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Oculomotor nerve

The oculomotor nerve is the third (CN III) cranial nerve (TA: nervus oculomotorius or nervus cranialis III). It is a mixed nerve containing motor, parasympathetic and sympathetic fibers. It arises from the midbrain and passes through the cavernous sinus to the orbit where it is responsible for t...

Obstructive hydrocephalus

Obstructive hydrocephalus is a term usually used to denote obstructive non-communicating hydrocephalus. It is actually a term that causes confusion as used in the above sense implies that communicating hydrocephalus does not have an obstruction to CSF flow/absorption; this is not true as the m...

Notch sign (disambiguation)

There are many so-called notch signs. They include: focal notch in the wall (or tail extending from) a 2nd branchial cleft cyst between the internal and external carotid arteries peripheral notches in the contour of a solitary pulmonary nodule (SPN) suggests malignancy thymic notch sign late...

Normal facial nerve enhancement on MRI

The normal facial nerve (CN VII) can demonstrate some enhancement post gadolinium, with the prevalence of which segments is highly variable depending on the MRI sequence 4-8. Enhancement may be asymmetric 4-6. It has been attributed to the circumneural facial arteriovenous plexus. Typical sites...

Neurogenic bladder

Neurogenic bladder is a term applied to a dysfunctional urinary bladder that results from any lack of coordination between the central nervous system and the somatic nervous system, 5 including injuries to the central or peripheral nerves that control and regulate urination. Injury to the brain,...

Neurocysticercosis

Neurocysticercosis is caused by the CNS infection with the pork tapeworm Taenia solium, which is endemic in most low-income countries where pigs are raised. This form of cysticercosis is a relevant cause of seizures in endemic areas. Epidemiology The disease is endemic in Central and South Ame...

Neurofibromatosis type 1

Neurofibromatosis type 1 (NF1), also known as von Recklinghausen disease, is a multisystem neurocutaneous disorder, the most common phakomatosis, and a RASopathy. Additionally, it is also one of the most common inherited CNS disorders, autosomal dominant disorders, and inherited tumor syndromes....

Nerve to stapedius

The nerve to stapedius arises from the facial nerve to supply the stapedius muscle. The branch is given off in the facial nerve's mastoid segment, as it passes posterior to the pyramidal process. Damage to this branch with resulting paralysis of stapedius leads to hypersensitivity to loud noise...

Neuroblastoma

Neuroblastomas are tumors of neuroblastic origin. Although they may occur anywhere along the sympathetic chain, the vast majority arise from the adrenal gland. They represent the most common extracranial solid childhood malignancy and are the third commonest childhood tumor after leukemia and b...

Midline nasal region lesions

A variety of congenital midface anomalies occur in children. Although rare, these disorders are clinically important because of their potential for connection to the central nervous system. Lesions presenting as a midline nasal mass include: nasal glioma nasal encephalocele nasal dermoid cyst...

Nasopharyngeal choristoma

A nasopharyngeal choristoma is a rare, non-neoplastic mass (type of choristoma) typically located in the lateral aspect of the nasopharynx without intracranial extension. These lesions are composed of fibrovascular tissue and fat. Resection is curative. Differential diagnosis nasopharyngeal ca...

Nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis (NSF), also known as nephrogenic fibrosing dermopathy, occurs almost exclusively in patients with renal impairment and is associated with the administration of gadolinium-based contrast agents (GBCAs) used in MRI. The American College of Radiology (ACR) has divide...

Möbius syndrome

Möbius syndrome, also known as congenital facial diplegia syndrome, is a rare congenital condition characterized by the absence or underdevelopment of the nuclei of the abducens (CN VI) and facial nerve (CN VII). Epidemiology Möbius syndrome is rare with an estimated incidence of ~1 case per 1...

Myelitis

Myelitis is a collective term simply referring to any inflammation of the spinal cord. It is a form of myelopathy. The two major sub types include: leukomyelitis multiple sclerosis ADEM transverse myelitis ideopathic transverse myelitis secondary transverse myelitis: viral, neurosyphilis ...

Mycotic aneurysm

Mycotic aneurysms are aneurysms arising from infection of the arterial wall, usually bacterial. It is a complication of the hematogenous spread of bacterial infection, classically from the heart. Epidemiology Mycotic aneurysms are thought to represent only a minority of (0.65-2.6%) of all aor...

