Transcript Disorders of Neural Tube Closure

Disorders of Neural Tube
Closure
Jan M. Eckermann, MD, PGY-3
Department of Neurosurgery
Loma Linda University Medical Center
Review of Neuroembryology
• Dorsal induction
• Primary neurolation: 3-4 wks gestation
Brain and upper spine
• Secondary neurolation: 4-5 wks gestation
Distal spine
Neural groove
Neural tube
Whereyouat??
Disorders of neural tube closure
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Chiari I-IV
Encephaloceles
Anencephaly
Corpus Callosum Agenesis
Spinal Dysraphism (Spina bifida)
- Menigoceles
- Myelomeningoceles
Tethered chord
Chiari I
ANATOMY
• Peglike cerebellar tonsils displaced into
upper cervical canal ( >10mm)
• HCP 25%
• Syringomyelia 60%
• Skeletal anomalies 25%
Chiari I: displaced tonsils
Chiari I: syringomyelia
Chiari I: syringomyelia
Chiari I
Clinical
• Asympotmatic (30%)
• Headache
• Weakness
• Cerebellar signs
• Herniation >12mm invariably symptomatic
Chiari I
Treatment
• Observation if asymptomatic
• Surgery if symptomatic: p-fossa
decompression +- cervical laminectomy
Whereyouat??
Chiari II
Anatomy
• Calvarial defects “Lueckenschaedel”
• Small p-fossa
• Fenestrated falx
• HCP in 90%
• Myelomeningocele in 100%
• Syringohydromyelia in 50%-90%
Chiari II: Brain MRI
Chiari II: lueckenschaedel, falx
Chiari II
Clinical
• Dysphagia
• Apneic spells
• Stridor
• Aspiration
• Arm weakness
Chiari II
Treatment
• Shunt
• P-fossa decompression
• Repair of MM
Chiari III and IV
Chiari III
Most severe form. Chiari II + low occiptial or high
cervical encephalocele. Usually incompatible with
life
Chiar IV
Severe cerebellar hypoplasia or absence. No
herniation
Extremely rare
Whereyouat??
Enephaloceles
• Anatomy
• Failure of the anterior neural tube to close
due to genetic, infection, or toxic reasons.
• 1/1000
• Distorted parts of the (covered) brain
protruding extracalvarially
Encephalocele
Anatomy
Occipital 90%
Parietal 10%
Transsphenoidal
Frontoethmoidal
Nasal
Encephaloceles
• Parietal encephalocele
• Frontoethmoidal
encephalocele
Encephaloceles
• Clinical
Depends on involvement
• Treatment
Surgical excision of sac with water-tight
dural closure
Anencephaly
• 1/1000
• Anencephaly is a defect in the closure of
the neural tube during fetal development.
• Large defect of the calvarium, meninges,
and scalp.
• Incompatible with life.
Anencephaly
Corpus Callosum Agenesis
• Expansion of third ventricle
• May present with HCP, seizures
• May be incidental finding without any
clinical significance
Whereyouat??
Spinal Dysraphism (spina bifida)
• Spina bifida occulta: 20-30% in North
Americans, often incidental, cutaneous
manifestations
• Spina bifida aperta:
• Meningocele
• Myelomeningocele
Spinal Dysraphism
• Spina bifida occulta
Spinal Dysraphism
• Meningocele
Spinal Dysraphism
• Myelomeningocele
Meningocele
• 1-2/1000
• 1/3 have neurological deficits
• Surgical repair with water-tight dural
closure
Meningomyelocele
• 1-2/1000 live birth
• Failure of complete
•
closure of caudal
neural tube
85% occur in lumbar
region
Meningomyelocele
Meningomyelocele
Myelomeningocele
• Clinical
• Mild to complete LE paralysis
• Ruptured vs unruptured
• Urinary incontinence
• Skeletal abnormalities
Myelomeningocele
• Treatment
• If open, Gent and Naf IV
• Prone, bottom up
• Telfa with wet gauze over lesion
• Surgical closure within 36hrs
• Shunt if overt HCP
• Urologic and Orthopaedic consultation
Lipomyelomeningocele
• Present with back mass, bladder
problems, paralysis
• Cutaneous stigmata
• Symptoms are due to tethered cord and
cord compression from fatty mass
• Treatment is surgical decompression
Whereyouat??
Tethered Cord Syndrome
• Anatomy
• Low conus medullaris
• Short, thick filum terminale
• Intradural lipoma
Tethered Cord Syndrome
Tethered Cord Syndrome
• Clinical
• Cutaneous findings
• Gait difficulties
• Visible muscle atrophy
• LE sensory deficits
• Bladder dysfunction
• Scoliosis
Tethered Cord Syndrome
• Treatment
• Laminectomy with division of filum
terminale
• Removal of lipoma if present
• Followed with MRI
Thank you