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Tandem lesion (cerebrovascular)

Tandem lesion (or tandem occlusion) is a term used in cerebrovascular imaging and intervention to refer to the simultaneous presence of high-grade stenosis or occlusion of the cervical internal carotid artery and thromboembolic occlusion of the intracranial terminal internal carotid artery or it...

Benign oligemia

Benign oligemia occurs when the brain's ability to autoregulate cerebral blood flow (CBF) by vasodilation is exceeded and cerebral blood flow begins to reduce. If this reduction is left unchecked, eventually neurological dysfunction and eventual infarction will occur. There is, however, a wind...

Superior petrosal vein

The superior petrosal vein, also known as Dandy’s vein or simply the petrosal vein, is the largest vein in the posterior cranial fossa, draining the anterior aspect of the cerebellum and brainstem into the superior petrosal sinus. Gross anatomy Each superior petrosal vein is usually formed by...

Time-to-Maximum (Tmax)

Time-to-Maximum (Tmax) is a perfusion parameter used both in CT perfusion and MRI perfusion and reflects the time delay between the contrast bolus arriving in the proximal large vessel arterial circulation (arterial input function) and the brain parenchyma 1. It is calculated by deconvoluting th...

Anterior meningocele

Anterior meningocele is characterized by herniation of CSF-filled sac through a an anterior osseous defect. It usually occur in sacral region where is it termed an anterior sacral meningocele although it can also in other areas like the thorax 2. When occurring in the sacrum, it is often fou...

Placode

Placode (or neural placode) refers in terms of radiology to a segment of non-neurulated neural tissue, which has had development frozen in the neural plate stage. A placode can be found in all open spinal dysraphisms and in some closed spinal dysraphisms. In the former, the placode is exposed to...

Stroke protocol (CT)

A CT stroke protocol, often referred to as a code stroke CT, has become a fairly widespread and standardized approach to imaging patients presenting with acute neurological symptoms that may represent cerebral infarction or cerebral hemorrhage (together grouped under the vague term stroke). In...

Lenticulostriate infarct

Lenticulostriate infarcts are lacunar infarcts resulting from occlusion of single lenticulostriate perforating arteries. Terminology They should not be confused with striatocapsular infarcts that represent larger strokes resulting from occlusion of multiple lenticulostriate arteries.

Minamata disease

Minamata disease is a neurologic condition caused by organic mercury poisoning. Epidemiology It is usually caused by the ingestion of methylmercury-contaminated seafood 1. Clinical presentation Typical neurological findings in Minamata disease include: sensory disturbances tunnel vision h...

Hypoglossal nucleus

The hypoglossal nuclei, exist as paired nuclei within the medulla oblongata that provide motor innervation to the intrinsic and extrinsic muscles of the tongue (excluding palatoglossus) via the hypoglossal nerve. Gross Anatomy The hypoglossal nuclei are located within the tegmentum of upper me...

Morel laminar sclerosis

Morel laminar sclerosis is characterized by cortical laminar necrosis and gliosis, especially affecting the lateral frontal cortex. Pathology Postmortem neuropathologic studies in patients with Marchiafava-Bignami disease have described cortical laminar necrosis and gliosis, mainly in the thir...

Vestibular nuclei

The vestibular nuclei are a group of four small special sensory nuclei in the lower pons and upper medulla for the vestibular nerve component of the vestibulocochlear nerve. They are part of the extensive cranial nerve nuclei within the brainstem. Gross Anatomy The four nuclei are located adja...

Cochlear nuclei

The cochlear nuclei are a group of two small special sensory nuclei in the upper medulla for the cochlear nerve component of the vestibulocochlear nerve. They are part of the extensive cranial nerve nuclei within the brainstem. Gross Anatomy The dorsal and ventral nuclei are located in the dor...

