Radiographics ;24 3 — Aplasia or hypoplasia of the cerebellar vermis. This image shows wide opening of the fourth ventricle and absence of a cerebellar vermis. This appearance is characteristic of Dandy-Walker malformation. Imaging Findings: Wide opening of the fourth ventricle seen along the posterior edge continuous with a posterior fossa cystic space. No vermis is identified. The cerebellar hemispheres are maintained without evidence of hypoplasia or fusion.
Discussion: Dandy-Walker malformation shown here is characterized by abnormal vermian development. The vermis is either absent or profoundly hypoplastic.
There is associated dilation of the fourth ventricle with a large opening into a cystic posterior fossa space as shown here. The tentorium may be elevated because of a large posterior fossa. These patients may have associated hydrocephalus that can benefit from early shunting.
Developmental delay, seizures, mental retardation, and macrocephaly are common clinical manifestations. Macrocephaly is the most common clinical manifestation association with this condition and can be seen early in infancy. Magnetic resonance imaging of malformations of midbrain-hindbrain. J Comput Assist Tomogr ;40 1 — Subcortical band heterotopia. Imaging Findings: There is curvilinear subcortical band of abnormal signal that is isointense to gray matter on all sequences, most compatible with subcortical laminar heterotopia.
The thickness of the abnormal subcortical gray matter can vary from thin curvilinear to a thick band of tissue. Subcortical band heterotopia SBH is classified with lissencephaly complex agyria—pachygyria and not with the other heterotopias. SBH may result from less severe mutations of DSX or LIS1 gene, in addition, a genetic defect on X chromosome in the gene that codes for doublecortin is implicated in some of the cases. Based on the extent of abnormality on the spectrum, the patient can be asymptomatic or have seizures and intellectual impairment.
The most common form of heterotopias is subependymal or periventricular heterotopia, typically the nodular form. These heterotopias due to abnormal neuronal migration can be classified as follows: Subependymal periventricular heterotopia Subcortical nodular heterotopia not the band type; note that SBH is classified with lissencephaly as a part of the classic lissencephaly spectrum Marginal glioneuronal heterotopia or sometimes referred to as leptomeningeal heterotopias.
This is a rare entity, with glioneuronal proliferations overlying the cortex and protruding into the subarachnoid spaces. Classification system for malformations of cortical development: update Neurology ;57 12 — Guerrini R, Parrini E. Neuronal migration disorders. Neurobiol Dis ;— The diagnosis of band heterotopia.
Pediatr Neurol ;51 1 — Open-lip schizencephaly. Cleft lined by gray matter. It is a key feature for diagnosis. Imaging Findings: A large open cleft-like defect that communicates with the ventricle arrow and pial surface and is lined by gray matter. This is most compatible with open-lip schizencephaly. If the loss of brain tissue is minimal and the cleft walls are apposed, it is termed as closed-lip schizencephaly.
Discussion: Schizencephaly is a disorder of cortical malformation characterized by a gray matter—lined cleft that communicates with pial and ependymal lining. Depending on the amount of loss of neural tissue, the cleft can be wide as in this case, referred to as open-lip schizencephaly or minimal with apposed walls, namely, closed-lip schizencephaly.
In the latter, the demonstration of ependymal communication may be challenging, and usually, an outward dimple is noted in the ventricle wall. This can be associated with subependymal heterotopia usually adjacent to the ependymal continuation and juxtaposed dysplastic cortical gyri.
These are usually unilateral; however, one-third of the cases are bilateral. These are most common in the frontal or frontoparietal lobes. This is a rare abnormality and often found in conjunction with polymicrogyria. Depending on the severity of defect, the patients may be neurologically intact to profound neurologic defects, mental retardation, and developmental delay.
Nearly all patients have epilepsy. A developmental and genetic classification for malformations of cortical development: update Brain ; Pt 5 — Neuroimaging in disorders of cortical development.
