Updated: 1/8/2019

Diseases of Myelination

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  • A 32-year-old man presents to the emergency department with worsening lower extremity weakness. The patient was in his usual state of health until approximately one week prior to presentation, where he developed increased difficulty climbing the stairs. Now he is unable to stand. A few weeks ago he developed bloody diarrhea, which he attributes to drinking unpasteurized milk. On physcal examination, he has bilateral lower extremity 1/5 strength with absent patellar reflexes. (Guillain-Barre syndrome)
Guillain-Barré Syndrome
  • Introduction
    • acute inflammatory demyelinating polyradiculopathy (AIDP)
      • most common presentation
    • inflammatory demyelination of peripheral nerves
    • autoimmune attack of peripheral Schwann cells due to molecular mimicry
      • previous Campylobacter jejuni and Mycoplasma pneumoniae
        • may have an association with Zika virus infection
  • Presentation 
    • symptoms
      • symmetric weakness usually begins in distal limbs and moves proximally
        • can begin proximally or a combination of proximally and distally
    • physical exam
      • decreased or absent deep tendon reflexes
      • cranial nerve involvement common resulting in facial paralysis
      • autonomic dysfunction resulting in cardiac irregularities and fluctuations in blood pressure
  • Evaluation 
    • LP
      • albuminocytologic dissociation 
        • ↑ CSF protein with normal cell count
  • Treatment
    • almost all patients survive and achieve complete recovery in several weeks
    • respiratory support is critical until recovery
      • pulmonary function testing
    • plasmapheresis or IV immunoglobulin
      • equal efficacy; no additive benefit
  • Prognosis, prevention, and complications
    • prognosis
      • low mortality
    • complications
      • respiratory failure
Progressive Multifocal Leukoencephalopathy (PML)
  • Introduction 
    • widespread CNS demyelination due to destruction of oligodendrocytes
    • associations
      • latent JC virus reactivation
      • ↑ risk with natalizumab
      • ↑ risk with rituximab
    • seen in the immunosuppressed
      • HIV infection
        • < 200 per mm3
      • organ transplant patients
  • Presentation
    • subacute neurological deficits
      • e.g., hemiparesis, monoparesis, ataxia, altered mental status
  • Evaluation
    • clinical diagnosis with MRI imaging
      • MRI
        • symmetric or asymmetric lesions in multifocal areas
    • PCR of CSF for JC virus
    • brain biopsy
  • Treatment
    • patients with HIV
      • antiretroviral therapy
    • natalizumab-associated
      • stop agent
      • initiate plasma exchange
  • Prognosis, prevention, and complications
    • prognosis
      • HAART therapy improves survival in patients with HIV
    • prevention
      • improving CD4+ count in patients with HIV
    • complications
      • death
Acute Disseminated (Postinfectious) Encephalomyelitis
  • Introduction
    • autoimmune inflammatory demyelination of the CNS secondary to infection or vaccination
      • via infection
        • e.g., chickenpox and measles
      • via vaccinations
        • e.g., rabies and smallpox
  • Presentation
    • symptoms
      • acute and rapidly progressive development
        • multifocal neurological deficits
          • altered mental status
          • motor deficits
          • cranial nerve neuropathy
          • ataxia
          • sensory deficit
  • Evaluation
    • clinical diagnosis
  • Treatment
    • high-dose corticosteroids
      • IVIG or plasma exchange if poor response
    • acyclovir
  • Prognosis, prevention, and complications
    • prevention
      • no small pox vaccine before 12 months of age
    • complications
      • neurologic impairment
Metachromic Leukodystrophy
  • Introduction
    • autosomal recessive lysosomal storage disease due to deficient arylsulfatase A 
    • inability to degrade sulfatides → sulfatide build up → myelin breakdown
  • Presentation
    • symptoms
      • diverse neurological impairment depending on subtype
        • e.g., motor skill regression in late infantile subtype
  • Evaluation
    • arylsulfatase enzyme activity in leukocytes
      • decreased
    • biopsy
      • neural tissue metachromatic lipid deposits
  • Treatment
    • no curative treatment
Charcot-Marie-Tooth Disease
  • Introduction
    • also known as hereditary motor and sensory neuropathy (HMSN)
    • group of disorders negatively affecting peripheral nerves and/or myelin 
      • genetically distinct disorders
  • Presentation
    • symptoms
      • peroneal nerve neuropathy
        • lower leg atrophy
          • "inverted bottle" appearance
      • diminished or absent reflexes
      • decrease vibration and proprioception sense
      • pes cavus
  • Treatment
    • supportive
Central Pontine Myelinolysis (CPM)
  • Introduction
    • pontine demylination
      • loss of corticospinal and corticobulbar tracts
        • due to rapid correction of hyponatremia
        • can result in "locked-in syndrome"
  • Presentation
    • symptoms
      • pseudobulbar palsy with spastic quadriparesis
        • locked-in like presentation
          • can move eyes and blink
      • may also include cognitive function changes
  • Prognosis
    • often fatal
 

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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
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(M1.NE.4768) A 4-year-old previously healthy male presents with 4 days of intermittent vomiting and 5-6 daily loose stools. His mother noted bloody stools and decreased oral intake of food and water over the last 24 hours. He is normally in daycare; however, he has been home for the past 3 days. On physical exam his temperature is 102.2°F (39°C), blood pressure is 140/90 mmHg, pulse is 120/min, respirations are 22/min and O2 saturation is 99% on room air. He has dry mucous membranes. On abdominal exam you note diffuse tenderness to palpation without rebound or guarding. There are no masses, hepatosplenomegaly, and bowel sounds are hyperactive. Ultrasound of the right lower quadrant is negative for appendicitis. Stool is guaiac positive. He receives 15mg/kg acetaminophen and fluids are started. The next day, he complains of lower extremity weakness and tingling. On repeat exam, lower extremity strength is 3/5 with diminished patellar deep tendon reflexes. Which of the following lab findings would most likely be seen in this patient? Review Topic

QID: 109064
1

Gram stain positive CSF

30%

(80/266)

2

Peripheral eosinophilia

15%

(39/266)

3

Xanthochromia on cerebrospinal fluid analysis

11%

(29/266)

4

Increased cerebrospinal fluid protein with normal cell count

28%

(74/266)

5

Oligoclonal bands on cerebrospinal fluid analysis

12%

(31/266)

M1

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PREFERRED RESPONSE 4

(M1.NE.77) A 26-year-old man presents to his primary doctor with one week of increasing weakness. He reports that he first noticed difficulty walking while attending his sister's graduation last week, and yesterday he had difficulty taking his coffee cup out of the microwave. He remembers having nausea and vomiting a few weeks prior, but other than that has no significant medical history. On exam, he has decreased reflexes in his bilateral upper and lower extremities, with intact sensation. If a lumbar puncture is performed, which of the following results are most likely? Review Topic

QID: 106891
1

High neutrophils, high protein, low glucose, high opening pressure

14%

(15/106)

2

High lymphocytes, normal protein, normal glucose, normal opening pressure

24%

(25/106)

3

High lymphocytes, high protein, low glucose, high opening pressure

17%

(18/106)

4

Normal cell count, high protein, normal glucose, normal opening pressure

27%

(29/106)

5

Normal cell count, normal protein, normal glucose, normal opening pressure

9%

(10/106)

M1

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PREFERRED RESPONSE 4
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