Abducens (cranial nerve VI palsy)


This is a clinical diagnosis

Clinical features:

Horizontal diplopia
In neutral gaze, normal appearance or head is slightly turned to the unaffected side (compensation for unopposed medial rectus)
On movement: Affected eye fails to abduct

Investigations to consider:

Blood tests:

  • ESR: giant cell arteritis
  • TFT, glucose
  • ANCA: Wegner’s granulomatosus
  • HbA1c
  • ESR


  • Out rules hydrocephalus: false localising sign

MRI with and without contrast:

  • Brainstem pontine lesions (multiple sclerosis, glioma)
  • Image base of the skull to exclude nasopharyngeal carcinoma

MRA head or CTA head:

  • ICA aneurysm

Multiple sclerosis investigations
If painful:

  • Consider petrous temporal apex syndrome, superior orbital fissure syndrome & cavernous sinus syndrome,


Treat the cause if found
If painless & idiopathic:

  • Consider conservative management & follow up

Causes of abducens nerve palsy (CN VI):

Nuclear & fasciular:

  • Tumours: glioma
  • Part of a Brainstem stroke syndrome
  • Multiple sclerosis

Basilar area:

  • Meningitis:
    • Bacterial, Meningovascular syphilis
    • TB meningitis
    • Fungal meningitis
  • Basilar artery aneurysm

Petrous tip area:

  • Raised intracranial pressure ‘false localising sign’
  • Hydrocephalus
  • Mastoiditis
  • Nasophareygeal tumours, paranasal sinus tumours
  • Lateral sinus thrombosis

Cavernous sinus area:

  • Internal Carotid artery aneurysm
  • Cavernous sinus thrombosis
  • Tumours: Intrasellar & extrasellar tumours e.g. pituitary, chordoma, meningioma, Nasopharymgeal tumours, craniopharygioma

Superior orbital fissure & Orbital apex area:

  • Tumours: nasopharygeal, meningioma, hemangioma, glioma, sarcoma, Hand-Schuller-Christian disease, metastasis
  • AVMs
  • Tolosa-Hunt syndrome
  • Pseudotumour of the orbit


  • Idiopathic
  • Vasculopathy:
    • Atheroma, Hypertension, Diabetes mellitus
    • Giant cell arteritis
  • Wegner’s granulomatosus

Related articles:

  • Approach to diplopia,
  • Also see superior orbital fissure syndrome, Tolosa Hunt syndrome, skull base syndromes