Dermatologic Surgery


Figure 8-1 Trigeminal (cranial nerve V) and cervical plexus cutaneous sensory nerves. The concha and external auditory canal are variably innervated by branches of the vagus, glossopharyngeal, and facial nerves. (From Bolognia JL, Jorizzo JL, Rapini RP. Dermatology, 3rd Ed. Elsevier. 2012)


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Figure 8-2 Sensory innervation of the palmar and dorsal surface of the right hand. (From Bolognia JL, Jorizzo JL, Rapini RP. Dermatology, 3rd Ed. Elsevier. 2012)

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Figure 8-3 Sensory innervation of the dorsal and plantar surface of the right foot. (From Bolognia JL, Jorizzo JL, Rapini RP. Dermatology, 3rd Ed. Elsevier. 2012)

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Figure 8-4 Sensory innervation of the external ear. (A) Anterolateral view. (B) Posterior view. (From Bolognia JL, Jorizzo JL, Rapini RP. Dermatology, 3rd Ed. Elsevier. 2012)

Motor innervation (Tables 8-3, 8-4 and Fig. 8-5)


Muscles of facial expression are innervated by CN VII (facial nerve); facial muscles receive motor innervation from their underside


Boards Factoid: as a minor function, CN VII also provides sensory input for anterior tongue (via chorda tympani branch) and a small amount of the external auditory meatus


Facial nerve emerges from the stylomastoid foramen; the nerve travels within the parotid gland and then splits into 5 branches: temporal, zygomatic, buccal, mandibular, and cervical branches (“To Zanzibar By Motor Car”)



Table 8-3


Motor Innervation of the Head and Neck


































Facial Nerve (CN VII) Branch Muscles Innervated and Normal Function Nerve Injury-Related Findings Other Comments
Temporal

Frontalis (eyebrow elevation)


Corrugator supercilii (pulls eyebrows inferomedially)


Upper portion of orbicularis occuli (tight closure of eyelids, blinking)

Inability to elevate eyebrows ➔ eyebrow ptosis

Targets for Botox:


Frontalis (horizontal forehead wrinkles)


Orbicularis (“crow’s feet”)


Corrugator supercilii (vertical glabellar lines, scowling appearance)

Zygomatic

Orbicularis occuli (lower portion)


Nasalis, alar portion (flares nostrils)


Procerus (foreshortening of nose, “horizontal glabellar lines”)


Upper lip muscle(s):


Zygomaticus major (mouth angle retractor/elevator, main muscle responsible for smiling)

Inability to tightly shut eyes (+/− lower lid ectropion), flare nostrils, and elevate upper lip

Targets for Botox:


Procerus (“horizontal glabellar lines”)


Nasalis, alar portion (flared nostrils)

Buccal

Buccinator (important muscle of mastication, works with orbicularis oris to keep cheeks pressed tightly against teeth ➔ prevents food accumulation; also allows for high-pressure blowing)


Depressor septi nasi (pulls columella toward lip)


Nasalis, transverse portion (“bunny lines”)


Upper lip muscles:


Orbicularis oris (pursing/puckering of lips, apposition of corners of mouth, pulls the lips tight up against teeth, and is required for clear speech)


Zygomaticus major and minor (mouth angle retractors/elevators, main muscles responsible for smiling!)


Risorius (mouth angle retractor/elevator, a lesser role in smiling)


Levator anguli oris (mouth angle retractor/elevator)


Levator labii superioris (elevates and everts upper lip, responsible for “gummy smile”)


Levator labii superioris alaque nasi (flares nostril and elevates upper lip)


Lower lip muscle(s):


Orbicularis oris


Food accumulation between cheek and teeth


Uneven facial expression at rest and with smiling (vs only upon smiling with marginal mandibular)


Inability to pucker/purse lips


Drooling as a result of ↓lip sealing ability


Speech is muffled, cannot enunciate letters M, V, F, P, and O


↓ability to wrinkle nose (↓bunny lines)


Damage to the buccal branch of CN VII is the most likely to cause eating problems (food accumulation + drooling) and muffled speech


