3Here is the vertex of a normal brain Here is the vertex of a normal brain. Note the regular pattern of gyri and sulci. A sulcus is the depth between one gyrus and the next. The thin meninges cover the surface, but have been stripped away over part of the central fronto- parietal region at the right to reveal more clearly the sulci. The central fissure is where the extension of the dura between the hemispheres, called the falx cerebri, would be.
4The meninges have been removed at the vertex of a normal brain to reveal the A Rolandic fissure with the precentral gyrus (motor cortex) and the postcentral gyrus (somesthetic cortex).
16Myxopapillary ependymoma which is typically found arising in the filum terminale of the spinal cord. Note the cells around papillations that have a myxoid connective tissue core. Surgical removal is made easier if this tumor has not grown around nerve roots of the cauda equina.
17medulloblastoma.The irregular posterior fossa mass that is seen here near the midline of the cerebellum and extending into the fourth ventricle above the brainstem is a medulloblastoma. This is one of the "small round blue cell" tumors and it most often occurs in children.
18Here is the microscopic appearance of a medulloblastoma with small round blue cells.
19Here is a cystic astrocytoma of the cerebellum in a child Here is a cystic astrocytoma of the cerebellum in a child. Most childhood brain tumors arise below the tentorium, which is the reverse of the adult. Gliomas in children, therefore, are most common in the posterior fossa. They are often cystic (so-called "juvenile astrocytomas")
20This discreet firm neoplasm was removed from the surface of a peripheral nerve. It is a schwannoma (neurilemmoma) which arises from the nerve sheath Schwann cells.
21The cut surface of a schwannoma is similar to that of many mesenchymal neoplasms, with a "fish flesh" soft tan appearance.
24These are the classic microscopic appearances of a schwannoma, which is benign. Note the more cellular "Antoni A" pattern on the left with palisading nuclei surrounding pink areas (Verocay bodies). On the right is the "Antoni B" pattern with a looser stroma, fewer cells, and myxoid change.
25This glioma of the cerebral hemisphere demonstrates a mass effect This glioma of the cerebral hemisphere demonstrates a mass effect. Note the variegation of the neoplasm, with areas of red, tan, white, and brown
26Even if a glioma is "low grade" it can still be bad, depending upon the location. This glioma of the brainstem is in the worst possible location-- it cannot be resected.
27This sagittal section of brain demonstrates a large brainstem glioma This sagittal section of brain demonstrates a large brainstem glioma. Most gliomas are astrocytomas.
28This glioma is arising in the cerebral hemisphere This glioma is arising in the cerebral hemisphere. As in most gliomas, it is difficult to tell where the margin is.
29This astrocytoma demonstrates increased cellularity and pleomorphism, as compared to normal brain. Note the very pleomorphic cell in the center.
30This is the worst possible form of glioma--a glioblastoma multiforme (GBM). These neoplasms are quite vascular with prominent areas of necrosis and hemorrhage. Note how this one has crossed the midline to the opposite hemisphere.
32This glioblastoma multiforme (GBM) demonstrates marked cellularity with marked hyperchromatism and pleomorphism. Note the prominent vascularity as well as the area of necrosis at the left with neoplastic cells palisading around it.
33Here is another example of pseudopalisading necrosis of neoplastic cells in a glioblastoma multiforme (GBM). The cells of a GBM can infiltrate widely, particularly along white matter tracts, and even through the CSF.
35At the left is seen a metastasis from a lung carcinoma At the left is seen a metastasis from a lung carcinoma. Metastases most often appear at the border of the grey and white matter in the distribution of the middle cerebral artery, as in this case, because that is where the blood flow (vascular distribution) is most likely to take metastases.
41The large hemorrhage in this adult brain arose in the basal ganglia region of a patient with hypertension. This is one cause for a "stroke".
42Hemorrhages involving the basal ganglia area (the putamen in particular) tend to be non-traumatic and caused by hypertension, which damages and weakens the small penetrating arteries. A mass effect with midline shift, often with secondary edema, may lead to herniation.
