Scalp & Calvarial Reconstuction Flashcards
Describe the vascular supply to the scalp
- Superficial temporal artery
- Occipital artery
- Supratrochlear
- Supraorbital
- Posterior auricular
Describe the anatomy of the STA
- terminal branch of ECA
- supplies largest territory on lateral scalp
- becomes subcutaneous above tragus
- travels within the TPF
- divides into anterior and posterior branch 2cm above arch
Describe anatomy of occipital artery
- branch of ECA
- enters scalp 2cm from midline at superior nuchal line (occipital protruberance)
- divides into medial and 2 lateral
Describe anatomy of STA and SOA
- both branches of ICA, ophthalmic
- STA located inline with medial canthus
- SOA located inline with medial limbus
- SOA exits SOforamen
- both travels superficial to frontalis muscle
Describe anatomy of scalp and temporal region
Skin
Subcutaneous layer - cnotains vessels just above galea, nerves, lymphatic
Aponeurosis - Galea-frontalis-occipitalis-TPF
Loose areolar layer - contains emissary veins connecting to intracranial venous sinuses = becomes parotidomasseteric fascia
Pericranium - derives blood supply from middle meningeal and intracranial vessels = becomes deep temporal fascia
Describe the sensory innervation of the scalp
All 3 branches of trigeminal, cervical spine and plexus
1- V1 (Supraorbital) - deep branch pierces pericranium and travels laterally until 1cm medial to STline, it pierces galea and supply frontoparietal scalp
- superficial branch pierces frontalis and supplies anterior forehead/hairline
2- V2 (Zygomaticotemporal) - temporal region
3- V3 (ATN) - temporal region
4- Greater and lesser occipital n - posterior scalp
5- Greater auricular n - posterior ear/lobule
Describe the cours eof the frontal branch
- at level of Zarch, CN branch courses in loose areolar plane=parotidomasseteric fascia
- continues to travel superficial and will be just below TPF/SMAS at 2cm above the arch
- approaches frontalis and innervates from beneath muscle
Describe anatomic layers of calvarium
- Outer table
- Diploe
- Inner table
- Epidural space
- dura mater
- Subdural space
Note: Parietal and occipital bone is thickest, temporla thinnest
How do you classify scalp defects?
- Congenital vs Acquired
- Partial vs Full thickness
- Size (subtotal vs total)
What is your DDX for a scalp defect?
Congenital
- Cutis Aplasia (absence of skin)
- Ectodermal Dysplasia (absence of hair/nail/teeth)
- Conjoined twins
Acquired
- Trauma
- Infection
- Burn
- Iatrogenic (Post-op post RTX)
- Androgenic alopecia
- Post skin cancer resection
Describe your goals of scalp reconstruction
- debridement
- maintain hairline
- reconstruct like w like ie. hairbearing tissue
- stable durable coverage of calvarium
Describe management of scalp defect according to size
<3cm : 1’ closure (with galea scoring as needed)
3-6cm : local flap (rotation, advancement, pin-wheel, 3rhomboid, bilobed, pinwheel, tissue expansion
6-10cm: large rotation flap, bucket handle, Orticochea 3flap, tissue expansion, subtotal scalp flap
>10cm : pericranial flap +STSG, free flap
Describe your management plan according to partial vs full thickness defect
PARTIAL
- STSG and plan 2’ recon if hair missing
FULL THICKNESS
- Outer table removal and STSG
- Pericranial flap + STSG - flap based on named art
- Local flaps with galeal scoring
- pinwheel, 3adj. rhomboid, rotation (<6cm)
- Orticochea, bucket handle (6-10)
- Subtotal scalp flap rotation and graft donor (>10cm)
- Tissue Expansion then local flap
- Distant pedicled flap
- Microvascular flap
Describe the orticochea flap
Used for occipital defect
3 flaps are raised in subgaleal plane and scored
1 large + 2 smaller, where width of 2smaller is 1/2 that of 1’ defect
