MYELOMENINGOCELE

1. MYELOMENINGOCELE
Dr. RUTAYISIRE François Xavier
PGY1
Common surgical conditions module
University of Rwanda
Lecturer: Prof. Ntaganda Edmond

2. Definition
Myelomeningocele:
A congenital defect in vertebral arches with cystic
dilatation of meninges and structural or functional
abnormality of spinal cord or cauda equina.
A type of Spina bifida

4. Epidemiology/genetics
• Incidence of myelomeningocele(MMC) is 1–2/1000 live births
(0.1–0.2%).
• Risk increases to 2–3% if there is one previous birth with MMC,
and 6–8% after two affected children.
• The risk is also increased in families where close relatives (e.g.
siblings) have given birth to MMC children, especially when on
the mother’s side of the family.
• Prenatal folate (in the form of folic acid) lowers the incidence of
MMC
• Incidence may increase in times of war, famine or economic
disasters, but it may be gradually declining overall.
• Additionally, higher incidence rates were reported in females,
increased maternal age, and lower socioeconomic status.
• Considering ethnicity, Latins were the most affected population in the
united states.

5. Etiology
• The etiology behind myelomeningocele is often multifactorial.
• Environmental, maternal, and genetic factors.
• Environmental factors: exposure to radiation, pesticides, organic solvents, and
teratogens.
• Maternal factors: irregular maternal nutrition, low folic acid supplementation,
caffeine and alcohol consumption, smoking, the use of anticonvulsants, in
addition to certain maternal illnesses such as diabetes, obesity, hyperthermia,
and anxiety.
• Genetic factors: However, most of the cases of myelomeningocele are sporadic in
origin and occur in a non-genetic pattern. Though, some genetic factors might
increase the risk of occurrence, for instance, the presence of chromosomal
anomalies of trisomy 18 or 13 and patients with an affected twin or first-degree
relative.

6. Embryology
• Spina bifida is caused by the failure
of the neural tube
to close during the first month of
embryonic development (often
before the mother knows she is
pregnant).
• Under normal circumstances, the
closure of the
neural tube occurs around the 23rd
(rostral closure)
and 27th (caudal closure) day after
fertilization.

7. Clinical features
• The presentation of a newborn in the postnatal period:
• Presence of a sac extending from the vertebral column, covered with
meninges, filled with cerebrospinal fluid and neural tissue.
• Signs of Neurogenic bladder, paraplegia, sphincter dysfunction, motor
and sensory impairments in which they all can deteriorate with age.
abnormal sexual development in adulthood.
• The clinical presentation is dependent on the site of the spinal lesion
at the vertebral column.
• The higher the level affected, the more deficits occur, and the worse
the prognosis of the patient.

8. T12 complete paralysis of all muscles in LL
L1 weak to moderate hip flexion, palpable contraction in sartorius
L2 strong hip flexion and moderate hip adduction
L3 normal hip adduction & almost normal knee extension
L4
normal hip adduction, knee extension & dorsiflexion/inversion of foot; some hip abduction in
flexion
L5
normal adduction, flexion & lateral rotation of hip; moderate abduction; normal knee extension,
moderate flexion; normal foot dorsiflexion; hip extension absent; • produces dorsiflexed foot
and
flexed thigh
S1
normal hip flexion & abduction/adduction, moderate extension and lateral rotation; strong knee
flexion & inversion/eversion of foot; moderate plantarflexion of foot; extension of all toes, but
flexion only of terminal phalanx of great toe; normal medial & lateral hip rotation; complete
paralysis of foot intrinsic (except abductor and flexor hallucis brevis); • produces clawing of toes
and flattening of sole of foot
S2
difficult to detect abnormality clinically; • with growth this produces clawing of the toes due to
weakness of intrinsic muscles of sole of foot (innervated by S3)
Findings in various levels of MMC lesion

