Deformities

2.4.1 Ptosis

Definition

Paralysis of the levator palpebrae muscle with resulting drooping of one or both upper eyelids (from the Greek ptosis, a falling). The following forms are differentiated according to their origin (see also Etiology):

❖ Acquired ptosis:

- Paralytic ptosis.

- Sympathetic ptosis.

- Myotonic ptosis.

- Traumatic ptosis.

Epidemiology. On the whole ptosis is a rare disorder. Etiology: Ptosis may be congenital or acquired.

Fig. 2.4 Congenital ptosis of the levator palpebrae muscle causes the upper eyelid to droop; usually the deformity is unilateral. Amblyopia will result if the center of the pupil is covered.

— Congenital ptosis.

— Congenital ptosis.

Fig. 2.4 Congenital ptosis of the levator palpebrae muscle causes the upper eyelid to droop; usually the deformity is unilateral. Amblyopia will result if the center of the pupil is covered.

Congenital ptosis. The disorder is usually hereditary and is primarily autosomal dominant as opposed to recessive. The cause is frequently aplasia in the core of the oculomotor nerve (neurogenic) that supplies the levator palpe-brae muscle; less frequently it is attributable to an underdeveloped levator palpebrae muscle (myogenic).

Acquired ptosis:

❖ Neurogenic causes:

- Oculomotor palsy (paralyticptosis).

- Lesions in the sympathetic nerve (sympatheticptosis) is Horner's palsy (ptosis, miosis, and enophthalmos).

❖ Myogenic ptosis: myasthenia gravis and myotonic dystrophy.

❖ Traumatic ptosis can occur after injuries.

Symptoms. The drooping of the upper eyelid may be unilateral (usually a sign of a neurogenic cause) or bilateral (usually a sign of a myogenic cause). A characteristic feature of the unilateral form is that the patient attempts to increase the palpebral fissure by frowning (contracting the frontalis muscle). Congenital ptosis (Fig. 2.4) generally affects one eye only; bilateral symptoms are observed far less frequently (7%).

Diagnostic considerations: Congenital ptosis. The affected eyelid in general is underdeveloped. The skin of the upper eyelid is smooth and thin; the superior palpebral furrow is absent or ill-defined. A typical symptom is "lid lag" in which the upper eyelid does not move when the patient glances down. This important distinguishing symptom excludes acquired ptosis in differential diagnosis. In about 3% of all cases, congenital ptosis is associated with epicanthal folds and blepharophimosis (Waardenburg syndrome).

Congenital ptosis can occur in varying degrees of severity and may be complicated by the presence of additional eyelid and ocular muscle disorders such as strabismus.

U Congenital ptosis in which the upper eyelid droops over the center of the pupil always involves an increased risk of amblyopia.

Acquired ptosis:

❖ Paralytic ptosis in oculomotor palsy (see also Chap. 17) is usually unilateral with the drooping eyelid covering the whole eye. Often there will be other signs of palsy in the area supplied by the oculomotor nerve. In external oculomotor palsy, only the extraocular muscles are affected (mydriasis will not be present), whereas in complete oculomotor palsy, the inner ciliary muscle and the sphincter pupillae muscle are also affected (internal oph-thalmoplegia with loss of accommodation, mydriasis, and complete loss of pupillary light reflexes).

❖ Myasthenia gravis (myogenic ptosis that is often bilateral and may be asymmetrical) is associated with abnormal fatigue of the striated extraocular muscles. Ptosis typically becomes more severe as the day goes on.

❖ Sympathetic ptosis occurs in Horner's palsy (ptosis, miosis, and enophthal-mos).

H Rapidly opening and closing the eyelids provokes ptosis in myasthenia gravis and simplifies the diagnosis.

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