Choline is a precursor of acetylcholine (ACH), a component of cell membranes which is commonly examined in MR spectroscopy. It resonates at 3.2 ppm chemical shift.
It is a marker of cellular membrane turnover and therefore elevated in neoplasms, demyelination and gliosis. In the setting of glio...
Chondrosarcomas are malignant cartilaginous tumours that account for ~25% of all primary malignant bone tumours. They are most commonly found in older patients within the long bones, and can arise de novo or secondary from an existing benign cartilaginous neoplasm. On imaging these tumours have ...
Chondrosarcomas of the base of the skull are rare compared with other skull base tumours but are an important differential diagnosis as surgical resection and management are affected by the preoperative diagnosis.
Chondrosarcomas of the base of the skull make up only a small fract...
The Chorda tympani is a nerve that arises from the mastoid segment of the facial nerve, carrying afferent special sensation from the anterior two-thirds of the tongue via the lingual nerve, as well as efferent parasympathetic secretomotor innervation to the submandibular and sublingual glands.
Chordoid gliomas of the third ventricle are rare slow growing well-circumscribed low-grade tumours lesions that arise from the anterior wall or roof of the third ventricle.
Epidemiological data is limited due to the rare nature of this finding and less than 100 cases have been pu...
Chordoid meningiomas are uncommon histological variants of meningiomas, and due to their predilection for rapid growth and local recurrence are designated as grade 2 tumours under the current WHO classification of CNS tumours.
Chordoid tumours are encountered in a very wide age range (possibly...
Chorea is a type of dyskinesia characterised by sudden, rapid, involuntary, and purposeless movements that happen during a person’s normal voluntary movement. It is a clinical symptom related to different aetiologies, such as infectious, inflammatory, vascular, hereditary (e.g. Huntington's dise...
Chorioretinitis refers to inflammation of the retina and choroid. As a delayed sequelae, it is one of the causes of calcification of the globe. It is often considered a form of posterior uveitis.
various congenital infections such as 2,3
rubella: ocular rubella
A choristoma is simply a collection of microscopically normal cells or tissues in an abnormal location. This is different to a hamartoma which is derived only from local tissues.
adrenal choristoma (myelolipoma)
facial nerve choristoma
Choroidal detachment is a detachment of the choroid from the underlying sclera due to the accumulation of fluid in the suprachoroidal space generally due to increased intraocular pressure (IOP), as observed in some settings:
exudative: fluid accumulatin...
Choroidal epithelial cells are one of the three types of ependymal cells, themselves a type of glial cell. They cover the surface of the choroid plexus and produce cerebrospinal fluid (CSF). 1.
The choroidal fissure is a thin C-shaped cleft of the lateral ventricle, located along the medial wall, and to which choroid plexus is attached. It runs between the fornix and the thalamus, and it separates the temporal lobe from the optic tract, midbrain and hypothalamus.
A choroidal fissure cyst refers to a benign intracranial cyst occurring at the level of choroidal fissure. They frequently represent either an arachnoid cyst, neuroglial cyst or a neuroepithelial cyst 2. They are therefore a location based diagnosis rather than a distinct pathological entity.
Choroid plexitis is a general term referring to an inflammatory process affecting the choroid plexus; it is usually due an infectious process. It is rarely seen as an isolated process and is commonly found in association with encephalitis, meningitis, or ventriculitis 1. The choroid plexus can a...
The choroid plexus is located within the cerebral ventricles and is made of epithelial cells, loose connective tissue (tela choroidea) and permeable capillaries. It produces cerebrospinal fluid.
roof of the temporal horns of the lateral ventricles, extending along the ...
Choroid plexus carcinomas are malignant neoplasms arising from the choroid plexus. They are classified as a WHO grade III tumour and while there is considerable overlap in imaging characteristics it carries significantly poorer prognosis than both WHO grade II atypical choroid plexus papilloma, ...
Antenatal choroid plexus cysts are benign and are often transient typically resulting in utero from an infolding of the neuroepithelium.
They should not be confused with adult choroid plexus cysts (which are very commonly found at autopsy and likely degenerative), large intraventricular simpl...
Choroid plexus hyperplasia (CPH), also known as villous hypertrophy of the choroid plexus, is a rare benign condition that is characterised by bilateral enlargement of the entire choroid plexus in lateral ventricles without any discrete masses. This can result in overproduction of CSF and commun...
