enhanced by severe left inferior rectus restriction. See also Chapter 14. (Courtesy of Steven A. Newman, MD.)

In cases of suspected fatigable ptosis caused by myasthenia gravis, the patient fixates on the clinician’s hand, which is elevated to provoke extreme upgaze. The clinician watches for progressive ptosis as the patient attempts to hold this position. A patient without myasthenia gravis can maintain the position without developing ptosis. The Cogan lid-twitch sign, a feature of myasthenia gravis, is identified by having the patient fixate in downgaze for a few seconds and then rapidly refixate straight ahead. The sign appears as an upward overshoot of the eyelid followed by fluttering as the lid settles into position.

Evaluation of facial motor function includes assessing the strength of the orbicularis oculi and other facial muscles. Eyelid closure should be assessed to determine if it is incomplete (lagophthalmos). Reinnervation phenomena, such as synkinesis with eyelid closure and facial tics, may be signs of a previous injury to CN VII (see Fig 11-8). The clinician should note the presence of exophthalmos (eg, thyroid eye disease; see Chapter 14) or enophthalmos. Enophthalmos may result in apparent ptosis and narrowing of the palpebral fissure because the eyelid follows the contour of the globe as the eye retracts into the orbit. Anisocoria (see Chapter 10) may suggest sympathetic nervous system disruption, which will alter eyelid position. Dysfunction of CN III with parasympathetic nervous system involvement may also present with ptosis and anisocoria, as well as an ocular motility deficit. Finally, “neighboring” cranial nerves should be assessed. If ptosis is caused by CN III weakness, the functions of CN IV, CN V, and CN VI should also be evaluated. Ocular motility should be checked for subtle weakness. Similarly, if CN VII dysfunction is found, facial sensation and hearing should be evaluated.

Ptosis

Congenital Ptosis

The most common form of congenital ptosis is thought to result from dystrophic development of the levator muscle without associated innervational abnormalities. Congenital ptosis is typically associated with decreased levator function, eyelid lag, and poorly formed (or absent) upper eyelid crease. Congenital ptosis (Fig 11-5) may be unilateral or bilateral and may be associated with other congenital ocular or orbital abnormalities, including blepharophimosis syndrome, congenital fibrosis of the extraocular muscles, superior rectus weakness, and Marcus Gunn jaw-winking syndrome (Fig 11-6). This last phenomenon is a synkinetic movement of the eyelid associated with jaw movement. In the external pterygoid–levator form of the syndrome, the eyelid elevates with movement of the mandible to the opposite side, jaw protrusion, or wide opening of the mouth. With the internal pterygoid–levator form, the eyelid elevates when the teeth are clenched. In some patients with Marcus Gunn jaw-winking syndrome, ptosis may worsen with movement of the jaw, although this finding is not common. Congenital tumors, such as hemangiomas and neurofibromas (see Fig 11-1) may also lead to congenital ptosis. Such tumors are typically associated with a palpable mass. Whatever the origin of a child’s congenital ptosis, the ophthalmologist must be aware of the potential for amblyopia as a result of occlusion or anisometropia.

Figure 11-5 Congenital ptosis of the right upper eyelid in a 2-year-old child. (Courtesy of Rod Foroozan, MD.)

Figure 11-6 Marcus Gunn jaw-winking syndrome. A, This 25-year-old has mild right upper eyelid ptosis. B, Opening the mouth results in eyelid retraction. This pattern indicates synkinesis between the fifth nerve and the third nerve. (Reprinted

with permission from Levin LA, Arnold AC, eds. Neuro-Ophthalmology: The Practical Guide. New York: Thieme; 2005.)

Acquired Ptosis

Table 11-1 lists the most common causes of acquired ptosis. Neurogenic ptosis requires careful attention to associated abnormalities in pupillary size and extraocular movements. Bilateral ptosis may be the only manifestation of a nuclear third nerve palsy (see Chapter 8). Cerebral ptosis occurs in association with a lesion of the cerebral (typically right) hemisphere. The ptosis may be bilateral or unilateral, and in the majority of cases it is transient.

Table 11-1

Suspicion of the presence of systemic disorders such as myasthenia gravis, chronic progressive external ophthalmoplegia, oculopharyngeal dystrophy, and myotonic dystrophy (discussed in Chapter 14) requires questions regarding the patient’s general strength, fatigability, dysphagia, and family history. Botulism leads to bilateral ptosis associated with poorly reactive pupils and ophthalmoplegia. Such patients also have associated facial paralysis and generalized proximal muscle weakness. Areflexia, ataxia, and ophthalmoplegia characterize Miller Fisher syndrome, a variant of Guillain-Barré syndrome (discussed later in the chapter). In addition to bilateral ptosis, such patients may also have facial diplegia, as well as respiratory and swallowing difficulties. Longterm use of steroid eyedrops is thought to lead to ptosis as a localized steroid-induced myopathy of the levator muscle. Posterior sub-Tenon steroid injections have also been associated with ptosis. The levator muscle, aponeurosis, or the insertion site of the aponeurosis may be adversely affected by such injections.

Levator aponeurotic defects are the most frequent cause of acquired ptosis, replacing the former concept of “senile” ptosis. This ptosis is caused by stretching, dehiscence, or disinsertion of the levator aponeurosis. Aponeurotic ptosis may occur with frequent eye rubbing or prolonged contact lens use, and may also be caused or exacerbated by intraocular surgery, perhaps because of use of an eyelid speculum. Because the levator muscle itself is healthy, levator function is usually normal. Patients with aponeurotic defects usually have a high eyelid crease.

Traumatic and mechanical causes of acquired ptosis are generally evident from inspection of the eyelids and require appropriate medical or surgical therapy.

Averbuch-Heller L, Leigh RJ, Mermelstein V, Zagalsky L, Streifler JY. Ptosis in patients with hemispheric strokes. Neurology. 2002;58:620–624.