43A blood clot is seen over the external surface of the dura A blood clot is seen over the external surface of the dura. Thus, this is an epidural hematoma. Such a location for hemorrhage is virtually always the result of trauma that causes a tear in the middle meningeal artery.
4411The dura has been reflected back (with a small portion visible at the lower right) to reveal a subdural hematoma. Such a blood clot is usually the result of trauma with tearing of the bridging veins.
45The dura has been reflected above to reveal the bridging veins that extend across to the superior aspect of the cerebral hemispheres. These can be torn with trauma, particularly if there is significant cerebral atrophy that exposes these veins even more.
46Here is a bilateral chronic subdural hematoma Here is a bilateral chronic subdural hematoma. The blood clots are brown to tan because of organization. Since the bleeding is venous, subdurals can form more slowly and insidiously than clots from arterial hemorrhages. Subdurals are most common in the very young and the elderly.
47The white arrow on the black card marks the site of a ruptured berry aneurysm in the circle of Willis. This is a major cause for subarachnoid hemorrhage.
48The circle of Willis has been dissected, and three berry aneurysms are seen. Multiple aneurysms are seen in about 20-30% of cases of berry aneurysm. Such aneurysms are "congenital" in the sense that the defect in the arterial wall is present from birth, but the actual aneurysm takes years to develop, so that rupture is most likely to occur in young to middle age adults.
49The subarachnoid hemorrhage from a ruptured aneurysm is more of an irritant producing vasospasm than a mass lesion.
50Another cause for hemorrhage, particularly in persons aged 10 to 30, is a vascular malformation. Seen here is a mass of irregular, tortuous vessels over the left posterior parietal region.
51The intraventricular and intracerebral hemorrhage seen here was due to a ruptured vascular malformation. The hemorrhage from such a lesion (which is most often histologically an arteriovenous malformation--AVM) can be intracerebral or extend into ventricles or subarachnoid space.
52The microscopic appearance of this vascular malformation reveals the dilated, tortuous, worm-like vascular channels. Such lesions may bleed a small amount and be the cause for a seizure disorder.
53The characteristic location of the hemorrhage in this brain is consistent with a fall backwards resulting in a contrecoup injury to the inferior frontal and temporal lobes. This has resulted in extensive contusions and subarachnoid hemorrhage.
54A coronal section through the frontal lobes reveals extensive contusions involving the inferior gyri. This was a contrecoup injury from a fall in the bathtub by an elderly person.
55he orange-brown, scalloped appearance of these lesions is consistent with old contusions. The resolution left behind hemosiderin from the hemorrhage that produces the orange-brown staining.
56Seen here are remote contusions, mainly of the right inferior frontal lobe. The crests of the gyri are most susceptible to the traumatic forces.
57The lesions seen here are the result of extensive blunt force trauma to the head in a vehicular accident. Mainly the gyri are affected with hemorrhage from contusions and lacerations.
58The extensive white matter petechial hemorrhages seen here are typical for fat embolism syndrome. Interestingly, neurologic signs and symptoms usually appear about a week after the initiating event, such as long bone fractures in a vehicular accident.
59The arteriolar sclerosis that results from chronic hypertension leads to small lacunar infarcts, or "lacunes", one of which is seen here in the pons. Such lesions are most common in basal ganglia, deep white matter, and brain stem.
60An acute cerebral infarct is seen here An acute cerebral infarct is seen here. Such infarcts are typically the result of arterial thrombosis or embolism.
61The bilaterally symmetric dark discolored areas seen superiorly and just lateral to the midline represent recent infarction in the watershed zone between anterior and middle cerebral arterial circulations. Such watershed infarctions can occur with relative or absolute hypoperfusion of the brain.
62This is an intermediate to remote infarct in the distribution of the middle cerebral artery.
63A thrombosis of the internal carotid artery is seen here A thrombosis of the internal carotid artery is seen here. Arterial thromboses are far more common in the brain than venous thromboses (by a ratio of about 100 to 1).
64This angiogram demonstrates an embolic obstruction of a branch of the left common carotid artery just past the first main bifurcation.