Cranial nerve nuclei

The cranial nerve nuclei are a series of bilateral grey matter motor and sensory nuclei located in the midbrain, pons and medulla that are the collections of afferent and efferent cell bodies for many of the cranial nerves. Some nuclei are small and contribute to a single cranial nerve, such as...

Facial nucleus

The facial nucleus or facial motor nucleus is the efferent nucleus of the facial nerve. Gross Anatomy The nucleus is located in the caudal lower aspect of the pontine tegmentum at the level of the middle cerebellar peduncles. It lies dorsal to the medial lemniscus and ventral and medial to the...

Oculomotor nucleus

The oculomotor nucleus is a small somatic motor nucleus in the midbrain and one of the two nuclei for the oculomotor nerve. Gross Anatomy The nucleus is located in the central midbrain at the level of the superior colliculus ventral and medial periaqueductal grey matter. It lies immediately ve...

Edinger-Westphal nucleus

The Edinger-Westphal nucleus is a small parasympathetic motor nucleus in the midbrain and one of the two nuclei for the oculomotor nerve. It is one of the cranial nerve nuclei. Gross Anatomy The nucleus is located in the central midbrain at the level of the superior colliculus ventral and medi...

Abducent nucleus

The abducent or abducens nucleus is a small motor nucleus in the pons for the abducens nerve. Gross anatomy The nucleus is located in the paramedian dorsal lower pons in the floor of the fourth ventricle lateral to the medial longitudinal fasciculus. The nucleus forms a longitudinal paramedian...

Trochlear nucleus

The trochlear nucleus is a small motor nucleus in the midbrain for the trochlear nerve. Gross Anatomy The nucleus is located in the midbrain at the level of the inferior colliculus ventral and medial periaqueductal grey and dorsal to the medial longitudinal fasciculus. It lies just caudal to ...

Neoplastic intracranial aneurysm

Neoplastic intracranial or cerebral aneurysms, also known as oncotic aneurysms, are a rare type of intracranial aneurysm attributed to metastatic tumor emboli. Epidemiology The entity is rare, with fewer than 100 cases being reported in the English literature at the time of a 2015 systematic r...

Intracranial aneurysm (overview)

Intracranial aneurysms, also called cerebral aneurysms, are aneurysms of the intracranial arteries. The most common morphologic type is the saccular aneurysm. Pathology There is not a universal classification for the types of intracranial aneurysms, resulting in a heterogeneous mix of terms ba...

Diagnostic and Statistical Manual of Mental Disorders

The Diagnostic and Statistical Manual of Mental Disorders (more commonly known as the DSM) is published by the American Psychiatric Association and is the most widely used guide to psychiatric diseases in clinical practice and research globally. The first edition was published in 1952; the lates...

Dorsal vagal nucleus

The dorsal vagal nucleus, also known as the vagal nucleus, dorsal nucleus of the vagus nerve or the dorsal motor nucleus of the vagus nerve, is a elongated nucleus within the medulla oblongata that provides parasympathetic motor innervation to the viscera of the thorax and abdomen. It is the lar...

Orgogozo stroke scale

The Orgogozo stroke scale was designed to assess middle cerebral artery stroke 1-3. This scale's use has become rarer in contemporary literature due to the widespread adoption of the NIH Stroke Scale, however basic knowledge may assist interpretation of older literature 4,5. Classification co...

Calcar avis

Calcar avis is an elevation of white matter projecting from the medial wall of the occipital horn of the lateral ventricle. It is variably conspicuous, depending on how deep the calcarine sulcus is. Gross anatomy The calcar avis is located on the medial wall of the occipital horn, near the ju...

Scandinavian Stroke Scale

The Scandinavian Stroke Scale was designed for ease of use by non-neurologists1. It is simpler than the NIHSS and has comparable performance in predicting death or dependence after stroke 2. The degree of neurological impairment measured by the Scandinavian Stroke Scale has been shown to correla...

