A sphenoid wing meningioma is a benign brain tumor near the sphenoid bone.
A sphenoid wing meningioma is a benign brain tumor near the sphenoid bone.
A meningioma is a benign brain tumor. It originates from the arachnoid (not the dura), the tissue covering the brain and spinal cord lying deep to the dura. Meningiomas are much more common in females, and are more common after 50 years of age. Of all cranial meningiomas, about 20% of them are in the sphenoid wing. In some cases, deletions involving chromosome 22 are involved.
Sphenoid wing meningiomas are diagnosed by the combination of suggestive symptoms from the history and physical and neuroimaging by magnetic resonance imaging (MRI) or computer averaged tomography (CT). Tumors growing in the inner wing (clinoidal) most often cause direct damage to the optic nerve leading especially to a decrease in visual acuity, progressive loss of color vision, defects in the field of vision (especially cecocentral), and an afferent pupillary defect. If the tumor continues to grow and push on the optic nerve, all vision will be lost in that eye as the nerve atrophies. Proptosis, or anterior displacement of the eye, and palpebral swelling may also occur when the tumor impinges on the cavernous sinus by blocking venous return and leading to congestion. Damage to cranial nerves in the cavernous sinus leads to diplopia. Cranial nerve VI is often the first affected, leading to diplopia with lateral gaze. If cranial nerve V-1 is damaged, the patient will have pain and altered sensation over the front and top of the head. Horner's syndrome may occur if nearby sympathetic fibers are involved.[ citation needed ]
Tumors found in the external third of the sphenoid are of two types: en-plaque and globoid meningiomas. En plaque meningiomas characteristically lead to slowly increasing proptosis with the eye angled downward. Much of this is due to reactive orbital hyperostosis. With invasion of the tumor into the orbit, diplopia is common. Patients with globoid meningiomas often present only with signs of increased intracranial pressure. This leads to various other symptoms including headache and a swollen optic disc. The differential diagnosis for sphenoid wing meningioma includes other types of tumors such as optic nerve sheath meningioma, cranial osteosarcoma, metastases, and also sarcoidosis. Following the physical exam, the diagnosis is confirmed with neuro-imaging. Either a head CT or MRI with contrast such as gadolinium is useful, as meningiomas often show homogenous enhancement. Angiography looking for signs like stretched arteries may be used to supplement evaluation of vascular involvement and to determine whether embolization would be helpful if surgery is being considered.[ citation needed ]
Meningiomas have been divided into three types based on their patterns of growth. Histological factors that increase the grade include a high number of mitotic figures, necrosis and local invasion. Treatment of sphenoid wing meningiomas often depends on the location and size of the tumor. Gamma knife radiation and microscopic surgery are common options. Their encapsulated, slow growth makes meningiomas good targets for radiosurgery. In one series, less than one-third of clinoidal meningiomas could be completely resected without unacceptable risk of damaging of blood vessels (especially the carotid artery) or cranial nerves, risks that are lower with radiosurgery. If surgery is done and the entire tumor cannot be removed, then external beam radiation helps reduce recurrence of the growth. In fact, surgery followed by radiation at recurrence provided excellent tumor control in cases where gross-total resection cannot be achieved. [1] Most all meningiomas grow very slowly and almost never metastasize to other parts of the body. In part because of its slow growth, if a tumor is asymptomatic and found only by imaging, the best course is often observation with serial clinical exams and imaging. Possible indications for intervention would be a rapid increase in growth or involvement of cranial nerves. Untreated, one small series showed survival rates ranging from five to over twenty years, though most had unilateral blindness as well as paresis of extraocular movements.
Higher grade tumors have been shown to correspond with higher recurrences. Depending on the grade and extent of resection, from less than 1 in 10 to over two-thirds of tumors will recur after surgical excision. Follow-up clinical exams, as well as neuroimaging, can aid in detecting recurrences. As many meningiomas have receptors for progesterone, progesterone blockers are being investigated. Two other drugs that are being studied for use are hydroxyurea and interferon alpha-2b.
