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Coding for Nervous System Diagnoses – ICD-10-CM Compared to ICD-9-CM – PART 1

Among the various improvements to ICD-10-CM is the addition of two new chapters to represent the eye and adnexa, and the ear and mastoid process.

In ICD-9-CM all diseases of the nervous system, including the eye/adnexa and the ear/mastoid processes, are represented in chapter 6. In ICD-10-CM only those diseases of the nervous system are represented in chapter 6. Diseases of the sense organs each have their own chapter in ICD-10-CM.

Chapter 6 of ICD-10-CM includes categories G00-G99, diseases of the nervous system, arranged in blocks. Here is a quick glimpse at those blocks:

G-00-G09  Inflammatory diseases of the central nervous system

G10-G14   Systemic atrophies primarily affecting the central nervous system

G20-G26   Extrapyramidal and movement disorders

G30-G32   Other degenerative diseases of the nervous system

G35-G37   Demyelinating diseases of the nervous system

G40-G47   Episodic and Paroxysmal disorders

G50-G59   Nerve, nerve root and plexus disorders

G60-G65   Polyneuropathies and other disorders of the peripheral nervous


G70-G73   Diseases of the myoneural junction and muscle

G80-G83   Cerebral Palsy and other paralytic syndromes

G89-G99   Other disorders of the nervous system

Chapter 7 of ICD-10-CM is an entirely new chapter. Chapter 7 represents the diseases of eyes and adnexa, formerly appearing in chapter 6 with the diseases of the nervous system in ICD-9-CM. Chapter 7 includes categories H00-H59 arranged in the following blocks.

Here is a quick glimpse at those blocks:

H00-H05  Disorders of the eyelid, lacrimal system and orbit

H1-H11    Disorders of the conjunctiva

H15-H22  Disorders of the sclera, cornea, iris and ciliary body

H25-H28  Disorders of the lens

H30-H36  Disorders of the choroid and retina

H40-H42  Glaucoma

H43-H44  Disorders of the vitreous body and globe

H46-H47  Disorders of the optic nerve and visual pathways

H49-H52  Disorders of ocular muscles, binocular movement, accommodation and


H53-H54  Other disorders of the eye and adnexa

H59           Intraoperative and postprocedural complications and disorders of the eye

and Adnexa, not elsewhere classified

Finally, chapter 8 also is entirely new in ICD-10-CM. This chapter of diseases of the ear and mastoid process includes categories H60-H95 represented in the following blocks. The arrangement of these blocks makes it easier to identify the types of conditions that occur in the external ear (block 1), middle ear (block 2), and inner ear (block 3).

Here is a quick glimpse at those blocks:

H60-H62  Diseases of the external ear

H65-H75  Diseases of the middle ear and mastoid

H80-H83  Diseases of the inner ear

H90-H94  Other disorders of the ear

H95          Intraoperative and post-procedural complications and disorders of ear and

mastoid process, Not elsewhere classified

Each one of these chapters encompasses quite a few changes. The changes include greater specificity, the delineation of laterality, and several more “code first underlying disease” notes, with the addition also of bilateral sides for diseases of the eye and adnexa.

In the currently published version of ICD-10-CM, we have chapter-specific guidelines related to chapter 6 (diseases of the nervous system) and chapter 7 (diseases of the eye and adnexa), but do not have chapter-specific guidelines for chapter 8 (diseases of the ear and mastoid process).

In the articles to follow, we will dive into each one of these chapters to look at the specific differences, changes, and updates to terminology.

Stay tuned!

For more ICD-10 articles, please visit our ICD-10 Updates page.

— Compiled by former CIPROMS ICD-10 Coordinator, Angela Hickman, CPC, CEDC, AHIMA-Approved ICD-10 CM/PCS Trainer, AHIMA Ambassador. All rights reserved. For use or reprint in your blog, website, or publication, please contact us at cipromsmarketing@ciproms.com.


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