neurologic disorders
Sixth Cranial (Abducens) Nerve Palsy
Diagnosis of Sixth Cranial Nerve Palsy
MRI (or CT) If vasculitis is suspected, erythrocyte sedimentation rate (ESR), antinuclear antibodies, and rheumatoid factor A 6th nerve palsy is usually obvious, but the cause is not. If retinal venous pulsations are seen during ophthalmoscopy, increased ICP is unlikely. CT is often done because it is often immediately available. However, MRI is the test of choice; MRI provides greater resolution of the orbits, cavernous sinus, posterior fossa, and cranial nerves. If imaging results are normal but meningitis or benign intracranial hypertension is suspected, lumbar puncture is done. If vasculitis is suspected clinically, evaluation begins with measurement of ESR, antinuclear antibodies, and rheumatoid factor. Other tests may be done depending on the suspected cause of 6th cranial nerve palsy. In children, if increased ICP is excluded, an upper respiratory infection may be the cause of 6th nerve palsy. 