65This intermediate infarct of the frontal lobe shows liquefactive necrosis with formation of cystic spaces as resolution begins.
66Here is a cerebral infarct from an arterial embolus, which often leads to a hemorrhagic appearance. There is edema which obscures the structures. The acutely edematous infarcted tissue may produce a mass effect. Note the decrease in size of the ventricle on the left with shift of the midline.
67The infarction seen here has punctate hemorrhages The infarction seen here has punctate hemorrhages. This infarct was caused by an embolus.
68The neurons are the most sensitive cells to anoxic injury The neurons are the most sensitive cells to anoxic injury. Seen here are red neurons which are dying as a result of hypoxia.
69This cerebral infarction demonstrates the presence of many macrophages at the right which are cleaning up the lipid debris from the liquefactive necrosis.
70The surface of the brain with cerebral edema demonstrates widened gyri with a flattened surface. The sulci are narrowed.
71Acute cerebral swelling can also often produce herniation of the cerebelllar tonsils into the foramen magnum. Note the cone shape of the tonsils around the medulla in this cerebellum.
72The end result of temporal medial lobe herniation is compression of the brainstem (midbrain and pons) and stretching of small arterial branches to cause Duret hemorrhages, as seen here in the pons.
75One cause for acute brain swelling is infection One cause for acute brain swelling is infection. The yellow-tan clouding of the meninges seen here is due to an exudate from acute meningitis.
76The yellow-tan exudate of acute bacterial meningitis seen here obscures the sulci.
77This is another case of acute meningitis This is another case of acute meningitis. It is important to make the diagnosis and begin antibiotic treatment as soon as possible. Clinical signs may include: headache, neck stiffness (from irritation of spinal nerve roots), fever, and clouded consciousness.
78Here is another example of an acute meningitis from bacterial infection. The cerebrospinal fluid (CSF) in such cases typically has a low glucose, high protein, and many PMN's. A gram stain should be done to identify organisms.
79Microscopically, a gram stain reveals gram negative diplococci within a neutrophil, typical for Neisseria meningitidis. Gram stain and culture can be performed on cerebrospinal fluid obtained via lumbar puncture. A variety of bacteria can cause meningitis, but several are more common, and have an incidence more frequent at certain ages:
80Disseminated infections can be seen in immunocompromised hosts. Such infections can include fungi. Seen here are branching hyphae of Aspergillus invading a cerebral vessel. Aspergillus likes to invade vessels and produce hemorrhage and thrombosis
81The hemorrhages seen here in the temporal lobe are due to Herpes simplex virus infection. Viral infections produce mononuclear cell infiltrates microscopically.
82cerebral abscess. There is a liquefactive center with yellow pus surrounded by a thin wall. Abscesses usually result from hematogenous spread of bacterial infection, but may also occur from direct penetrating trauma or extension from adjacent infection in sinuses.
84Note the marked dilation of the cerebral ventricles Note the marked dilation of the cerebral ventricles. This is hydrocephalus. Hydrocephalus can be due to lack of absorption of CSF or due to an obstruction to flow of CSF
85Anencephaly is absence of the fetal cranial vault Anencephaly is absence of the fetal cranial vault. Exposure of cerebral tissue to amniotic fluid precludes brain development. Anencephaly is a form of neural tube defect that is typically an isolated birth defect that is not related to chromosomal abnormalities.
86The absence of the fetal cranial vault in anencephaly is shown here The absence of the fetal cranial vault in anencephaly is shown here. The incidence of anencephaly, one form of neural tube defect, has been reported to occur as frequently as 1 to 5 in live births in the past. However, dietary folic acid supplementation by mothers- to-be before and during pregnancy can reduce the incidence of such birth defects. The rate of anencephaly is now less than 1 in 10,000 live births in some places.
87This large mid-thoracic meningomyelocele is another form of neural tube defect (NTD). The genetic polymorphisms due to mutations in the methylene tetrahydrofolate reductase gene may increase the risk for NTDs. Folate is a cofactor for this enzyme, which is part of the pathway of homocysteine metabolism in cells. The C677T and the A1298C mutations are associated with elevated maternal homocysteine concentrations and an increased risk for NTDs in fetuses. Mothers who supplement their diets with folate prior to and during pregnancy can often reduce this risk.