Neuroimaging Clin N Am ;14 2 — Morphological features and associated anomalies of schizencephaly in the clinical population: detailed analysis of MR images. Neuroradiology ;44 5 — White matter lining the cyst wall.
The white matter lining is typically seen with porencephalic cyst as in this case, distinguishing it from schizencephaly. Porencephalic cyst. The lack of gray matter lining the cyst wall differentiates this from schizencephaly. Hydranencephaly on the other hand is much more severe with profound loss of brain tissue and a large fluid-filled cavity.
Imaging Findings: Right parietal parasagittal cystic cavity without any septations or internal complexity. It is lined by nongliotic white matter arrow with thinning of the overlying cortex.
Discussion: Porencephaly refers to CSF-containing cavity that replaces normal brain parenchyma. Porencephaly, multicystic encephalomalacia, and hydranencephaly are related entities, with differences in age of the patient at the time of insult and also the degree of insult. Rarely, a familial form is seen because of COL4A1 mutation encoding type IV collagen, basement membrane component, resulting in porencephalic cyst, intracranial hemorrhages, and aneurysms.
The typical porencephalic cyst, also known as an encephaloclastic porencephaly or type I porencephaly, results from insult after late second trimester. These are smooth-walled cavities with no or only minimal surrounding gliosis. Hydranencephaly refers to an extreme form of bilateral porencephaly and is due to disruption of the fetal anterior circulation and destruction of the developing cerebral hemispheres.
Each cerebral hemisphere is replaced by a large fluid-filled sac covered by thin meninges. This is referred to as multicystic encephalomalacia. The porencephalic cyst typically results from vascular insult or is infectious in etiology. Acquired cysts can also happen from injury late in life and are usually secondary to trauma, surgery, ischemia, or infarction.
Most common etiology is felt to be periventricular hemorrhagic infarction, either arterial or venous. The location of the lesion varies with the nature of the insult. If it is secondary to vascular insult, the lesion is seen in vascular distribution. Injury resulting from mild to moderate hypotension tends to be in watershed areas. With severe hypotension, only the immediate periventricular white matter may be spared.
If hypoglycemia is the inciting event, lesions tend to be in parietal and occipital lobes. With infection, the site is nonspecific, reflecting the region of brain involvement by infection.
On imaging, cystic degeneration develops 7 to 30 days after the insult. The cavities can be unilateral or bilateral and cortical or subcortical and usually, although not invariably, communicate directly with the ventricular system.
The wall is smooth with no or only minimal surrounding gliosis. Wallerian degeneration can be evident in distant white matter tracts. Differential Diagnosis: Differential diagnosis includes arachnoid cyst extra-axial in location; no changes in the adjacent brain parenchyma , ependymal cyst intraventricular; no changes in the adjacent brain parenchyma , and neuroglial cyst intra-axial; typically, no changes in the adjacent brain parenchyma, no evidence for distant wallerian degeneration, and does not communicate with the ventricular system.
Occasionally, it may be difficult to differentiate a small porencephalic cyst from this entity. COL4A1 mutation in a neonate with intrauterine stroke and anterior segment dysgenesis. Pediatr Neurol ;— Naidich TP, ed.
Imaging of the brain. Expert radiology series. Intracranial cysts: radiologic-pathologic correlation and imaging approach. Radiology ; 3 — Intracranial hypotension.
Diffuse pachymeningeal enhancement is seen throughout the brain and partially imaged upper cervical cord. In the provided clinical setting, these findings are compatible with intracranial hypotension. Dural venous engorgement. The dural enhancement seen in these patients is thought to have resulted from venous engorgement and not infection, trauma, or any congenital abnormality.
Imaging Findings: Diffuse pachymeningeal enhancement is seen arrows A on axial postcontrast T1w image. On sagittal T1w, there is depression of the floor of third ventricle dotted arrow, B and mild tonsillar descent arrow B. These findings in the current clinical setting are consistent with intracranial hypotension. Discussion: Intracranial hypotension ICH can be spontaneous or acquired, the common causes being a lumbar puncture, surgery, and trauma. It typically presents as orthostatic headache, although nonpositional and exertional headaches have been reported.
