of Frontal Trigger Sites

Fig. 9.1

Preoperative markings showing the position of the supraorbital nerve (SON) at the mid-pupillary line and the supratrochlear nerve (STN) at 1.5–1.7 cm from the midsagittal line. This is very helpful to orient the endoscope tip during the procedure and to avoid nerve injuries

../images/481431_1_En_9_Chapter/481431_1_En_9_Fig2_HTML.png — Fig. 9.2

Surgical devices for endoscopic myotomies. For this minimally invasive, single-entry technique, it is necessary to use a modified endoscope with fibre light transmission and a wire loop for electrocautery at the distal end

Local anaesthesia is administered in a subgaleal plane (Figs. 9.3 and 9.4) in order to dissect the muscular plane from the underlying periosteum improving the quality of endoscopic visualization.

../images/481431_1_En_9_Chapter/481431_1_En_9_Fig3_HTML.png — Fig. 9.3

We recommend performing first peripheral nerve block by injecting small amount of anaesthetic solution at the exit of SON and STN at about 5–6 mm above the medial aspect of the eyebrow

../images/481431_1_En_9_Chapter/481431_1_En_9_Fig4_HTML.png — Fig. 9.4

Infiltration with diluted anaesthetic solution (40-cc Carbocaine 1% + 40-cc NaCl 0.9% and 20-cc sodium bicarbonate) facilitates the dissection of the submuscular plane. We recommend placing the needle tip just above the periosteum of the frontal bone

In order to facilitate the dissection, we find useful to pierce eyebrows with 1-0 nylon suspension sutures (Figs. 9.5 and 9.6), held by surgeon’s assistant during the operation.

../images/481431_1_En_9_Chapter/481431_1_En_9_Fig5_HTML.png — Fig. 9.5

Once the area is infiltrated with local anaesthetic, the eyebrows are pierced with suspension sutures (1-0 nylon or silk) to further elevate the dissection plane during the procedure

../images/481431_1_En_9_Chapter/481431_1_En_9_Fig6_HTML.png — Fig. 9.6

The second operator pulls up the suspension sutures. This manoeuvre eases endoscope insertion and visualization of the operatory field. In our experience this technical tip did not cause any nerve injuries and it did not elicit post-operative pain

The surgeon performs a 1.5 cm skin incision about 2 cm behind the hairline (Fig. 9.7) to mask the resulting scar after the operation. Blunt dissection is then performed in the subgaleal plane (Fig. 9.8) with scissors from the skin incision to the superciliary area. This is a critical step of the procedure as an extensive dissection below the orbital septum might cause intra-orbital haemorrhage; therefore, we always recommend placing a finger above the eyebrow to secure the orbital area. Laterally, the medial border of the temporalis fossa represents the limit of the dissection plane.

../images/481431_1_En_9_Chapter/481431_1_En_9_Fig7_HTML.png — Fig. 9.7

Midline 1.5 cm long incision. Note the location just 1–2 cm behind the hairline in order to mask the resulting scar. The scalpel should be kept parallel to hair bulbs to prevent follicle injuries and avoid the risk of scarring alopecia at the entry site

../images/481431_1_En_9_Chapter/481431_1_En_9_Fig8_HTML.png — Fig. 9.8

Sovraperiosteal undermining

At this point, a modified surgical endoscope is introduced through the skin incision behind the hairline (Fig. 9.9) and the procedure continues under direct endoscopic visualization (Fig. 9.10). The endoscope is specifically designed to carry out the procedure with a single access: it is equipped with a straight Hopkins telescope with fibre light transmission and an elliptical-tipped wire loop for electrocautery at its distal end [19].

../images/481431_1_En_9_Chapter/481431_1_En_9_Fig9_HTML.png — Fig. 9.9

Endoscope insertion through the skin incision. Note the function of suspension sutures on the eyebrows

../images/481431_1_En_9_Chapter/481431_1_En_9_Fig10_HTML.png — Fig. 9.10

Operative setting

Once the subgaleal plane is clearly visualized in the monitor, the surgeon can proceed with selective myotomies of the corrugator and depressor supercilii muscles (Figs. 9.11, 9.12, 9.13, and 9.14). Special care is taken to preserve supraorbital and supratrochlear neurovascular bundles during the procedure.