2.1 Embryology (Pt 2 Disorders of the NS) Flashcards
Give 3 Neural tube defects (cranial & Spinal)
1) Anencephaly
2) Spina bifida
3) Hydrocephalus
Give 2 conditions caused by an abnormality of neural cell migration
How do they differ?
Hirschsprung’s disease:
Caused by failure of neural cells to migrate to one structure (the colon). Thus there will be an aganglionic megacolon.
Di George syndrome: failure to migrate to multiple structures
- thyroid deficiency
- immunodeficiency 2° to thymus defect
- cardiac defects
- abnormal facies
Give 3 maternal risk factors for developmental disorders
State one way in which risk may be reduced?
1) Diabetes
2) Malabsorption
3) Previous children or personal birth defects
Folic acid pre-conceptually in first trimester reduces incidence by 70%
Give an example of a maternal serum marker that may be useful in diagnosis of NS disorders
α-fetoprotein
Give 2 examples of failure to close the neural tube at the cephalic end
Give an example of failure to close the neural tube at the caudal end
State if these are open or closed defects
Cranial:
1) Anencephaly (open)
2) Arnold-Chiari deformity (open)
Caudal:
Spina bifida (open)
What is Anencephaly and what does it result it?
When does it usually occur?
What is the prognosis and are reflex actions present?
When the cephalic end of neural tube fails to close. Results in absence of a major portion of brain, skull, or scalp. The remaining brain tissue often exposed
Usually occurs between 23rd and 26th day
There is NO possibility of ever gaining consciousness.
Reflex actions: breathing responses to sound or touch occur.
State which condition is associated with each description
What is Hydrocephalus and is it aquired or congenital?
Give a condition it is commonly associated
How it is treated?
Give 2 potential causes of this (aquired and congenital)
Build-up of CSF, which puts pressure on the brain. Can be aquired or congenital
Common in spina bifida
Readily treatable by use of shunt
Causes:
1) blockage of ventricular system e.g due to a tumour or bleed
2) overproduction of CSF due to infection
Compare an open vs closed NT defect
Open defects such as anencephaly are usually fatal.
Closed defects, more usually in the more caudal parts of the spinal cord can cause a range of disability from minimal to severe.
What is an Arnold Chiari Deformity?
State 3 things that may occur as a result of this
When the Inferior cerebellum and medulla oblongata, protrude into the vertebral canal.
What may occur:
- Deformed Medulla and pons are
- Hydrocephalus.
- Malformation of lower cranial nerves
What is Myelochisis?
Failure of caudal neural folds to close.
Most severe of the defects.
What is Holoprosencephaly?
List 3 facial deformities it is often associated with
Failure of prosencephalon to divide into two cerebral hemispheres
Facial deformities:
1) Single orbit with two eyes, one eye or no eye
2) Proboscis-type nose located above eye
3) Cleft lip and palate
What is Spina Bifida?
Where does it most commonly occur?
Does it cause neurological deficits?
When part of the neural tube does not develop or close properly
It can occur anywhere along length but most commonly in the lumbosacral region
May be neurological deficits but NOT associated with mental retardation
What are the 3 types of Spina Bifida?
1) Spina bifida occulta
2) Meningocele
3) Meningomyelocele
2 and 3 are both types of Spina Bifida cystica
What is Spina Bifida Cystica?
List the 2 types
Will there be functional impairments?
Cyst at caudal end of spine. The spinal cord and/or meninges may be found in the cyst
2 types: Meningocele and Meningomyelocele
Spinal cord may be be impaired depeneding on the type
What is Spina Bifida Occulta?
Is spinal cord function impaired?
Failure of inferior neuropore to close
Vertebral arch(es) fails to develop in caudal area
Spinal cord function is usually normal
What is a Meningocele
Is spinal cord function impaired?
Form of spina bifida cystica
Only the meninges is in the sac
The spinal cord function may be impaired and thus the signs and symptoms vary with location and severity
What is a Meningomyelocele?
List 3 functional impairments
Form of spina bifida cystica
Both meninges and spinal cord in sac. There is always abnormal growth spinal cord
Functional impairments:
1) Lower extremity paralysis
2) Bowel and bladder dysfunction
3) Loss of sensation to lower limbs
What is Cerebral Palsy?
A motor function disorder caused by a permanent non-progressive brain lesion. (means damage doesn’t worsen over time)
Present at birth or shortly thereafter
Non-curable, life-long condition which may be congenital or acquired
State the 5 classifications, by number of limbs involved, in Cerebral Palsy
- Quadriplegia: all 4 limbs
- Diplegia: all 4 limbs, legs more severely affected than arms
- Hemiplegia: one side of body; arm is usually more involved than leg
- Triplegia: three limbs are involved, usually both arms and a leg
- Monoplegia- only one limb is affected, usually an arm
List the 4 movement signs of Cerebral Palsy and state what each is
1) Rigidity: ↑ tone throughout range of movement
2) Dyskinesia: Involuntary movements and changes in muscle tone. damage to basal ganglia and extrapyramidal pathways
3) Athetosis: Slow writhing movements of limbs
4) Chorea: Quick jerky movements of trunk and proximal limb muscles
List the 3 Degrees of severity of Cerebral Palsy
1) Mild – 20% of cases
2) Moderate – 50% 0f cases: require self help to be mobile
3) Severe – 30 % 0f cases: require help from carers to be mobile etc..
What determines the type of CP?
What areas may be involved?
Classification according to neurological deficit
The extent and area of damage determines altered individual movement pattern. Areas involved inclue:
▪ Pyramidal
▪ Extrapyramidal
▪ Mixed
List the 4 ways CP be classified according to the type of movement disorder
Explain what each type is
1) Spastic CP: too much muscle tone or tightness. Movements are stiff, especially in legs, arms, and/or back
2) Athetoid CP (dyskineticCP): affect movements of entire body. Involves slow,uncontrolled body movements and low muscle tone; hard for person to sit straight and walk
3) Ataxic CP- least common. Disturbed balance & depth perception.Poor muscle tone, staggering walk, unsteady hands. Damage is in cerebellum
4) Combined Types: both movement & number of limbs involved are combined
Give 4 broad causes of CP and 2 specific causes within each
1) Thrombophilias
- Thrombosis in placental circulation
- Coagulation abnormalities in mother and foetus eg. factor V mutation
2) An insult to the brain
- a fixed, static lesion in motor centres of brain
- Rh incompatibility, illness, O2 deprivation
3) Placental problems
- In utero infection e.g. rubella or CMV
- placenta infarction or thrombosis
4) Post natal
- Infection
- Head trauma
Give 4 problems associated with CP in children
- Mental retardation
- Epilepsy 20-50% > generalised
- Speech disorders 50% delay/ dysarthria
- Vision and hearing 25%
- Behaviour abnormalities
- Learning difficulties
What is the prognosis of a child with CP?
Children with only mild to moderate disability can expect a normal life expectancy, can lead a relatively independent life
Dependant upon social acceptance, support services
Give 4 Treatments and/or Management of CP symptoms
1) Medication for spasticity eg. Diazepam, anti-epileptics
2) Surgery eg. orthopaedic hip, ankle, tendon release
3) Nutritional support
4) Splints for the limbs or head