Cranial nerves are the nerves that emerge directly from the brain, of which there are conventionally considered twelve pairs. Cranial nerves relay information between the brain and parts of the body, primarily to and from regions of the head and neck, including the special senses of vision, taste, smell, and hearing.
The danger triangle of the face consists of the area from the corners of the mouth to the bridge of the nose, including the nose and maxilla. Due to the special nature of the blood supply to the human nose and surrounding area, it is possible, albeit extremely unlikely, for retrograde infection from the nasal area to spread to the brain, causing cavernous sinus thrombosis, meningitis or brain abscess.
The abducens nerve or abducent nerve, also known as the sixth cranial nerve, cranial nerve VI, or simply CN VI, is a cranial nerve in humans and various other animals that controls the movement of the lateral rectus muscle, one of the extraocular muscles responsible for outward gaze. It is a somatic efferent nerve.
The trochlear nerve, also known as the fourth cranial nerve, cranial nerve IV, or CN IV, is a cranial nerve that innervates just one muscle: the superior oblique muscle of the eye, which operates through the pulley-like trochlea. CN IV is a motor nerve only, unlike most other CNs.
The internal carotid artery is an artery in the neck which supplies the anterior circulation of the brain. In human anatomy, the internal and external carotids arise from the common carotid arteries, where these bifurcate at cervical vertebrae C3 or C4. The internal carotid artery supplies the brain, including the eyes, while the external carotid nourishes other portions of the head, such as the face, scalp, skull, and meninges.
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents. In the adult human, the volume of the orbit is 30 millilitres, of which the eye occupies 6.5 ml. The orbital contents comprise the eye, the orbital and retrobulbar fascia, extraocular muscles, cranial nerves II, III, IV, V, and VI, blood vessels, fat, the lacrimal gland with its sac and duct, the eyelids, medial and lateral palpebral ligaments, cheek ligaments, the suspensory ligament, septum, ciliary ganglion and short ciliary nerves.
Meningioma, also known as meningeal tumor, is typically a slow-growing tumor that forms from the meninges, the membranous layers surrounding the brain and spinal cord. Symptoms depend on the location and occur as a result of the tumor pressing on nearby tissue. Many cases never produce symptoms. Occasionally seizures, dementia, trouble talking, vision problems, one sided weakness, or loss of bladder control may occur.
Radiosurgery is surgery using radiation, that is, the destruction of precisely selected areas of tissue using ionizing radiation rather than excision with a blade. Like other forms of radiation therapy, it is usually used to treat cancer. Radiosurgery was originally defined by the Swedish neurosurgeon Lars Leksell as "a single high dose fraction of radiation, stereotactically directed to an intracranial region of interest".
Stereotactic surgery is a minimally invasive form of surgical intervention that makes use of a three-dimensional coordinate system to locate small targets inside the body and to perform on them some action such as ablation, biopsy, lesion, injection, stimulation, implantation, radiosurgery (SRS), etc.
Exophthalmos is a bulging of the eye anteriorly out of the orbit. Exophthalmos can be either bilateral or unilateral. Complete or partial dislocation from the orbit is also possible from trauma or swelling of surrounding tissue resulting from trauma.
The superior orbital fissure is a foramen or cleft in the skull. It lies between the lesser and greater wings of the sphenoid bone. It allows for many structures to pass, including the oculomotor nerve, the trochlear nerve, the ophthalmic nerve, the abducens nerve, the ophthalmic vein, and sympathetic fibres from the cavernous plexus.
Neurofibromatosis type II is a genetic condition that may be inherited or may arise spontaneously, and causes benign tumors of the brain, spinal cord, and peripheral nerves. The types of tumors frequently associated with NF2 include vestibular schwannomas, meningiomas, and ependymomas. The main manifestation of the condition is the development of bilateral benign brain tumors in the nerve sheath of the cranial nerve VIII, which is the "auditory-vestibular nerve" that transmits sensory information from the inner ear to the brain. Besides, other benign brain and spinal tumors occur. Symptoms depend on the presence, localisation and growth of the tumor(s), in which multiple cranial nerves can be involved. Many people with this condition also experience vision problems. Neurofibromatosis type II is caused by mutations of the "Merlin" gene, which seems to influence the form and movement of cells. The principal treatments consist of neurosurgical removal of the tumors and surgical treatment of the eye lesions. Historically the underlying disorder has not had any therapy due to the cell function caused by the genetic mutation.
