Diagnosis:
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
CT:
- 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,
Treatment:
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
Others:
- 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