Multiple sclerosis

Multiple sclerosis (MS) is a relatively common acquired chronic demyelinating disease involving the central nervous system, and is the second most common cause of neurological impairment in young adults, after trauma 19. Characteristically, and by definition, multiple sclerosis is disseminated i...

Mosaic pattern of bone

The mosaic bone pattern, also referred to as the jigsaw pattern of bone, is seen in Paget disease, where thickened, disorganized trabeculae lead to areas of sclerosis interspersed with lucent and more normal bone. See also Other Paget disease-related signs: banana fracture blade of grass sig...

Moyamoya disease

Moyamoya disease is an idiopathic, non-inflammatory, non-atherosclerotic progressive vasculo-occlusive disease involving the terminal supraclinoid internal carotid arteries and circle of Willis. Terminology The term moyamoya disease should be reserved for an idiopathic, sometimes familial, c...

Mixed vascular malformation

A mixed vascular malformation is a relatively common congenital cerebral vascular malformation, most frequently composed of a developmental venous anomaly and a cavernous malformation. As developmental venous anomalies seldom bleed, the risk of a mixed vascular malformation is determined by the ...

Primary mitochondrial disorders

Primary mitochondrial disorders (PMDs) are a clinically heterogeneous group of conditions caused by pathologic variants in mitochondrial DNA (mtDNA) or nuclear DNA (nDNA). There are many conditions that result from mitochondrial dysfunction affect the neurological and muscular systems in a vari...

Migraine

Migraines are a common primary headache disorder and can present variably. Typically they consist of debilitating headaches, accompanied by an aura in one-third of patients. Their etiology remains controversial, although changes in cerebral vessel reactivity are involved. Clinical presentation ...

Methyl methacrylate cranial prosthesis

A methyl methacrylate cranial prosthesis is of heterogeneous density, similar to muscle, and contains locules of gas. The most common cause of a bony defect is trauma, and repair of the defect is called a cranioplasty. The methyl methacrylate is the monomer form of the final plastic material, t...

Mesial temporal sclerosis

Mesial temporal sclerosis, also commonly referred to as hippocampal sclerosis, is the most common association with intractable temporal lobe epilepsy 2,3,5. It is seen in up to 65% of autopsy studies, although significantly less in imaging. Clinical presentation Most patients present with temp...

Meninx primitiva

The meninx primitiva refers to the collection of neural crest and mesenchyme (mesoderm) that surround the developing brain during gestation 3. This process occurs between the 3rd and 5th week of gestation. The meninx primitiva will eventually differentiate into the arachnoid mater, pia mater and...

Meningioma

Meningiomas are extra-axial tumors and represent the most common tumor of the meninges. They are a non-glial neoplasm that originates from the meningocytes or arachnoid cap cells of the meninges and are located anywhere that meninges are found, and in some places where only rest cells are presum...

Congenital spinal meningocele

Congenital spinal meningoceles are developmental anomalies of meningothelial elements displaced into the skin and subcutaneous tissues. Please refer to the meningocele article for a broad overview of all types of this condition. Pathology It is a defect of the neural tube, an embryonic struc...

Megalencephaly

Megalencephaly is a disorder characterized by an abnormally large brain. It is primarily a proliferative disorder of embryonic origin. It may involve all or part of the cerebral hemispheres and can be bilateral or unilateral. It is often associated with polymicrogyria or agyria. Terminology ...

Meningioangiomatosis

Meningioangiomatosis is a rare meningovascular hamartomatous plaque-like or mass-like cortical lesion extending to the overlying leptomeninges (crosses the boundary between intra- and extra-axial lesions). Given its frequent cortical location, often patients present with seizures. Epidemiology ...

Meninges

The meninges (singular: meninx) is a collective term for the three membranes that cover the brain and spinal cord and are covered in separate articles: cranial meninges spinal meninges History and etymology The word meninges arises from the Classical Greek μηνιγξ (transliteration: m...

Hemorrhagic intracranial metastases (mnemonic)

A mnemonic for primary malignancies responsible for hemorrhagic intracranial metastases is: MR CT BB MR CT HBO Mnemonic MR CT BB M: melanoma R: renal cell carcinoma C: choriocarcinoma T: thyroid carcinoma, teratoma B: bronchogenic carcinoma B: breast carcinoma MR CT HBO M: melanoma ...

MR spectroscopy

The technique of magnetic resonance spectroscopy (usually shortened to MR spectroscopy or MRS) allows tissue to be interrogated for the presence and concentration of various metabolites. Grossman and Yousem said "If you need this to help you, go back to page 1; everything except Canavan (disease...

Multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1), also known as Wermer syndrome, is an autosomal dominant genetic disease that results in proliferative lesions in multiple endocrine organs, particularly the pituitary gland, pancreas, and parathyroid glands. There are other multiple endocrine neoplas...

Middle cerebral artery (MCA) infarct

The middle cerebral artery territory is the most commonly affected territory in a cerebral infarction, due to the size of the territory and the direct flow from the internal carotid artery into the middle cerebral artery, providing the easiest path for thromboembolism. Clinical presentation Th...

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS)

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is one of many mitochondrial disorders. As mitochondria, which have their own DNA, are exclusively passed on from the mother these disorders are only maternally inherited. On imaging, it manifests as multifoca...

Lymphocytic hypophysitis

Lymphocytic hypophysitis is an uncommon non-neoplastic inflammatory condition that affects the pituitary gland. It is closely related to other inflammatory conditions in the region, namely orbital pseudotumor and Tolosa-Hunt syndrome. Epidemiology Lymphocytic hypophysitis is seen most frequent...

Lissencephaly-pachygyria spectrum

The lissencephaly-pachygyria spectrum is a useful way to describe the spectrum of diseases that cause relative smoothness of the brain surface and includes 1: agyria: no gyri pachygyria: broad gyri lissencephaly: smooth brain surface It is a basket term for a number of congenital...

Linear scleroderma

Linear scleroderma, also known as scleroderma en coup de saber, is a very focal form of scleroderma classically characterized by a linear band of atrophy involving the frontal or frontoparietal scalp and subjacent thinned calvaria associated with ipsilateral focal brain abnormalities. Linear sc...

Lesser petrosal nerve

The lesser petrosal nerve carries preganglionic parasympathetic fibers to the parotid gland. It is considered a branch of the glossopharyngeal nerve although it receives contributions from two further sources 3: tympanic plexus: glossopharyngeal nerve via Jacobson's nerve (main contribution) n...

Dysplastic cerebellar gangliocytoma

Dysplastic cerebellar gangliocytoma, perhaps better known as Lhermitte-Duclos disease, is a rare tumor of the cerebellum appearing as thickening and increase in T2 signal of the cerebellar folia giving this lesion a characteristic striated appearance. Epidemiology Dysplastic cerebellar gangli...

Lemon sign

The lemon sign, noted on antenatal imaging, is one of the many notable fruit-inspired signs. It is a feature when there appears to be an indentation of the frontal bone (depicting that of a lemon). It is classically seen as a sign of a Chiari II malformation and also seen in the majority (90-98%...

Leptomeningeal metastases

Leptomeningeal metastases, also known as carcinomatous meningitis and meningeal carcinomatosis, refers to the spread of malignant cells through the CSF space. These cells can originate from primary CNS tumors (e.g. in the form of drop metastases), as well as from distant tumors that have metasta...

Superior orbital fissure (mnemonic)

A mnemonic for all structures passing through the superior orbital fissure (superior to inferior) is: Long Fissures Seem To Store Only Nerves, Instead Of Arteries, Including Ophthalmic Veins Mnemonics for the nerves passing through the superior orbital fissure include: Lazy French Tarts Sit N...

Leigh syndrome

Leigh syndrome, also known as subacute necrotizing encephalomyelopathy (SNEM), is a mitochondrial disorder with progressive neurodegeneration that invariably leads to death, usually in childhood. Epidemiology Leigh syndrome is encountered in approximately 1 in 40,000 births, although some popu...

Lead poisoning

Lead poisoning or plumbism refers to the multi-organ toxicity exerted by exposure to lead. Manifestations differ based on a myriad of features including chronicity, exposure intensity, and age. Neurologic toxicity and hematologic toxicity are common features. Clinical manifestations vary, rangin...

Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a rare multisystem disease with a wide and heterogeneous clinical spectrum and variable extent of involvement. Terminology Langerhans cell histiocytosis was previously known as histiocytosis X. The newer term is preferred as it is more descriptive of its...

Juvenile nasopharyngeal angiofibroma

Juvenile nasopharyngeal angiofibromas are a rare benign, but locally aggressive, vascular tumors that occur almost exclusively in young men; usually between the ages of 10 and 18. On imaging, they present as a vividly enhancing soft-tissue masses centered on the sphenopalatine foramen. Given i...

