Abstract  Ptosis is a common feature of both benign essential blepharospasm and hemifacial spasm. Mechanisms include excessive protractor muscle tone, levator aponeurosis dehiscence, apraxia, or response to botulinum toxin therapy. Treatment modalities include botulinum toxin injections, surgical ptosis repair, and myectomy.

Benign Essential Blepharospasm

and Hemifacial Spasm

Etiology and Evaluation

Benign essential blepharospasm (BEB, Fig. 27.1) and hemifacial spasm (HFS, Fig. 27.2) share a common phenomenology with an overactive orbicularis oculi muscle and involuntary eyelid closure. The assessment of eyelid position is difficult in these patients, as the lid height is dynamic, and the lid height observed at any moment is related to a balance of retractor (levator) muscle and protractor (orbicularis and corrugator) muscles.

J.B. Holds (*)

Departments of Ophthalmology and Otolaryngology/ Head and Neck Surgery, Saint Louis University, Ophthalmic Plastic and Cosmetic Surgery, Inc., 12990 Manchester Road #102, St. Louis, Des Peres, MO, USA e-mail: jholds@sbcglobal.net

Ptosis is a common feature of both of these conditions. Excess orbicularis tone can completely overpower the levator muscle and close the eye (as in a wink). A variably ptotic eyelid is a common feature of BEB and HFS.

Ptosis can also result from the usual involutional mechanism. Involutional or aponeurotic ptosis commonly occurs with advancing age, but is also seen in a variety of other situations including after surgical or other trauma or with chronic rigid contact lens wear. It is hypothesized that the increased orbicularis muscle tone associated with BEB and HFS place increased stress on the levator aponeurosis and contribute to the development of ptosis by accelerating aponeurotic dehiscence.

In BEB, a form of dystonia, involuntary eyelid closure may occur due to apraxia of eyelid opening (Fig. 27.3). This is an additional movement disorder, commonly associated with BEB, characterized by an inability to voluntarily initiate eyelid opening. Patients with apraxia of eyelid opening may display an inability to voluntarily open the eyes while the BEB is inactive or relaxed.

A final mechanism of ptosis, which must be considered in these patients, is ptosis secondary to botulinum toxin injection. Botulinum therapy is considered in a majority of patients with BEB and HFS. Factors that predispose a patient to ptosis after botulinum therapy include high doses of toxin, deep injections, injection over the central eyelid, and preexisting ptosis. Botulinum therapy-associated ptosis typically develops within 1–2 weeks of treatment, and seldom lasts

more than a month. It is useful to evaluate patients with HFS and BEB 4–8 weeks after botulinum therapy. This aids in the assessment of the patients and their disease after botulinum therapy and before recurrent spasm and helps to guide further treatment.

Treatment

In treating ptosis associated with BEB and HFS, one must first attempt to determine the relative contribution of excess orbicularis muscle tone versus true baseline ptosis in the eyelid height. As BEB and HFS are generally intermittent, careful observation during the preoperative interview may allow the surgeon to determine true ptosis versus closure secondary to orbicularis muscle activity.

As both BEB and HFS are customarily treated with botulinum toxin, it is important to ascertain what is the patient’s predominant problem – ptosis (generally asymmetric and bilateral) or eyelid spasm. In patients whose eyelid spasm predominates, botulinum therapy is generally initiated first. It may be necessary to pass the patient through at least two cycles of botulinum therapy before considering ptosis surgery. If the ptosis is the predominant finding, it is reasonable to repair this before undertaking botulinum or other therapy.

If surgery is to be performed, it is helpful to schedule surgery in a window 4–8 weeks after botulinum therapy. This allows any preceding

botulinum therapy to settle in and resolve temporary ptosis which may be due to botulinum toxin. After 3 months, spasm is often returning, and intraand postoperative assessment of eyelid height may be a problem, if ptosis surgery is performed late in the treatment cycle.

Surgical repair is generally performed via a frontalis sling or external levator aponeurosis resection. External levator aponeurotic resection surgery is very adjustable. The external incision allows access to the orbicularis muscle, which is another object for treatment, via limited or radical myectomy surgery. In the setting of surgical myectomy, ptosis repair is virtually always bilateral. Even in surgical myectomy patients requiring no significant repositioning of upper eyelid position, the levator aponeurosis is generally reinforced at the time of myectomy surgery.

The completeness of myectomy surgery may be graded, and excision of several generous strips of orbicularis muscle at the time of ptosis repair often provides some improvement in the underlying eyelid spasm, lessening future botulinum toxin needs (both reduced total dose and increased duration of effect). Preoperative experience in observing the patient’s response to botulinum therapy allows the surgeon to appropriately determine whether no myectomy, a limited myectomy, or a radical myectomy is required at the time of ptosis surgery (Fig. 27.4).

Frontalis sling surgery is effective in patients with severe apraxia of eyelid opening or otherwise recalcitrant ptosis. It is often appropriate to