9. Hydrocephalus in
myelomeningocele
• Hydrocephalus (HCP) develops in 65–85%
of patients with MMC, and 5–10% of MMC
patients have clinically overt HCP at birth.
• Over 80% of MMC patients who will develop
HCP do so before age 6 mos.
• Most MMC patients will have an associated
Chiari type 2 malformation.
• Closure of the MMC defect may convert a
latent HCP to active HCP by eliminating a
route of egress of CSF.
Latex allergy in
myelomeningocele
• Up to 73% of MMC patients are
allergic to proteins present in latex.
• The allergy is thought to arise from
early and frequent exposure to latex
products during medical care for these
patients, and there is a suggestion
that latex-free surgery on these
infants may reduce the risk of the
development of latex allergy

10. Diagnosis
• The diagnosis of myelomeningocele is possible in the first trimester of
pregnancy.
• Amniocentesis is helpful and usually favored for high-risk patients.
• Ultrasonography is non-invasive, safe, effective, and often used for
second-trimester anomaly scanning.
• The vertebra can be visualized by 12 weeks of gestation, and
defects in closure of the vertebral arches can be detected.
• Fetal karyotyping and magnetic resonance imaging (MRI) could also
be an option if the tests were not sufficient for the diagnosis.

11. Management
• Once the diagnosis has been made, early surgical
repair of the spinal lesion is essential in preventing
further deficits and neurological damage. Prenatal
surgery was proven to be more effective than postnatal
surgery in lowering the occurrence of future
complications.
• Experimental treatment for the defect is to perform
surgery in utero as early as 22 weeks of gestation. The
fetus is exposed by an incision into the uterus, the
defect is repaired, and the infant is placed back in the
uterus.

12. Assessment and management of lesion
● Measure size of defect
● Assess whether lesion is ruptured or unruptured
○ Ruptured: start antibiotics (discontinue 6 hrs after MMC closure, or
continue if shunt anticipated in next 5 or 6 days)
○ Unruptured: no antibiotics necessary
● Cover lesion with Vaseline gauses, then sponges soaked in lactated
ringers or normal saline (form a sterile gauze ring around the lesion if it is
cystic and protruding) to prevent desiccation
● Trendelenburg position, patient on stomach (keeps pressure off lesion)
● perform surgical closure within 36 hrs unless there is a contraindication to
surgery (simultaneous shunt is not usually done except if overt
hydrocephalus (HCP) at birth).

13. • Post-natal surgery:- Closure of the Myelomeningocele is performed
immediately afterbirth if external CSF leakage is present and typically
within the first 24-48 hours in the absence of CSF leakage.
Multidisciplinary interventions needed to prevent progressive deterioration
of multiple body systems
• Treatment team consists of pediatric specialists in
◦ Physical medicine and rehabilitation
◦ Neurosurgery
◦ Urology
◦ Orthopedics along with
◦ Pediatric nursing
◦ Physical therapy
◦ occupational and recreational therapy
◦ psychology and
◦ medical social work

14. Prevention
• Prevention of many NTDs is possible if women take folic acid
[400 pig/day] starting at least 1 month prior to conception and
then throughout their pregnancy. Such a protocol reduces the
occurrence of NTDs by as much as 50% to 70%.
• Because approximately 50% of all pregnancies are unplanned,
it is recommended that all women of childbearing age take a
multivitamin containing 400 ug of folic acid daily.
• Furthermore, women who have had a child with an NTD or who
have a family history of NTDs should take 400 pg of folic acid
daily and then 4,000 pg [4 mg] per day starting at least 1 month
before conception through the first 3 months of pregnancy.
• The birth prevalence of NTDs in the United States has
decreased by approximately 25% to 1/1,500 births because
fortification of flour with folic acid was instituted in 1998.

15. References
• Mark S. Greenberg, Handbook of Neurosurgery 9th edition
• Langman’s Medical Embryology 14th edition
• Alruwaili AA, M Das J. Myelomeningocele. [Updated 2021 Jul
25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls
Publishing; 2021 Jan-. Available from:
https://www.ncbi.nlm.nih.gov/books/NBK546696/

16. Thanks