Neuroscience · Year 2 · from Neuroscience
Case 1: Neural Tube Defect - Myelomeningocele
Patient Presentation
Demographics: Newborn male, delivered at 38 weeks gestation
Chief Complaint: Prenatal diagnosis of spinal abnormality on routine ultrasound
History of Present Illness: A 28-year-old primigravida underwent routine prenatal screening at 18 weeks gestation. Ultrasound revealed a cystic lesion in the lumbar spine region with splaying of the posterior vertebral elements. Alpha-fetoprotein levels were elevated in both maternal serum and amniotic fluid. The mother reported irregular prenatal care and had not been taking folic acid supplementation prior to conception. Fetal MRI confirmed myelomeningocele at L4-L5 level. The infant was delivered via cesarean section to minimize trauma to the exposed neural tissue.
Physical Examination:
- Alert, appropriate cry and suck reflex
- Large open neural placode at the lower lumbar region measuring 4 cm x 5 cm with exposed neural tissue and leaking cerebrospinal fluid
- Flaccid paralysis of bilateral lower extremities
- Absent deep tendon reflexes in lower extremities
- No response to pinprick below the level of the umbilicus
- Urinary dribbling noted (neurogenic bladder)
- Head circumference at 95th percentile with bulging anterior fontanelle
Workup:
- Spinal ultrasound: Confirmed myelomeningocele at L4-L5
- Head ultrasound: Revealed hydrocephalus with dilated lateral and third ventricles; Chiari II malformation with hindbrain herniation
- MRI spine and brain: Confirmed lumbar myelomeningocele with associated tethered cord; Chiari II malformation with cerebellar tonsillar herniation through foramen magnum
Diagnosis: Lumbar myelomeningocele with Chiari II malformation and hydrocephalus
Treatment:
- Emergency surgical closure of the myelomeningocele within 24 hours of birth
- Ventriculoperitoneal shunt placement for hydrocephalus at 5 days of life
- Clean intermittent catheterization initiated for neurogenic bladder
- Physical therapy and orthopedic evaluation for lower extremity management
- Genetic counseling for family regarding recurrence risk (3-5% without folate, reduced to <1% with supplementation)
Clinical Pearl: Neural tube defects result from failure of neural tube closure during the fourth week of gestation. Folic acid supplementation (400 mcg daily) starting at least one month before conception reduces the risk by up to 70%. The level of the defect determines the extent of motor and sensory deficits below the lesion.