In addition to headaches, symptoms include neck stiffness, tinnitus, hyperacusis, photophobia, and nausea, as well as a wide variety of cranial nerve symptoms. Rarely, symptoms can be severe, even resulting in coma. The etiology for spontaneous ICH is commonly CSF leak in the spine, cervicothoracic spine being the most common location. Connective tissue disorders can also predispose to spontaneous CSF leak. CSF opening pressure of 1 cm in size.
Imaging Findings: There are multifocal and bilateral T2 and FLAIR hyperintense cortical greater than subcortical lesions compatible with cortical tubers. Axial T2-weighted images show multiple bilateral small hypointense nodules lining the lateral ventricles compatible with subependymal nodules.
Postgadolinium images show an enhancing mass at the level of the left foramen of Monroe suggestive of a SEGA. The classic triad of seizures, mental retardation, and adenoma sebaceum is present in only a minority of patients. Thus, diagnostic criteria have been developed with both major and minor criteria with two or more major criteria meeting diagnostic criteria for TS. CNS major criteria include cortical dysplasias including cortical tubers and radial migration lines , subependymal nodules, and SEGAs.
Additional major criteria include multiple skin findings hypomelanotic macules, angiofibromas, ungula fibromas, and shagreen patch , retinal hamartomas, cardiac rhabdomyomas, LAM, and renal AMLs. Subependymal nodules tend to line the lateral ventricles, have lower T2-weighted signal intensity than cortical tubers, and often calcify.
Subependymal nodules can enhance, and thus, serial imaging to look for interval growth is key to diagnosing SEGAs. SEGAs are most commonly located at the foramen of Monroe with a peak age at 8 to 18 years of age. It is important to diagnose these lesions as patients can present acutely with obstructive hydrocephalus and increased intracranial pressure if there is obstruction at the foramen of Monroe. White matter abnormalities include radial white matter bands that reflect altered migratory development of neurons and glial cells.
They are thin curvilinear or straight T2 hyperintense lines extending from the ventricles to the deep surface of cortical tubers. White matter cystic spaces can also be seen and follow CSF on all imaging sequences. Differential Diagnosis: Although cortical dysplasia and gray matter heterotopia can certainly cause seizures, gray matter heterotopia should follow gray matter on all imaging sequences and not enhance.
References: Northrup H, et al. Tuberous sclerosis complex diagnostic criteria update: recommendations of the International Tuberculosis Complex Consensus Conference. Pediatr Neurol ;49 4 — Roth J, et al. Subependymal giant cell astrocytoma: diagnosis, screening, and treatment. Pediatr Neurol ;49 6 — Umeoka S, et al. Pictorial review of tuberous sclerosis in various organs. Radiographics ;28 7 :e Hummingbird sign.
Seen in patients with progressive supranuclear palsy. Imaging Findings: On the sagittal T1-weighted image A , there is atrophy of the midbrain tegmentum and preserved profile of the pons compatible with the head and body of a hummingbird, the so-called hummingbird sign.
On the axial T2-weighted image B , atrophy of the midbrain tegmentum is noted. Discussion: Progressive supranuclear palsy is a neurodegenerative disease and is classified pathologically as a tauopathy. This is a disease of unknown etiology, and there is no gender predisposition. Patients generally present in their 60s. The typical patient with PSP has reduced facial expression, with marked reduction in blank frequency and overactivity of the frontalis muscle.
Patients also present with poor mobility and falls, parkinsonism, visual symptoms like double or blurred vision, and bulbar symptoms like dysarthria. Cognitive and behavioral problems may also occur. MRI is performed to exclude other diagnoses like stroke, tumor, and hydrocephalus.
