Updated: 2/27/2018

CNS Development

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Overview
  • CNS development (week 3)
    •  neuroectoderm (a subtype of ectoderm) → neural plate → brain and spinal cord 
  • Neural tube gives rise to
    • forebrain (prosencephalon) 
      • telencephalon 
        • cerebral cortex, lateral ventricles, caudate, putamen, hippocampus, olfactory bulbs
      • diencephalon
        • thalami, mammillary bodies, neurohypophysis, pineal gland, retina, optic nerve, chiasm, and tract
    • midbrain (mesencephalon)
    • hindbrain (rhombencephalon)
      • metencephalon
        • pons, cerebellum
      • mylencephalon
        • medulla
Neural tube defects
 

  • Failure of neuropores to fuse during week 4
    • vertebral arches do not fuse resulting in a connection between amnionic cavity and spinal canal
    • defect tends to occur in lumbosacral region
    • can be detected by testing maternal blood for ↑ α-fetoprotein (AFP)
      • if elevated and neural tube defect is present, then amniocentesis will show ↑ α-fetoprotein (AFP) and ↑ acetylcholinesterase 
    • associated with maternal folate deficiency commonly caused by: 
      • low folic acid intake during pregnancy 
      • medications that interfere with folate utilization 
        • Valproate, methotrexate, sulfasalazine, phenytoin
  • Spina bifida oculta
    • least severe variation with dura intact and no herniation
    • tuft of hair in lumbosacral region 
  • Spina bifida with meningocele
    • only meninges herniate through spinal defect forming a CSF filled sac, but spinal cord remains in spinal canal
  • Spina bifida with meningomyelocele
    • meninges and spinal cord herniate through defect
 

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Questions (5)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
Calculator

(M1.EB.6) A 24-year-old female with a history of recurrent infections, bipolar disorder, and no prenatal care gives birth to a male infant. On physical exam in the delivery room, you observe a tuft of hair over the infant's lumbosacral region. Which of the following drugs was this mother most likely taking during pregnancy? Review Topic

QID: 101900
1

Chloramphenicol

3%

(8/314)

2

Gentamicin

1%

(3/314)

3

Lithium

20%

(64/314)

4

Valproate

69%

(218/314)

5

Folic acid

5%

(17/314)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

(M1.EB.4753) A 25-year-old G1P1 with a history of diabetes and epilepsy gives birth to a female infant at 32 weeks gestation. The mother had no prenatal care and took no prenatal vitamins. The child’s temperature is 98.6°F (37°C), blood pressure is 100/70 mmHg, pulse is 130/min, and respirations are 25/min. On physical examination in the delivery room, the child’s skin is pink throughout and he cries on stimulation. All four extremities are moving spontaneously. A tuft of hair is found overlying the infant’s lumbosacral region. Which of the following medications was this patient most likely taking during her pregnancy? Review Topic

QID: 108832
1

Lithium

10%

(11/111)

2

Ethosuximide

6%

(7/111)

3

Warfarin

3%

(3/111)

4

Gentamicin

2%

(2/111)

5

Valproic acid

79%

(88/111)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 5
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