Endosaccular flow disruption devices

Endosaccular flow disruption devices, also simply known as flow disruptors, are used for the treatment of either ruptured or unruptured saccular, wide-neck, usually bifurcation as well as side-wall intracranial aneurysms. Their primary function is to stop blood from flowing into the aneurysm, al...

Wernicke's Korsakoff (mnemonic)

A mnemonic to recall some of the important features of Wernicke's Korsakoff syndrome is: COMBAT Mnemonic C: confusion, confabulatory amnesia O: ophthalmoplegia M: mamillary bodies B: B1(vitamin), bariatric surgery A: alcoholics T: thalami, tectal plate, third ventricle

Anosmia

Anosmia (also known as anosphresia or olfactory anesthesia) is the complete absence of the sense of smell. Terminology In addition to anosmia, there is also hyposmia (a.k.a. microsmia or olfactory hypoesthesia) representing a diminished sense of smell and parosmia (a.k.a. dysosmia or paraosmi...

Mathew stroke scale

The Mathew stroke scale is used to measure the degree of impairment from stroke 1. It was originally developed to evaluate the neurological status of patients treated with glycerol in acute stroke. Classification level of consciousness: comatose (0), stuporous (2), obtunded (4), lethargic but...

Canadian Neurological Scale

The Canadian Neurological Scale is a validated tool to evaluate stroke severity 1,2 designed to be performed on patients who are alert or drowsy. Patients who are stuporous or comatose are evaluated with the Glasgow Coma Scale (GCS) instead. Classification Section A is completed first. In the ...

Alcoholic cerebellar degeneration

Alcoholic cerebellar degeneration is a common type of acquired cerebellar ataxia characterized by chronic vermian atrophy 1. It is a sequela of chronic alcohol use or malnutrition. Terminology Alcoholic cerebellar degeneration has also been described in the literature as alcohol-related cerebe...

CHEDDA syndrome

CHEDDA syndrome stands for congenital hypotonia, epilepsy, developmental delay and digital anomalies. Is a newly discovered neurodevelopmental syndrome associated with mutations in a conserved histidine-rich motif within Atrophin-1 (ATN-1).1 Epidemiology CHEDDA syndrome is very rare, with only...

Drop metastases (mnemonic)

The primary intracerebral malignancies that may cause drop metastases to the subarachnoid space are: glioblastoma (GBM) and anaplastic astrocytoma medulloblastoma sPNET ependymoma germinoma choroid plexus carcinoma pineoblastoma/pineocytoma These can be remembered using this mnemonic: G...

Idiopathic intracranial hypertension (mnemonic)

Two useful mnemonics to remember the features of idiopathic intracranial hypertension are: VOMER MOVES Mnemonics VOMER V: ventricles of normal or reduced size O: optic disc protrusion M: Meckel's cave enlargement E: empty sella R: reduced caliber (stenosis) venous sinuses MOVES M: M...

Sturge-Weber syndrome (mnemonic)

Some key findings pertaining to Sturge-Weber syndrome may be recalled using the following mnemonics: STURGE CAPS 8 Cs Mnemonics STURGE CAPS S: seizures, sporadic T: tram-track gyriform calcification; trigeminal territory port-wine stain U: unilateral weakness (hemiparesis contralateral to...

Tuberous sclerosis (mnemonic)

The findings of tuberous sclerosis can be remembered with the help of the following mnemonic: HAMARTOMAS Mnemonic H: hamartomas (CNS, retinal and skin) A: angiofibroma (facial) or adenoma sebaceum M: mitral regurgitation A: ash-leaf spots R: rhabdomyoma (cardiac) T: tubers (cortical, sub...

Staghorn pattern of vascularity

The staghorn pattern of vascularity is a pathological term describing a pattern of vascularity seen on low-power light microscopy. It is defined by multiple thin-walled, sharply-branched and jagged vessels having an "antler-like" or "staghorn-like" appearance 1. It is classically described with...

