed, p841)Chordoma: A malignant tumor arising from the embryonic remains of the notochord. It is also called chordocarcinoma, chordoepithelioma, and notochordoma. (Dorland, 27th ed)Maxillary Nerve: The intermediate sensory division of the trigeminal (5th cranial) nerve. The maxillary nerve carries general afferents from the intermediate region of the face including the lower eyelid, nose and upper lip, the maxillary teeth, and parts of the dura.Pituitary Apoplexy: The sudden loss of blood supply to the PITUITARY GLAND, leading to tissue NECROSIS and loss of function (PANHYPOPITUITARISM). The most common cause is hemorrhage or INFARCTION of a PITUITARY ADENOMA. It can also result from acute hemorrhage into SELLA TURCICA due to HEAD TRAUMA; INTRACRANIAL HYPERTENSION; or other acute effects of central nervous system hemorrhage. Clinical signs include severe HEADACHE; HYPOTENSION; bilateral visual disturbances; UNCONSCIOUSNESS; and COMA.Prolactinoma: A pituitary adenoma which secretes PROLACTIN, leading to HYPERPROLACTINEMIA. Clinical manifestations include AMENORRHEA; GALACTORRHEA; IMPOTENCE; HEADACHE; visual disturbances; and CEREBROSPINAL FLUID RHINORRHEA.Carotid Artery Diseases: Pathological conditions involving the CAROTID ARTERIES, including the common, internal, and external carotid arteries. ATHEROSCLEROSIS and TRAUMA are relatively frequent causes of carotid artery pathology.Putaminal Hemorrhage: Intracranial bleeding into the PUTAMEN, a BASAL GANGLIA nucleus. This is associated with HYPERTENSION and lipohyalinosis of small blood vessels in the putamen. Clinical manifestations vary with the size of hemorrhage, but include HEMIPARESIS; HEADACHE; and alterations of consciousness.Cranial Fossa, Posterior: The infratentorial compartment that contains the CEREBELLUM and BRAIN STEM. It is formed by the posterior third of the superior surface of the body of the sphenoid (SPHENOID BONE), by the occipital, the petrous, and mastoid portions of the TEMPORAL BONE, and the posterior inferior angle of the PARIETAL BONE.Pituitary Diseases: Disorders involving either the ADENOHYPOPHYSIS or the NEUROHYPOPHYSIS. These diseases usually manifest as hypersecretion or hyposecretion of PITUITARY HORMONES. Neoplastic pituitary masses can also cause compression of the OPTIC CHIASM and other adjacent structures.Dissection: The separation and isolation of tissues for surgical purposes, or for the analysis or study of their structures.Eye Manifestations: Ocular disorders attendant upon non-ocular disease or injury.Orbital Pseudotumor: A nonspecific tumor-like inflammatory lesion in the ORBIT of the eye. It is usually composed of mature LYMPHOCYTES; PLASMA CELLS; MACROPHAGES; LEUKOCYTES with varying degrees of FIBROSIS. Orbital pseudotumors are often associated with inflammation of the extraocular muscles (ORBITAL MYOSITIS) or inflammation of the lacrimal glands (DACRYOADENITIS).Angiography, Digital Subtraction: A method of delineating blood vessels by subtracting a tissue background image from an image of tissue plus intravascular contrast material that attenuates the X-ray photons. The background image is determined from a digitized image taken a few moments before injection of the contrast material. The resulting angiogram is a high-contrast image of the vessel. This subtraction technique allows extraction of a high-intensity signal from the superimposed background information. The image is thus the result of the differential absorption of X-rays by different tissues.Radiosurgery: A radiological stereotactic technique developed for cutting or destroying tissue by high doses of radiation in place of surgical incisions. It was originally developed for neurosurgery on structures in the brain and its use gradually spread to radiation surgery on extracranial structures as well. The usual rigid needles or probes of stereotactic surgery are replaced with beams of ionizing radiation directed toward a target so as to achieve local tissue destruction.Lemierre Syndrome: A superinfection of the damaged oropharyngeal mucosa by FUSOBACTERIUM NECROPHORUM leading to the secondary septic THROMBOPHLEBITIS of the internal jugular vein.Ophthalmic Nerve: A sensory branch of the trigeminal (5th cranial) nerve. The ophthalmic nerve carries general afferents from the superficial division of the face including the eyeball, conjunctiva, upper eyelid, upper nose, nasal mucosa, and scalp.