Jacobson nerve

Jacobson nerve is the eponymous name of the tympanic branch of the glossopharyngeal nerve (CN IX) and arises from the inferior ganglion of the glossopharyngeal nerve. It also carries preganglionic parasympathetic fibers, from the inferior salivary nucleus, which eventually enter the otic ganglio...

Jaffe-Campanacci syndrome

Jaffe-Campanacci syndrome is characterized by: multiple non-ossifying fibromas of the long bones and jaw café au lait spots intellectual disability kyphoscoliosis hypogonadism or cryptorchidism ocular malformations cardiovascular malformations giant cell granuloma of the jaw axillary an...

Intraventricular meningioma

Intraventricular meningiomas are rare tumors usually encountered in adults and are somewhat distinct from the far more common extra-ventricular meningioma. On imaging, they classically present as vividly enhancing solid mass at the trigone of the lateral ventricles. Epidemiology Intraventricu...

Intracranial hemorrhage

Intracranial hemorrhage (ICH) is a collective term encompassing many different conditions characterized by the extravascular accumulation of blood within different intracranial spaces. A simple categorization is based on location: intra-axial hemorrhage intracerebral hemorrhage basal ganglia ...

Intracranial lipoma

Intracranial lipomas are not tumors as such, but rather a result of abnormal differentiation of embryologic meninx primitiva. They are frequently associated with abnormal development of adjacent structures. Terminology The term intracranial lipoma is used somewhat loosely. The broadest usage w...

Intracranial hypotension

Intracranial hypotension, also known as craniospinal hypotension is defined as cerebrospinal fluid (CSF) pressure <6 cm H2O in patients with clinical presentation compatible with intracranial hypotension, namely, postural headache, nausea, vomiting, neck pain, visual and hearing disturbances, an...

Intracranial arteries (variants)

Intracranial arterial variants, of which there are many, are collectively common. Their clinical significance may be variable but knowledge and recognition of these variants is fundamental, especially if surgical or endovascular treatments (e.g. for acute stroke, aneurysms or other vascular path...

Extraocular muscle involvement in thyroid associated orbitopathy (mnemonic)

A mnemonic to remember the order in which extraocular muscles are involved in thyroid-associated orbitopathy (TAO) is: I'M SLOw Mnemonic I: inferior rectus M: medial rectus S: superior rectus L: lateral rectus O: obliques muscles (superior oblique and inferior oblique) There is some deba...

Hypoglossal nerve

The hypoglossal nerve is the twelfth cranial nerve (CN XII) (TA: nervus hypoglossus or nervus cranialis XII). It arises from the medulla and passes through the hypoglossal canal to the neck, where it travels to the sublingual space to supply somatic motor innervation to all of the intrinsic and ...

Hypothalamic hamartoma

Hypothalamic hamartomas, also known as tuber cinereum hamartomas, are benign non-neoplastic heterotopias in the brain that typically occur in the region of the hypothalamus, arising from the tuber cinereum, a part of the hypothalamus located between the mammillary bodies and the optic chiasm. E...

Hypertrophic olivary degeneration

Hypertrophic olivary degeneration (HOD) is a rare condition characterized by a unique pattern of trans-synaptic degeneration. Typically it is caused by a lesion in the brainstem/cerebellum interrupting the triangle of Guillain and Mollaret, resulting in hypertrophy of the inferior olivary nucleu...

Hyperostosis frontalis interna

Hyperostosis frontalis interna is characterized by benign overgrowth of the inner table of the frontal bone. The etiology is unknown. The condition is generally of no clinical significance and an incidental finding. It is typically bilateral and symmetrical and may extend to involve the parietal...

Hyperostosis frontoparietalis

Hyperostosis frontoparietalis is a variant of the more common and more well known hyperostosis frontalis interna. As the name suggests, there is benign overgrowth exclusively of the inner table of the frontal bones and parietal bones. Characteristic features include sparing of the midline and ou...

Hydromyelia

In hydromyelia, there is dilatation of the central canal of the spinal cord. The dilatation is lined by the normal ependymal lining of the central canal. The term can refer to dilatation of the persistent central canal of the spinal cord which communicates with the fourth ventricle (cavity wall...

Huntington disease

Huntington disease (HD), also known as Huntington chorea, is an autosomal dominant trinucleotide repeat neurodegenerative disease characterized by a loss of GABAergic neurons of the basal ganglia, especially atrophy of the caudate nucleus and putamen (dorsal striatum). Huntington disease is clin...

