What is Webino syndrome?

WEBINO Syndrome: Clinical Features, Diagnosis, and Management

WEBINO syndrome (Wall-Eyed Bilateral Internuclear Ophthalmoplegia) is characterized by bilateral adduction impairment, nystagmus of the abducting eye, and primary gaze exotropia, typically caused by lesions in the medial longitudinal fasciculus (MLF) in the midbrain. 1, 2

Clinical Features

• WEBINO presents with a unique spectrum of ocular motility abnormalities including:

  • Primary gaze exotropia (wall-eyed appearance) 1, 2
  • Bilateral adduction impairment (inability to move eyes inward) 1, 2
  • Nystagmus of the abducting eye (jerking movements when eyes move outward) 1, 2
  • Deficiency of convergence 3

• Additional neurological symptoms may include:

  • Diplopia (double vision) - often the presenting complaint 1, 4
  • Gait ataxia in some cases 1

Etiology

• The most common causes of WEBINO syndrome include:
  • Ischemic stroke affecting the midbrain tegmentum and MLF (as seen in older patients) 1, 4
  • Demyelinating diseases, particularly multiple sclerosis (more common in younger patients) 1, 3
  • Rarely, myasthenia gravis (important differential diagnosis) 3
  • Iatrogenic causes (medication-related, such as with immunosuppressants like tacrolimus) 1

Pathophysiology

• WEBINO syndrome results from bilateral damage to the medial longitudinal fasciculus (MLF) in the midbrain tegmentum 1, 2
• The MLF coordinates conjugate eye movements by connecting the abducens nucleus (CN VI) with the oculomotor nucleus (CN III) 2
• Damage to these pathways disrupts the coordination between lateral and medial rectus muscles, leading to the characteristic eye movement abnormalities 2, 4
• The exotropia (outward deviation) in primary gaze distinguishes WEBINO from standard bilateral internuclear ophthalmoplegia 2

Diagnosis

• Diagnosis is primarily clinical, based on the characteristic triad of:

  • Bilateral adduction deficit
  • Nystagmus in the abducting eye
  • Primary position exotropia 1, 2

• Neuroimaging is essential to confirm diagnosis and identify underlying cause:

  • MRI brain with special attention to brainstem structures, particularly the midbrain tegmentum 1, 4
  • MRI may reveal ischemic lesions, demyelinating plaques, or other pathologies affecting the MLF 1, 4

• Additional diagnostic tests based on clinical suspicion:

  • For suspected myasthenia gravis: Tensilon test and electromyography 3
  • For suspected multiple sclerosis: Complete neurological examination, CSF analysis, and evoked potentials 2

Management

• Treatment is primarily directed at the underlying cause:

  • For ischemic stroke: Standard stroke management protocols including risk factor modification 4
  • For multiple sclerosis: Disease-modifying therapies 2
  • For myasthenia gravis: Anticholinesterase medications (e.g., pyridostigmine) 3

• Symptomatic management of diplopia:

  • Prism glasses may help manage diplopia in some cases 2
  • Eye patching as a temporary measure 2

• Surgical options for persistent exotropia:

  • Transposition surgery has been reported to effectively alleviate exodeviation in chronic cases 5
  • May be considered when conservative measures fail and the condition is stable 5

Prognosis

• Prognosis varies depending on the underlying etiology:

  • In vascular causes, partial or complete recovery may occur over weeks to months 4
  • In myasthenia gravis, treatment with anticholinesterase medications can lead to complete remission 3
  • In multiple sclerosis, the course may be more variable with potential for recurrence 2

• Early recognition and prompt treatment of the underlying cause is essential for improving outcomes 4

Clinical Pearls

• WEBINO should prompt immediate neuroimaging to rule out serious underlying pathologies, particularly stroke 1, 4
• Don't overlook myasthenia gravis as a potential cause, especially in cases without obvious brain lesions on imaging 3
• The combination of bilateral adduction deficit with exotropia is the key diagnostic feature distinguishing WEBINO from other ocular motility disorders 2
• Comprehensive stroke risk factor management is essential in cases caused by ischemic events 4