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Fifth stage
Surgery
Lec-1
د
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ياسر
طاقة
1/1/2014
Developmental (Congenital) Abnormalities of the Nervous System
These include:
A. Arachnoid Cysts
B. Encephaloceles
C. Craniosynostosis
D. Chiari malformation
E. Spinal Dysraphism
A. Arachnoid Cysts:
These are fluid filled intracranial mass lesions formed by splitting of the
arachnoid membrane.
The sites of Arachnoid Cysts:
a. Around one-half are located in the Sylvian fissure.
b. Cerebellopontine angle.
c. Suprasellar region.
d. Posterior fossa regions.
Presentations:
a. They often present in paediatric age group.
b. Some remain asymptomatic.
c. Others enlarge in size causing a mass effect.
d. Others may present with haemorrhage.
Investigations:
a. CT Brain
b. MRI Brain
Treatment:
a. Conservative: by observation and follow up.
b. Surgery: reserved only for symptomatic cases.
c. Surgical options include:
1. Endoscopy and fenestration into a cistern or ventricle.
2. Shunting: e.g. cystoperitoneal shunt.
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B. Encephaloceles:
These are developmental herniation of cerebral tissue through a cranial
defect.
They occur with a frequency of approximately 1-4 in 1000 births.
Sites: they may be:
a. Occipital
b. Nasofrontal
c. Frontoethmoidal
d. Basal.
Treatment: Surgical repair in order to:
1. Prevent infection.
2. Reconstruct the skull.
C. Craniosynostosis:
These are premature fusion of the cranial sutures.
They may affect single or multiple sutures.
Premature fusion leads to restricted growth of the head resulting in
presentation with an abnormal head shape.
Types of Craniosynostosis:
a. Sagittal synostosis causes a narrow boat shaped head with frontal and
occipital bossing (Scaphocephaly).
b. Bicoronal synostosis causes a shortened forehead (Brachycephaly).
c. Metopic synostosis causes Trigonocephaly.
Diagnosis by CT brain with bone window.
Surgical Treatment aimed at:
1. Correction of deformity.
2. Prevent the development of raised intracranial pressure.
D. Chiari malformation: (called also Arnold-Chiari Malformations):
Herniation of posterior fossa contents (e.g. cerebellar tonsils) through the
foramen magnum.
Normally up to 5mm of tonsillar descent through the foramen magnum.
Chiari I: >5 mm of tonsillar descent.
Chiari II: descent of the tonsils and cerebellar vermis.
Chiari I Malformation present in young adults with headache, exacerbated
by coughing and straining.
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Chiari II malformation present in infancy with signs of brainstem
compression such as poor feeding, stridor and apnoeic spells.
Treatment of Chiari malformation include:
1. Treatment of associated Hydrocephalus, and then
2. Foramen magnum decompression.
E.
Spinal Dysraphism (SPINA BIFIDA )
Definition:
This is the most common developmental anomaly affecting the spinal column, and it
means failure of the neural tube to close fully, so there is split or open spine.
Types of spina bifida:
1. Spina bifida Occulta:
The posterior vertebral arch has a defect within it, but there is no herniation of the neural
tube.
This defect is found in 10% of the population.
On the skin over the defect various skin changes may be seen, e.g. hairy patch, an area of
pigmentation, a fatty lump or a dermal sinus.
2. Spina bifida Cystica:
In this situation there is skin covering the defect making a cyst like.
If this cyst contains CSF only it is called MENINGOCELE.
If there is neural tissue within the sac, it is called MYELOMENINGOCELE.
3. Spina bifida Aperta:
The neural tube is open with no skin coverage, through a defect in the posterior vertebral
arch.
CSF leakage usually occurs so there is a high risk of meningitis.
Aetiology:
90% of cases occur sporadically.
Hereditary factors: children of parents with spina bifida have a 5% risk of having the
condition.
Dietary factors: folic acid administration during pregnancy may lower its incidence;
folate deficiency may be a cause.
Some anticonvulsants medication may have a rule in their development.
Clinical Features:
a. Antenatal screening: by using:
Detection of alpha-fetoprotein in blood or in amniotic fluid obtained by amniocentesis.
The use of ultrasound.
Both tests allow the detection of such defects in over 80% of embryos with open neural
tube.
b. Post-delivery: General features include:
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1. The incidence is ranging from 1 to 8 per 1000 of the population.
2. Most problems of development tend to occur in the lumbosacral area and are
associated with changes in bladder and bowel functions.
3. The higher the lesion the more sever the defect tend to be, and the worse the
neurological condition.
4. If the lesion is open then there is associated risk of meningitis.
5. Other associated disorders include Arnold-Chiari malformations type II, and in up to
80% hydrocephalus.
c. Spina bifida occulta:
1. Usually asymptomatic. Accidental finding in X-rays.
2. Lipoma, skin dimple or a tuft of hair over the bifid spine.
3. Rarely urinary incontinence starting at adolescence.
d. Meningocele:
1. No neurological manifestations.
2. Cystic translucent swelling with an expansible impulse on coughing.
3. The swelling is compressible.
e. Myelomeningocele:
1. Paraplegia, wasting, or contractures, with sensory loss.
2. Trophic disturbances are marked, especially perforating ulcers of foot.
3. Other congenital anomalies associated, mainly hydrocephalus.
Investigations:
1. Head circumference measurement to check for an associated hydrocephalus.
2. Plain radiograph of the spine.
3. Ultrasound of the brain to exclude hydrocephalus.
4. CT and/or MRI brain to rule out hydrocephalus.
Treatment:
Spina bifida occulta requires no treatment in the majority of cases, but may require
surgery at a later stage if progressive neurological signs develop.
In the other forms of open spina bifida surgery should be performed as early as
possible, and include:
1. Closure of the defect as early as possible to avoid meningitis.
2. The hydrocephalus needs immediate shunting even prior to closure of the defect of
spina bifida.