Myelodysplasia (myelomeningocele, spinal bifida)

Author: Mark Karadsheh

Topic updated on 02/12/13 11:44am

Introduction

Group of congenital abnormalities caused by the fetal spinal cord failing to completely close
Epidemiology
- demographics
  - 0.1-0.2% incidence
- risk factors
  - folate deficiency
    - supplementation can decrease risk by 70%
  - maternal hyperthermia
  - maternal diabetes
  - valproic acid
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
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
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)

x	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
Physical exam
- 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
    
    L1
    
    L2
    
    L3
    
    L4
    
    L5
    
    S1
    
    HIP FLEXION
    
    HIP EXTENSTION
    
    HIP ADDUCTION
    
    HIP ABDUCTION
- 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	Cavo varus	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

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Qbank (4 Questions)

TAG

(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? Topic

Review Topic

1. Right sided femoral shortening osteotomy
2. Continued observation and routine follow-up
3. Left greater trochanteric advancement
4. Left sided pelvic osteotomy
5. Open reduction of the left hip

PREFERRED RESPONSE ▶

DISCUSSION: Hip dislocation in children with myelomeningocele may either be teratological or paralytic. Paralytic dislocation of the hip occurs because of paralysis of the hip abductors and extensors w/ unopposed pull of the hip flexors and adductors. Surgical reduction of hips in patients with spina bifida is associated with a high failure rate and therefore treatment indications are controversial. In general, reduction for patients with L4 level is most controversial and may be considered if unilateral. Dislocated hips in patients with L3 level and above are typically left alone. These indications may vary from center to center.

Gabrieli et al evaluated 20 patients, divided into two groups, with a diagnosis of low lumbar myelomeningocele using 3D gait analysis. All patients were community ambulators with a unilateral hip dislocation and no scoliosis. Gait symmetry corresponded to the absence of hip contractures or bilateral symmetrical hip contractures, and had no relation to the presence of hip dislocation. The authors concluded that in patients with a symmetric gait, reduction of the hip is unnecessary.

REFERENCES:

1. Herring JA, ed. Tachdjian's Pediatric Orthopaedics. 4th ed. Philadelphia, PA: WB Saunders; 2008:1431-1435.

2. Gabrieli AP, Vankoski SJ, Dias LS, Milani C, Lourenco A, Filho JL, Novak R. Gait analysis in low lumbar myelomeningocele patients with unilateral hip dislocation or subluxation. J Pediatr Orthop. 2003 May-Jun;23(3):330-4. PMID:12724595 (Link to Abstract)

Question Authors:

Joshua Blomberg MD, Eric Shirley MD, Dave Marcu MD,

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TAG

(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? Topic

Review Topic

FIGURES: A

1. L1 level requiring triple arthrodesis
2. L3 level requiring triple arthrodesis
3. L3 level requiring posterior transfer of the anterior tibial tendon
4. L5 level requiring triple arthrodesis
5. L5 level requiring posterior transfer of the anterior tibial tendon

PREFERRED RESPONSE ▶

DISCUSSION: This patient has a L5 level myelomeningocele as he is an ambulator with talipes calcaneus demonstrated on the radiograph. L1 level myelomeningocele patients have externally rotated and flexed hips, equinovarus feet, require a HKAFO, and cannot functionally ambulate. L3 level myelomeningocele patients have adducted and flexed hips, recurvatum knee, equinovarus feet, require a KAFO, and are household ambulators. Park et al followed 31 patients with L5 or sacral level myelomeningocele and talipes calcaneus. They underwent posterior transfer of the anterior tibial tendon to balance the dynamic forces and obtain a plantigrade foot. The correction increased peak plantar flexion, decreased peak dorsiflexion, and increased peak pressures under the forefoot and midfoot. Illustration A displays the 3 year postoperative radiograph for the patient in Figure A. Triple arthrodesis should be avoided in most myelodysplastic patients and is used only for severe deformities with sensate feet.

Illustrations: A

REFERENCES:

1. Park KB, Park HW, Joo SY, Kim HW. Surgical treatment of calcaneal deformity in a select group of patients with myelomeningocele. J Bone Joint Surg Am. 2008 Oct;90(10):2149-59. PMID:18829913 (Link to Abstract)

2. Kasser JR. The foot. In: Morrissy RT, Weinstein SL, eds. Lovell & Winter's Pediatric Orthopaedics, 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005:1257-1328.

