Orbit/Oculoplastics Quiz 22
Appearance at presentation.
|A 2 year-old boy presents with drooping upper lids since birth.|
|Questions and Answers|
|1. What is the most likely diagnosis?|
Answer: Congenital Ptosis
2. What is the etiology of this lesion?
Answer: Congenital ptosis is most often caused by myogenic dysgenesis of the levator palpebrae muscle, which elevates the upper lid. Rather than normal muscle fibers, fibrous and adipose tissue are present in the muscle belly, diminishing its ability to contract and relax.
Other etiologies of ptosis in childhood should be considered in the differential diagnosis. The majority can be divided into myogenic and neurogenic causes. Myogenic causes include muscular dystrophy, chronic progressive external ophthalmoplegia (CPEO), oculopharyngeal dystrophy, and congenital fibrosis syndrome. Neurogenic causes include third nerve palsy, Horner’s syndrome, and myasthenia gravis. Congenital neurogenic ptosis may be synkinetic in nature as in the Marcus Gunn jaw-winking syndrome. The blepharophimosis syndrome is an autosomal dominant cause of ptosis and is characterized by a narrowed palpebral fissure, epicanthus inversus, and ptosis. Periorbital tumors such as plexiform neurofibromas, lymphoma, or rhabdomyosarcoma may produce a mechanical ptosis.
Certain findings on examination may help in elucidating the cause of the ptosis. For example, extraocular motility dysfunction may be seen in cases of muscular dystrophy, CPEO, oculopharyngeal dystrophy, congenital fibrosis syndrome, third nerve palsy, and myasthenia gravis. Also, pupillary abnormalities may be seen in cases of third nerve palsy and Horner’s syndrome. Congenital Horner’s syndrome may also be characterized by lower eyelid ptosis (elevation) and iris heterochromia (lighter pupil on the side of the abnormality). Unilateral ptosis that elevates with jaw movements is characteristic of Marcus Gunn jaw-winking syndrome.
3. What are the key clinical exam findings to obtain in the evaluation of this patient?
Answer: In order to properly evaluate ptosis, certain key measurements should be obtained. These include the palpebral fissure height (distance between upper eyelid and lower eyelid at the widest point), margin-to-reflex distance (distance between upper eyelid margin and pupillary light reflex), levator function (amount of upper eyelid excursion from downgaze to upgaze with frontalis muscle function negated), and upper eyelid crease (distance from upper eyelid margin to upper eyelid crease).
In congenital ptosis, the palpebral fissure height and margin-to-reflex distance would be expected to be less than normal. Levator function would also be expected to be significantly diminished in cases of classic congenital ptosis. The upper eyelid crease represents the site of levator muscle insertion into the skin and may be shallow or absent in congenital ptosis. Of note, patients with congenital ptosis may have eyelid lag on downgaze. This is in contrast to patients with acquired, involutional ptosis who often have worsening ptosis on downgaze.
Other exam findings to evaluate for include head position, chin elevation, and brow position. These features help demonstrate the functional impact of the ptosis on the patient. Lagophthalmos should also be checked for as its presence could predispose the patient to complications following ptosis repair such as corneal dryness and exposure keratopathy. Similarly, the presence of a normal Bell’s phenomenon (rotation of the eye upwards with forced eyelid closure) is important to consider in determining whether or not the patient is a good candidate for ptosis surgery. A poor Bell’s phenomenon may further predispose the patient to corneal complications following ptosis surgery.
4. What is the major risk to vision in a child with this condition?
Answer: Any child with congenital ptosis is at risk for developing amblyopia. It is of utmost importance to evaluate the patient’s visual function and refractive error in all cases in order to identify and treat patients at risk for amblyopia. In congenital ptosis, amblyopia may result from deprivation or anisometropia. Anisometropia typically develops due to mechanically induced astigmatism by eyelid compression of the cornea. Patients with congenital ptosis may also have strabismus which further places the patient at risk for amblyopia. If the ptosis is significant enough to pose a risk to the patient’s vision, surgery would be indicated sooner rather than later.
5. What are the treatment options?
Answer: Surgical correction can often be delayed until the patient is several years old. Waiting until this age allows more accurate pre-operative measurements. However, signs of amblyopia, strabismus, or consistent chin-up head posturing may necessitate early surgery. Non-surgical patients should be followed every 3 to 4 months to evaluate for signs of amblyopia. Surgical techniques include levator resection, Muller’s muscle resection, and eyelid suspension to the frontalis muscle.
Levator resection is most effective in patients whose levator function is relatively good (at least 4mm). The amount of levator resected should correlate with the degree of pre-operative levator function; i.e. patients with poorer levator function will require a larger levator resection to appropriately correct the ptosis.
Muller’s resection is rarely performed in cases of congenital ptosis. It is most appropriate in cases of minimal ptosis (less than 2mm of ptosis). In particular, it is effective in the treatment of ptosis due to Horner’s syndrome in which there is a disruption of sympathetic innervation to Muller’s muscle.
When levator function is poor (usually less than 4mm), frontalis suspension is usually performed. Frontalis suspension is designed to attach the eyelid to the frontalis muscle such that elevation of the brow results in elevation of the eyelid. Frontalis suspension may be performed using autogenous fascia lata, human donor fascia lata, or synthetic materials. Autogenous fascia lata has the best long-term results. However, this technique requires harvesting and an additional operative site. Autogenous fascia lata can be readily harvested from the leg in children over the age of 3. Donor fascia lata obviates the need for harvesting and additional surgery, but it may induce immune-mediated inflammation and ultimately rejection leading to poorer long-term outcomes. Synthetic materials such as non-absorbable sutures (Prolene or Mersilene), polytetrafluorethane (Gore-Tex) and Silastic rods are being increasingly used. They may improve eyelid elasticity and allow easier adjustment or removal if necessary.
In all cases, the surgical goal is to lessen the degree of ptosis while not elevating the lid too high resulting in corneal exposure and lagophthalmos. The surgical outcome may need to be a compromise between cosmetic and functional results.
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Malone TJ, Nerad JA: The surgical treatment of blepharoptosis in oculomotor nerve palsy. Am J Ophthalmol 1988 Jan 15; 105(1): 57-64.
Yilmaz N, Hosal BM, Zilelioglu G: Congenital ptosis and associated congenital malformations. J AAPOS 2004 Jun; 8(3): 293-5.