Keywords: Chapter 28, CNS
Anaplastic astrocytoma
An astrocytoma with histologic features of anaplasia, high cellularity, atypical nuclei, some mitoses.
Aneurysm
A focal pouch-like or fusiform dilatation of arteries.
Arterio-venous malformation (AVM)
Abnormal connection between artery and vein most often secondary to residual direct communication (shunting), normal in early embryonic life. Dural AVMs may be acquired in later life.
Astrocytoma
A neoplasm of astrocytes.
Basilar meningitis
Fibrinous meningitis occupying the base of the brain and basal cisterns, caused by M. tuberculosis.
Cerebral histoplasmosis, cryptococcosis, mucor myocosis, aspergillosis
CNS involvement in the above listed fungal infections, usually in association with immuno deficiency, in the case of mucor, with poorly treated diabetes also.
Cerebral vasculitis
Usually either bacterial or autoimmune (e.g., systemic lupus erythematosus) often responsible for multiple small infarcts. Sometimes present in brain only.
Choked disc, papilledema
Intracranial increased venous pressure transmitted to veins of optic disc causing bulging of same. A valuable diagnostic sign for ophthalmologists, but damaging in its own right to the retina and vision.
Cysticercosis
Encysted larvae of the tapeworm Taenia solium.
Dementia paralytica
Subacute meningoencephalitis, predominantly frontal, in advanced syphilis.
Ependymoma
A neoplasm of ependyma of cerebral ventricles, or central canal and filum terminale of spinal cord.
Epidural (extradural) hematoma
Originates from traumatic rupture of the middle meningeal artery.
Germ cell tumors
Histologically identical to gonadal counterparts (germinoma, embryonal carcinoma, yolk sac tumor-entodermal sinus tumor, choriocarcinoma, teratoma). Most often seen in pineal area, next, suprasellar.
Glioblastoma multiforme
A highly malignant form of astrocytoma with areas of necrosis and vascular-endothelial proliferation in addition to anaplastic astrocytes.
Hemangioblastoma
Usually cerebellar, sometimes hemispheric, brain stem or spinal cord localization, or multiple. A tumor composed of capillaries and "stromal cells" (the latter of unknown histogenesis).
Herniation
In cases of increased intracranial pressure, portions of the brain, most closely located to "exit" areas, will be pushed into those openings and create damage by compression and self compression. Most important, herniation of cerebellar tonsil(s) into foramen magnum with compression of medulla oblongata, and herniation of uncus of hippocampus (medial temporal lobe) into tentorial incisure, compressing the midbrain from one or both sides.
HIV encephalitis
This inflammation which regularly features multinucleated giant cells is caused by the human immunodeficiency virus itself and is not an opportunistic infection due to low resistance.
Meningioma
A tumor of arachnoidal cells.
Microglial nodule
A commonly seen feature in viral encephalitis.
Multi-infarct dementia
A series of small strokes, usually of the small "lacunar" type, bringing about gradual "step-wise" dementia.
Mycotic aneurysm
Focal bulging of arterial wall secondary to weakening of same by an embolic infectious process (almost always due to pyogenic bacteria, not fungi).
Negri body
Intracytoplasmic neuronal inclusion in rabies.
Neurofibromatosis
Autosomal dominantly inherited disorder with multiple neurofibromas of skin and nerves, cafe-au-lait spots, ocular abnormalities. Type I- mostly skin and nerve lesions, optic nerve and hypothalamic gliomas. Type II- has bilateral acoustic schwannomas, multiple meningiomas, ependymomas.
Oligodendroglioma
A neoplasm of oligodendroglial cells. Pineal parenchymal tumors (pineoblastoma, pineocytoma), Neoplasms of pineal body cells. Interestingly, much less common than germ cell tumors in the pineal area.
Progressive multifocal leukoencephalitis (PMLE)
A papova virus infection of oligodendrocytes causing multicentric demyelination. Usually seen in immunodeficient patients (lymphoma, leukemia, AIDS, organ transplant recipients)
Schwannoma/neurinoma/neurilemmoma
A tumor of Schwann cells. May develop from cranial nerves III-XII and from spinal nerve roots, as well as from Schwann cells of peripheral nerves. In the head, by far most commonly seen in vestibular branch of the 8th (acoustic) nerve (nobody knows why?) In the spinal cord, almost exclusively in dorsal and not ventral nerve roots (nobody knows why)
Selective vulnerability of neurons
The same degree of ischemia or anoxia does not harm equally the neurons of the brain. Individually, pyramidal cells of Ammon's horn (particularly the first segment, or Sommer's sector) and cerebellar Purkinje cells are most vulnerable as well as cortical neurons of the 3d and 5th layer. In addition, the cerebral cortex is more vulnerable in the sulci than in the crown of the convolutions.
Stroke
A suddenly, or at least rapidly developing injury to the brain due to vascular/circulatory causes. The two main categories of strokes are ischemic and hemorrhagic, the first resulting in infarct(s), the second in mass hemorrhage.
Sturge-Weber syndrome (Encephalo-facial angiomatosis)
Hemangiomas of the face in area of trigeminal nerve innervation and distended veins of leptomeninges, usually in parieto-occipital area. Seizures commonly seen due to the latter. Not familial or inherited!
Subdural hematoma
Usually originates from traumatic rupture of the "bridging veins" connecting cortical veins to intradural sinuses.
Tabes dorsalis
Treponemal damage to posterior spinal nerve roots causes ascending wallerian degeneration of posterior column tracts (gracilis and cuneatus).
Transient ischemic attacks (TIA)
"mini-strokes" with symptoms of a cerebrovascular accident, but with fast return to normal or near normal neurological status. Initially believed to be caused by vasospasm, these days mostly microemboli (fibrin emboli) which dissolve on their own are believed to be the cause. They often herald a big stroke in the area where they occurred.
Tuberous sclerosis
Familial disease, part malformative, part neoplastic. Irregularly built nerve cell-glial cell conglomerates (tubers) involve cerebral cortex (seizures), similar masses with giant astrocytes stud ventricular walls ("candle guttering"). The latter, much less commonly the former, may lead to neoplasia ("subependymal giant cell astrocytoma" of tuberous sclerosis).
von Hippel-Lindau syndrome
Hemangioblastoma of the retina and CNS hemangioblastoma(s). Familial. Additional features may include adrenal pheochromocytomas, renal cysts, renal cell carcinomas, pancreatic cysts and tumors, neoplasms of the epididymis.
Waterhouse-Friderichsen syndrome
A complication of meningococcemia and some other Gram-negative sepsis. Seen in early phases of meningococcal meningitis. Massive adrenal hemorrhagic necrosis may lead to severe shock.
Watershed infarct
In severe hypotension/shock the systemic blood pressure is not sufficient to pump arterial blood to the very end of the vascular branches. In the cerebral cortex not enough blood gets to the "watershed zones" between anterior and middle cerebral artery or middle and posterior cerebral artery territories respectively, and in those areas linear infarcts are apt to develop.