Updated: 6/17/2021

Myelodysplasia (myelomeningocele, spinal bifida)

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  • summary
    • Myelodysplasia is a common group of congenital disorders caused by various chromosomal abnormalities that lead to the failure of closure of the fetal spinal cord and present with anatomic anomalies and neurological impairment of varying degree. 
    • Diagnosis can be made in utero with fetal ultrasound. 
    • Treatment involves a multidisciplinary approach to address neurological, genitoturinary, and orthopedic manifestations.
  • Epidemiology
    • Demographics
      • 0.1-0.2% incidence
    • Risk factors
      • folate deficiency
        • supplementation can decrease risk by 70%
      • maternal hyperthermia
      • maternal diabetes
      • valproic acid
  • Etiology
    • Genetics
      • chromosomal abnormalities
        • up to 10% of fetuses have a chromosomal abnormality
          • trisomy 13
          • trisomy 18
          • triploidy
          • various single-gene mutations
    • Associated conditions
      • orthopaedic manifestations
        • pathologic fractures
        • spine deformities
          • scoliosis
          • kyphosis
        • hip dysplasia
          • hip dislocations
          • contractures
        • knee deformities
          • tibial torsion
          • contractures
        • foot deformities
      • neurosurgical manifestations
        • Type II Arnold-Chiari malformation
          • most common associated congenital abnormality
        • hydrocephalus
          • 70% incidence
        • tethered cord
      • urological manifestations
        • neurologic bladder
    • Special considerations
      • IgE mediated latex allergy
        • results in profound anaphylaxis
        • present in 20 to 70% of patients with this disorder
  • Classification
    • Forms of myelodysplasia
      • spinal bifida oculta
        • defect in vertebral arch with confined cord and meninges
      • meningocele
        • protruding sac without neural elements
      • myelomeningocele
        • protruding sac with neural elements
      • rachischisis
        • neural elements exposed with no covering
    • Function level (described by lowest functioning level)
    • Function level
      (described by 
      lowest functioning level)
      Level
      Function
      Primary Motion
      Primary Muscles
      L2
      • Nonambulatory

      L3
      • Marginal Household ambulator
      • High risk of hip dislocation
      • Hip flexion
      • Hip adduction
       
      • Iliopsoas (lumbar plexus, femoral n.)
      • Hip adductors (obturator n.)
      L4
      • Household ambulator plus
      • Key level because quadriceps can function
      • Knee extension
      • Ankle dorsiflexion & inversion
      • Quadriceps (femoral n.)
      • Tibialis anterior (deep peroneal n.)
      L5
      • Community ambulator
      • Toe dorsiflexion
      • Hip extension
      • Hip abduction
       