Carotid near-occlusion

Carotid near-occlusion is a special form of severe carotid artery stenosis that results in a partial or complete collapse of the distal internal carotid artery lumen due to underfilling. It should not be confused with carotid pseudo-occlusion due to terminal intracranial internal carotid arter...

Blepharospasm

Blepharospasm is a type of focal dystonia where there is involuntary eyelid closure due to overactivity of muscles around the eyes, particularly orbicularis oculi. Epidemiology The prevalence of blepharospasm is 32 per 100,000 population with males more often affected than females (M:F = 3:2) ...

Germinal matrix hemorrhage (grading mnemonic)

A mnemonic to remember the radiological grading of germinal matrix hemorrhage is: CV2P Mnemonic It can be read as a central venous line C: limited to the caudothalamic groove/ germinal matrix ( grade I ) V: expansion into ventricles less than 50% ( grade II ) V: dilated ventricles ( grade...

Pterional approach (neurosurgery)

The pterional or fronto-temporo-sphenoidal approach is one of the most frequently performed neurocranial craniotomy/craniectomy approaches and allows access to numerous important supratentorial anatomical substrates of vascular and neoplastic pathology. History It was originally described and ...

Cirrhosis (CNS manifestations)

There are several central nervous system complications that can arise in the setting of cirrhosis, which can be classified as those which are general (essentially hepatic encephalopathy) and those that are specific to the cause of cirrhosis. General manifestations The major manifestation is he...

Smoker's criteria

Smoker’s criteria use three quantitative measures of basilar artery morphology to diagnose dolichoectasia: laterality bifurcation height surrogate measures for tortuosity and elongation basilar artery diameter represents the degree of dilatation The application of Smoker’s criteria provid...

Pituitary xanthomatous lesions

Pituitary xanthomatous lesions (which includes xanthomatous hypophysitis and pituitary xanthogranuloma) are rare sellar/suprasellar lesions, which are often only diagnosed postoperatively and present a diagnostic challenge as they are difficult to differentiate from other sellar lesions such as ...

GM2 gangliosidoses

The GM2 gangliosidoses are a small group of three closely-related rare genetic conditions, all due to a deficiency of beta-hexosaminidase, an enzyme vital for the metabolism of GM2 gangliosides in lysosomes, especially important in the brain. The GM2 gangliosidoses form a subgroup of the lysosom...

Progressive myoclonic epilepsy

The progressive myoclonic epilepsies form a disparate group of rare severe conditions that are characterized by deteriorating action myoclonus, although other CNS symptoms and signs are often present. Unverricht–Lundborg disease (EPM1) Lafora body disease (EPM2) action myoclonus renal failure...

Isolated diffuse ground-glass opacification

Isolated diffuse ground-glass opacification/opacity (GGO) has a relatively well-defined differential diagnosis although this remains broad and clinical correlation, like many respiratory diseases, is key to diagnosis. Differential diagnosis Miller et al. have described the following different...

Radiotracers for SPECT brain imaging

Radiotracers for SPECT brain imaging are divided into two classes: diffusible and not-diffusible radiotracers; this distinction lies in the ability (or not) to cross the blood-brain barrier (BBB). The not-diffusible radiotracers - composed of ions or polar molecules - are unable to cross the li...

Germinal matrix

The germinal matrix is an embryological structure in the fetal brain which is only seen in the fetus and in premature neonates. It is the most vulnerable area of the fetal brain and associated pathology carries significant mortality and morbidity. Gross anatomy The germinal matrix is usually...

Pericallosal cistern

The pericallosal cistern is an unpaired subarachnoid cistern containing the pericallosal artery. It lies between the superior surface of the corpus callosum and the inferior edge of the falx cerebri and extends from the genu to the splenium of the corpus callosum 1-3.

Hollenhorst plaque

Hollenhorst plaques are seen on clinical examination of the retina and are the result of cholesterol emboli at the retinal arteriole bifrication 1. They most commonly originate from the carotid or aortic atheroscleroritc plaque 2. Hollenhorst plaques are a a risk factor for ischemic stroke and a...

