Third [oculomotor] nerve palsy, bilateral

This code signifies a complete or partial paralysis of the third cranial nerve affecting both eyes. This condition impairs the function of several extraocular muscles, leading to symptoms such as ptosis, ophthalmoplegia (inability to move the eye in certain directions), and pupillary abnormalities.

Apply this code when documentation clearly indicates bilateral involvement of the oculomotor nerve palsy. This diagnosis is typically supported by neurological examination findings demonstrating impaired adduction, elevation, and depression of both eyes, often accompanied by bilateral ptosis and dilated pupils.

• Ensure documentation specifies "bilateral" involvement; otherwise, a unilateral code (H49.01 or H49.02) or unspecified code (H49.00) may be more appropriate.
• Distinguish from other cranial nerve palsies, particularly abducens (sixth nerve) or trochlear (fourth nerve) palsies, which affect different eye movements.
• Always look for and code any underlying cause of the third nerve palsy, such as aneurysm, tumor, or diabetes, if documented.