Holoprosencephaly

Holoprosencephaly (HPE) is a rare congenital brain malformation resulting from incomplete separation of the two hemispheres. Classically three subtypes have been recognized, however additional entities are now included in the spectrum of the disease. The three main subtypes, in order of decreas...

Hippocampus

The hippocampus (plural: hippocampi) or historically the cornu Ammonis, is an important component of the human brain, situated in the temporal lobe. It plays a role in information processing and the reproductive cycle and is involved in Alzheimer disease. Gross anatomy Location The hippocampu...

High riding jugular bulb

A high riding jugular bulb indicates the dome (roof) of the jugular bulb extends more superiorly in the petrous temporal bone than is typical. The transverse level above which a jugular bulb is considered high riding has been variably defined as the following 1,6,8: floor of the internal acoust...

Hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a rare inherited disorder characterized by abnormal blood vessel formation in the skin, mucous membranes, and organs including the lungs, liver, and central nervous system. Epidemiology Worldwide prevalen...

Hemifacial spasm

Hemifacial spasm is characterized by episodic facial spasms due to irritation of the facial nerve (CN VII). Epidemiology Most cases present above the age of 40 years and with a 2:1 female predominance 4. Clinical presentation Often the condition begins insidiously with painless spasm of the ...

Meningeal hemangiopericytoma (historical)

Hemangiopericytomas of the meninges are rare tumors of the meninges, now considered to be an aggressive form of solitary fibrous tumors of the dura. They often present as large and locally aggressive dural masses, frequently extending through the skull vault. They are difficult to distinguish on...

Heerfordt syndrome

Heerfordt syndrome, also known as Heerfordt-Waldenström syndrome or uveoparotid fever, is a variant of sarcoidosis, comprising of: fever parotid enlargement facial palsy ocular involvement (anterior uveitis) Epidemiology The exact prevalence is unknown, as only isolated case reports exist....

Hemorrhagic intracranial metastases

Hemorrhagic intracranial metastases are considered to represent between 3-14% of all cerebral metastases (cf. 1-3% of gliomas are hemorrhagic). These classically originate from: melanoma renal cell carcinoma choriocarcinoma thyroid carcinoma: papillary carcinoma of the thyroid has the highe...

Pantothenate kinase-associated neurodegeneration

Pantothenate kinase-associated neurodegeneration (PKAN), historically also known as Hallervorden-Spatz syndrome, is an autosomal recessive disorder causing involuntary spasticity and progressive dementia. It is a subset of neurodegeneration with brain iron accumulation (NBIA). Epidemiology Cla...

Herpes simplex encephalitis

Herpes simplex (HSV) encephalitis is the most common cause of fatal sporadic fulminant necrotizing viral encephalitis and has characteristic imaging findings. Two subtypes are recognized which differ in demographics, virus, and pattern of involvement. They are 1: neonatal herpes encephalitis ...

Hemangioblastoma (central nervous system)

Hemangioblastomas are tumors of vascular origin and occur both sporadically and in patients with von Hippel Lindau disease. They are WHO grade 1 tumors, which can occur in the central nervous system or elsewhere in the body, including kidneys, liver, and pancreas. These tumors generally present...

Grey matter heterotopia

The grey matter heterotopias are a relatively common group of conditions characterized by interruption of normal neuronal migration from near the ventricle to the cortex, thus resulting in "normal neurons in abnormal locations" 2. They are a subset of disorders of cortical formation 3-4. Grey m...

Gradenigo syndrome

Gradenigo syndrome consists of the triad of: suppurative otitis media with persistent otorrhea and ear pain abducens nerve palsy, secondary to involvement of the nerve as it passes through Dorello canal retro-orbital pain, or pain in the cutaneous distribution of the frontal and maxillary div...

Gliomatosis cerebri

Gliomatosis cerebri is an uncommon growth pattern of diffuse gliomas that involves at least three lobes by definition, has frequent bilateral growth and may extend to infratentorial structures 8. There often is an important discordance between clinical and radiological findings, as it may be cli...

Central nervous system germinoma

Intracranial germinomas, also known as dysgerminomas or extra-gonadal seminomas, are a type of germ cell tumor and are predominantly seen in pediatric populations. They tend to occur in the midline, either at the pineal region (majority) or along the floor of the third ventricle/suprasellar regi...

Geniculate ganglion

The geniculate or genicular ganglion contains fibers for taste and somatic sensation and is located in the petrous temporal bone. Gross anatomy It is located at the first genu of the facial nerve at the anterior most part of the Fallopian canal at the junction between the labyrinthine and tym...

