What is the initial workup for a patient presenting with intermittent diplopia (double vision)?

Initial Workup for Intermittent Diplopia

The initial workup for intermittent diplopia should include a detailed sensorimotor examination, determination of monocular versus binocular diplopia, and appropriate neuroimaging based on clinical findings. 1

Step 1: Distinguish Between Monocular and Binocular Diplopia

• Monocular diplopia: Persists when one eye is covered; typically caused by ocular media abnormalities

  • Perform refraction and biomicroscopic examination of ocular media
  • Refer to ophthalmologist for further evaluation
  • No neuroimaging typically required

• Binocular diplopia: Resolves when either eye is covered; indicates misalignment of visual axes

  • Continue with neurological and sensorimotor evaluation

Step 2: Detailed History and Examination

Key History Elements:

• Onset (sudden vs. gradual)
• Pattern (constant vs. intermittent)
• Direction of diplopia (horizontal, vertical, or torsional)
• Worse at distance or near
• Associated symptoms (pain, headache, neurological symptoms)
• History of trauma, surgery, or systemic disease

Essential Examination Components:

• Visual acuity and refraction
• Pupillary examination (especially for CN III palsy)
• Ocular motility assessment:
  • Versions, ductions, saccades, pursuit, vergence
  • Alignment in multiple gaze positions
  • Cover-uncover and alternate cover testing
  • Prism measurements
• Forced duction testing (to distinguish restriction from paresis)
• Specialized tests:
  • Double Maddox rod, Lancaster red-green test, or Hess screen for torsional diplopia
  • Lights on/off test for retinal diplopia
• Fundus examination for torsion
• Exophthalmometry for proptosis

Step 3: Localization-Based Evaluation

Cranial Nerve Palsies

• CN III (Oculomotor) Palsy:

  • If pupil-involving: Urgent CTA to rule out aneurysm 2
  • If pupil-sparing: MRI brain with contrast focusing on brainstem and cavernous sinus

• CN IV (Trochlear) Palsy:

  • Often traumatic in origin
  • MRI brain with contrast if no history of trauma
  • Vertical diplopia worse on downgaze and contralateral gaze

• CN VI (Abducens) Palsy:

  • Horizontal diplopia worse at distance and toward affected side
  • MRI brain with contrast focusing on brainstem, cavernous sinus, and prepontine cistern
  • Consider CT venogram if cavernous sinus thrombosis suspected

Neuromuscular Junction and Muscle Disorders

• Consider ocular myasthenia if:
  • Variable or fatigable diplopia
  • Ptosis
  • Pattern doesn't fit single cranial nerve palsy
• Consider thyroid eye disease if:
  • Proptosis
  • Lid retraction
  • Restrictive pattern on forced duction testing

Central Causes

• For internuclear ophthalmoplegia or skew deviation:
  • MRI brain with contrast focusing on brainstem
• For multiple cranial nerve palsies:
  • MRI brain/orbits with contrast focusing on cavernous sinus and orbital apex

Step 4: Imaging Selection

• CT Orbits (non-contrast): First choice for orbital trauma or suspected metallic foreign body 1
• MRI Orbits with contrast: Preferred for suspected extraocular muscle or soft tissue abnormalities 1
• MRI Brain with contrast: For suspected brainstem, cavernous sinus, or cranial nerve pathology 1
• CTA Head: Urgent for pupil-involving CN III palsy to rule out aneurysm 2, 3
• CT Venogram: For suspected cavernous sinus thrombosis 2

Special Considerations

• Patients >60 years with recent onset diplopia: Check inflammatory markers (ESR, CRP) to rule out giant cell arteritis 2
• Vital sign abnormalities (bradycardia, heart block) with orbital trauma may indicate oculocardiac reflex from muscle entrapment requiring urgent intervention 1
• Skew deviation: May be associated with cervical spondylosis causing vertebrobasilar insufficiency; requires neurological evaluation 4
• Retinal causes: Consider maculopathy if patient has small or no deviation on cover testing but persistent diplopia 1

Management Approach

• Temporary measures while awaiting diagnosis:

  • Occlusion of one eye
  • Prism glasses for small deviations
  • Botulinum toxin for persistent diplopia

• Definitive treatment based on etiology:

  • Most vasculopathic cranial nerve palsies resolve within 3-6 months
  • Surgical correction may be needed if diplopia persists beyond 6 months 1

Remember that while many causes of diplopia are benign, some require immediate recognition and treatment to prevent vision and life-threatening outcomes 5. A systematic approach focusing on localization is essential for accurate diagnosis and optimal patient care.