What is the term for when Extraocular Muscles (EOM) do not track index finger movements on a neuro exam?

Ophthalmoplegia: When EOMs Fail to Track Index Finger Movements

When extraocular muscles (EOMs) do not track properly during index finger movements on neurological examination, this is called ophthalmoplegia or gaze palsy, depending on the specific pattern of impairment.

Types of Tracking Abnormalities

Ophthalmoplegia

• Complete ophthalmoplegia: Inability of all EOMs to move the eyes
• Partial ophthalmoplegia: Limited movement in specific directions
• Internuclear ophthalmoplegia (INO): Specific impairment of adduction on lateral gaze due to medial longitudinal fasciculus lesions

Assessment Technique

When evaluating EOM function, the examiner should:

• Test both versions (binocular motility) and ductions (monocular motility) 1
• Note any limitation, overaction, or incomitance (change in angle in different gaze positions) 1
• Evaluate smooth pursuit and saccadic eye movements 1
• Test for vertical gaze palsy (especially downward gaze) 1
• Assess for optokinetic nystagmus 1

Clinical Significance

Abnormal EOM tracking has significant implications for morbidity and mortality as it may indicate:

1. Neurological disorders:

   • Stroke (especially posterior circulation) 1
   • Multiple sclerosis (particularly with INO) 1
   • Brain tumors (especially brainstem lesions) 2

2. Neuromuscular junction disorders:

   • Myasthenia gravis
   • Lambert-Eaton syndrome

3. Cranial nerve pathology:

   • CN III (oculomotor) palsy: Impaired adduction, elevation, and depression
   • CN IV (trochlear) palsy: Impaired intorsion and depression
   • CN VI (abducens) palsy: Impaired abduction 1

Diagnostic Approach

Physical Examination Pearls

• Document the pattern of involvement (which directions of gaze are affected) 1
• Test for pupillary involvement (pupil-involving vs. pupil-sparing) 1
• Evaluate for associated nystagmus 1
• Assess for head posture compensation 1
• Perform forced duction testing when mechanical restriction is suspected 3

Imaging Considerations

• MRI brain is preferred for subacute, slowly progressive presentations 1
• CT head without contrast is reasonable for initial imaging in acute settings 1
• MRA/CTA should be considered when vascular causes are suspected 1

Common Pitfalls to Avoid

1. Incomplete examination: Failing to test all cardinal positions of gaze
2. Missing subtle nystagmus: Not holding gaze long enough in extreme positions 2
3. Overlooking mechanical causes: Not distinguishing between neurogenic and mechanical limitations
4. Inadequate imaging: Using inappropriate imaging modalities for suspected pathology 1

Clinical Pearls

• Isolated CN VI palsy may indicate increased intracranial pressure without direct nerve compression 1
• Multiple ipsilateral cranial nerve palsies affecting CN III, IV, and VI suggest a lesion at the cavernous sinus or orbital apex 1
• Decreased velocity of saccades may be an early sign of progressive supranuclear palsy 1
• Asymmetric rigidity, alien hand, and apraxia with ophthalmoplegia raise suspicion for corticobasal syndrome 1

Remember that abnormal EOM tracking is not merely a localized ocular finding but may represent the first sign of a serious neurological condition requiring urgent evaluation and management.