89Here is anterior vermian atrophy of the cerebellum in a patient with chronic alcoholism.
90The small petechial hemorrhages in the mammillary bodies seen here are characteristic for Wernicke's disease, another complication of chronic alcoholism with thiamine deficiency.
91Seen here in white matter is a large "plaque" of demyelination. The plaque has a grey-tan appearance. Such plaques are typical for multiple sclerosis (MS). These plaques lead to the clinical appearance of transient or progressive loss of neurological function. Since the disease is multifocal and the lesions appear over time, the clinical findings can be quite varied.
92Here is a demyelinated plaque in a patient with multiple sclerosis (MS). The lesions can be seen with MRI scans, but the appearance in the CSF of increased protein from IgG that demonstrates oligoclonal bands on electrophoresis is very consistent with this diagnosis.
93Amyotrophic lateral sclerosis (ALS) is uncommon. It begins in middle age and proceeds to death in several years. There is loss of anterior horn cells, so that patients present with progressive weakness that proceeds to paralysis from neurogenic muscular atrophy. Because of the loss of anterior horn cells, the anterior (ventral) spinal motor nerve roots demonstrate atrophy, as seen here in comparison with normal ventral spinal cord nerve roots
94Where are the anterior horn cells in this section of spinal cord Where are the anterior horn cells in this section of spinal cord? They are absent in a patient with amyotrophic lateral sclerosis (ALS).
95This Luxol-fast-blue stain of spinal cord in a patient with ALS demonstrates lateral column degeneration with gliosis--the "sclerosis" of ALS.
96These enlarged, pale neurons are in a baby with Tay-Sachs disease, which is seen mostly in persons of European Jewish heritage. The disease is often first noticed at an age of 6 months, because the baby is not progressing developmentally
97This is an example of neuronophagia in which a dying neuron is surrounded by microglial cells
98The cerebral atrophy seen here mainly in the frontal and parietal regions is characterized by narrowed gyri and widened sulci. The atrophy seen here was due to senile dementia of the Alzheimer's type (Alzheimer's disease).
99In this case of Alzheimer's disease, there is more marked atrophy seen superiorly and laterally, with sparing of the occipital region.
100The characteristic microscopic findings of Alzheimer's disease include "senile plaques" which are collections of degenerative presynaptic endings along with astrocytes and microglia. These plaques are best seen with a silver stain, as seen here in a case with many plaques of varying size.
101The plaques of Alzheimer's disease are seen here with a silver stain The plaques of Alzheimer's disease are seen here with a silver stain. Such plaques are most numerous in the cerebral cortex and hippocampus. This dementia is marked mainly by progressive memory loss.
102This is a neurofibrillary "tangle" of Alzheimer's disease This is a neurofibrillary "tangle" of Alzheimer's disease. The tangle appears as long pink filaments in the cytoplasm. They are composed of cytoskeletal intermediate filaments.
103Neurofibrillary tangles of Alzheimer's disease are also seen best with a silver stain, as shown here.
104The very marked frontotemporal atrophy seen here is due to another much less common type of dementia known as Pick's disease.
105The marked atrophy of Pick's disease, a senile dementia, produces "knife-like" thinning of the gyri in frontal lobes and temporal lobes.
106The apparent enlargement of the ventricles seen here is due to atrophy of the head of the caudate from neuronal loss with Huntington's disease, an autosomal dominant condition characterized clinically by choreiform movements.
107At the left, normal numbers of neurons in the subtantia nigra are pigmented. At the right, there is loss of neurons and loss of pigmentation with Parkinson's disease.
108the left, an H and E stain demonstrates a rounded pink cytoplasmic Lewy body in a neuron of the cerebral cortex from a patient with diffuse Lewy body disease, which can be a cause for dementia. Lewy bodies can also be seen in substantia nigra with Parkinson's disease. An immunoperoxidase stain for ubiquitin, seen at the right, helps demonstrate the Lewy bodies more readily.