KEY FACTS Terminology Extraventricular obstructive hydrocephalus (EVOH): Enlarged ventricles due to mismatch between cerebrospinal fluid (CSF) formation, absorption Synonym: “Communicating” hydrocephalus Imaging Impaired absorption of CSF distal to 4th ventricle outlet foramina Ventricular size varies with duration of obstruction All…
KEY FACTS Terminology Intraventricular obstructive hydrocephalus (IVOH) = obstruction proximal to foramina of Luschka, Magendie Acute (aIVOH) Chronic “compensated” (cIVOH) Imaging aIVOH = “ballooned” ventricles plus indistinct (“blurred”) margins “Fingers” of CSF extend into periventricular white matter Most striking around…
KEY FACTS Terminology Cystic CSF cavity of septum pellucidum (SP) Occurs ± cavum vergae (CV) Imaging Elongated finger-shaped CSF collection between lateral ventricles Cavum septi pellucidi (CSP): Between frontal horns of lateral ventricles CV: Posterior extension between fornices CV is…
Gross and Imaging Anatomy Ventricles and Choroid Plexus Basic embryology : Early in embryonic development, the forebrain cavity divides into 2 lateral ventricles, which develop as outpouchings from the rostral 3rd ventricle and are connected to it by the interventricular…
KEY FACTS Terminology Inferior olivary nucleus (ION) degeneration Unique type of transsynaptic neuronal degeneration Olivary deafferentation thought to be source of ensuing hypertrophic olivary degeneration (HOD) Usually caused by primary lesions in dento-rubro-olivary pathway (anatomical triangle of Guillain-Mollaret) Triangle of…
KEY FACTS Terminology Diaschisis = sudden loss of function in brain connected to (but at distance from) damaged area Crossed cerebellar diaschisis (CCD) = decreased blood flow/metabolism in cerebellar hemisphere contralateral to supratentorial infarct Imaging Acute: CT/MR perfusion shows ↓…
KEY FACTS Terminology Spinocerebellar ataxias (SCAs) Spinocerebellar atrophy; spinocerebellar degeneration Previously known as Marie ataxia, inherited olivopontocerebellar atrophy, spinocerebellar degeneration Inherited progressive neurodegenerative disorders Clinically, genetically very heterogeneous (> 60 types) – SCA 3 most frequent subtypes 2 groups: Autosomal…
KEY FACTS Terminology Wallerian degeneration (WaD) Secondary anterograde degeneration of axons and their myelin sheaths caused by interruption of the axonal integrity or damage to neuron Imaging Primary lesion is cortical or subcortical with WaD in descending white matter tracts…
KEY FACTS Terminology Amyotrophic lateral sclerosis (ALS) Selective degeneration of somatic motor neurons of brainstem/spinal cord and large pyramidal neurons of motor cortex Eventual loss of corticospinal tract (CST) fibers Imaging Small percentage demonstrate CST hyperintensity As CST is normally…
KEY FACTS Terminology Neurodegenerative disease characterized by supranuclear palsy, postural instability, mild dementia Imaging Midbrain atrophy (penguin or hummingbird sign) Sagittal T1WI shows concave/flat upper border of midbrain (normally convex) Axial T1WIs show abnormal concavity of lateral margins of midbrain…