Metastases to the choroid plexus from extracranial tumours are rare, but nonetheless should be included in the differential diagnosis of an intraventricular mass. They are most commonly found within the lateral ventricles, presumably because a large proportion of the choroid plexus is located th...
Choroid plexus papillomas are an uncommon, benign (WHO grade I) neuroepithelial intraventricular tumour which can occur in both the paediatric (more common) and adult population.
On imaging, these tumours are usually identified in the fourth ventricle in adults and in the lateral ventricles in...
Choroid plexus tumours can be classified as primary or secondary neoplasms of the choroid plexus:
choroid plexus papilloma (CPP)
WHO Grade I, and WHO Grade II when atypical
choroid plexus carcinoma (CPC)
WHO Grade III
Choroid plexus xanthogranulomas are common, incidental and almost invariably asymptomatic lesions. It is unclear in much of the literature whether they represent a distinct entity from adult choroid plexus cysts, but they share imaging characteristics and are only likely to be distinguishable on...
There are many signs in radiology that are related to Christmas:
snowcap sign in avascular necrosis
in total anomalous pulmonary venous return
in pituitary macroadenomas
snowstorm appearance in complete hydatidiform and testicular microlithiasis
holly leaf sign in calcified pl...
There are several viral and prion infections which can result in a chronic encephalitis with slow progression into brain atrophy. These have a very poor prognosis with no effective treatment.
Some of these include:
progressive multifocal leukoencephalitis
subacute sclerosing panencephalitis
Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired demyelinating disease involving peripheral nerves, and is generally considered the chronic counterpart to Guillain-Barré syndrome (GBS).
Patients typically present with a gradual and protracted (> 2 ...
Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) is an uncommon and only recently described disorder characterised by infiltration of the brain by inflammatory cells. It has a predilection for the pons, with fairly characteristic curvilinea...
Chronic otomastoiditis (COM) should be considered a separate entity from acute otomastoiditis, and is defined as persistent or recurrent inflammation of the middle ear and mastoid, lasting usually for a minimum of 12 weeks, and resulting in permanent perforation of the tympanic membrane.
Chronic traumatic encephalopathy is a neurodegenerative tauopathy that is thought to result from mild repetitive head trauma.
The exact incidence and prevalence are unknown. It is most commonly seen in amateur and professional sports players where head contact is common (e.g. box...
The cingulate gyrus lies on the medial aspect of the cerebral hemisphere. It forms a major part of the limbic system which has functions in emotion and behaviour. The frontal portion is termed the anterior cingulate gyrus (or cortex) 1-2.
The cingulate gyrus extends fr...
The cingulate sulcus is situated directly superior to the cingulate gyrus, which is formed by the medial surface of the cerebral hemisphere that is directly above the corpus callosum.
The cingulate sulcus sign has been proposed as being useful as an MRI feature of idiopathic normal pressure hydrocephalus (NPH). It denotes the posterior part of the cingulate sulcus being narrower than the anterior part. The divider between the anterior and posterior parts of the sulcus being a...
The Circle of Willis is an arterial polygon formed as the internal carotid and vertebral systems anastomose around the optic chiasm and infundibulum of the pituitary stalk in the suprasellar cistern. This communicating pathway allows equalization of blood-flow between the two sides of the brain,...
Cerebral vascular malformations encompass a large variety vascular lesions which differ in haemodynamics, structure and prognosis. Some can be life threatening (e.g. vein of Galen aneurysmal malformations, arteriovenous malformations) whilst others are almost always incidental and asymptomatic (...
Spinal meningeal cysts can be classified according to a system published by Nabor et. al 2:
type I: extradural meningeal cyst without neural tissue
type Ia: extradural spinal arachnoid cyst
type Ib: sacral meningocele
type II: extradural meningeal cyst containing neural tissue, e.g. Tarlov c...
Classification system for malformations of cortical development organises a myriad of conditions into one of three major underlying groups according to the main underlying mechanism:
group I: abnormal cell proliferation or apoptosis
group II: abnormal neuronal migration
group III: abnormal co...
Classification systems for malformations of the cerebellum are varied and are constantly being revised as greater understanding of the underlying genetics and embryology of the disorders is uncovered. A classification proposed by Barkovich et al. in 2009 1 divides cerebellar malformations in two...
Classification systems for midline abnormalities of the brain and skull are varied and constantly changing as the underlying embryology and genetics are uncovered. A relatively simple and robust classification system is based on the location of abnormalities, always remembering that midline abno...
Claude syndrome is one of the brainstem stroke syndromes in which there is infarction of the dorsomedial aspect of the midbrain.
