Frontalis Muscle Advancement

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Article initiated by:

Anne Barmettler, MD

All contributors:

Moshe Isaac Weber, Anne Barmettler, MD, Michael T Yen, MD

Assigned editor:

Anne Barmettler, MD

Review:

Assigned status Up to Date

 by Anne Barmettler, MD on March 27, 2025.

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Surgical Therapy

Introduction:

Sagittal view of the upper lid and brow before and after FM advancement

Frontalis muscle (FM) advancement is a surgical technique used to correct severe blepharoptosis with poor or absent levator palpebrae function. In this procedure, a frontalis muscle flap is connected to the tarsus, enabling direct eyelid elevation by the frontalis.

History:

Frontalis muscle advancement was first described in 1901 by Fergus, who used a single incision hidden in the eyebrow to create a flap of occipitofrontalis muscle that was 2 cm wide and 5 cm long. However, this technique was not widely accepted. FM advancement was popularized in 1982 by Song, who described a dual-incision approach: an infra-brow incision for flap creation and an eyelid crease incision for tarsus exposure. An L-shaped FM flap was created using a 2.5 cm horizontal incision with a single 3-3.5 cm vertical incision placed medially. A lateral vertical incision was avoided as the FM innervation from the frontal branch of the facial nerve originates laterally.

In 1988, Zhou used a single eyelid crease incision and a rectangular FM flap, which became the standard for FM advancement surgeries. Zhou created this flap with two shorter parallel 1.5-2 cm vertical incisions made approximately 2 cm apart from each other.

Patient Selection

Surgical Planning:

FM advancement can be used to treat moderate to severe blepharoptosis with a levator function of less than 4-6 mm. It is effective for both congenital and acquired forms. For congenital ptosis with visual axis impairment, FM advancement should be performed as early as possible to avoid amblyopia. The early maturation of the FM allows for early correction, with cases reported as young as 15 months. However, surgery is often deferred until age three.

FM advancement can be useful for patients with previous failed ptosis surgery, such as levator resection or advancement, or frontalis slings, although natural anatomic planes may be obscured by scaring in these cases. FM advancement, with and without combined levator resection, has also been used to treat synkinetic ptosis (Marcus Gunn Jaw-winking).

FM advancement can be used with caution in patients at increased risk of exposure keratitis, such as those with Weak Bell’s phenomenon or poor tear production; purposeful undercorrection can be considered in these cases.

Anatomical Considerations:

Brow structures in relation to FM advancement flap

The FM primarily lifts the brow, which results in minor elevation of the eyelid. It originates in the galeal aponeurosis and inserts into the skin and subcutaneous tissue of the eyebrow. The FM is mobile on the underlying bone at the orbital rim and brow, but is adherent to the subcutaneous tissue. A portion of the FM fibers extend inferiorly and interdigitate into the orbicularis oculi, particularly at the lateral portion of the brow.

Neurovascular anatomy is particularly important as careful dissection is required to minimize risk of damage to the neighboring structures (see below). The FM receives its blood supply through the supraorbital branch of the ophthalmic artery, the supratrochlear artery, and the superficial temporal arteries. After exiting the supraorbital foramen, the supraorbital nerve branches ascend medially under the frontalis muscle. The supraorbital neurovascular bundle runs superiorly, beginning 22.5+/-4.1 mm from the midline at the superior orbital margin. It travels slightly laterally as it ascends, reaching 33.3+/-5.9 mm from the midline at the midpoint of the FM. The distance of the lowest branches of the frontal branch of the facial nerve to the supraorbital margin when entering the FM are 7.6±1.5 mm.

While the levator naturally pulls the eyelid with a superior and posterior force vector, the FM pulls directly superiorly. In FM advancement, this upward vector can lead to lid tenting or popping, as the lid is pulled upward and even off the eye in superior gaze, particularly in those with deep set eyes.

