28: Nervous System

Question 1

Neural tube defects, also called dysraphic anomalies reflect impaired closure of the dorsal aspect of the vertebral column. The abnormalities are classified according to extent of the defect ranging in deverity from spina bifida oculta to meniniocele, meningiomyelocele, and rachischisis.

Answer 1

d

Question 2

Spina bifida?

A NTD restricted to the vertebral arches and is asymptomatic.

Answer 2

d

Question 3

Meniniocele?

Meniniocele permits protrusion of the meninges as a fluid-filled sac.

Answer 3

d

Question 4

Meningiomyelocele?

Meningiomyelocele exposes the spinal canal and causes the nerve roots to be entrapped.

Answer 4

d

Question 5

Rachischisis?

Rachischisis is the most extreme defect, without a recognizable spinal cord.

Answer 5

w

Question 6

Syringomyelia is a congenital malformation in which a tubular cavitation (syrinx) extends for variable distances along the entire length of the spinal cord.

Answer 6

w

Question 7

What supplement decreases NTDs?

Folic acid

Answer 7

w

Question 8

Thiamine deficiency causes Werneke syndrome and beriberi.

Answer 8

w

Question 9

What is an Arnold-Chiari malformation?

Arnold-Chiari malformation is a condition in which the brainstem and cerebellum are compacted into a shallow, bowl-shaped posterior fossa whith a low-positioned tentorium.

The cerebellar vermis is herniated below the level of the foramen magnum.

Answer 9

w

Question 10

Anencephaly?

Congenital absence of all or major part of the brain.

Answer 10

w

Question 11

Holoprosencephaly?

A microcephalic brain in which the interhemispheric fissure is absent.

Answer 11

w

Question 12

Hydromyelia is the term for dilation of the central canal of the spinal cord.

Answer 12

w

Question 13

What is congenital hydrocephalus? Cause?

Congenital hydrocephalus refers to an excessive amount of CSF and ventriucular enlargement. Tis caused by congenital atresia of the aqueduct of sylvius.

Histologic exam of the midbrain may disclose multiple atretic channels or an aqueduct narrowed by gliosis.

Since the infantile crainium expands easily, symptoms of increased intracrainial pressure are generally absent.

Conculsions are common, & optic atrophy with blindness can occur.

Answer 13

w

Question 14

CSF consitutes an accessory circulatory system adapted to the needs of the CSF. CSF is formed by the choroid plexus. The choroid plexus stretches along the roof of the third ventricle and then angles posteriorly to span the lateral ventricles.

Answer 14

w

Question 15

CSF flows from its intraventricular origin to sites of reabsorption, principally via the arachnoid villi, into the dural sinuses.

CSF transports metabolites, serves as a medium for clearing metabolic waste, and cushions the structures contained within it.

Answer 15

w

Question 16

Abnormalities of the cerebral gyri are associated with mental retardation.

Answer 16

w

Question 17

Polymicrogyra?

Polymicrogyra is a congenital disorder in which the surface of the brain exhibits an excessive number of small, irregularly sized, randomly distributed gyral folds.

Answer 17

w

Question 18

Arrhinencephaly?

Loss of the olfactory tracts

Answer 18

w

Question 19

Lissencephaly?

Congenital disorder in which the cortical siface of the cerebral hemispheres is smooth or has imperfectly formed gyri.

Lisso = smooth

Answer 19

w

Question 20

Pachygyra = a condition in which the gyri are reduced in number and are usually broad.

Answer 20

w

Question 21

Congenital defects of the CNS are often associated with chromosomal abnormalities, which are best exemplified by trisomies of chromosomes 13, 14, 15 = holoprosencephaly & chromosome 21 = Down syndrome.

Answer 21

w

Question 22

Holoprocencephaly is a microcephalic brain in which the interhemispheric fissure is absent. The horseshoe-shaped cerebral hemispheres have fused frontal poles, across which the gyri show an irregular horzontal orientation.

Holoprosencephaly is not compatible with life beyond a few weeks or months.

Answer 22

w

Question 23

Tabes dorsalis?

Tabes dorsalis is a feature of tertiary syphilis and is characterized by chronic fribrosing meningitis, which constricts the posterior root of the spinal cord. The posterior roots contain sensory nerves that originate in the spinal ganglia and form the posterior columns of the spinal cord. Compression of sensory nerves that originate in the posterior roots causes lancinating pain in the extremities. It also damages the transmission of propioceptive impuses causing ataxia (gait disturbances).

Answer 23

w

Question 24

Amylotrophic lateral sclerosis?

AML is a motor neuron disease that does NOT affect the posterior columns.

Answer 24

w

Question 25

Freidreich ataxia is an autosomal dominant trait that involves the spinal cord in a complex way. It affects not only the centripetal pathways (spinocerebellar and posterior columns), but also the efferent corticospinal tracts.

Answer 25

w

Question 26

Subacute combined degeneration is due to vitamin B12 deficiency and involves not only the posterior columns, but also the anterior horn cells and the spinocerebellar and coricospinal tracts.

Answer 26

w

Question 27

Alzheimer disease?

Alzheimers is the most common cause of dementia in the elderly. It is an insidious & progressive neurologic disorder, characterized clinically bu loss of memory, cognitive impairment, difficulty with language, and eventual dementia. It features atrophy of the brain, with widening of the sulci and bilateral atrophy of the gyri, particularly the frontal and hippocampal cortex. Bronchopneumonia is the usual lethal outcome of Alzheimer disease.

Answer 27

w

Question 28

A brain biopsy showing spongiform degeneration of the gray matter, characterized by individual and clustered vacuoles, with no evidence of inflammation = prion disease, deposition of APrP amyloid.

Answer 28

w

Question 29

Question 10-

Answer 29

w