Clinical picture is characteristic and includes ipsilateral oculomotor nerve palsy and contralateral upper and lower limb ataxia 1-4.
The claustrum is a vertical curved sheet of subcortical grey matter oriented sagittally between the white matter tracts of the external capsule and extreme capsule. It is lateral to the putamen and medial to the insular cortex. It is not part of the basal ganglia.
There are lateral and medial t...
The claw sign is useful in determining whether a mass arises from a solid structure or is located adjacent to it and distorts the outline.
It refers to the sharp angles on either side of the mass, which the surrounding normal parenchyma forms when the mass has arisen from the parenchyma. As suc...
Clear cell ependymomas are a histological variant of ependymoma characterised by prominent perinuclear cytoplasmic clearing, reminiscent of oligodendrogliomas 1.
They are typically encountered in younger patients and usually in the supratentorial compartment 1.
They have a tendency to be qui...
Clear cell meningiomas are a histological variant of meningioma with poorer prognosis and a higher rate of recurrence. They are therefore considered WHO grade 2 tumours, regardless of mitotic index, cellular atypia/anaplasia, or presence of brain invasion.
Clear cell meningiomas ...
Clinically isolated syndrome (CIS) is the first episode suggestive of demyelination 1,2. It can either be monofocal (single lesion) or multifocal 1,2. Not all patients with CIS will go on to develop multiple sclerosis however if at presentation there are changes on MRI suggestive of MS, then the...
Clinically unclassifiable parkinsonism (CUP) is a term applied to patients who have some parkinsonism features, but who do not fulfil clinical criteria for a particular disorder such as:
progressive supranuclear palsy (PSP)
multiple system atrophy (MSA-P)
The differential of a mass involving or arising from the clivus is a relatively narrow one and can be divided into whether the lesion arises from the skull base itself, the intracranial compartment above or the base of skull below.
When evaluating the clivus it is important to compare the marro...
CNS aspergillosis results from angioinvasive infection of the central nervous system by the fungus Aspergillus spp. Along with CNS cryptococcosis, it is one of the most common fungal opportunistic infections of the central nervous system.
The disease predominates in immunocompromi...
CNS capillary telangiectasiae(s) are small, asymptomatic low flow vascular lesions of the brain.
As these lesions are asymptomatic, diagnosis usually matches the age of first imaging with MRI, and as such are most frequently found in middle-aged and elderly adults. Their inciden...
CNS cryptococcosis results from infection of the central nervous system with the yeast-like fungus Cryptococcus neoformans. It is the most common fungal infection and second most common opportunistic infection of the central nervous system.
For a general discussion of infection with this organi...
This article aims to be a collection of articles that represent central nervous system infectious (CNS) diseases.
The organisms involved in CNS infections vary depending on the specific location of infection. Bacteria, viruses, fungi, parasites, and prions can all ...
CNS lymphoma refers to the involvement of the central nervous system with lymphoma. It can be broadly divided into primary and secondary, with a number of special types of also recognised.
primary CNS lymphoma (PCNSL)
MALT lymphoma of the dura 5
secondary CNS lymphoma...
The acronym COACH describes a syndrome associated with:
C - cerebellar vermis defect (Joubert syndrome)
O - oligophrenia
A - ataxia
C - coloboma
H - hepatic fibrosis
There only as little as 11 cases having been reported in the English medical literature....
Coalescent mastoiditis is simply the term given to acute otomastoiditis when mucoperiosteal disease extends to involve the bone. The septae which normally separate one mastoid air cell from another are resorbed. This change is only easily appreciated on thin section bone-algorithm through the te...
CoA synthase protein associated neurodegeneration (CoPAN) is a type of neurodegeneration with brain iron accumulation (NBIA).
Patients typically present with a variety of symptoms including spastic-dystonic paraparesis, Parkinsonism, cognitive impairment, obsessive-compul...
Coccidioidal meningitis refers to central nervous system involvement of the dimorphic fungus Coccidioides spp, mainly Coccidioides immitis and Coccidioides posadasi.
Coccidioidomycosis is endemic to many parts of North, Central, and South America 1. It usually only manifests as co...
Coccidioidomycosis refers to an infection caused by the dimorphic fungus Coccidioides spp, usually localised to the lungs. This disease is not to be confused with the similarly named paracoccidioidomycosis.
The most common forms of Coccidioides spp are Coccidioides immitis and Coc...