      • EHL (deep peroneal n.)
      • EDL (deep peroneal n.)
      • Gluteus med.& min. (superior gluteal n.)
      S1
      • Normal ambulator
      • Foot plantar flexion
      •  Gastroc-soleus (tibial n.) 
      S2
      • Normal ambulator
      • Toe plantar flexion 
      • FHL (tibial n.) 
      S3,4
      • Normal ambulator
      • Bowel & bladder function
  • Imaging
    • Radiographs
      • useful for monitoring
        • scoliosis/kyphosis
        • hip dysplasia
        • pathologic fractures
    • MRI
      • change in neurologic exam prompts urgent MRI to rule out cord tethering
  • Studies
    • Labs
      • alpha-fetoprotein (AFP)
        • elevated in 75% of children with open spina bifida
        • obtain during second trimester
  • Pathologic Fractures
    • Introduction
      • fractures of the long bones are common due to osteopenia
      • frequency increases with the higher the level of the defect
      • common in hip and knee in children ages 3 to 7 years of age
      • fractures are often confused with
        • infection
        • osteomyelitis
        • cellulitis
    • Treatment
      • short period of immobilization in a well-padded splint
        • indications
          • fractures in satisfactory alignment
        • technique
          • well-padded cast
          • avoid long-term casting
            • may lead to
              • osteopenia
              • repeat fractures
  • Scoliosis
    • Introduction
      • may result from
        • muscle imbalance (neurogenic) or
        • congenital malformation (e.g., hemivertebrae)
          • defined as curve > 20°
      • higher the functional level, the greater the incidence of scoliosis
        • 100% scoliosis rate with defects in thoracic levels
      • consider cord tethering in rapidly progressing deformities
    • Treatment
      • nonoperative
        • bracing not effective
      • operative
        • ASF and PSF with pelvic fixation
          • indications
            • progressive curve
            • indicated in most situations as bracing is not effective
          • technique
            • anterior fusion required due to dysplastic posterior elements that may impair posterior fusion
          • complications
            • high psuedoarthrosis rate
            • high incidence of infection (15 to 25%)
              • due to poor soft tissue coverage of posterior spine
  • Congenital Kyphosis
    • Introduction
      • present in 10-15% with myelodysplasia
      • usually congenital and progressive
    • Physicalexam
      • Gibbus deformity may cause recurrent skin breakdown due to pressure points when sitting
    • Treatment
      • operative
        • kyphectomy with fusion and posterior instrumentation
          • indications
            • progressive deformity
          • technique
            • check shunt function prior to kyphectomy
              • shunt failure during surgery may result in death
  • Hip Disorders
    • Hip dislocation
      • introduction
        • most common at L3 level due to unopposed hip flexion and adduction
      • treatment
        • nonoperative
          • indications
            • all levels
          • technique
            • close observation
        • operative
          • indications
            • surgical treatment of dislocated hips is controversial
    • Hip abduction contracture
      • introduction
        • can cause pelvic obliquity and scoliosis
      • treatment
        • proximal division of fascia lata and distal iliotibial band release (Ober-Yount procedure)
          • indications
            • contractures interfere with sitting or bracing
    • Hip flexion contracture
      • introduction
        • common in high lumbar or thoracic defects
      • treatment
        • anterior hip release with tenotomy of the iliopsoas, sartorius, rectus femoris, and tensor fascia lata
          • indications
            • contractures greater than 40 degrees
  • Knee Disorders
    • Weak quadriceps
      • introduction
        • common condition affecting children with myelodysplasia
      • treatment
        • KAFO (knee-ankle-foot orthotic)
    • Flexion contracture
      • introduction
        • not as important to treat in wheelchair bound patients
      • treatment
        • hamstring lengthening +/- posterior capsulotomy
          • indications
            • greater than 20 degrees of knee flexion contracture
        • supracondylar extension osteotomy
          • indications
            • older patients
            • those who have failed soft tissue procedures
    • Extension contracture
      • introduction
        • less common than flexion contractures
      • treatment
        • serial casting
          • indications
            • extension contracture limiting ambulation or sitting
          • technique
            • goal is to reach 90 degrees of flexion
    • Tibial rotational deformities (torsion)
      • treatment
        • observation and orthotics
          • Indications
            • children less than 5 years old
        • distal tibial derotational osteotomy
          • indications
            • children older than 5 years
  • Foot and Ankle deformities
    • Introduction
      • very common
        • 60 - 90% incidence
        • due to high incidence of lower nerve root involvement
      • Myelodysplasia foot deformity by level
        Level 
        Foot Deformity
        Proper orthosis
        L1 & L2
        Equinovarus
        HKAFO
        L3
        Equinovarus
        KAFO
        L4
        Cavovarus
        AFO
        L5
        Calcaneovalgus
        AFO
        S1
        Foot deformity
        shoes
    • Clubfeet (talipes equinovarus)
      • introduction
        • 30% incidence with myelodysplasia
          • most common foot deformity
        • very rigid
        • insensate in the foot (different from idiopathic clubfeet)
      • treatment
        • serial casting
          • indications
            • initial treatment of choice
          • complications
            • high complication rate with serial casting
        • posteromedial lateral release
          • indications
            • failure of serial casting
          • technique
            • perform when child 12-18 months old
    • Foot dorsiflexion deformity
      • introduction
        • seen with L5 or sacral level patients
        • unopposed anterior tibialis causes dorsiflexion deformity
      • treatment
        • posterior transfer of the anterior tibial tendon
          • indications
            • inability to achieve neutral foot with bracing
    • Vertical talus
  • Prognosis
    • Survival and neurologic impairment depend on level of spinal segment involved
    • Untreated infants have a mortality rate of 90-100%
    • Ability to ambulate
      • L3 or above are mostly confined to a wheelchair
      • L5 level patients have a good prognosis for independent ambulation

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(OBQ11.90) A 4-year-old girl with an L3 myelomeningocele presents for routine follow-up. Pelvic radiographs reveal a complete dislocation of the left hip with well formed acetabulum, and a normal right hip. Her gait is symmetric with use of a walker and brace. Which of the treatment options should be offered to the patient at this time?

