What are the most common causes of subarachnoid hemorrhage? Trauma Rupture of aneurysm What is the pathophysiology of subdural hematoma? Deceleration/acceleration forces        Tear bridging veins What vessels are damaged in epidural hematomas? Damage to middle meningeal artery Hemorrhage at grey-white junction Corpus callosum  Brainstem What is the most common cause of intracerebral hemorrhage? Hypertensive hemorrhage What vessels are involved in hypertensive hemorrhage? Deep penetrating arteries Where do cerebral artery aneurysms tend to occur? Branch points of intracranial vessels What are structures that can be affected by acute stroke? Obscuration of lentiform nuclei Loss of insular ribbon Why are the lentiform nuclei obscured in acute stroke? Proximal MCA occlusion leading to limited flow to the lenticulostriate arteries Concha bullosa - pneumatization of the middle turbinate What is concha bullosa associated with? Nasal septal deviation Haller cell - Infraorbital ethmoid air cell What is the most common intracranial abnormality in battered children? Subdural hematoma Where do traumatic subdural hematomas tend to occur? Parieto-occipital region Interhemispheric fissure What separates the frontal and parietal lobes? Central (Rolandic) sulcus What regions in the brain regions affected by MS? 1. Periventricular 2. Spinal cord 3. Juxtacortical (touching cortex) 4. Infratentorial What is the difference between focal and broad based herniation? Focal herniation - less than 90 degrees of disc circumference Broadbased herniation - anywhere between 90-180 degrees What is the difference between migration and sequestration? Migration - displaced disc material away from site of extrusion Sequestration - displaced disc material has lost connection with the parent disc What is the order of involvement of the extraocular muscles in thyroid eye disease? I'M SLO I - inferior rectus M - medial rectur S - superior rectus L - lateral rectus O - obliques What are the most common intramedullary, intradural tumors? Ependymomas Astrocytomas What are the different types of nerve sheath tumors? Schwannomas Neurofibromas What findings are associated with neurofibromatosis II? M - Multiple I - Inherited S - Schwannomas M - Meningiomas E - Ependymomas What syndrome is associated with multiple neurofibromas? Neurofibromatosis Type I What additional findings in a peripheral nerve sheath tumor that go along with Neurofibromatosis Type I? Kyphoscoliosis Ribbon ribs (rib dysplasia) Scalloping of the posterior vertebral body (dural ectasia) What is the most common tumor associated with chronic temporal lobe epilepsy? Ganglioglioma What is the most common central cause of precocious puberty? Hypothalamic hamartoma What are the most common tumors of the optic nerve? Glioma (most common) Meningioma Meningiomas grow in linear fashion along optic nerve "Tram track" - pattern of enhancement of sheath May also be extensive calcified What syndrome are optic nerve gliomas associated with? Neurofibromatosis Type I How can one distinguish ependymomas from astrocytomas in the spinal cord? Astrocytomas - longer segment of cord involvement More likely to be infiltrative LESS LIKELY - hemorrhage or tumor cyst What is the pathophysiology of Sturge Weber syndrome? Fetal cortical veins fail to develop normally Leads to chronic venous ischemia Sturge Weber Syndrome Cortical "tram track" calcification Atrophy of affected side (side with port wine stain) Enlarged ipsilateral choroid plexus What is cranial nerves are most commonly affected by schwannomas? Cranial nerve VIII (eight is most common) Cranial nerve V What is the differential diagnosis for mass type lesions that cross midline? Glioblastoma Multiforme Lymphoma Tumefactive MS Joubert syndrome Vermian hypogenesis leading to "molar tooth" appearance  of 4th ventricle and superior cerebellar peduncles What is the definition of holoprosencephaly? Failure of cleavage of prosencephalon into telencephalon and diencephalon What are the most and least severe forms of holoprosencephaly? Alobar - most severe form Semilobar - in between Lobar - least severe form What are the two major types of cholesteatomas? Pars flaccida (80%) Pars tensa (15%) What is the most common tumor of the middle ear? Glomus tympanicum paraganglioma Vertebra plana (pancake vertebral body) Sparing of disc space Cytomegalovirus What are characteristic imaging and clinical findings of carotid cavernous fistula? Dilation of superior opthalmic vein Proptosis What is the most common tumor in the lateral ventricle of a child? Choroid plexus papilloma What part of the lateral ventricles are affected