Cochlear implants (CI) are a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf or severely hard of hearing. Unlike conventional hearing aids, the cochlear implant does not amplify sound, but works by directly stimulating any functioning audi...
Cochlear incomplete partition is a group of cochlear malformations associated with variable degree of inner ear architecture defects.
It is classified in three groups:
cochlear incomplete partition type I (IP-I)
a severe form of IP-I is known as cystic cochleovestibular malformation
Cochlear incomplete partition type I (IP-I) is a type of cochlear anomaly associated with sensorineural hearing loss.
The main findings on CT are:
absent interscalar septum
wide (most common) or normal cochlear nerve canal
Absence of these structu...
Cochlear incomplete partition type II (IP-II) is a type of cochlear anomaly associated with sensorineural hearing loss.
It should not be confused with Mondini anomaly, which his an historic term for a combination of IP-II and large vestibular aqueduct.
On CT, the co...
Cockayne syndrome is a rare autosomal recessive dysmyelinating disease. Cockayne syndrome is classified among the childhood leukodystrophies, and brain imaging findings are cardinal features suggesting the diagnosis of Cockayne syndrome. Previously published Cockayne syndrome imaging studies hav...
Coffin-Siris syndrome, first described in 1970, is a rare genetic abnormality.
It occurs more frequently in females (with a M:F of ~4:1).
It is thought most likely to relate to a gene on chromosome 7, however its exact location has yet to be determined.
The Cognard classification of dural arteriovenous fistulas correlates venous drainage patterns with increasingly aggressive neurological clinical course. It was first described in 1995 1 and at the time of writing (July 2016) is probably the most widely used classification system for dural arter...
COL4A1 brain small-vessel disease is an autosomal dominant monogenic COL4A1-related disorder that primarily causes cerebral small vessel disease.
The exact prevalence is unknown, but the condition is likely under-diagnosed.
The clinical presentation is vari...
COL4A1-related disorders are a group of autosomal dominant disorders caused by a mutation in the COL4A1 gene.
The exact prevalence is unknown, but the group of disorders is considered to be under-recognised, especially asymptomatic variants 1.
The clinical ...
COLD syndrome is the acronym for the concurrent diagnosis of Cowden syndrome and Lhermitte-Duclos disease. It has been suggested that COLD syndrome should be considered a phakomatosis 1.
The collateral sulcus, also known as the medial occipitotemporal sulcus, runs anteroposteriorly on the inferior surface of the temporal lobe and occipital lobe. Anteriorly it is sometimes continuous with the rhinal sulcus 1-3.
Anteriorly, it separates the fusiform gyrus laterally, from the par...
Coloboma is collective term encompassing any focal discontinuity in the structure of the eye, and should not be confused with staphylomas, which are due to choroidal thinning.
Most commonly colobomas are due to failure of closure of the choroidal fissure posteriorly. Typically colob...
Colpocephaly is a descriptive term to a disproportionate prominence of the occipital horns of the lateral ventricles. It can result from a wide range of congenital insults.
Patient may present with motor abnormalities, cognitive deficit, visual abnormalities, and seizures...
The column of Burdach, also known as the cuneate fasciculus or fasciculus cuneate, represents the lateral portion of the dorsal columns and carries input from between and including C1 and T6 1.
The cuneate fasciculus is responsible for transmitting vibration, conscious proprioception...
The column of Goll, also known as the gracile fasciculus or fasciculus gracilis, represents the medial portion of the dorsal columns and carries input from below and including T7 1.
The gracile fasciculus is responsible for transmitting vibration, conscious proprioception, and fine (d...
Combined cerebral oedema is a type of cerebral oedema in which there is a mixed pattern of both cytotoxic and vasogenic cerebral oedema.
It is usually associated with severe systemic damage, such as with:
severe sepsis / severe inflammatory condition
The combined conduit score (CCS) is a grading scheme for the assessment of the degree of transverse-sigmoid sinus stenosis in the setting of idiopathic intracranial hypertension. The score was initially developed for ATECO MR venography 1.
Assessment is performed using maximum inten...
There are a number of white matter tracts that cross the midline, connecting the two cerebral hemispheres. These are known as commissures and include:
hippocampal commissure (psalterium)
Communicating hydrocephalus is a type of hydrocephalus where CSF is able to leave the ventricular system.
Communicating hydrocephalus is commonly used as the opposite of obstructive hydrocephalus which leads to much unnecessary confusion, as most causes of communicating hydrocepha...