Paranasal sinuses and facial bones (lateral view)

The lateral paranasal sinuses and facial bones view is a nonangled lateral radiograph showcasing the facial bones (i.e. mandible, maxilla, zygoma, nasal, and lacrimal bone) and paranasal sinuses. Indications This view is useful in assessing any inflammatory processes or fractures to the facial...

Pulvinar (disambiguation)

Pulvinar may refer to: pulvinar thalamic nuclei (classically involved in variant Creutzfeldt-Jakob disease, see pulvinar sign) Haversian fat pad of the hip (which covers the central non-articular part of the acetabulum)

Fontanelle

Fontanelles are the soft membraneous regions of the fetus and neonate calvarium where the corners of three or four developing flat bones meet and allow for the growth over the skull over the developing brain. There are two main, palpable fontanelles in the midline: anterior fontanelle, the lar...

Inferior petro-occipital vein

The inferior petro-occipital vein is located immediately inferior to the petro-occipital suture and provides a communication between the internal carotid artery venous plexus of Rektorzik, or less commonly the cavernous sinus, anteromedially and the jugular bulb, or less commonly the inferior pe...

Microvascular decompression

Microvascular decompression is a surgical procedure for cranial nerve compression syndrome, most often carried out for trigeminal neuralgia, or less frequently hemifacial spasm and glossopharyngeal neuralgia. It is usually carried out via a retrosigmoid craniotomy. The culprit blood vessel, eit...

Anterior condylar confluence

The anterior condylar confluence is an extracranial venous structure at the base of skull that communicates extensively with regional veins and dural venous sinuses. It is located immediately anterior to the hypoglossal canal and medial to the jugular vein, just inferior to the jugular bulb an...

Internal carotid artery venous plexus of Rektorzik

Internal carotid artery venous plexus of Rektorzik (also known as the petro-occipital venous plexus) is a plexus of small veins that surrounds the petrous segment internal carotid artery proximal to the cavernous sinus as it passes through the base of skull. It is believed that the plexus serv...

Skull (submentovertex view)

The skull submentovertex view is an angled inferosuperior radiograph of the base of skull. As this view involves radiographic positioning that is uncomfortable for the patient and with CT being more sensitive to bony detail, this view is rapidly becoming obsolete. Indications This view is usef...

Functional neuroanatomy

Functional neuroanatomy is the study of the functional connections in the brain and spinal cord, distinct but interconnected with the structural or "more conventional" anatomic descriptions of the central nervous system. It focuses on the relationship between structure and function and hence it ...

Marginal sinus (foramen magnum)

The marginal sinus is a dural venous sinus and runs along the inner margin of foramen magnum. It has numerous communications with regional venous structures 1-2: anteriorly: basilar venous plexus posteriorly: occipital sinus laterally sigmoid sinus veins of the hypoglossal canal inferiorl...

Clival diploic veins

Clival diploic veins are veins that travel through the body of the clivus connecting intracranial venous structures on the inner surface of the skull (e.g. basilar venous plexus, inferior petrosal sinuses, marginal sinus, internal carotid artery venous plexus of Rektorzik, inferior petro-occipit...

Cavernous sinus gas

Cavernous sinus gas locules can be seen in several settings. iatrogenic pneumocephalus secondary to gas embolism (especially venous gas embolism) from IV access (can be a relatively common finding in the absence of direct trauma and does not usually require treatment). traumatic pneumoce...

Transitional aneurysm

Transitional aneurysms, also referred to as transitional paraclinoid aneurysms, are saccular cerebral aneurysms arising from the clinoid-ophthalmic segment of the internal carotid artery (ICA) and near the distal dural ring with potential risk for subarachnoid hemorrhage. After an anterior turn...

Hypothermia

Hypothermia is defined as a core body temperature of ≤35°C and is a life-threatening state. It may be accidental or induced 1.