Unlike frontalis sling procedures, which connect the FM to the frontalis through use of fascia latta grafts or synthetic materials, FM advancement directly transfers the pulling power of the FM to the tarsus. This theoretically leads to greater improvement of ptosis in superior gaze with less lid lag in inferior gaze. Additionally, it has the advantages of avoiding autologous fascia latta acquisition, as well as eliminating the infection and migration risks of synthetic or donor slings.

Surgical Technique

Modified surgical steps of Zhou’s FM advancement technique:

Dissection path of FM advancement

The procedure is usually performed using local anesthesia for adults and general anesthesia for children. A skin incision is first made at the location of the desired future eyelid crease. This is then dissected to reveal the anterior surface of the tarsus.

Dissection continues superiorly in the sub-orbicularis plane, superficial to the OS, until the superior orbital rim is reached.  Dissection is then redirected anteriorly. From the posterior side of the FM, the FM-orbicularis connection is transected horizontally, granting access to the anterior side of the FM.

Dissection continues superiorly, to mobilize the FM through biplanar dissection of both the anterior and posterior of the FM. This is progressed 1-2 cm above the orbital rim. The transverse supraorbital vein and subcutaneous vascular plexus in this region create a risk for bleeding and may complicate this dissection.

Once the FM is mobilized, two parallel vertical incisions are made to create a rectangular FM flap. The incisions are made 1.5-2 cm in length and 1.5-2.5 cm apart in adults and 1-1.5 cm in length and 1-2 cm apart in children. Care should be taken to avoid the supraorbital neurovascular bundle which lies medially.

With the eye in primary gaze, the flap is connected to the tarsus with one to three partial thickness horizontal mattress sutures. The eyelid is raised to either the limbus or 3 mm above the pupil in bilateral cases or 1 mm above the non-ptotic lid in unilateral cases.

Excess flap is then resected, eyelid crease forming sutures are placed, and the skin is closed. Some surgeons place a Frost suture for corneal protection.

Postoperatively, 2-3 mm of lagophthalmos may be seen. This usually improves over the following months.

Surgical Variations:

There are many variations in surgical techniques for FM advancement. Vertical incision length ranges from 0.5-2 cm, while some variations forgo vertical incisions altogether. Some techniques use additional vertical incisions to split the flap into two or three parts for a more even distribution of force. Similarly, the width of the flap is often adjusted based on the size and age of the patient, although it is generally smaller than palpebral fissure width. While the plane of dissection is generally kept superficial to the orbital septum, techniques dissecting below the OS, or including the orbital septum in the flap are common.

A few surgical adjustments have been proposed to decrease lid tenting, popping, and lagophthalmos. Remirez describes dissecting the orbital septum from the orbital rim and passing the FM flap below the orbital septum, changing the direction of pull to mimic the superior and posterior vector of the levator. Medel recommends a similar concept, where the FM flap is passed through the levator aponeurosis. A combined FM and levator advancement has also been used, relying on increasing levator function to improve the force vector.

Outcomes

Outcomes are generally favorable. Rates of undercorrection and overcorrection typically range from 2.1-20% and 0.7-4.6%, respectively. Due to the superior vector of the FM, popping of the lid and crease obliteration can occur, particularly in superior gaze. Repurposing the FM can also lead to a loss of forehead wrinkles. Zhang found a 77.5% success rate for the conventional FM flap and a 90.0% success rate for a modified flap with no vertical incisions. The modified FM flap without vertical incisions had lower rates of hematoma formation, FM paralysis, frontal hypoesthesia, and exposure keratitis. While much of the literature surrounding FM advancement originally came from China, Taiwan, and Korea, the procedure’s successful outcomes led to increasing popularity in Europe and, then, the USA . Future research should investigate long-term outcomes of FM advancement beyond five years.

Complications

·        Hematoma formation

·        Eyelid lag

·        Lagophthalmos

·        Entropion

·        Supraorbital nerve injury

·        Transient hypoesthesia

·        Asymmetric eyelids

·        Asymmetric brow wrinkling

·        Under/over correction

·        Infection

·        Bleeding

·        Skin discoloration

·        Anesthesia risks