2026 ICD-10-CM Diagnosis Code R29.818Other symptoms and signs involving the nervous system

ICD-10-CM Codes›R00–R99›R25-R29›R29

ICD-10-CM R29.818
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

R29.818 is a billable ICD-10-CM diagnosis code for other symptoms and signs involving the nervous system. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nervous system signs and symptoms.

Code Identity

ICD-10-CM Code
R29.818
Billable Status
Yes — Valid for Submission
Code Describes
Other symptoms and signs involving the nervous system
Short Description
Other symptoms and signs involving the nervous system
Same as the full description in the CMS dataset.
Parent Code
R29.81
Other symptoms and signs involving the nervous system

Code Classification

ChapterR00–R99Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
SectionR25-R29Symptoms and signs involving the nervous and musculoskeletal systems
CategoryR29Other symptoms and signs involving the nervous and musculoskeletal systems
This CodeR29.818Other symptoms and signs involving the nervous system

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Abnormal findings on diagnostic imaging of skull and head
  • Abnormal neurovascular status of distal limb
  • Abnormality of myotome
  • Absence of receptor sites
  • Alopecia, progressive neurological defect, endocrinopathy syndrome
  • Alteration in tissue perfusion
  • Arthropathy of the elbow associated with a neurological disorder
  • Autosomal recessive cerebellar ataxia, pyramidal signs, nystagmus, oculomotor apraxia syndrome
  • Barany's sign
  • Barber's chair sign
  • Barber's chair sign positive
  • Bilateral deficit of nervous system structures
  • Brudzinski's sign positive
  • Bulbar neurological symptom
  • Bulging fontanelle
  • Cerebrospinal fluid flow finding
  • Chvostek sign positive
  • Congenital nystagmus
  • Congenital nystagmus with sensory abnormality
  • Cord sign
  • Crossed laterality
  • Decrease in receptor sites
  • Decreased intracranial pressure adaptive capacity
  • Decreased pain threshold
  • Difficulty accepting base of support
  • Difficulty performing oral motor functions
  • Does not accept base of support
  • Does not move blade of tongue
  • Does not perform oral motor functions
  • Effects of lightning
  • Empty delta sign
  • Extrapyramidal sign
  • Filling defect
  • Finding of intracranial pressure
  • Finding related to ability to accept base of support
  • Finding related to ability to move blade of tongue
  • Finding related to neurovascular status of limb
  • Flail arm
  • Flail motion
  • Fluctuation of cerebral spinal fluid
  • Froment's sign positive
  • Hippocampal pressure groove
  • Hoover sign of lower limb
  • Impaired peripheral neurovascular function
  • Increase in receptor sites
  • Ineffective tissue perfusion
  • Inequality in size of cerebral ventricles
  • Kernig's sign positive
  • Level of fontanelle - finding
  • Long tract sign
  • Low pain threshold
  • Midline shift of brain
  • Named sensory sign
  • Neck pain co-occurrent with neurological deficit following whiplash injury to neck
  • Nervous system problem
  • Neurodisability
  • Neurological complication following vaccination
  • Neurological deficit
  • Neurological disorder due to obesity
  • Neurological disorder monitoring status
  • Neurological drug side effects
  • Neurological injury from lightning
  • Neuronal depopulation
  • Neurovascular deficit
  • No reactive accommodation reflex
  • Orthostatic intolerance
  • Pain threshold - finding
  • Past pointing present
  • Piebald trait with neurologic defects syndrome
  • Pronator drift
  • Pseudoparalysis
  • Pseudoparalysis due to generalized arthritis
  • Pyramidal sign
  • Receptor site alteration
  • Reduced flow of cerebrospinal fluid
  • Romberg's sign positive
  • Spinal atrophy, ophthalmoplegia, pyramidal syndrome
  • Surface receptor redistribution
  • Tinel's sign positive
  • Transient monoplegia
  • Unable to accept base of support
  • X-linked intellectual disability with hypogammaglobulinemia and progressive neurological deterioration syndrome

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Deficit
      • neurologic NEC
    • Depression(acute) (mental)
      • cerebral
    • Disorder(of)
      • neurological NEC
    • Hypofunction
      • cerebral
    • Monoplegia
      • transient
    • Paralysis, paralytic(complete) (incomplete)
      • leg
        • transient or transitory
    • Paralysis, paralytic(complete) (incomplete)
      • transient
        • arm or leg NEC
    • Problem(with) (related to)
      • neurological NEC
    • Pseudoparalysis
      • arm or leg
    • Symptoms NEC
      • involving
        • nervous system
          • specified NEC

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR SYM010
Nervous system signs and symptoms
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Orthostatic Intolerance

    symptoms of cerebral hypoperfusion or autonomic overaction which develop while the subject is standing, but are relieved on recumbency. types of this include neurocardiogenic syncope; postural orthostatic tachycardia syndrome; and neurogenic orthostatic hypotension. (from noseworthy, jh., neurological therapeutics principles and practice, 2007, p2575-2576)

Patient EducationClinical

Neurologic Diseases

The brain, spinal cord, and nerves make up the nervous system. Together they control all the workings of the body. When something goes wrong with a part of your nervous system, you can have trouble moving, speaking, swallowing, breathing, or learning. You can also have problems with your memory, senses, or mood.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert R29.818 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
781.99 Nerve/musculskel sym NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About R29.818Overview

Is R29.818 (Other symptoms and signs involving the nervous system) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other symptoms and signs involving the nervous system on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Can R29.818 be a principal diagnosis?

Use it with care. This is a symptom code, so once a definitive diagnosis explaining the other symptoms and signs involving the nervous system is established, that condition takes the principal position instead.

What is the ICD-9 equivalent of R29.818?

Under the General Equivalence Mappings, other symptoms and signs involving the nervous system converts to ICD-9-CM 781.99 (nerve/musculskel sym NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.