Porus trigeminus

The porus trigeminus is the dural foramen at the entrance of the Meckel cave. Gross anatomy The porus trigeminus is the dural foramen at the trigeminal depression of the petrous apex through which the trigeminal nerve passes as it extends from the prepontine cistern of the posterior cranial fo...

Subcallosal line

The subcallosal line connects the inferior surface of the genu of the corpus callosum to the inferior surface of the splenium and is used to define an axial plane for imaging of the brain 1. The alternative AC-PC line is most commonly used, however, the subcallosal plane remains recommended fo...

Axial plane for imaging of the brain

A consistent axial plane for imaging of the brain needs to be chosen to allow for reproducible image acquisition and comparison. Unlike the sagittal plane, which is intrinsically defined by our inherent left-right plane of symmetry, axial and coronal planes need to be agreed upon and over the ye...

Subdural drain

Subdural drains (SDDs) are inserted as a neurosurgical procedure to manage subdural hygromas 1 and chronic subdural hematomas 2. The drain is ideally closed system 1. It may, for example, be a Jackson-Pratt catheter3 or subdural evacuating port system 4. To insert a SDD, a skin incision is mad...

Twig-like middle cerebral artery

Twig-like middle cerebral artery or rete mirabile anomaly describes a discontinuity of a single trunk of the middle cerebral artery with several small vessels reconstituting the artery and giving it a twig-like appearance. Distally, normal vascular anatomy of the MCA branches need to be present ...

Ice cream cone sign (disambiguation)

The ice cream cone sign may refer to: ice cream cone sign (middle ear ossicles) ice cream cone sign (vestibular schwannoma)

Motor nucleus of the trigeminal nerve

The motor nucleus of the trigeminal nerve is the only motor nucleus of the four main trigeminal nerve nuclei. Gross anatomy The motor nucleus is a paired structure located within the mid-to-upper pons (tegmentum). It lies anteromedial to the main sensory nucleus and adjacent to the lateral asp...

Sandwich sign (disambiguation)

The sandwich sign is used for two different imaging appearances: sandwich sign (Marchiafava-Bignami disease) sandwich sign (mesentery) Sandwich sign has also been coined for the appearance of: primary pleural lymphoma 1,2 mediastinal lymphoma 3 marrow edema and hemorrhage on MRI of flexion...

Primary lateral sclerosis

Primary lateral sclerosis (PLS) is a form of motor neuron disease (MND). Clinical presentation Diagnosis The diagnosis is clinical, after exclusion of structural, neurodegenerative and metabolic mimics. Pathology It is characterized by a slowly progressive upper motor neuron syndrome. Rad...

Spinal nucleus of the trigeminal nerve

The spinal nucleus of the trigeminal nerve is one of three major nuclei that make up the trigeminal sensory nerve nuclear complex along with the main sensory nucleus and the mesencephalic nucleus 1-2. Gross anatomy The spinal nucleus of the trigeminal nerve is a paired structure and is an infe...

Mesencephalic nucleus of the trigeminal nerve

The mesencephalic nucleus of the trigeminal nerve is one of three major nuclei that make up the trigeminal sensory nerve nuclear complex along with the main sensory nucleus and the spinal nucleus 1-2. Gross anatomy The mesencephalic nucleus is a paired structure located at the mesopontine junc...

Doughnut sign (orbit)

The doughnut sign of optic nerve sheath meningioma refers to the appearance of this tumor on coronal CT/MRI. The meningioma forms a thick cuff of enhancing tumor around the central non-enhancing optic nerve, mimicking the appearance of a ring doughnut. It is the coronal equivalent of the tram-tr...

Apoplexy

Apoplexy is a term that has been part of medical terminology since antiquity and now means a sudden and catastrophic clinical presentation restricted to a few intracranial events, namely pituitary apoplexy and the far less common pineal apoplexy. Importantly, it remains a term that denotes a cli...