Findings supportive of PSP include T2 hyperintensity and atrophy of the midbrain, thinning of the substantia nigra, and atrophy of the putamen and globus pallidus. The hummingbird or penguin sign in PSP patients is seen on a midsagittal plane as atrophy of the midbrain tegmentum and preserved profile of the pons.
The decreased ratio of the area of the midbrain to the area of pons has also been shown to differentiate patients with PSP from normals and multisystem atrophy. Hot cross bun sign seen in patients with MSA multisystem atrophy refers to cruciform hyperintensity through the pons on axial T2-weighted image, representing the selective loss of myelinated transverse pontocerebellar fibers and neurons in the pontine raphe with sparing of the pontine tegmentum and corticospinal tracts see below.
It has also been described in patients with parkinsonism, CJD, and spinocerebellar atrophy. Study of the rostral midbrain atrophy in progressive supranuclear palsy. J Neurol Sci ; 1— 2 — New and reliable MRI diagnosis for progressive supranuclear palsy. Neurology ;64 12 — Shrivastava A. The hot cross bun sign. Radiology ; 2 — Progressive supranuclear palsy. Pract Neurol ;7 1 — Atrophied and hyperintense left hippocampus.
Mesial temporal sclerosis. Imaging Findings: The hippocampus on the left is atrophic with loss of its normal internal architecture. Imaging findings are compatible with left mesial temporal sclerosis.
Discussion: Mesial temporal sclerosis MTS is the most common cause of partial complex seizures in the adult population. Secondary signs of MTS include dilatation of the ipsilateral temporal horn as well as volume loss of the ipsilateral fornix and mammillary body.
There is also controversy in the literature whether febrile seizures as a child leads to MTS as an adult. Initial treatment is with antiepileptic medications. References: Lee DH, et al. MR in temporal lobe epilepsy: analysis with pathologic confirmation.
Meiners LC, et al. Temporal Lobe Epilepsy: the various MR appearances of histologically proven mesial temporal sclerosis. Shinar S. Febrile seizures and mesial temporal sclerosis.
Epilepsy Curr ;3 4 — MRI of the brain with contrast. CT shows right parietal gyral calcification suggestive of Sturge-Weber. MRI with contrast is the next best step. Encephalotrigeminal angiomatosis. Another name for Sturge-Weber Syndrome is encephalotrigeminal angiomatosis.
Figure 1. A noncontrast CT scan with right parietooccipital curvilinear gyral calcification as well as subcortical calcifications. There is also prominence of the right choroid in comparison to the left. Figure 2. Gradient echo sequence shows low signal corresponding to the calcifications on CT. On the T1-weighted sequence, there is no intrinsic T1 shortening. Postgadolinium images demonstrate right-sided leptomeningeal enhancement and pial angiomatosis. The right choroid is noted to be prominent, and there is subtle volume loss of the right cerebral hemisphere in comparison to the left.
Findings are compatible with Sturge-Weber Syndrome. Discussion: Sturge-Weber Syndrome or encephalotrigeminal angiomatosis is a neurocutaneous disorder characterized by facial port-wine stain and pial angiomatosis involving one cerebral hemisphere.
SturgeWeber is a rare disease affecting approximately 1 in 50, to , people. Unlike the other phakomatoses, Sturge-Weber is felt not to be hereditary and rather results from a somatic mutation the GNAQ gene on chromosome 9q Patients present with seizures within the first year of life, mental retardation, and glaucoma, along with the classic port-wine stain.
The port-wine stain usually involves the ophthalmic division V1 of the trigeminal nerve, unilaterally and ipsilateral to the intracranial abnormality.
However, given how rare Sturge-Weber is, most patients with a port-wine stain simply have an isolated, uncomplicated finding. Imaging findings of Sturge-Weber include gyral and subcortical calcifications, cerebral atrophy, ipsilateral choroid plexus enlargement, and leptomeningeal enhancement with pial angiomatosis all within the same cerebral hemisphere.
