Lid Retraction and Lid Lag
What Is the Anatomy of the Eyelids and What Brainstem Structures Control Lid Elevation?
In normal adults, the upper lid just covers the superior cornea (1–2 mm) and the lower lid lies slightly below the inferior corneal margin. Eyelid elevation occurs with contraction of the levator palpebrae superioris (LPS) muscle innervated by the oculomotor nerve. Accessory muscles include Müller’s muscle (sympathetic innervation), which is embedded in the LPS and inserts mainly on the tarsal plate, and the frontalis muscle (innervated by the temporal branch of the facial nerve), which helps to retract the lid in extreme upgaze (Schmidtke, 1992). Tone in the LPS normally parallels that of the superior rectus muscle, and in extreme downgaze both muscles are completely inhibited. However, there is an inverse relationship between the LPS and the superior rectus during forced lid closure where the eye elevates (Bell’s phenomenon). The motor neurons for both levator muscles are in the unpaired central caudal nucleus (CCN), located at the dorsal caudal pole of the oculomotor complex adjacent to the medial rectus and superior rectus subdivisions. Within the CCN, motor neurons of both LPS muscles are intermixed. The region of the nuclear complex of the posterior commissure is involved in lid-eye movement coordination (Schmidtke, 1992).
The upper lid position is abnormal if it exposes a white band of sclera between the lid margin and the upper corneal limbus. This may be due to lid retraction (related to overactivity of the LPS, contracture of the LPS, or hyperactivity of Müller’s muscle), or lid lag, which is noted on attempted downgaze. Bartley divided lid retraction into four categories: neurogenic, myogenic (including disease processes affecting the neuromuscular junction), mechanical, and miscellaneous (Bartley, 1996). This chapter adopts this classification, discusses the etiologies of lid lag and lid retraction, and suggests a diagnostic approach.
What Are the Neurogenic Causes of Lid Retraction and Lid Lag?
Neurogenic eyelid retraction and lid lag may be due to supranuclear, nuclear, or infranuclear lesions affecting the LPS or conditions that produce hyperactivity of the sympathetically innervated Müller’s muscle (Miller, 1985). Preterm infants may have a benign transient conjugate downward gaze deviation with eyelid retraction thought to be due to immature myelination of vertical eye movement control pathways (Kleinman, 1994; Miller, 1985). Approximately 80% of normal infants of 14 to 18 weeks of age may demonstrate bilateral transient lid retraction (“eye-popping reflex”) when ambient light levels are suddenly reduced. Both of these phenomena are usually benign and typically require no evaluation if transient and in isolation (class IV, level C).
Dorsal mesencephalic supranuclear lesions may result in eyelid retraction, which is noted when the eyes are in the primary position of gaze or on looking upward (Collier’s sign or posterior fossa stare). Unlike the retraction from thyroid orbitopathy (see below), with midbrain lid retraction there is typically no retraction in downgaze. Patients with dorsal mesencephalic lesions often have associated vertical gaze palsies and other dorsal midbrain findings. The etiologies of the dorsal midbrain syndrome and the workup of these patients are discussed in Chapter 14. Spells of lid retraction lasting 20 to 30 seconds that may be seen with impending tentorial brain herniation may be due to a dorsal mesencephalic mechanism (Miller, 1985).
Lesions of the medial and/or principal portion of the nuclear complex of the posterior commissure (NPC) are involved in lid-eye coordination and provide inhibitory modulation of levator motor neuronal activity (Schmidtke, 1992). Clinical and experimental evidence suggests an inhibitory premotor network in the periaqueductal gray (the supraoculomotor area or supra III) that is dorsal to the third cranial nerve nucleus and projects from the NPC to the central caudal subnucleus (Galetta, 1993a,b, 1996; Schmidtke, 1992). Lesions in the region of NPC may produce excessive innervation to the lids with lid retraction in primary position. Bilateral eyelid retraction and eyelid lag with minimal impairment of vertical gaze has been described with a circumscribed unilateral lesion immediately rostral and dorsal to the red nucleus involving the lateral periaqueductal gray area in the region of the NPC (Galetta, 1993a,b, 1996). Eyelid lag without retraction has also been described in pretectal disease, implying that these lid signs may have separate neural mechanisms (Galetta, 1996). Vertical gaze paralysis without eyelid retraction may occur. In these cases the fibers and nucleus of the posterior commissure are spared and the lesions involve the rostral interstitial nucleus of the medial longitudinal fasciculus (MLF), the interstitial nucleus of Cajal, and the periaqueductal gray area (Schmidtke, 1992). Ipsilateral ptosis and contralateral superior eyelid retraction may be due to a nuclear oculomotor nerve syndrome (plus-minus lid syndrome) (Galetta, 1993b; Gaymard, 1992; Vertrugno, 1997). The plus-minus syndrome results from a unilateral lesion of the third nerve fascicle with extension rostrally and dorsally to involve the nucleus of the posterior commissure or its connections. The plus-minus syndrome has been described with glioma, third nerve palsy, orbital myositis, myasthenia gravis, congenital ptosis, and orbital trauma (Vertrugno, 1997). Also, a patient has been described with a nuclear third nerve palsy, sparing the caudal central nucleus and its efferent fibers, who had no ipsilateral ptosis but had contralateral lid retraction (Gaymard, 2000). The contralateral eyelid retraction was thought to be due to damage to fibers from the NPC, most probably in the region of the supraoculomotor area, and it is inferred from this case that inhibitory connections between the NPC and the central caudal nucleus are unilateral and crossed. A similar crossed pattern may also exist for excitatory afferents to the central caudal nucleus as hemispheric lesions result in contralateral ptosis.
