Chapter G00-G99
Diseases of the nervous system
This chapter includes disorders affecting the brain, spinal cord, and peripheral nerves. Conditions such as epilepsy, multiple sclerosis, Parkinson’s disease, and migraine are coded here. It also includes inflammatory nervous system diseases (like meningitis) when not classified as infectious elsewhere. Neuropathies, nerve compression syndromes (e.g., carpal tunnel), and demyelinating diseases fall within this range.
Because the nervous system controls motor function, sensation, cognition, and autonomic regulation, disorders here can cause wide-ranging symptoms. Precise coding helps distinguish acute vs. chronic neurological conditions and specific nerve involvement.
Clinical & Coding Guidelines
Excludes2 (Partial exclusion)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Subordinate Sections
Inflammatory diseases of the central nervous system
G00-G09
Systemic atrophies primarily affecting the central nervous system
G10-G14
Extrapyramidal and movement disorders
G20-G26
Other degenerative diseases of the nervous system
G30-G32
Demyelinating diseases of the central nervous system
G35-G37
Episodic and paroxysmal disorders
G40-G47
Nerve, nerve root and plexus disorders
G50-G59
Polyneuropathies and other disorders of the peripheral nervous system
G60-G65
Diseases of myoneural junction and muscle
G70-G73
Cerebral palsy and other paralytic syndromes
G80-G83
Other disorders of the nervous system
G89-G99