Top 10 neurology-related diagnosis codes

There are 69,101 ICD-10 codes for neurology related diagnoses. A seemingly endless number of devices and pharmaceuticals can help treat various neurological or central nervous system conditions.

Neurological disorders can lead to disability and hospitalization, especially for aging individuals. Age plays a role in the increasing frequency and severity of neurological diseases, and it can also contribute to the progression of an existing disease.

ICD-10 codes for diseases of the central nervous system start with ‘G’. In recognition of Alzheimer’s and brain awareness month, we put together a list of the top neurology or central nervous system related diagnosis ICD-10 codes.

Top 10 neurology-related diagnosis codes by volume in 2021

ICD-10 Code 

ICD-9 Code 

ICD-10 Description 

# Total Diagnoses 

% Total Diagnoses 

# Principal Diagnoses 

% Principal Diagnoses 

G35 

340 

Multiple sclerosis 

547,259 

5.40% 

482,799 

8.10% 

G20 

3320 

Parkinson's disease 

477,799 

4.70% 

379,495 

6.40% 

G4733 

32723 

Obstructive sleep apnea (adult) (pediatric) 

542,037 

5.40% 

379,268 

6.40% 

G40909 

34590 

Epilepsy, unspecified, not intractable, without status epilepticus 

346,570 

3.40% 

247,867 

4.20% 

G43709 

34670 

Chronic migraine without aura, not intractable, without status migrainosus 

309,884 

3.10% 

244,836 

4.10% 

G43719 

34671 

Chronic migraine without aura, intractable, without status migrainosus 

256,455 

2.50% 

209,053 

3.50% 

G43009 

34610 

Migraine without aura, not intractable, without status migrainosus 

278,197 

2.70% 

176,613 

3.00% 

G9340 

34830 

Encephalopathy, unspecified 

235,761 

2.30% 

137,992 

2.30% 

G629 

3579 

Polyneuropathy, unspecified 

306,953 

3.00% 

137,956 

2.30% 

G40209 

34540 

Localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with complex partial seizures, not intractable, without status epilepticus 

175,744 

1.70% 

131,877 

2.20% 

Fig 1.  Data is from the Definitive Healthcare ClaimsMx product. Data is accurate as of June 2022. 

What are the most common neurological disorders?

In 2021, Multiple Sclerosis (ICD-10 code G35), had the highest prevalence of diagnoses in this grouping, with 482,799 principal diagnoses and 547,259 total diagnoses. Also known as MS, it’s a potentially disabling disease of the brain and spinal cord (central nervous system). This condition causes the immune system to attack the protective sheath (myelin) that covers nerve fibers causes Inflammation and lesions, making it difficult for the brain to send signals to the rest of the body. Eventually, the disease can cause permanent damage or deterioration of the nerves.

MS can occur at any age, however onset typically occurs between 20 and 40 years of age. Both younger and older people can be affected. Women are more than two to three times as likely as men are to have relapsing-remitting MS. There are other risk factors as well including family history of MS, having certain types of infections such as Epstein-Barr, low vitamin-D levels, and certain autoimmune diseases.

Parkinson’s disease ranked as the second most common disorder diagnosis in 2021 (ICD-10 code G20). Parkinson's disease is a progressive nervous system disorder that affects movement. Symptoms start gradually, sometimes starting with a barely noticeable tremor in just one hand. Tremors are common, but the disorder also commonly causes stiffness or slowing of movement¹. Parkinson’s disease is rarely seen in young adults, typically developing at 60 years of age or older. Men are statistically more likely to be stricken with the disease and those who are regularly exposed to pesticides or herbicides may also be at increased risk.

Additional problems may be seen with Parkinson’s, including cognitive problems, depression and emotional changes, swallowing problems, chewing and eating problems, sleep problems and sleep disorders, rapid eye movement sleep behavior disorder, bladder problems and constipation.

How does the central nervous system work?

The nervous system coordinates the body’s actions and sensory information by transmitting signals to and from different parts of the body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to these events.

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1. Mayo Clinic. “Parkinson's Disease.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 24 Mar. 2022, https://www.mayoclinic.org/diseases-conditions/parkinsons-disease/symptoms-causes/syc-20376055. 

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