QID: 3513
1

Right sided femoral shortening osteotomy

1%

(33/2231)

2

Continued observation and routine follow-up

61%

(1370/2231)

3

Left greater trochanteric advancement

3%

(56/2231)

4

Left sided pelvic osteotomy

4%

(90/2231)

5

Open reduction of the left hip

30%

(675/2231)

L 3 C

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(SAE10PE.41) The addition of which of the following food supplements may lead to a decrease in neural tube defects?

QID: 7229
1

Vitamin D-1,25

0%

(0/332)

2

Vitamin B-12

1%

(4/332)

3

Niacin

0%

(1/332)

4

Folic Acid

97%

(322/332)

5

Thiamine

1%

(4/332)

L 1 E

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(OBQ10.133) An 18-year-old ambulatory female with spina bifida presents with a painful planovalgus left foot. She has failed treatment with orthoses and heel-cord stretching regimens. Ankle radiographs demonstrate that the distal tibia is tilted 15° into valgus relative to the long axis. Which of the following treatment options would best correct the deformity?

QID: 3226
1

Triple arthrodesis of the ankle

4%

(106/2584)

2

Supramalleolar osteotomy

83%

(2136/2584)

3

Medial tibial epiphysiodesis

1%

(32/2584)

4

Calcaneal lengthening osteotomy and tendo-Achilles lengthening

10%

(253/2584)

5

Midfoot osteotomy combined with plantar release

2%

(46/2584)

L 2 C

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(OBQ10.27) A 6-year-old boy with spina bifida presents to your clinic with a progressive foot deformity. He can walk independently and ankle dorsiflexion and toe extension demonstrate full strength. He has a bulky, hypertrophied heel pad, but no open ulceration. Foot radiographs are displayed in Figure A. What myelomeningocele level does this patient have and what surgical procedure is indicated for the foot?

QID: 3115
FIGURES:
1

L1 level requiring triple arthrodesis

0%

(12/3578)

2

L3 level requiring triple arthrodesis

2%

(62/3578)

3

L3 level requiring posterior transfer of the anterior tibial tendon

9%

(317/3578)

4

L5 level requiring triple arthrodesis

8%

(297/3578)

5

L5 level requiring posterior transfer of the anterior tibial tendon

80%

(2872/3578)

L 2 C

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(OBQ09.53) Patients with myelomeningocele have an allergic response (type 1 hypersensitivity) to latex by what cellular mechanism?

QID: 2866
1

IgE-directed antibodies

80%

(1375/1722)

2

IgM-directed antibodies

9%

(156/1722)

3

IgA-directed antibodies

6%

(95/1722)

4

Overactive complement system

2%

(43/1722)

5

Hyperactive killer-T cells

3%

(50/1722)

L 2 C

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(SAE07PE.85) An 18-month-old infant with myelomeningocele and rigid clubfeet has grade 5 quadriceps and hamstring strength, but no muscles are functioning below the knee. What is the best treatment option for the rigid clubfeet?

QID: 6145
1

Triple arthrodesis

25%

(77/311)

2

Soft-tissue releases as necessary

34%

(107/311)

3

Tendon transfers to balance the feet in a neutral plantigrade position

14%

(42/311)

4

Physical therapy for range of motion and stretching

13%

(39/311)

5

Botulinum injections followed by serial casting

15%

(46/311)

L 5 E

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(SAE07PE.41) A newborn with myelomeningocele has no movement below the waist and has bilateral hips that dislocate with provocative flexion and adduction. What is the best treatment option for the hip instability?

QID: 6101
1

A Pavlik harness with the hips in 90 degrees of flexion and 60 degrees of abduction

38%

(75/197)

2

A spica cast with the hips in 100 degrees of flexion and 70 degrees of abduction

5%

(9/197)

3

Observation with range-of-motion exercises to minimize contractures

51%

(100/197)

4

Open reduction through an anterior hip approach

2%

(3/197)

5

Open reduction through a medial hip approach

1%

(2/197)

N/A E

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