2.1 Embryology (Pt 2 Disorders of the NS)

Question 1

Give 3 Neural tube defects (cranial & Spinal)

Answer 1

1) Anencephaly
2) Spina bifida
3) Hydrocephalus

Question 2

Give 2 conditions caused by an abnormality of neural cell migration

How do they differ?

Answer 2

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

Question 3

Give 3 maternal risk factors for developmental disorders

State one way in which risk may be reduced?

Answer 3

1) Diabetes
2) Malabsorption
3) Previous children or personal birth defects

Folic acid pre-conceptually in first trimester reduces incidence by 70%

Question 4

Give an example of a maternal serum marker that may be useful in diagnosis of NS disorders

Answer 4

α-fetoprotein

Question 5

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

Answer 5

Cranial:

1) Anencephaly (open)
2) Arnold-Chiari deformity (open)

Caudal:

Spina bifida (open)

Question 6

What is Anencephaly and what does it result it?

When does it usually occur?

What is the prognosis and are reflex actions present?

Answer 6

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.

Question 7

State which condition is associated with each description

Answer 7

Question 8

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)

Answer 8

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

Question 9

Compare an open vs closed NT defect

Answer 9

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.

Question 10

What is an Arnold Chiari Deformity?

State 3 things that may occur as a result of this

Answer 10

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

Question 11

What is Myelochisis?

Answer 11

Failure of caudal neural folds to close.

Most severe of the defects.

Question 12

What is Holoprosencephaly?

List 3 facial deformities it is often associated with

Answer 12

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

Question 13

What is Spina Bifida?

Where does it most commonly occur?

Does it cause neurological deficits?

Answer 13

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

Question 14

What are the 3 types of Spina Bifida?

Answer 14

1) Spina bifida occulta
2) Meningocele
3) Meningomyelocele

2 and 3 are both types of Spina Bifida cystica

Question 15

What is Spina Bifida Cystica?

List the 2 types

Will there be functional impairments?

Answer 15

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

Question 16

What is Spina Bifida Occulta?

Is spinal cord function impaired?

Answer 16

Failure of inferior neuropore to close

Vertebral arch(es) fails to develop in caudal area

Spinal cord function is usually normal

Question 17

What is a Meningocele

Is spinal cord function impaired?

Answer 17

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

Question 18

What is a Meningomyelocele?

List 3 functional impairments

Answer 18

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

Question 19

What is Cerebral Palsy?

Answer 19

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

Question 20

State the 5 classifications, by number of limbs involved, in Cerebral Palsy

Answer 20

1. Quadriplegia: all 4 limbs
2. Diplegia: all 4 limbs, legs more severely affected than arms
3. Hemiplegia: one side of body; arm is usually more involved than leg
4. Triplegia: three limbs are involved, usually both arms and a leg
5. Monoplegia- only one limb is affected, usually an arm

Question 21

List the 4 movement signs of Cerebral Palsy and state what each is

Answer 21

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

Question 22

List the 3 Degrees of severity of Cerebral Palsy

Answer 22

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..

Question 23

What determines the type of CP?

What areas may be involved?

Answer 23

Classification according to neurological deficit

The extent and area of damage determines altered individual movement pattern. Areas involved inclue:

▪ Pyramidal

▪ Extrapyramidal

▪ Mixed

Question 24

List the 4 ways CP be classified according to the type of movement disorder

Explain what each type is

Answer 24

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

Question 25

Give 4 broad causes of CP and 2 specific causes within each

Answer 25

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

Question 26

Give 4 problems associated with CP in children

Answer 26

1. Mental retardation
2. Epilepsy 20-50% > generalised
3. Speech disorders 50% delay/ dysarthria
4. Vision and hearing 25%
5. Behaviour abnormalities
6. Learning difficulties

Question 27

What is the prognosis of a child with CP?

Answer 27

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

Question 28

Give 4 Treatments and/or Management of CP symptoms

Answer 28

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