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Lesions of the withdrawing (VI) nerve (n. abducens)
Last reviewed: 04.07.2025
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Topical diagnostics of damage to the abducens (VIth) nerve is possible at the following three levels:
- I. Level of the nucleus of the abducens nerve.
- II. Level of the abducens nerve root.
- III. Level (trunk) of the nerve.
I. Damage to the VI nerve at the level of its nucleus in the brainstem
| Lesion of the nucleus of the sixth nerve | Paralysis of gaze towards the lesion. |
| Dorsolateral pons lesion | Ipsilateral gaze palsy, peripheral paresis of facial muscles, dysmetria, sometimes with contralateral hemiparesis (Foville syndrome) |
II. Damage at the level of the root of the VI nerve
| Lesion of the root of the sixth nerve | Isolated paralysis of the muscle that turns the eyeball outward. |
| Lesion of the anterior paramedian parts of the pons | Ipsilateral paralysis of the muscles innervated by the VI and VII nerves, plus contralateral hemiparesis (Millard-Gubler syndrome). |
| Lesion in the prepontine cistern area | Paralysis of the abductor oculomotor muscle, with or without contralateral hemiparesis (if the corticospinal tract is involved) |
III. Damage to the trunk of the abducens nerve.
| Lesion in the area of the apex of the pyramid (Dorello canal) | Paralysis of the abductor muscle of the eye (VI nerve); hearing loss on the same side, facial (especially retroorbital) pain (Gradenigo syndrome) |
| Cavernous sinus | Isolated involvement of the VI nerve; or involvement of the VI nerve plus Horner's syndrome; III, IV nerves and the first branch of the trigeminal nerve may also be affected. Exophthalmos, chemosis. |
| Superior orbital fissure syndrome | Lesion of the VI nerve with variable involvement of the III, IV nerves and the first branch of the V nerve. Exophthalmos is possible. |
| Orbit | Symptoms of damage to the VI nerve (and other oculomotor nerves), decreased visual acuity (II nerve); variable exophthalmos, chemosis. |
Possible causes of isolated damage to the VI (abducens) nerve: diabetes mellitus, arterial hypertension (in these forms, the VI nerve paralysis has a benign course and usually undergoes regression within 3 months), aneurysms, strokes, metastases, pituitary adenomas, sarcoidosis, giant cell arteritis, multiple sclerosis, syphilis, meningioma, glioma, traumatic brain injury and other lesions. In addition, damage at the level of the VI nerve nucleus is observed in congenital Mobius syndrome: horizontal gaze palsy with diplegia of the facial muscles; Duane retraction syndrome with gaze palsy, retraction of the eyeball, narrowing of the eye slit and adduction of the eyeball.
Damage to the VI nerve must be differentiated from pseudoabducens syndromes: dysthyroid orbitopathy, bilateral convergence spasm, myasthenia, congenital Duane syndrome, concomitant strabismus and other causes.
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