If defect lateral to midline, larger flap is based contralaterally
Not for vertex defects
Name distant pedicled flaps for scalp defect recon
- pectoralis major (mastoid region defect)
- trapezius (occipital region defect)
- lat dorsi (temporal/periorbital
Name free flaps for scalp recon
- Lat dorsi (for total scalp coverage)
- Gracilis (for partial)
- RFFF, ALT, Scapular
Indications for free flap for scalp recon
- ORN, post-op radiation planned
- large malignancies
- infection, osteomyelitis
Describe principles of using tissue exmpanders for scalp recon
- subgaleal placement
- Incision placed away from defect and from future flap
- flap length => 2x height
- 2.5xSA of defect => base SA of expander
- overexpand by 30-50%
What are the subunits of the forehead
Central
Temporal
brow
Describe your reconstructive ladder for forehead defect
- 1’ closure
- 2’ intention
- STSG + crane principle
- Local flaps (defect <1/3 of forehead) - incision along hairline
- central - advancement
- lateral
- Rotation (worthen)
- Rotation advancement (need backcut, along hairline)
- Rhomboid
- TIssue Expansion (defect >1/3 of forehead)
- Free flap (defect>1/2 of forehead)
- Integra and stsg (>1/2 of forehead)
Describe the Juri flap
- For anterior hairline defects
- based on parietal (posterior branch) of STA
- temporoparietal region flap - needs delay procedure to reduce risk of tip ncerosis and maintain length on narrow pedicle
How do you classify cranium defects?
By location (prehairline, posthairline, supraorbital brow)
By defect composition (FT, bone only)
WHat are surgical pricniples for cranioplasty
- adequate debridement
- water tight dural repair
- obliteration of dead space
- tension free closure of vascularized tissue
- preserve hair bearing tissue
- stable soft tissue coverage
What are options for calvarial reconstruction
- Autogenous material
- Split calvarium
- Split rib
- Alloplastic material
- Titanium
- PMMA (methyl methacrylate)
- PEEK (polyetherether ketone)
- Hydroxyapatite cement
- MEDPOR (porous polyethylene)
Describe the adv and disadv of titanium material for cranioplasty
*need 1cm overlap on edges beyond defect for fixation
ADVANTAGE
- inert
- CT less artifact, MRI ok
- no FB reaction
- can integrate with bone
DISADVANTAGE
- higher infx rate compared to autologus recon
- conducts heat/cold
Describe the adv and disadv of PMMA material for cranioplasty
PMMA - methylmethacrylate, can be porous
ADVANTAGE
- customized
- radiolucent
- no heat conduction
DISADVANTAGE
- exothermic rxn - can cause heat injury
- risk of infx
Describe the adv and disadv of PEEK material for cranioplasty
Polyether ether ketone
ADVANTAGE
- customized
- radiolucent
DISADVANTAGE
- not pliable - palpable edges
- non porous
Describe the adv and disadv of MEDPOR material for cranioplasty
Porous polyethylene
ADVANTAGE
- pliable
- customized
DISADVANTAGE
- susceptible to infx due to porosity
Describe the adv and disadv of hydroxyapetite material for cranioplasty
HExagonal form of CaPO4 - can cover titanium mesh????
ADVATNGES
- contours, resorbable??
DISADVANTAGES
- brittle
What are complications of cranioplasty?
Flap loss
CSF leak
Wound infection/abscess
Meningitis/encaphalitis
List the ways to identify the main trunk of facial nerve in total parotidectomy?
1- tympanomasoid suture: points to the stylomastoid foramen = exit point of the main trunk of the facial nerve. Main trunk is founfd 8mm below TM suture exiting styloid foramen
2- Trace nerve branches distal to proximal
3- Tragal pointer: 1cm inferior, anterior and deep to tragal pointer, finds “pes anserinus”
4- posterior belly of digastric: trunk lies 1cm deep to the insertion point og posterior belly of digastric