The cavernous sinus within the human head is one of the dural venous sinuses creating a cavity called the lateral sellar compartment bordered by the temporal bone of the skull and the sphenoid bone, lateral to the sella turcica.
Sixth nerve palsy, or abducens nerve palsy, is a disorder associated with dysfunction of cranial nerve VI, which is responsible for causing contraction of the lateral rectus muscle to abduct the eye. The inability of an eye to turn outward, results in a convergent strabismus or esotropia of which the primary symptom is diplopia in which the two images appear side-by-side. Thus, the diplopia is horizontal and worse in the distance. Diplopia is also increased on looking to the affected side and is partly caused by overaction of the medial rectus on the unaffected side as it tries to provide the extra innervation to the affected lateral rectus. These two muscles are synergists or "yoke muscles" as both attempt to move the eye over to the left or right. The condition is commonly unilateral but can also occur bilaterally.
The middle cranial fossa, deeper than the anterior cranial fossa, is narrow medially and widens laterally to the sides of the skull. It is separated from the posterior fossa by the clivus and the petrous crest.
Cavernous sinus thrombosis (CST) is the formation of a blood clot within the cavernous sinus, a cavity at the base of the brain which drains deoxygenated blood from the brain back to the heart. This is a rare disorder and can be of two types–septic cavernous thrombosis and aseptic cavernous thrombosis. Most commonly the form is of septic cavernous sinus thrombosis. The cause is usually from a spreading infection in the nose, sinuses, ears, or teeth. Staphylococcus aureus and Streptococcus are often the associated bacteria.
Chiasmal syndrome is the set of signs and symptoms that are associated with lesions of the optic chiasm, manifesting as various impairments of the affected's visual field according to the location of the lesion along the optic nerve. Pituitary adenomas are the most common cause; however, chiasmal syndrome may be caused by cancer, or associated with other medical conditions such as multiple sclerosis and neurofibromatosis.
The cerebellopontine angle syndrome is a distinct neurological syndrome of deficits that can arise due to the closeness of the cerebellopontine angle to specific cranial nerves. Indications include unilateral hearing loss (85%), speech impediments, disequilibrium, tremors or other loss of motor control. The cerebellopontine angle cistern is a subarachnoid cistern formed by the cerebellopontine angle that lies between the cerebellum and the pons. It is filled with cerebrospinal fluid and is a common site for the growth of acoustic neuromas or schwannomas.
Cavernous hemangioma, also called cavernous angioma, venous malformation, or cavernoma, is a type of venous malformation due to endothelial dysmorphogenesis from a lesion which is present at birth. A cavernoma in the brain is called a cerebral cavernous malformation or CCM. Despite its designation of a hemangioma, a cavernous hemangioma is not a tumor as it does not display endothelial hyperplasia. The abnormal tissue causes a slowing of blood flow through the cavities, or "caverns". The blood vessels do not form the necessary junctions with surrounding cells, and the structural support from the smooth muscle is hindered, causing leakage into the surrounding tissue. It is the leakage of blood, referred to as hemorrhage, that causes a variety of symptoms known to be associated with the condition.
Endoscopic endonasal surgery is a minimally invasive technique used mainly in neurosurgery and otolaryngology. A neurosurgeon or an otolaryngologist, using an endoscope that is entered through the nose, fixes or removes brain defects or tumors in the anterior skull base. Normally an otolaryngologist performs the initial stage of surgery through the nasal cavity and sphenoid bone; a neurosurgeon performs the rest of the surgery involving drilling into any cavities containing a neural organ such as the pituitary gland. The use of endoscope was first introduced in Transsphenoidal Pituitary Surgery by R Jankowsky, J Auque, C Simon et al. in 1992 G.