Main sensory nucleus of the trigeminal nerve

The main or chief sensory nucleus of the trigeminal nerve is one of three major nuclei that make up the trigeminal sensory nerve nuclear complex along with the mesencephalic nucleus and the spinal nucleus 1-2. It also receives fibers from the glossopharyngeal nerve. Some older texts refer to it...

Central herniation

Central herniation is the subtype of downward transtentorial herniation of the brain that involves descent of the diencephalon and midbrain. It usually occurs with other types of downward herniation such as uncal herniation. Clinical manifestations The clinical syndrome of central herniation c...

Lesch-Nyhan syndrome

Lesch-Nyhan syndrome is a rare X-linked genetic disease caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT). Epidemiology Affects 1 per 380,000 individuals, which are nearly all male given the X-linked inheritance 1. Clinical presentation hyperuricemia-...

Petrosphenoidal ligament

The petrosphenoidal ligament, also known as Gruber ligament or petroclival ligament, forms the superior border of Dorello canal, the conduit for the abducens nerve. Terminology The ligament has previously been known as the petroclinoid ligament (ligamentum petroclinoideum) but it actually does...

Milky Way (disambiguation)

The Milky Way (disambiguation) has been used for two different radiological appearances: Milky Way appearance on mammography Milky Way sign in peripheral multifocal leukoencephalopathy

Nucleus ambiguus

The nucleus ambiguus is a large longitudinal nucleus within the medulla oblongata that provides motor innervation to muscles of the pharynx, larynx and soft palate in addition to housing preganglionic nuclei involved in the parasympathetic nervous system augmentation of heart rate 1,2. Gross an...

Corpora amylacea

The corpora amylacea ("bodies of starch") are a histologic finding, encountered more frequently in the brain, prostate, lung, and uterus. The corpora amylacea are thought to be sulfated glycosaminoglycans 1. Some have described it as a localized amyloidosis 2. In the prostate they appear to ar...

Cistern of the lamina terminalis

The cistern of the lamina terminalis is one of the unpaired CSF-filled subarachnoid cisterns. Gross anatomy The cistern of lamina terminalis lies anterior to the anterior wall of the 3rd ventricle in the midline and appears like a high-top tent with a diamond-shaped floor1. It acts as a connec...

Transitional meningioma

Transitional meningiomas are also known as mixed meningiomas because they have components of meningothelial and fibrous subtypes of meningiomas. Their epidemiology, clinical aspects, radiographic characteristics, treatment, prognosis, and differential diagnosis are in the main article (see meni...

Propylene glycol peak

Propylene glycol is one of the possible peaks in MR spectroscopy (MRS) and resonates at 1.13 ppm. Propylene glycol (1,2-propanediol) is a solvent of various intravenous drugs (e.g. phenobarbital), which is the ﬁrst therapeutic choice for neonatal convulsions ref. Due to metabolic immaturity, n...

Filling defect

A filling defect is a general term used to refer to any abnormality on an imaging study which disrupts the normal opacification (filling) of a cavity or lumen. The opacification maybe physiological, for example, bile in the gallbladder or blood in a dural venous sinus, or maybe due to the instal...

Methotrexate-induced myelopathy

Methotrexate-induced myelopathy is an uncommon toxic manifestation of intrathecal methotrexate administration that closely mimics subacute combined degeneration of the cord but with normal vitamin B12 and copper 1,2. It is far less common than methotrexate-related leukoencephalopathy. Epidemiol...

Interpeduncular angle

The interpeduncular angle is defined as the angle formed by the posterior half of the cerebral peduncles on axial images. The interpeduncular angle has been proposed as a sensitive and specific measure of intracranial hypotension (reduced) and progressive supranuclear palsy (PSP) (increased)1,2....

Craniectomy

A craniectomy is a common neurosurgical procedure in which a portion of the skull is resected, but not put back (cf. craniotomy in which the bone flap is re-attached to the surgical defect) 1. The defect is usually covered over with a skin flap. If the defect is closed by a prosthetic covering t...

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