Germinoma

Germinoma is a term that if unqualified, usually refers to a tumor of the brain but can also refer to similar tumors of other regions particularly the ovary and testis. dysgerminoma of the ovary seminoma of the testis CNS germinoma: see WHO classification of CNS tumors All t...

Ganglioglioma

Gangliogliomas are uncommon, usually low-grade, CNS tumors. They are considered long-term epilepsy-associated tumors (LEATs) with medically refractory epilepsy being a common clinical presentation. This tumor has a predilection for the temporal lobes, although they have been described in all par...

Fragile X-associated tremor/ataxia syndrome

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a progressive degenerative movement disorder resulting from a fragile X “premutation”, defined as 55-200 CGG repeats in the 5’-untranslated region of the FMR1 gene 1. The premutation can expand in subsequent generations (during oogenesis) to...

Fatty falx cerebri

A fatty falx cerebri is a benign entity in which there is fat within the extradural neural axis compartment located between the two visceral layers of the falx. Epidemiology According to one study, it is a common finding seen in ~7.5% of patients 1. This can be more common in older patients 1...

Venous vascular malformation of the facial nerve

Venous vascular malformations of the facial nerve, previously known as facial nerve hemangiomas, are rare benign vascular malformations of the facial nerve usually presenting as a facial nerve palsy, which can be rapid in onset mimicking a Bell palsy. Terminology As they do not appear to have...

Facial nerve

The facial nerve is the seventh (CN VII) cranial nerve and comprises two roots, a motor root and a smaller mixed sensory, taste and parasympathetic root, known as nervus intermedius, which join together within the temporal bone (TA: nervus facialis or nervus cranialis VII). The facial nerve has...

Facial nerve schwannoma

Facial nerve schwannoma, also known as facial nerve neuroma/neurilemoma, is a schwannoma that arises from the facial nerve. They are generally uncommon, and when involving the temporal bone, make up less than 1% of all temporal bone tumors. Epidemiology Facial nerve schwannoma is a rare tumor ...

Facial nerve choristoma

Facial nerve choristomas are rare, being characterized by non-neoplastic proliferation of smooth muscle cells and fibrous tissue. Facial nerve choristomas presumably can occur anywhere along the course of the facial nerve (CN VII), although the only cases reported are in the internal acoustic me...

Facial colliculus

The facial colliculus is an elevation on the floor of the fourth ventricle and is not formed by the facial nucleus, but by the fibers of the facial nerve arching backward around the abducent nucleus before turning forwards once more in the caudal pons. Related pathology A lesion involving the ...

Eye of the tiger sign (globus pallidus)

The eye of the tiger sign refers to symmetric bilateral abnormal low signal on T2-weighted MRI (due to abnormal accumulation of iron) in the globus pallidus with central high signal (due to gliosis and spongiosis). The eye of the tiger sign is most classically associated with pantothenate kinas...

External petrosal nerve

The external petrosal nerve is one of the three branches from the geniculate ganglion. It carries sympathetic fibers from the sympathetic plexus surrounding the middle meningeal artery, coursing extradurally laterally to the greater and lesser petrosal nerves on the petrous ridge's anterior surf...

Extradural hemorrhage

Extradural hematoma (EDH), also known as an epidural hematoma, is a collection of blood that forms between the inner surface of the skull and outer layer of the dura, which is called the endosteal layer. They are usually associated with a history of head trauma and frequently associated skull fr...

External auditory canal atresia

External auditory canal atresia, also known as congenital aural atresia, is characterized by complete or incomplete bony atresia of the external auditory canal (EAC), often in association with a dysplastic auricle and an abnormal middle ear cavity or ossicles. Epidemiology The incidence is 1 i...

Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell, non-familial multisystemic histiocytosis, with widespread manifestations and of highly variable severity. The most common presenting symptom is bone pain. Epidemiology Erdheim-Chester disease is a rare, non-inherited disease of middl...

Epidural lipomatosis

Epidural lipomatosis refers to an excessive accumulation of fat within the spinal epidural space resulting in compression of the thecal sac. In severe cases, compression may be symptomatic. The lumbar region is most frequently affected. Epidemiology The demographics of affected individuals ref...

Intracranial epidermoid cyst

Intracranial epidermoid cysts are uncommon congenital lesions which account for about 1% of all intracranial tumors. They result from inclusion of ectodermal elements during neural tube closure, and typically present in middle age due to mass effect on adjacent structures. Their content, derived...

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