What is the workup for unilateral ptosis (drooping of one eyelid) without neurological symptoms?

Diagnostic Approach for Unilateral Ptosis Without Neurological Symptoms

The workup for unilateral ptosis without neurological symptoms should begin with a comprehensive eye examination focusing on pupillary responses, sensorimotor function, and fundus examination to rule out potentially serious underlying conditions. 1

Initial Assessment

• Perform a detailed medical and ocular history, asking specifically about symptom onset (sudden vs. gradual), variability with fatigue, and any associated symptoms 2
• Conduct a comprehensive eye examination with particular attention to:
  • Pupillary responses in both bright and dim illumination to detect anisocoria 2, 3
  • Complete sensorimotor examination to assess for subtle strabismus 2
  • Fundus examination to evaluate for papilledema or optic atrophy 2
• Determine the severity of ptosis (minimal: 1-2mm, moderate: 3-4mm, severe: >4mm) 4
• Assess levator function by measuring lid excursion from downgaze to upgaze 4

Diagnostic Considerations Based on Clinical Findings

When Pupil is Involved

• Pupil-involving third nerve palsy requires urgent neuroimaging with MRI with gadolinium and MRA or CTA to rule out posterior communicating artery aneurysm 2, 3
• If high suspicion for aneurysm despite normal MRA/CTA, consider catheter angiogram 2

When Pupil is Spared

• Classic pupil-sparing third nerve palsy with complete ptosis and complete motility dysfunction suggests microvascular etiology (diabetes, hypertension, hyperlipidemia) 2
• However, partial involvement of extraocular muscles or incomplete ptosis even with spared pupil warrants neuroimaging to rule out compressive lesions 2

When Ptosis Varies with Fatigue

• Consider myasthenia gravis and perform:
  • Ice test or rest test 1
  • Consider acetylcholine receptor antibody testing if clinical suspicion is high 1
  • Single-fiber EMG may be necessary in seronegative cases 1

When Ptosis is Associated with Proptosis

• Consider orbital mass or infiltrative process
• MRI orbits without and with contrast is recommended 2, 1
• In children, consider plexiform neurofibroma, especially if associated with periorbital asymmetry 2

Special Considerations

• In children with unilateral ptosis, rule out pseudoptosis and consider congenital causes 5
• If ptosis is the only manifestation without other neurological symptoms, advanced neuroimaging is typically not required as first-line investigation 1
• In isolated unilateral ptosis with normal pupillary function and no other neurological symptoms, consider aponeurotic or myogenic causes 4

Pitfalls to Avoid

• Failing to recognize pupil-involving third nerve palsy as a potential neurosurgical emergency 1, 3
• Assuming microvascular etiology in pupil-sparing third nerve palsy without thorough evaluation 2
• Missing myasthenia gravis due to variable presentation and potential seronegativity 1
• Overlooking orbital masses, especially in cases with proptosis 2
• Neglecting to evaluate children with unilateral ptosis for amblyopia, which can lead to permanent vision loss if untreated 4, 5

Management Considerations

• Treatment depends on etiology, severity of ptosis, levator function, and presence of additional abnormalities 4
• For minimal ptosis, Müller's muscle conjunctival resection may be considered 4
• For moderate ptosis with levator function of 5-10mm, shortening of the levator palpebrae or levator advancement may be appropriate 4, 6
• For severe ptosis with levator function <5mm, frontalis suspension is typically indicated 4, 7