Paroxysmal superior rectus with LPS spasm is a rare and unique disorder described in a single patient with multiple sclerosis (Ezra, 1996). Paroxysms of vertical diplopia and lid retraction in this patient lasted 3 to 4 seconds, and examination revealed intermittent right hypertropia, lid retraction, and restriction of downgaze. Magnetic resonance imaging (MRI) revealed multiple lesions consistent with multiple sclerosis, including a lesion in the midbrain in the region of the third nerve fascicle. Carba-mazepine stopped all the symptoms that were thought due to spontaneous spasm of the superior rectus/levator complex.
Bilateral episodic retraction of the eyelids may occur as a manifestation of epileptic discharges associated with petit mal or myoclonic seizures or due to “levator spasms” during an oculogyric crisis (Miller, 1985). Lid lag may occur on a supranuclear basis in progressive supranuclear palsy, likely due to defective inhibition of the levator nuclei during downward gaze (Friedman, 1992; Miller, 1985). Lid lag may occur in the acute phases of Guillain-Barré syndrome (Tan, 1990), and lid retraction may also occur with parkinsonism (Miller, 1985; Tan, 1990). Lid retraction has also been described with Fisher syndrome (Al-Din, 1994) and POEMS (peripheral neuropathy, organomegaly, endocrinopathy, M-protein, and skin changes) syndrome (Gheradi, 1994).
Rhythmic upward jerking of the lids (eyelid nystagmus) refers to eyelid twitches that are synchronous with the fast phase of horizontal nystagmus on lateral gaze. It has been ascribed to lateral medullary disease where it may be inhibited by near effort. Lid nystagmus may also be provoked by convergence (Pick’s sign) in cerebellar or medullary pathology. There is a slow down drift of the lid corrected by an upward flick. Rhythmic upward jerking of the eyelids may also be associated with vertical nystagmus, palatal myoclonus, or convergence-retraction nystagmus (Miller, 1985) (see Chapters 14 and 17).
Eyelid retraction may also occur from paradoxic levator excitation that may be congenital or acquired supranuclear, nuclear, or infranuclear lesions (Miller, 1985). Paradoxic lid retraction may occur with jaw movement or swallowing (the Marcus Gunn jaw-winking phenomenon). This trigemino-oculomotor synkinesis occurs on a congenital basis. Levator contraction with contraction of the external pterygoid muscle is the most common form of trigemino-oculomotor synkinesis (Miller, 1985). The involved eyelid is usually ptotic, but may be normal or even retracted while the jaw muscles are inactive. Elevation of the lid occurs when the mandible is moved to the opposite side, when the mandible is projected forward or the tongue protruded, or on wide opening of the mouth. These patients commonly have other associated ocular abnormalities including strabismus (e.g., double elevator palsy or superior rectus palsy), amblyopia, and anisometropia (Miller, 1985). Another rare form of trigemino-oculomotor synkinesis is levator contraction with contraction of the internal pterygoid muscle (i.e., eyelid elevation with closure of the mouth or clenching of the teeth). Treatment of cases of Marcus Gunn jaw-winking phenomenon includes occlusion therapy for amblyopia, strabismus surgery, and surgery to correct the ptosis or retraction (Miller, 1985). Paradoxical eyelid retraction may also occur ipsilaterally in congenital or acquired horizontal gaze or abducens palsies (Miller, 1985).
Eyelid retraction may also occur with aberrant regeneration of the third nerve. The lid may elevate when the eye adducts, elevates, or depresses (Stout, 1993) (see Chapter 11