Complications of cranial radiation therapy are fairly common, particularly in long-term survivors, and especially in paediatric patients.
Cranial radiotherapy is used for a variety of brain tumours, either in isolation or in combination with concurrent chemotherapy. Complications from irradiati...
Concurrent suprasellar and pineal region lesions have a relatively short differential to be considered, including:
other germ cell tumours
embryonal cell carcinoma
yolk sac tumour (endodermal sinus tumour)
primary CNS lymphoma
The condylar canal, or canalis condylaris, is a skull base canal in the posterior cranial fossa, located in the condylar fossa.
location: in the condylar fossa of the posterior cranial fossa, posterior to the occipital condyles
emissary veins, connecting the sigmoid sinus to...
The confluence of sinuses, also known as the torcula or torcular herophili is the site of the confluence of:
superior sagittal sinus
The anatomy is highly variable and three types can be distinguished:
type 1: superior sagittal sinus drains...
Congenital absence of the internal carotid artery (ICA) is a rare anomaly that occurs in less than 0.01% of the population. It encompasses agenesis, aplasia, and hypoplasia 1.
The most common type of collateral flow is through the circle of Willis, through the anterior communicating artery (ACO...
Congenital anomalies of the posterior arch of the atlas (C1) are relatively common anomalies. They may range from partial defects presenting as clefts to complete absence of the posterior arch (aplasia).
These anomalies are classified according to Currarino (see below). It should not be confuse...
Congenital calvarial defects are a group of disorders characterised by congenital calvarial bone defects that vary in severity.
CT with 3D shaded surface reformats is the best imaging tool as it demonstrates calvarial defects and bone margins:
Congenital cerebral toxoplasmosis is a manifestation of congenital toxoplasmosis and refers to development of cerebral toxoplasmosis in the fetus through maternal transmission.
Please refer on congenital toxoplasmosis to a broad discussion on epidemiology and pathology.
Congenital cholesteatomas are identical to epidermoid cysts, differing only in name and location.
They are intraosseous inclusions of ectoderm, and are therefore comprised of keratin debris and cholesterol. Characteristically, they are located at the petrous apex. In contrast middle...
Congenital cytomegalovirus infection results from intra-uterine fetal infection by cytomegalovirus (CMV).
CMV is the most common cause of intra-uterine infection and most common cause of congenital infective and brain damage, occurring in 0.2-2.4% of live births.
Antibodies to ...
A congenital facial palsy (CFP) is an uncommon cause of neonatal asymmetric crying facies, which are more frequently due to absence or hypoplasia of the depressor anguli oris muscle, often associated with other congenital anomalies.
CFP are reported with an incidence of ~0.2% of ...
Congenital muscular dystrophies (CMD) are a heterogeneous group of autosomal recessive myopathies presenting at birth with hypotonia, delayed motor development, and early onset of progressive muscle weakness, confirmed with a dystrophic pattern on muscle biopsy.
Congenital anomalies of the ossicles are most frequently associated with external ear abnormalities also, although they can occur in isolation.
They cause conductive hearing loss (CHL).
When bilateral they are most frequently genetic, with autosomal dominant inheritance, whereas unilateral a...
Congenital spinal meningoceles are developmental anomalies of meningothelial elements displaced into the skin and subcutaneous tissues.
Please refer on menigocele article for a broad overview of all types of this condition.
It is defect of the neural tube, an embryonic structure th...
Congenital ventriculomegaly can have a large number of syndromic associations.
fetal alcohol syndrome
A conjoined root is a type of developmental anomaly involving a nerve root. It is the most common nerve root developmental anomaly of the cauda equina being twice as common as two roots in the same foramen, the next most common anomaly.
The incidence in cadaveric studies is about ...
Connatal cysts, also known as coarctation of the lateral ventricles or frontal horn cysts, are cystic areas adjacent to the superolateral margins of the body and frontal horns of the lateral ventricles and are believed to represent a normal variant.
The incidence is 0.7% in low bi...
Contrast-induced neurotoxicity, also known as iodinated contrast-induced encephalopathy, is a rare complication of iodinated intravascular contrast resulting in a usually temporary neurological deficit. CT imaging findings can be dramatic, demonstrating contrast staining and oedema, but spontane...
The conus medullaris is the terminal end of the spinal cord.
After the cord terminates, the nerve roots descend within the spinal canal as individual rootlets, collectively termed the cauda equina. The conus medullaris most commonly terminates at the L1/2 intervertebral disc leve...