Targets for Botox:


Levator labii superioris (“gummy smile”)


Nasalis, transverse portion (“bunny lines”)

Marginal mandibular

Lower lip muscles:


Orbicularis oris


Depressor anguli oris (lip depressor/retractor)


Depressor labii inferioris (lip depressor/retractor)


Mentalis (lower lip protrusion, chin elevator)


Platysma, upper portion (intercalates with lip depressors/retractors)


Face appears normal at rest but asymmetric when smiling


Drooling


Inability to evert lower lip

Marginal mandibular is at highest risk of causing permanent motor deficits because has only 1–2 rami (in contrast to multiple rami for zygomatic and buccal branches) and is covered by thin skin and thin platysma
Cervical Platysma (depresses lower jaw, tenses neck skin) ↓ability to depress lower jaw to express melancholy (“grimacing”) Botox can be used to target platysma (“platysmal bands”)

(Adapted From Bolognia JL, Jorizzo JL, Rapini RP. Dermatology, 3rd Ed. Elsevier. 2012)



Table 8-4


Cutaneous Danger Zones
























































Target Structure Danger Zone Associated Adverse Event Other Comments
Vascular occlusion from filler/steroid injections
Labial/angular artery Near base of ala Skin necrosis Rx: nitroglycerin paste, LMWH, and hyaluronidase (if HA filler)
Supratrochlear artery Glabellar region Skin necrosis, blindness Same as above
Motor nerve injury
Temporal nerve Most susceptible to injury as it crosses over the zygomatic arch Unilateral frontalis paralysis, eyelid ptosis Temporal nerve runs a diagonal course from 0.5 cm below the tragus to 1.5 cm above the lateral brow; nerve is superficially located within the facia as it crosses the zygomatic arch
Zygomatic nerve (less common) Malar cheek Inability to completely close eyes ➔ corneal desiccation Main trunks of zygomatic and buccal branches of facial nerve lie fairly deep ➔ less commonly injured than temportal and marginal mandibular
Marginal mandibular nerve Most susceptible 2–3 cm inferolateral to oral commissure, as it passes over the mandible Facial asymmetry upon smiling (normal at rest), and inability to protrude lower lip, drooling
Spinal accessory nerve (cranial nerve XI) Most susceptible to injury at Erb’s point = site where cervical plexus emerges; located along posterior border of SCM) Winged scapula, inability to abduct arm, and shoulder pain

Erb’s point localization: 6 cm inferior to the midpoint of an imaginary line drawn between the mastoid process and angle of jaw


Great auricular and lesser occipital nerves also arise from Erb’s point

Ulnar nerve Susceptible to injury around medial epicondyle of humerus “Claw-hand” deformity; weakness in wrist flexion, loss of flexion of fourth and fifth digits, and loss of sensation in ulnar distribution
Other
Parotid duct A line drawn from tragus to mid portion of the upper lip approximates its course; duct courses over masseter, pierces buccinator, and drains into the mouth at second upper molar Parotid duct injury ➔ sialocele (distinguished from a seroma by ↑↑amylase levels) Rx: repair via microsurgery

(Modified from Robinson et al. Surgery of the Skin, 3rd Ed. Elsevier. 2014)






8.2 Surgical instruments and needles



Scalpel handles


Bard-Parker standard handle (most common): flat; holds common blades such as the #15, #11, and #10


Beaver handle: round or hexagonal; holds smaller, sharper blades; useful for confined spaces or delicate tissue


Scissors


Basics


Short-handled scissors useful for delicate work


Long-handled scissors extend the surgeons reach and are useful for undermining


Curved blades useful for undermining cysts


Straight blades useful for trimming tissue and cutting sutures


Serrated blades grab tissue better


Sharp-tipped scissors puncture tissue easily and are best for dissection


Blunt-tipped scissors are best for delicate undermining


Scissor types


Iris scissors: sharp-tipped and short-handled; blades may be straight or curved; best for sharp dissection


Gradle scissors: similar to iris but blades curved and tapered to a fine point at tip; best for dissection of delicate tissue such as periorbital skin


