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2025 ICD-10-CM code G99

Other disorders of nervous system in diseases classified elsewhere.

G99 should never be used as the primary diagnosis code.It must be used in conjunction with a code for the underlying disease. Use the most specific code available within the G99 series when applicable.

Medical necessity for the services related to the neurological disorder should be supported by documentation of the severity of the condition and its impact on the patient's function.

Clinicians should diagnose these conditions based on medical history, signs, symptoms, physical and neurological examination. Laboratory studies (e.g., CBC, chemistry profiles) and diagnostic studies (e.g., EMG, NCS, MRI, myelography, EEG) may be necessary.

IMPORTANT More specific codes exist within the G99 category (G99.0-G99.8) for autonomic neuropathy (G99.0, G99.1) and myelopathy (G99.2) among others.Always use the most specific code available.

In simple words: This code is used when someone has a nervous system problem that's part of another disease.The main disease is coded first, then this code is added to show the nervous system is also affected.

This code encompasses neurological disorders that occur as a component of other systemic diseases classified elsewhere. The primary disease should be coded first, followed by G99 to specify the neurological involvement.

Example 1: A patient with diabetes develops autonomic neuropathy affecting their heart rate and digestion. Diabetes is coded first, followed by G99.0 for autonomic neuropathy in endocrine and metabolic diseases. , A patient with cancer develops myelopathy due to spinal cord compression.The cancer diagnosis is coded first, and G99.2 is added to specify the myelopathy., A patient with lupus experiences neurological symptoms.The lupus diagnosis is coded first, followed by the appropriate G99 code specifying the neurological manifestation (if a more specific code is not available).

Documentation should clearly establish the connection between the underlying disease and the nervous system disorder.Include all relevant diagnostic test results, clinical findings, and the physician's assessment.

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