first in hydrocephalus? The atria How can one distinguish hydrancephaly versus hydrocephalus? Hydrocephalus - always mantle of brain parenchyma What are the TORCH infections? T - toxoplasmosis O - Other (varicella) R - Rubella C - cytomegalovirus (CMV)H - Herpes simplex What infection is suspected in the setting of a normal size head and intracranial calcifications (parenchymal, not periventricular)? Toxoplasmosis What are the two types of cephaloceles? Meningocele - protrusion of meninges through calvarial defect Encephalocele - protrusion of brain tissue through calvarial defect What is the difference between a sulcus and gyrus? Sulcus - depression/fissure in surface of brain Gyrus - gyri are surrounded by sulci (depressions) What are the stages of development of the cerebral cortex? Proliferation Migration Cortical organization What disorders result from abnormalities of neuronal cell proliferation? Too many cells - hemimegancephaly Too few cells - microlissencephaly/microcephaly How can one distinguish epidermoid cysts from arachnoid cysts on diffusion weighted imaging? Epidermoid cysts - keratin material restricts free diffusion of water Arachnoid cysts - no restriction of diffusion of water What are the parts of the corpus callosum? Genu - anterior Body  Splenium - posterior How does CSF flow from the ventricular system? Lateral ventricles > Foramen of Monro > Third ventricle > Cerebral aqueduct (Aqueduct of sylvius) > Fourth ventricle > Foramen of Magendie/Luschka How do brain metastases present in children versus adults? Children - leptomeningeal spread Adults - gray-white junction What is the expected spectroscopy profile of glioblastoma? High choline Low NAA What is the one pathologic condition that does not manifest in low NAA (and high choline)? Canavan disease- markedly elevated NAA level Often megalocephaly What is a cholesterol granuloma? Granulation tissue in the middle ear What is a cholesteatoma histologically? Epidermoid cyst What are the major types of cholesteatomas and how often do they occur? Acquired (98%) Congenital (2%) What is choanal atresia? Block of back of nasal passage due to bone or membrane What syndrome are angiomyolipomas associated with? Tuberous sclerosis Esthesioneuroblastoma Enhancing cribiform plate mass with cysts at tumor/brain margin What is the white matter above the ventricles called? Corona radiata Creutzfeldt Jacob disease T2 hyperintensity/restricted diffusion - Caudate - Putamen - Thalamus (hockey stick) - Cortex What space is used to determine the location of masses in the suprahyoid space? Parapharyngeal space Balo concentric sclerosis Variant of MS - alternating bands of demyelinated white matter Bilateral thalamic infarcts - internal cerebral vein thrombosis (straight sinus, vein of Galen) Venous infarcts - often bilateral, midline and hemorrhagic Bilateral thalamic and midbrain infarcts - Artery of Percheron infarct Single arterial trunk coming off PCA supplying portion of thalamus and midbrain 3 year old boy with seizures Neonatal hypoglycemia Neurocysticercosis - Most common location in subarachnoid space Atlanto-occipital dissociation - basion dens interval is greater than 12 mm What are the two most common odontogenic tumors? Odontoma ("tooth hamartomas") Ameloblastoma Young male presenting with muscle spasms and seizures X-linked adrenoleukodystrophy - genetic defect in paroxysmal oxidation of fatty acids Posterior periventricular white matter changes Can get areas of enhancement (not seen in metachromatic leukodystrophy) What is the MOST common hereditary leukodystrophy? Metachromatic leukodystrophy Indentation of the frontal bones (typically seen before 24 weeks) Associated with: Spina bifida Chiari II Malformation 11 year old with history of dystonia Pantothenate kinase degeneration (previously known as Hallervorden-Spatz syndrome) - excess iron accumulation in globus pallidi Low signal intensity of globus pallidi surrounding central small hyperintense area Differential diagnosis? Dysmelinating disease - "Tigroid" appearance of white matter Metachromatic Leukodystrophy Pelizaeus-Merzbacher disease Diagnosis on the left and diagnosis on the right? Left - thyroid opthalmopathy (spares tendinous insertion) Right - orbital pseudotumor (can involve tendinous insertion) Orbital pseudotumor is associated with a more acute onset involving decreased motion and pain What syndrome is this lesion commonly associated with? Lhermitte Duclos  lesion - likely hamartomatous malformation Associated with Cowden disease How to differentiate mega cisterna magna from an arachnoid cyst? Arachnoid cyst - has mass effect