Question Authors:

Michael Hughes MD, Eric Shirley MD,

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TAG

(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? Topic

Review Topic

1. Triple arthrodesis of the ankle
2. Supramalleolar osteotomy
3. Medial tibial epiphysiodesis
4. Calcaneal lengthening osteotomy and tendo-Achilles lengthening
5. Midfoot osteotomy combined with plantar release

PREFERRED RESPONSE ▶

DISCUSSION: A planovalgus foot deformity in patients with spina bifida may arise from distal tibia or foot deformity. In this case, the deformity is occuring through the distal tibia, and therefore is best treated with a supramalleolar osteotomy as the patient is skeletally mature.

Valgus occuring through the hindfoot can be treated with a calcaneal lengthening procedure to lengthen the lateral column of the foot and reduce the talonavicular joint. It is usually combined with a tendo-achilles lengthening, and offers further benefit in that it usually corrects the accompanying midfoot abduction deformity. Arthrodesis has been suggested for severe foot deformity, however is usually avoided because it increases the risk of skin sores and Charcot changes in the foot.

In skeletally immature patients with ankle valgus, Stevens et al performed a medial malleolar epiphysiodesis in 31 children (50 feet). They noted an average angular correction of 9.7°. With respect to patient/parent satisfaction, 22 of 31 noted improvement, eight reported no change, and one expressed disappointment.

REFERENCES:

1. Stevens PM, Belle RM. Screw epiphysiodesis for ankle valgus. J Pediatr Orthop. 1997 Jan-Feb;17(1):9-12. PMID:8989692 (Link to Abstract)

Question Authors:

Joshua Blomberg MD, Eric Shirley MD, Michael Hughes MD,

Please Rate Educational Value!

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Average 2.0 of 14 Ratings

TAG

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

Review Topic

1. IgE-directed antibodies
2. IgM-directed antibodies
3. IgA-directed antibodies
4. overactive complement system
5. hyperactive killer-T cells

PREFERRED RESPONSE ▶

DISCUSSION: As described by the review by Drennan, patients with myelomeningoceles undergoing surgery should undergo special precautions to ensure a latex-free environment. It is thought that patients develop these allergies due to repeated exposure to latex which is derived from the rubber tree. The allergic or hypersensitivity response is IgE mediated (answer 1).

REFERENCES:

1. Drennan JC: Current concepts in myelomeningocoele. Instr Course Lect 1999;48:543-550 PMID:10098082 (Link to Abstract)

2. Herring JA: Disorders of the spinal cord, in Herring JA (ed): Tachdjian’s Pediatric Orthopaedics, ed 4. Philadelphia, PA, WB Saunders, 2008, pp 1405-1482

Question Authors:

Paul D. Kim MD, Eric Shirley MD,

Please Rate Educational Value!

3.0

Average 3.0 of 12 Ratings

Groups

ABOS II: Myelodysplasia (myelomeningocele, spinal bifida)

General - Oral Boards Review

7/29/2011

0 responses

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Evidence & References Show References

Level of Evidence 4 (Case Series)

Park KB, Park HW, Joo SY, Kim HW. Surgical treatment of calcaneal deformity in a select group of patients with myelomeningocele. J Bone Joint Surg Am. 2008 Oct;90(10):2149-59. PMID:18829913 (Link to Abstract)
Stevens PM, Belle RM. Screw epiphysiodesis for ankle valgus. J Pediatr Orthop. 1997 Jan-Feb;17(1):9-12. PMID:8989692 (Link to Abstract)

Textbooks

Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009
Orthopaedic Knowledge Update 10, John M Flyn. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2011
Hoppenfeld SP. Surgical Exposures in Orthopaedics: The Anatomic Approach. Lipponcott, Williams, and Wilkins, Philadelphia, PA, Copyright 2009
Orthopaedic In-training Examination (OITE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Self-Assessment Examination (SAE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Herring JA, ed. Tachdjian's Pediatric Orthopaedics. 4th ed. Philadelphia, PA: WB Saunders; 2008:1431-1435.
Kasser JR. The foot. In: Morrissy RT, Weinstein SL, eds. Lovell & Winter's Pediatric Orthopaedics, 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005:1257-1328.

Undefined

Gabrieli AP, Vankoski SJ, Dias LS, Milani C, Lourenco A, Filho JL, Novak R. Gait analysis in low lumbar myelomeningocele patients with unilateral hip dislocation or subluxation. J Pediatr Orthop. 2003 May-Jun;23(3):330-4. PMID:12724595 (Link to Abstract)
Drennan JC: Current concepts in myelomeningocoele. Instr Course Lect 1999;48:543-550 PMID:10098082 (Link to Abstract)
Herring JA: Disorders of the spinal cord, in Herring JA (ed): Tachdjian’s Pediatric Orthopaedics, ed 4. Philadelphia, PA, WB Saunders, 2008, pp 1405-1482

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Myelodysplasia (myelomeningocele, spinal bifida)

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