What cerebellar disorders can cause diplopia?

Cerebellar Disorders That Can Cause Diplopia

Cerebellar dysfunction can cause diplopia through several mechanisms, with skew deviation being the most common cerebellar-related cause of binocular vertical misalignment and double vision. 1

Primary Cerebellar Causes of Diplopia

Skew Deviation

• Results from damage to vestibular-cerebellar pathways
• Presents with vertical diplopia and torticollis (head tilt)
• Associated with subjective tilting of the visual world
• Anatomical correlations:
  • Rostral pons/midbrain lesions → contralateral hypotropia and head tilt
  • Vestibular periphery/medulla/caudal pons lesions → ipsilateral hypotropia and head tilt 1

Cerebellar Esotropia

• Often misdiagnosed as lateral rectus paresis/abducens palsy
• Characterized by:
  • Concomitant esotropia (worse at distance)
  • No slowing of abducting saccades
  • Full abduction with gaze-evoked nystagmus
  • Progressive worsening over time 2

Other Cerebellar Disorders Associated with Diplopia

1. Demyelinating Disorders

   • Multiple sclerosis affecting cerebellar pathways
   • Acute disseminated encephalomyelitis 1

2. Cerebellar Stroke/Ischemia

   • Posterior circulation infarcts
   • Can cause skew deviation and other oculomotor abnormalities 1

3. Cerebellar Tumors

   • May cause diplopia through direct compression or disruption of cerebellar pathways 3

4. Spinocerebellar Ataxias

   • SCA6 commonly presents with diplopia and progressive ataxia
   • Involves functional and structural changes in cerebellar connectivity 4

5. Acute Cerebellitis

   • Presents with truncal ataxia, dysmetria, and headache
   • Can cause diplopia in severe cases 1

6. Vestibular Neuritis with Cerebellar Involvement

   • Can cause skew deviation and diplopia
   • Associated with severe vertigo, dizziness, nausea, and vomiting 5

7. Cerebellar Degenerative Disorders

   • Familial cerebellar ataxia
   • Idiopathic cerebellar ataxia 2

Clinical Evaluation

Key Examination Elements

• Complete sensorimotor evaluation with three-step test
• Upright-supine test (helps differentiate skew deviation from other causes)
• Assessment for associated neurological signs:
  • Nystagmus (gaze-evoked, downbeat)
  • Internuclear ophthalmoplegia (INO)
  • Horner's syndrome
  • Ataxia
  • Hearing loss 1

Diagnostic Approach

1. Distinguish cerebellar causes from cranial nerve palsies:

   • Cerebellar esotropia: full abduction with gaze-evoked nystagmus
   • Abducens palsy: limited abduction with no nystagmus

2. Neuroimaging:

   • MRI brain with contrast is preferred over CT for cerebellar pathology
   • Provides better visualization of posterior fossa structures 1

Management of Cerebellar-Related Diplopia

Treatment Options

1. Address underlying cause when possible (tumor removal, stroke management)

2. Symptomatic management:

   • Prisms to control diplopia while waiting for recovery
   • Botulinum toxin injections for persistent misalignment
   • Strabismus surgery for stable, non-resolving cases 1, 3

3. Novel approaches:

   • Transcranial magnetic stimulation has shown promise in some cases of SCA6-related diplopia 6

Important Considerations

• Cerebellar causes of diplopia may be misdiagnosed as isolated cranial nerve palsies
• Cerebellar esotropia tends to worsen over time, unlike many other causes 2
• Associated cerebellar signs may develop years after the initial presentation of diplopia
• Early recognition and appropriate neuroimaging are essential for proper diagnosis and management

Patients with cerebellar-related diplopia should be referred to neurology or neuro-ophthalmology for comprehensive evaluation and management of the underlying cerebellar disorder.