The distribution tends to progress from posterior to anterior with the occipital and parietal lobes involved greater than the frontal and temporal lobes. Infratentorial involvement is not classic but does occur as well. References: Adams ME, et al. A spectrum of unusual neuroimaging findings in patients with suspected Sturge-Weber syndrome. Juhasz C, et al.
Multimodality imaging of cortical and white matter abnormalities in Sturge-Weber syndrome. Nozaki T, et al.
Syndromes associated with vascular tumors and malformations: a pictorial review. Radiographics ;— Corticospinal tract. Death occurs due to respiratory failure. Imaging Findings: Coronal T2-weighted image A demonstrates increased signal in the bilateral corticospinal tracts. Discussion: ALS, also known as motor neuron disease, is a neurodegenerative disorder characterized by progressive muscular paralysis secondary to degeneration of motor neurons in the primary motor cortex, brainstem, and spinal cord.
The diagnosis of sporadic ALS is based on clinical signs and symptoms, and there is marked phenotypic heterogeneity. In patients who have a clinically definite disease, conventional MRI is not required.
In patients who have clinically probable or possible disease, MR imaging is useful to rule out ALS mimic syndromes like multiple sclerosis, ischemia, cervical spondylotic myelopathy, and other causes of myelopathy. Death usually occurs 3 to 5 years after onset because of respiratory failure.
This finding is not very specific and has been described in healthy subjects. Corticospinal tract signal intensity changes do not correlate with clinical scores of the disease. Additionally, a characteristic low signal intensity of the precentral cortex on T2-weighted images has been observed; again, this finding is neither very sensitive nor specific.
Advanced imaging techniques including MR spectroscopy decrease in the NAA level and NAA to creatinine ratio , diffusion tensor imaging decrease in fractional anisotropy , and functional MRI may be helpful for prognostication. The present and the future of neuroimaging in amyotrophic lateral sclerosis. Vascular dementia. No specific regional pattern of neurodegeneration or neocortical atrophy is obvious.
No evidence of stigmata of lacunar infarctions. Discussion: Cognitive decline may have various etiologic underpinnings. Vascular cognitive impairment VCI is one of those causes. VCI is associated with FLAIR signal changes that suggest underlying small vessel disease, lacunar infarction or infarctions in strategic locations such as watershed distribution and association cortex. In this example, there are no significant white matter changes to suggest this entity, making this the least likely etiology to explain cognitive decline.
In addition, memory loss with gait difficulties and urinary incontinence may be seen with normal pressure hydrocephalus. The presence of moderate ventriculomegaly without commensurate increase in sulcal volume may be seen with normal pressure hydrocephalus.
However, early changes from these entities may remain occult on structural imaging; therefore, despite lack of a specific pattern of neurodegeneration on these images, these other entities remain considerations in the appropriate clinical setting. References: Harper L, et al. An algorithmic approach to structural imaging in dementia.
J Neurol Neurosurg Psychiatry ;85 6 — Palm WM, et al. Ventricular dilation: association with gait and cognition. Ann Neurol ;66 4 : — Following are the key images from an MRI. CNS vasculitis B. Progressive multifocal leukoencephalopathy C. Lymphoma in immunocompetent individuals D. Multiple sclerosis 1b Which of the following tests is most useful in confirmation of the diagnosis of primary angiitis of the CNS? Conventional cerebral angiography B. MR angiography with contrast C. High-resolution vessel wall imaging D.
Surgical biopsy 2 A year-old male with neck pain and vertigo presents to the emergency department. T1w axial with contrast and blood suppression B. T1w axial with fat saturation C. T2w axial with fat saturation D. T2w axial with contrast and blood suppression 2b What is the most common imaging manifestation of the above diagnosis? Arterial stenosis B. Intimal flap C.
Intimal hematoma D. Pseudoaneurysm 3 A year-old male with sudden-onset right-sided weakness and altered mental status. Digital subtraction angiography B. CT angiography and CT perfusion C.
