H49.12 Fourth [trochlear] nerve palsy, left eye

Billable ICD-10-CM code, FY2026.

Applies from H49 Paralytic strabismus

Excludes2 (not included here)

• internal ophthalmoplegia (H52.51-)
• internuclear ophthalmoplegia (H51.2-)
• progressive supranuclear ophthalmoplegia (G23.1)

MS-DRG index

Defines the logic of DRG(s) 123 in MDC 02.

Approximate ICD-9-CM (GEMs)

• 378.53 Fourth or trochlear nerve palsy (approximate)

Code annotations containing back-references to H49.12

Back-references to H49.1

• Type 2 Excludes: G52 Disorders of other cranial nerves ("paralytic strabismus due to nerve palsy (H49.0-H49.2)")

Nearby codes

• H49.02 Third [oculomotor] nerve palsy, left eye
• H49.03 Third [oculomotor] nerve palsy, bilateral
• H49.1 Fourth [trochlear] nerve palsy
• H49.10 Fourth [trochlear] nerve palsy, unspecified eye
• H49.11 Fourth [trochlear] nerve palsy, right eye
• H49.12 Fourth [trochlear] nerve palsy, left eye (this code)
• H49.13 Fourth [trochlear] nerve palsy, bilateral
• H49.2 Sixth [abducent] nerve palsy
• H49.20 Sixth [abducent] nerve palsy, unspecified eye
• H49.21 Sixth [abducent] nerve palsy, right eye
• H49.22 Sixth [abducent] nerve palsy, left eye