Craniofacial Muscles

16 Spastic Facial Muscle Disorders
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16.8.4.1 Myectomy
(a) Surgical Myectomy : Surgical myectomy can be divided into limited and
extended myectomy depending on the extent of muscle removal. To determine
which surgical method should be used, the strength of the orbicularis oculi
muscle should be objectively tested 2 weeks after BoNT injection. In patients
with a partial response to BoNT, limited surgical myectomy can be considered,
whereas in patients with no response to BoNT, extended myectomy is more
likely to be bene fi cial. Up to 75% of patients obtain signi fi cant subjective and
objective relief for at least 12 months.
(b) Limited Myectomy : Limited myectomy includes the pretarsal, preseptal, and
orbital portions of orbicularis oculi muscle.
(c) Extended Myectomy : In extended myectomy, there is surgical extirpation of all
the eyelid protractors, including the procerus and corrugators muscles as well
as orbicularis oculi muscle.
Myectomy can be performed through a lid crease incision, suprabrow incision, coronal
incision, or a combination. Mid-forehead or hairline incisions can be considered
in patients with brow ptosis. In most cases, the procedure can be approached
with a lid crease incision, and dermatochalasis and blepharoptosis should be corrected
simultaneously if necessary. Limited myectomy should be performed by
resecting the orbicularis muscle in three en bloc sections. First, the pretarsal orbicularis
between the eyelid crease incision and a position 2.5 mm superior to the lashes
is dissected away. At least 1–2 mm of muscle strip from the eyelid margin should be
left for to allow for normal blinking. Second, the preseptal and orbital orbicularis
muscle from the superior edge of the incision to the inferior edge of the eyebrow is
dissected away. Finally, the orbicularis muscle over the temporal raphe is resected.
For extended myectomy, visualization of the corrugators and lateral procerus can
be enhanced by a suprabrow incision but good exposure of these structures can often
be obtained through the eyelid crease incision without making a suprabrow scar.
Complications of orbicularis myectomy surgery
(a) Button - hole skin defect : During resection of the muscles, the skin over the muscles
can be damaged.
(b) Orbital hemorrhage : This can occur from incomplete hemostasis before wound
closure.
(c) Skin necrosis : Eyelid skin or scalp fl ap necrosis can develop if the subdermal
plexus underneath the dermis is signi fi cantly damaged.
(d) Inclusion cyst formation : In closing the upper lid crease incision, it is important
to evert the thin wound edges, as there is a tendency for the edges of the thin
skin fl aps to roll under and cause inclusion cyst formation.
(e) Alopecia : A thin band of muscle should be left beneath the eyebrow to prevent
alopecia.
(f) Multiple eyelid creases : Adhesion between the dermis and levator palpebrae
superioris muscle or aponeurosis may cause multiple eyelid creases. The orbital