What is the most accurate diagnosis? Thunderclap headache B. Positional vertigo C. Painful visual loss D. Gait disturbances 4b Which of the following is the key feature in reversible cerebral vasoconstriction syndrome RCVS? Complete resolution of symptoms but persistent imaging findings C. Treatment by magnesium is crucial D. Complete resolution of symptoms and imaging findings within 3 months 5 A year-old male with conjunctival chemosis and proptosis presents for initial evaluation.
Key images from a CTA head are provided below. Developmental in nature B. Posttraumatic etiology C. Postinflammatory changes D. Related to radiation therapy 5b What specific ocular abnormality is seen with the above diagnosis? Orbital varix B. Carotid cave aneurysm C. Engorgement of the superior ophthalmic vein D. Retrobulbar hemorrhage 5c What is the most likely etiology for mass-like lesion in left cavernous sinus?
Lymphoma B. Meningioma C. Tolosa-Hunt syndrome D. Arterialized cavernous sinus 6a What is the most likely diagnosis? Developmental venous anomaly DVA B. Cavernous malformation C.
Arteriovenous malformation AVM D. Presence of intraparenchymal nidus B. Large-vessel arterial feeder C. Deep venous drainage D.
Key images are shown below. Abnormal oxygenation B. Subarachnoid hemorrhage C. Meningitis D. Pial vascular engorgement 7b Which of the following is an accepted management strategy for this condition? Vascular stenting B. Endovascular aneurysm coil embolization C.
Intravenous antibiotics 8 A year-old female with severe headache presents to the ER for further assessment. High-dose aspirin use B. Oral contraceptive use C.
Cocaine abuse D. Uncontrolled hypertension 8b Which of the following venous structures is part of deep venous drainage? Vein of Trolard B. Sylvian vein D. Internal cerebral vein 9 A year-old female with acute-onset altered mental status and abnormal head CT shown below. What is the most likely diagnosis? Basilar meningeal exudates B. Prepontine mass C. Aneurysmal subarachnoid hemorrhage D. Benign perimesencephalic hemorrhage 10 A year-old female smoker and hypertensive with acute-onset severe headache presents to the ER.
Key images from noncontrast head CT and cerebral angiogram are shown below. Cerebral vasospasm B. Large-vessel thrombosis C. Associated dissection D. Hydrocephalus Patient had subsequent deterioration of clinical status. Following key images from a CT angiogram are shown. LMCA dissection C. Basilar stenosis D. Basilar thrombosis 11 A year-old male presents to the ER with disorientation and ataxia. What is the diagnosis in the above case?
Artery of Percheron infarct B. Deep venous sinus thrombosis C. Creutzfeldt-Jakob disease D. Bithalamic glioma 12 A year-old diabetic female with sudden-onset headache, blurry vision, and facial numbness, and paresthesias was sent for an MRI.
Orbital pseudotumor B. Tolosa-Hunt syndrome C. Cavernous sinus thrombosis D. Carotid—cavernous fistula 12b What the additional abnormality shown on these images predisposes to this diagnosis? Skull base trauma B. Paranasal sinus infection C. Maxillary sinus mucocele D. Cavernous carotid dissection 13 A year-old male with abnormal head CT. An MRI was performed for better assessment, as shown below.
Cavernoma B. Developmental venous anomaly C. Arteriovenous malformation D. Oligodendroglioma 14 A year-old female presented for evaluation of pulsatile tinnitus. On otoscopic evaluation, a retrotympanic mass with reddish hue was seen behind the tympanic membrane. A CT was performed for further assessment. Glomus tympanicum B. Aberrant internal carotid artery C.
Congenital cholesteatoma D. Jugular bulb dehiscence 14b The above entity is often associated with which of the following secondary findings? Absence of cervical ICA and enlargement of inferior tympanic canaliculus B. Absence of the sigmoid plate of the jugular foramen C. Middle ear ossicular erosion or displacement D. Dehiscence of the tegmen tympani 15 A year-old patient was found down and brought to the ER.
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