Updated: 6/23/2018

Cerebrospinal Fluid (CSF)

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https://upload.medbullets.com/topic/113025/images/brain_ventricle.jpg
Overview
 
                               
 
Snapshot
  • A 22-year-old male presents with altered mental status, fever, and headache. The patient is able to sluggishly answer questions. Passive flexion of the neck leads to spontaneous contraction of the hips. Pain is elicited when attempting to fully extend the knee while his hips are at a 90 degree angle. A skin finding is shown to the right.
Introduction
  • Function
    • serves as a mechanical cushion for the CNS
      • protects the brain against concussive injury
    • removal of metabolites
      • CSF flow is one-way
    • hormone and hormone-releasing factor transportation
    • homeostasis
      • CSF pH affects ventilation and cerebral blood flow
  • Production
    • produced by the choroid plexus epithelial cells within ventricles
      • found in lateral, third, and fourth ventricles
    • reabsorbed into circulation by arachnoid granulations
      • enters dural venous sinuses
      • entire volume of CSF is recycled 2-3 times per 24 hours
  • Ventricular system communications
    • lateral ventricle → 3rd ventricle
      • via the interventricular foramen of Monro
    • 3rd ventricle → 4th ventricle
      • via the cerebral aqueduct (Aqueduct of Sylvius)
    • 4th ventricle → subarachnoid space via
      • foramina of Luschka (lateral)
      • foramen of Magendie (medial)
  • Compared to the serum:
    • ↓↓ protein
    • ↓ glucose
    • ↓ pH
    • K+, Ca2+, Mg2+
    • same Na+
Presentation
 
Cerebrospinal Fluid Analysis
Test Normal Bacterial Viral Fungal/TB
Opening pressure
  • ≤ 20 cm H
    2
    O
  • normal or slightly ↑
Color
  • Clear
  • Cloudy
  • Clear
  • Cloudy
Cell count
  • 0-5 cells/µL
  • ↑ (PMN)
  • ↑ (Lymphocytes)
  • ↑ (Lymphocytes)
Protein
  • < 45 mg/dL
  • Slighty ↑
CSF:Serum glucose
  • > 0.6
  • Normal
 
  • Hydrocephalus
    • dilated ventricles via several types
      • communicating
        • ↓ reabsorption of CSF
          • scarring of arachnoid granulations following meningitis
        • ↑ production of CSF (rare)
          • choroid plexus papilloma
      • noncommunicating/obstructive
        • obstructed flow of CSF 
          • stenosis at narrow point along ventricular system
            • e.g., at the cerebral aqueduct, foramen of Monro
          • Chiari II malformation
          • Dandy-Walker syndrome
      • normal pressure (NPH)
        • ↓ reabsorbtion of CSF with chronic dilation of ventricles and normal CSF pressure 
        • distortion of corona radiata produces triad of 
          • urinary incontinence
          • dementia
          • apraxic gait
          • "wet, wacky, wobbly"
        • imaging
          • enlarged ventricles on CT/MRI
        • treatment 
          • peritoneal shunt
      • ex vacuo
        • ↑ in CSF due to ↓ in brain size 
          • e.g., Alzheimer disease
        • ventricles appear large but CSF pressure is normal
 

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Questions (4)
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
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(M1.NE.4671) A 75-year-old man is brought to a neurologist by his daughter. She says that her father has had several falls over the last six months. He has also begun having periodic urinary incontinence. She originally attributed these changes to 'old-age.' However, he has now started to become increasingly forgetful. She is concerned that he may have Alzheimer's disease and decided to bring him to the office for evaluation. Physical exam is notable for abnormal gait. Urinalysis is negative for nitrites and leukocyte esterase. CSF analysis shows: Opening pressure: 100 mm H20; Total protein: 20 mg/100mL; WBCs < 5/mm^3. MRI results are shown in Figure A. Which of the following is the most likely mechanism of his disease process? Review Topic

QID: 107132
FIGURES:
1

Bacterial infection

4%

(2/54)

2

Viral infection

4%

(2/54)

3

Beta-amyloid plaque deposition

39%

(21/54)

4

Scarring of arachnoid granulations

41%

(22/54)

5

Ventricular stenosis

7%

(4/54)

M1

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PREFERRED RESPONSE 4
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(M1.NE.27) An 88-year-old man is brought to his primary care physician by his son. The patient has been in excellent health his entire life, but in the last few years appears to have grown steadily confused. He frequently calls his son about things that they have already discussed, forgets where he has placed his keys, and recently the patient's son noticed several unpaid bills on the patient's desk at home. The patient is upset at being "dragged" into see the physician and claims that everything is fine--he is just "getting older". A complete neurologic exam is normal except for significant difficulty with recall tasks. In the course of the medical work-up, you obtain a CT scan and see the findings in figure A. What is the most likely cause of this patient's CT findings? Review Topic

QID: 101691
FIGURES:
1

Blockage of the cerebral aqueduct

17%

(35/209)

2

Cortical atrophy

71%

(149/209)

3

Increased CSF production

5%

(11/209)

4

Congenital malformation

1%

(2/209)

5

Infection

0%

(1/209)

M1

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PREFERRED RESPONSE 2
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