Westcott scissors: spring-loaded instrument similar in appearance to Castro-Viejo; good for delicate eyelid dissection


Mayo scissors: characterized by its ~1 : 1 handle-to-blade ratio; primary purpose is coarse dissection


Metzenbaum scissor: long handles with blunt tips ➔ useful for blunt dissection in areas that require long reach


Supercut scissors: one blade has a razor edge; “supercut” blades are available on most scissor types listed above and often are denoted with black handles


Needle drivers


Basics


Smaller needle drivers with smooth jaws


Ideal for small, delicate needles


Advantages: smooth jaws have ↓risk of tearing small sutures (6-0 and smaller) and are less damaging to fine needles (P-3 and smaller)


Disadvantages: needles not grasped as tightly as with serrated needle drivers ➔ ↑needle twisting


Caution: larger needles will ruin small needle drivers


Larger, serrated jaws


Ideal for larger needles and work on trunk


Advantages: serrated jaws hold needles more securely (prevents twisting)


Disadvantage: damages delicate needles, shreds small sutures


Forceps


Basics


Serrated forceps: easier to grab needle, but results in ↑tissue crush injury


Toothed forceps: harder to grasp needle, but handles tissue gently (↓crush injury)


Combination forceps: have both teeth as well as serrated platforms ➔ allows for gentle tissue handling and easier grasping of needle


Types


Adson: relatively large forceps; useful for trunk and extremities


Bishop-Harmon forceps: small, fine-tipped instruments; most useful for delicate tissues such as the eyelids; always have 3 holes in handles to make them lighter in weight and easier to grip


Jeweler’s forceps: have very pointy ends; most useful for suture removal


Other instruments


Hemostats: used to grasp bleeding vessels before ligation


Skin hooks: available in many forms;


“Skin rake”: a skin hook with multiple hooks


Hooks are the least traumatic way to handle tissue (during electrosurgery and suturing), but are a sharps hazard


Periosteal elevator: used to remove periosteum or separate nail plate from nail bed


Chalazion clamp: useful for eyelid surgery or on the lip to stop bleeding needles


Surgical needles


Needle is composed of three parts:


Shank (swage): swaged portion that attaches to suture; weakest part of needle ➔ do NOT grasp here, it will bend or break the needle


Size of suture track is determined by shank size, not suture size


Body: middle part; strongest portion of needle ➔ always grasp here with needle driver; comes in various curvatures (most common is 3/8 circle)


Tip: sharp tip that may be round (tapered) or cutting; minimize grasping of tip ➔ contact w/ other instruments quickly dulls the tip


Three types of needle tips:


Round (tapered): only the tip pierces tissue (no sharp edges along arc of needle); is less likely than cutting needles to tear tissues; used for deep soft tissues (fat and muscle); difficult to pass through skin


Cutting: triangular-shaped needle point; preferred for skin because it easily passes through tissue; two types:


Conventional cutting: cutting surface is on inner portion of needle arc; ↑risk of sutures tearing through wound edge (this is because the cutting edge of needle faces toward the wound edge)


Reverse cutting: cutting surface is on outer portion of needle arc; ↓risk of sutures tearing through wound edge


For a more detailed discussion on surgical tools, please read: Weber LA. The surgical tray. Dermatol Clin. 1998 Jan;16(1):17–24. PMID: 9460575.



8.3 Suture techniques



Knots


Surgeon’s knot: most commonly used; essentially a square knot; first knot is double thrown to prevent slippage


Aberdeen hitch knot: used to tie the end of a running subcutaneous suture; is more compact, more secure, and uses less material than surgeon’s knot


Cuticular/epidermal suturing


Simple interrupted: used for wounds under moderate to high tension; directing the needle away from the wound results in ↑eversion and less frequent sunken scars


Simple running: used for wounds under minimal tension; faster to place than interrupted sutures; ↑risk of wound dehiscence


Running locked sutures: provides hemostasis, but has risk of strangulation


Vertical mattress: strongly everts (Vertical = eVert) wound edges, eliminates dead space, and decreases wound edge tension


