Chapter 19 - Skull Base Surgery

Question 1

Approaches to anterior skull base

Answer 1

Subfrontal
Transfrontal osteoplastic flap
Frontotemporal - orbitozygomatic
Transmaxillary sinus
Transfacial
LeFort osteotomy
Facial translocation
Lateral infratemporal fossa
Fisch A(Anterior transposition of VII), B (sigmoid to petrous tip), C (includes cavernous sinus)
Incisions: Coronal, gullwing, Weber Ferg, lynch, lat rhin

Question 2

Approaches to Middle skull base

Answer 2

transoral, transeptal, palatal split, mandibular split, MCF subtemporal, all anterior approaches

Question 3

Approaches to posterior skull base

Answer 3

transoral, palatal split, translab, retrosigmoid, subocc

Question 4

CT scan cuts needed for skull base surgery

Answer 4

1mm (fine cut)

Question 5

Contraindications to endoscopic skull base surgery

Answer 5

involvement of orbit and facial skin

need to transverse major neurovascular structures

Question 6

Normal adult ICP

Answer 6

10-20 cm H2O

Question 7

Describe segments of ICA

Answer 7

Cervical
Petrous
Lacerum
Cavernous
Clinoid
Ophthalmic
Communicating
Please Let Children Consume Our Candy

Question 8

Relationship between crista ethmoidalis and sphenopalatine foramen

Answer 8

Crista is just anterior to SPF

Question 9

Vidian canal

Answer 9

inferolateral aspect of sphenoid sinus
vidian nerve (has PNS, SNS from greater and deep petrosal nerve)
br of ICA

Question 10

How to repair skull base defects

Answer 10

dura- temporalis fascia, fascia lata, allogenic
bony- cartilage, septum/turb/split calverial graft
Mucosa- free, fascia, fat, NSF

Question 11

Nasoseptal flap artery

Answer 11

posterior br sphenopalatine artery, wide arc of rot

Question 12

Sites to harvest free mucosal graft

Answer 12

inf/mid turbinate, septum, nasal floor

Question 13

Free flaps used for large SB deficits

Answer 13

ALT, RFFF, lat, rectus myocutaneous

Osseocutaneous: fibula, scapular

Question 14

Rate of skull base complications (surgical vs medical)

Answer 14

Surg 5-20%
Medical 8-40%
Endoscopic has fewer compl than open

Question 15

Medications that decrease CSF production

Answer 15

Acetazolamide, furosemide, digoxin

Question 16

Medication that decreases ICP

Answer 16

steroids

Question 17

How can excess CSF drainage lead to a CSF leak

Answer 17

generates negative intracranial pressure, creating ball valve –> pneumocephalus

Question 18

Sx of pneumocephalus

Answer 18

HA, dizzy, N/V, seizure, depressed neuro status, mass effect

Question 19

Tx of sx pneumocephalus

Answer 19

remove nasal packing, clamp lumbar drain
Emergent needle aspiration if severe sx
Revise reconstruction, may need air diversion (trach)

Question 20

Size of skull base defect that can be repaired with single layer

Answer 20

<1cm

Question 21

Perioperative ABx for skull base surgery

Answer 21

ESBS wound infection rate 2%

IV Ceph +/- Vanc or Augmentin