Sixth cranial nerve palsy, or abducens nerve palsy, is a disorder associated with dysfunction of cranial nerve VI (the abducens nerve), which is responsible for contracting the lateral rectus muscle to abduct (i.e., turn out) the eye.
The most common causes of VIth nerve palsy in adults are:
More common: Vasculopathic (diabetes, hypertension, atherosclerosis), trauma, idiopathic.
Abducens nerve palsies reportedly occur in 10% to 60% of patients, whereas other cranial nerve palsies occur much less frequently. A woman with benign intracranial hypertension and facial diplegia who showed complete resolution of her cranial nerve palsies after control of her elevated intracranial pressure with a lumboperitoneal shunt. The pathophysiologic course of cranial nerve palsies in patients with Idiopathic intracranial hypertension is uncertain but in most cases probably represents a nonspecific pressure-related phenomenon, as was clearly demonstrated in this patient 1)
Giant cell arteritis
Cavernous sinus mass (e.g. meningioma, Brain stem Glioblastoma aneurysm, metastasis)
Multiple sclerosis, sarcoidosis/vasculitis
Stroke (usually not isolated)
Almost unilateral. Often delayed 5-14 days post LP, usually recovers after 4-6 weeks.
Unspecific side effects which cannot clearly be differentiated from pure post-lumbal puncture complaints are reported to occur in up to 28%. The probably underlying pathogenetic mechanisms are discussed together with former animal experiments which revealed a local toxity of the contrast medium at the central nervous tissue and the surrounding membranes 3).
Five patients who developed abducens palsy after myelography with watersoluble contrast media are reported. These palsies can be compared to abducens palsies after spinal anesthesia and diagnostic lumbar puncture. They are most likely due to the lumbar puncture. The arguments for this explanation are discussed. The experience with these five patients suggests a greater incidence of postpuncture abducens palsy after myelography with watersoluble contrast media than after spinal anesthesia or lumbar puncture. If this first impression is verified, it could point to an additional toxic action 4).
Abducens nerve palsy is the most common complication after transvenous embolization (TVE) for cavernous sinus dural arteriovenous fistula. Abducens nerve palsy is reported to have a good prognosis after the symptoms have been alleviated 5).
The inability of an eye to turn outward results in a convergent strabismus or esotropia of which the primary symptom is diplopia which is worse when looking towards the affected side.
The condition is commonly unilateral but can also occur bilaterally.
The unilateral abducens nerve palsy is the most common of the isolated ocular motor nerve palsies.