In a contact lens wearer with bilateral eyelid twitching that worsens when the eyes are closed tightly, intermittent fasciculations elsewhere (including a prior lip twitch), no weakness, normal recent comprehensive metabolic panel and complete blood count, and concern for amyotrophic lateral sclerosis (ALS) or brain tumor, what is the most likely diagnosis and recommended management?

Benign Eyelid Myokymia (Benign Fasciculation Syndrome)

This patient has benign eyelid myokymia (eyelid twitching) likely exacerbated by contact lens wear, and does NOT have ALS or a brain tumor based on the clinical presentation.

Clinical Reasoning

The clinical picture strongly argues against serious neurological disease:

• Bilateral eyelid twitching without weakness is incompatible with ALS. ALS is characterized by progressive motor neuron loss resulting in progressive muscle atrophy and weakness, not isolated fasciculations 1. The patient demonstrates normal strength (able to stand on one leg, able to whistle), and normal recent laboratory work, which effectively rules out ALS as a diagnosis.

• The pattern of symptoms indicates benign fasciculation syndrome. Chronic eyelid twitching (myokymia) is a common, benign phenomenon that can persist for weeks to months 2. The fact that twitching worsens with tight eye closure is characteristic of benign eyelid myokymia and has been documented in contact lens wearers 3. Women are more vulnerable to chronic eyelid twitching than men (3:1 ratio), and it tends to develop more in cold weather 2.

• Contact lens wear is a significant contributing factor. Contact lens-associated discomfort and dry eye disease can manifest with various ocular surface symptoms including eyelid twitching 4, 5. Contact lenses divide the tear film into pre- and post-lens layers, leading to tear film instability and increased friction between the lens and ocular surface 5.

Key Distinguishing Features from Serious Disease

Why this is NOT ALS:

• ALS presents with progressive weakness, muscle atrophy, and bulbar symptoms (difficulty chewing, swallowing, slurred speech) 1
• Fasciculations in ALS are accompanied by weakness and atrophy, not isolated twitching 1
• The patient has no weakness and normal function, which is incompatible with ALS pathology 1

Why this is NOT a brain tumor:

• Brain tumors causing facial symptoms would present with other neurological signs, cranial nerve deficits, or progressive unilateral (not bilateral) symptoms 6
• Normal recent labs and absence of progressive neurological deficits argue strongly against intracranial pathology 6

Management Approach

Immediate reassurance and conservative management:

1. Provide definitive reassurance that this is a benign condition not indicative of ALS or brain tumor. The presence of normal strength, bilateral (not unilateral) symptoms, and normal labs effectively excludes these diagnoses 2.

2. Address contact lens-related factors:

   • Evaluate for contact lens-associated dry eye disease with tear film assessment 5
   • Consider temporary discontinuation of contact lenses to assess symptom improvement 4, 5
   • If continued lens wear is desired, consider switching lens material, design, or using secretagogues like diquafosol or rebamipide (available in some countries) 5
   • Use preservative-free artificial tears if needed more than four times daily 7

3. Identify and eliminate triggers:

   • Counsel strongly against eye rubbing, as this is the only lifestyle factor linked to progression of ocular surface disease 8
   • Assess for sleep deprivation, caffeine intake, stress, and fatigue—common triggers of benign fasciculations 2
   • Evaluate for seasonal/environmental factors, as chronic eyelid twitching develops more frequently in cold weather 2

4. Monitor for atypical features requiring further evaluation:

   • Progression to unilateral facial weakness (would suggest Bell's palsy or other facial nerve pathology) 6
   • Development of true ptosis with fatigability (would warrant evaluation for myasthenia gravis with ice pack test, acetylcholine receptor antibodies, and possible edrophonium testing) 9, 10, 9
   • Persistent unilateral symptoms unresponsive to conservative measures (rare cases may indicate underlying brainstem lesions) 11

Common Pitfalls to Avoid

• Do not order unnecessary neuroimaging or extensive workup in the absence of weakness, progressive symptoms, or other neurological signs. This only increases patient anxiety and healthcare costs without clinical benefit 2.

• Do not dismiss the patient's cancer history as irrelevant—the "dent in leg" noted a year ago warrants clinical examination to ensure it is not related to breast cancer metastasis, though the ability to stand on one leg argues against significant pathology.

• Recognize that intermittent fasciculations elsewhere in the body are common in benign fasciculation syndrome and do not indicate ALS in the absence of weakness or atrophy 2.

The natural history of benign eyelid myokymia is self-limited resolution over weeks to months, though it may recur 2. Electrophysiological studies showed that approximately half of chronic eyelid twitching cases demonstrate delayed or absent R2 response in blink reflex and 45.8% have prolonged facial nerve latency, indicating minor facial nerve conduction defects that are benign and self-resolving 2.