Horizontal mattress: provides hemostasis (Horizontal = Hemostasis), eliminates dead space, and decreases wound edge tension; significant strangulation risk ➔ do not use in poorly vascularized areas


Pulley suture: modified vertical mattress suture; used for wounds under high tension


Running horizontal mattress: same benefits as simple horizontal mattress, but is faster, provides ↑eversion, and ↓strangulation risk; improved outcomes relative to simple running sutures, but takes longer


Tip stitch: best stitch for flap and M-plasty tips; is a half-buried horizontal mattress suture


High-low (step-off stitch): used to correct imprecise dermal/subcuticular suturing, where one side of the wound edge is higher than the other (“step-off”)


Subcuticular/dermal suturing


Simple buried suture: traditional intradermal suture; results in minimal wound eversion and high rate of spitting sutures


Buried vertical mattress: has one exit point in the subcutaneous plane; everts tissue more than a simple buried suture


Set-back suture (“buried butterfly”): suture entry and exit points are both underneath the undermined wound surface; everts tissue maximally; results in ↓spitting sutures and ↑cosmetic outcomes than the buried vertical mattress technique


Running subcuticular: running sutures in superficial dermis, instead of along epidermal surface; primary advantage = lack of track marks; however, ↑rate of spitting sutures; typically used in combination w/ buried vertical mattress sutures


Purse-string: traditionally used to ↓wound size and ↓healing time, relative to second intention; a recent RCT study did not demonstrate any difference in cosmetic appearance or scar size, but there was a trend toward faster healing time


Pulley suture: buried (subcuticular) pulley suture is essentially just a series of two or more simple buried subcuticular sutures; primary advantage = permits wound closure under high tension; disadvantage = tissue strangulation


“Figure of 8”: main suturing method used to tie off bleeding vessels


Suture removal recommendations (largely anecdotal): head/neck ≤7 days, extremities/torso = 10 to 14 days; the longer the sutures remain in place ➔ ↓likelihood of dehiscence, but ↑cutaneous track-marks


Suspension sutures: anchor the overlying tissue to periosteum ➔ removes tension from leading edge of flaps; prevents distortion of a free margin (especially eyelid), also prevents flap “tenting” across a concavity



8.4 Wound closure materials



Suture types and properties (Tables 8-5 through 8-9)



Table 8-5


Suture Types






































Term Definition Comments
Suture type (absorbable vs nonabsorbable)
Absorbable sutures

Lose most of their tensile strength within 60 days


Natural fibers: digested by proteolysis


Synthetic fibers: broken down by hydrolysis


Most commonly used as “deep” sutures


Rate of loss of tensile strength is different than rate of suture absorption!!!


Tensile strength is lost long before suture is fully absorbed


↑absorption rate in moist areas, febrile or protein-deficient patients

Nonabsorbable sutures Maintains tensile strength for >60 days Most commonly used as superficial/epidermal sutures
Suture material (absorbable; natural vs synthetic)
Natural Derived from natural proteins (gut, silk)

Degraded by proteolysis


↑inflammatory reaction and are rapidly degraded

Synthetic Synthetic copolymers

Degraded by hydrolysis


↓inflammatory reaction and are slowly degraded

Configuration (monofilament vs multifilament [braided])
Monofilament Comprised of a single filament

Advantages: slide easily through tissue (because of ↓COF), harbors less bacteria than braided sutures (because of ↓capillarity), and low-minimal inflammatory reaction


Disadvantages: ↓knot security (because of ↑memory and ↓COF); poor “ease of handling” (because of ↓pliability and ↑memory)

Multifilament (braided) Comprised of multiple small filaments braided together

Advantages: ↑ease of handling (because of ↑pliability and ↓memory), ↑strength, and ↑knot security (because of ↑COF and ↓memory)


Disadvantages: ↑bacterial infections (because of ↑capillarity), and ↑inflammatory reaction

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May 4, 2017 | Posted by in Dermatology | Comments Off on Dermatologic Surgery

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