Nervous System Pathology

• most common primary malignant brain tumor
• consists of glial cells (supporting connective tissue in the CNS) that still have ability to multiply
• Radiographic Appearance: MRI; CT (non-enhanced) shows a single heterogeneous mass (isodense to hypodense); CT (contrast enhanced) shows a homogeneous lesion with irregular ring of enhancement

• benign tumor that arises from arachnoid lining cells and is attached to the dura
• Radiographic Appearance: MRI; CT (head) shows rounded, sharply delineated, hyperdense tumor abutting a dural surface; CT (spine) myelogram demonstrates location of mass as a filling defect

• result of trauma, acute arterial bleeding usually caused by laceration of the medial meningeal artery of its branches
• acute neurological symptoms and emergency surgery to relieve intracranial pressure
• Radiographic Appearance: CT - biconvex peripheral high-density lesion, showing midline shift

• venous bleeding, most commonly from ruptured veins between the dura and meninges
• slower bleed (than arterial) with gradual neurologic deficits
• Radiographic Appearance: CT: acute - crescent-shaped peripheral high-density lesion; chronic - isodense lesion

• injury to brain tissue (commonly frontal and anterior temporal) caused by movement of brain within skull after blunt trauma
• Radiographic Appearance: CT - low-density areas that usually enhance (after contrast injection) for several weeks

sharp lucent line that is often irregular or jagged

fracture of the zygomatic arch and the orbital floor or rim combined with separation of the zygomaticofrontal suture

suggestive finding for fracture may be air-fluid level in the sphenoid sinus seen on lateral projection of skull using horizontal central ray

• traumatic hemorrhage into the brain parenchyma resulting from shearing forces to intraparenchymal arteries usually at the junction of the gray and white matter
• Radiographic Appearance: CT - will-circumscrided, homogeneous, high-density region surrounded by low-density regions of edema

• principle cause of hemorrhage is hypertensive vascular disease
• can also be a congenital berry aneurysm or an arteriovenous malformation
• Radiographic Appearance: CT - new hematoma appears as a homogeneously dense, well-defined, round or oval lesion, becoming isodense over time; 6 month-old hematoma appears as a well-defined, low-density lesion

• injury to surface veins, cerebral parenchyma, or cortical arteries can produce bleeding into the ventricular system
• Radiographic Appearance: CT - increased density within the basilar cisterns, cerebral fissures, and sulci

• major cause of hemorrhage is rupture of berry aneurysm
• most common locations are origins of the posterior cerebral and anterior communicating arteries and the trifurcation of the middle cerebral artery
• Radiographic Appearance: CT - noncontrast scan initially shows high attenuation of blood in the subarachnoid space

• cerebrovascular disease refers to any process that is caused by an abnormality of the blood vessels or blood supply to the brain
• can be divided into three categories: completed stroke, TIA's and intracranial hemorrhage

• sudden loss of brain function caused by the interruption of flow of blood to the brain (ischemic stroke approx 80%) or the rupture of blood vessels in the brain (hemorrhagic stroke)
• interruption of blood flow or the rupture of blood vessels causes neurons in the affected area to die (cerebral infarct) and effects of a stroke depend on where the brain was injured, as well as how much damage occured
• Radiographic Appearance: the purpose of immediate CT evaluation in the acute stroke patient is not to confirm the diagnosis of a stroke but to exclude intracranial hemorrhage before treatment; CT - (initially) a triangular or wedge-shaped hypodensity on noncontrast scan with mass effect seen 7-10 days after onset

• caused by temporary interruption of blood flow to the brain
• symptoms are similar to an ischemic stroke except they are temporary
• an important warning sign for increased risk of stroke
• Radiographic Appearance: ultrasound of MRI

• gradual loss of neurons results in enlargement of the ventricular system and sulci
• Radiographic Appearance: CT - low density periventricular regions

• diffuse form of progressive cerebral atrophy that develops at an earlier age than the senile period (presenile dementia)
• Radiographic Appearance: CT - cerebral atrophy with enlarged ventricles and prominent cortical sulci

• atrophy of the caudate nucleus and putamen
• inherited condition that predominantly involves men and appears as dementia and typical choreiform movements (involuntary movements that are rapid jerky, and continuous)
• Radiographic Appearance: CT - focal ventricular dilatation; loss of normal shape of frontal horns

• major degenerative changes in nerve cells occur in the basal ganglia
• enzyme defect that results in an inadequate production of the neuronal transmitter substance dopamine
• disease is gradually progressive
• characterized by stooped posture, stiffness and slowness of movement, fixed facial expression, and involuntary rhythmic tremor of limbs that disappears with voluntary movement
• Radiographic Appearance: CT - appears similar to that of normal aging process

• dilatation of the ventricular system usually associated with increase intracranial pressure
• usually due to an obstruction of flow of the spinal fluid causing cranium enlargement
• insertion of a shunt between dilated ventricles and the heart or peritoneal cavity to decrease intracranial pressure and ventricular size
• Radiographic Appearance: CT - demonstrates ventricular dilatation and used for monitoring