Cranio-spinal Anomalies

Question 1

What is Chiari type 1?

Answer 1

cerebellar tonsillar herniation (more than 5 mm is often quoted)

Question 3

No 1 risk with chiari surgery

Answer 3

respiratory depression and especially during night - sleep apne. Usually within 5 days. Close monitoring needed.

Question 3

How long are chiari 1 in 62% of surgeries?

Answer 3

C1.

Question 4

What is the surgical procedure for chiari 1?

Answer 4

Suboccipital craniotomy and C1-C3 laminectomy with dural patch grafting.

Question 5

Which is the chiari 1 group of patients with most favourable results from surgery?

Answer 5

Those with cerebellar syndrome. 87% improvement.

Question 6

What eye-symtom is characteristic of Chiari 1?

Answer 6

Downbeat nystagmus.

Question 7

How many pt w Chiari type 1 have occipital H/A as their only complaint?

Answer 7

10%

Question 8

What are the three clustering of symtoms for chiari 1?

Answer 8

1. Foramen magnus compression syndrome 22%-
   ataxia, corticospinal and sensory deficits, cerebellar signs and lower CN palsies. 37% H/A.
2. central cord syndrome (65%) - dissociated sensory loss (loss of pain and temp), occasionally segmental weakness and long tract signs (syringomyelic signs). 11% lower CN palsies.
3. Cerebellar symtoms (11%)- truncal and limb ataxia, nystagmus, dysarthria

Question 9

Does the tonsills normally aschend or deschend with age?

Answer 9

Aschend.

Question 10

What is the maximal (mm) herniation of tonsills to be called Chiari type 1?

Answer 10

29mm.

Question 11

what is the main benefit of decompressive surgery for chiari 1?

Answer 11

To arrest progression.

(Pain also usually respond well and 87% of pt w cerebellar syndrome improve)

Question 12

What is CHiari type 2 associated to?

Answer 12

myelomeningocele

Question 13

If a pt with MM also have chiari 2, they usually have also a third problem. Which?

Answer 13

hcph.

Question 14

What is the difference between a neonate and an older child developing symtoms of chiari 2?

Answer 14

neonate: Rapid neurological deterioration w profound brainstem dysfunction over a period of days.

Older children: More insidious symtoms and rarely as severe.

Question 15

Clinical signs of Chiari 2?

Answer 15

• swallowing difficulties69%
  -poor feeding, -cyanosis during feeding, -nasal regurgitation, -decreased gag reflex
• apneic spells 58% - impaired ventilatory drive
• stridor 56% (vocal cord paralysis)
• aspiration 40%
  *arm weakness
  *optisthonos
  *Downbeat nystagmus
  *weak/absent cry
  *facial weakness

Question 16

What do we think is the pathophysiology behind chiari 2?

Answer 16

Dysgenesis of the brainstem. NOT due to tethering of the cord as previously belived.

Question 17

Associated findings to chiari type 2

Answer 17

• hcph
• syringomyelia
• trapped 4th ventricle
• cerebellomedullary compression
• Agenesis/dysgenesis of corpus callosum.

Question 18

What is an entrapped 4th ventricle?

Question 19

Treatment recomendations greenberg p 299 for Chiari 2

Answer 19

• FUNCTIONING CSF shunt for hcph FIRST
• If dysphagia, stridor or apneic spells are present - posterior foss decompression is recommended BUT!! If stridor or abductor larygeal palsy is present preop, tracheostomy -usually temporary-is recomended.

Question 20

Absolute need postoperatively after posterior fossa decompression of chiari 2 ?

Answer 20

Close resoiratory monitoring for obstruction or ventilatory drive reduction.

Question 21

Expeditious brainstem decompression should be performed if:

Answer 21

• neurogenic dysphagia
  *stridor
  OR *apneic spells are present in a chiari 2 pt.

Question 22

So what is the main etiological difference between chiari 1 and chiari 2?

Answer 22

Chiari 1 has a wide range of etiologies and are often secondary to other scenarios.
Chiari 2 is a developmental malformation.