CPT Code Overview

CPT 64645 is used to report chemodenervation of one extremity, specifically for each additional extremity involving five or more muscles. This code is listed separately in addition to the primary procedure code. The service type is destruction by neurolytic agent within the nervous system, commonly performed in an office setting (Place of Service 11). Chemodenervation procedures are utilized to manage conditions characterized by abnormal muscle tone or movement, providing targeted relief and improved function for affected extremities.

Clinical Context

A patient with a neurological condition such as spastic quadriplegic cerebral palsy, hereditary spastic paraplegia, or multiple sclerosis presents to a neurology or physical medicine and rehabilitation clinic. The patient exhibits significant muscle spasticity or dystonia in multiple extremities, affecting five or more muscles in each additional extremity. The provider determines that chemodenervation is indicated to reduce abnormal muscle tone and improve function. The procedure is performed in the office setting, targeting the affected muscles in the additional extremity using a neurolytic agent (e.g., botulinum toxin). Guidance techniques such as needle electromyography or muscle electrical stimulation may be used to ensure accurate injection. The primary procedure is coded with 64644 or 64642, and 64645 is reported for each additional extremity treated (5 or more muscles).

Coding Specifications

• Modifier 95873/95874: Used when needle electromyography or muscle electrical stimulation guidance is performed during chemodenervation. Only one guidance code should be reported per corresponding chemodenervation code.

• Modifier 50: Indicates a bilateral procedure. Modifier 50 should NOT be reported in conjunction with 64645.

Related Diagnoses

• G04.1 Tropical spastic paraplegia: Relevant for patients with progressive spasticity requiring chemodenervation.

• G11.4 Hereditary spastic paraplegia: Indicates hereditary causes of spasticity, often managed with chemodenervation.

• G24.02 Drug induced acute dystonia: Acute dystonic reactions may require chemodenervation for symptom control.

• G24.09 Other drug induced dystonia: Other dystonic movements from medications may be treated with chemodenervation.

• G24.1 Genetic torsion dystonia: Genetic dystonia syndromes often benefit from targeted muscle chemodenervation.

• G24.2 Idiopathic nonfamilial dystonia: Nonfamilial dystonia can cause abnormal muscle tone, managed with chemodenervation.

• G24.8 Other dystonia: Encompasses other dystonic disorders suitable for chemodenervation.

• G24.9 Dystonia, unspecified: Used when dystonia is present but not further specified; chemodenervation may be indicated.

• G25.89 Other specified extrapyramidal and movement disorders: Includes movement disorders that may cause spasticity or dystonia, treated with chemodenervation.

• G35.A Relapsing‑remitting multiple sclerosis: MS patients may develop spasticity requiring chemodenervation.

• G35.B0 Primary progressive multiple sclerosis, unspecified: Progressive MS can cause muscle spasticity managed with chemodenervation.

• G35.B1 Active primary progressive multiple sclerosis: Active disease may present with spasticity needing intervention.

• G35.B2 Non-active primary progressive multiple sclerosis: Even in non-active MS, spasticity may persist and require treatment.

• G35.C0 Secondary progressive multiple sclerosis, unspecified: Secondary progressive MS often leads to spasticity.

• G35.C1 Active secondary progressive multiple sclerosis: Active secondary progressive MS may require chemodenervation for spasticity.

• G35.C2 Non-active secondary progressive multiple sclerosis: Spasticity may be present even in non-active disease.

• G35.D Multiple sclerosis, unspecified: General MS diagnosis; spasticity is a common indication for chemodenervation.

• G36.0 Neuromyelitis optica [Devic]: May cause spasticity or movement disorders managed with chemodenervation.

• G36.1 Acute and subacute hemorrhagic leukoencephalitis [Hurst]: Rare demyelinating disease; chemodenervation may be used for associated spasticity.

• G36.8 Other specified acute disseminated demyelination: Demyelinating diseases can cause spasticity requiring intervention.

• G36.9 Acute disseminated demyelination, unspecified: Spasticity from demyelination may be managed with chemodenervation.

• G37.0 Diffuse sclerosis of central nervous system: Sclerosis can lead to muscle tone abnormalities.

• G37.1 Central demyelination of corpus callosum: Demyelination may result in spasticity.

• G37.2 Central pontine myelinolysis: May cause movement disorders requiring chemodenervation.

• G37.3 Acute transverse myelitis in demyelinating disease of central nervous system: Spasticity from myelitis may be treated.

• G37.4 Subacute necrotizing myelitis of central nervous system: Spasticity may be present and managed with chemodenervation.

• G37.5 Concentric sclerosis [Balo] of central nervous system: Rare sclerosis variant; chemodenervation may be indicated.

• G37.9 Demyelinating disease of central nervous system, unspecified: Spasticity from demyelinating disease may require chemodenervation.

• G80.0 Spastic quadriplegic cerebral palsy: Severe spasticity in all limbs, commonly treated with chemodenervation.

• G80.1 Spastic diplegic cerebral palsy: Spasticity in both legs; chemodenervation is often used.

• G80.2 Spastic hemiplegic cerebral palsy: Spasticity in one side; chemodenervation targets affected muscles.

• G80.3 Athetoid cerebral palsy: Involuntary movements may be managed with chemodenervation.

• G80.4 Ataxic cerebral palsy: Ataxia may coexist with spasticity.

• G80.8 Other cerebral palsy: Other forms may present with spasticity or dystonia.

• G80.9 Cerebral palsy, unspecified: General CP diagnosis; spasticity is a common indication.

• G81.11 Spastic hemiplegia affecting right dominant side: Spasticity in right dominant side; chemodenervation may be used.

• G81.12 Spastic hemiplegia affecting left dominant side: Spasticity in left dominant side; chemodenervation may be used.

• G81.13 Spastic hemiplegia affecting right nondominant side: Spasticity in right nondominant side; chemodenervation may be used.

Related CPT Codes

• 64644: Chemodenervation of one extremity; 1‑4 muscle(s). Used as the primary code for chemodenervation when 1-4 muscles are treated in one extremity.

• 64642: Chemodenervation of one extremity; 1‑4 muscle(s) (base code for upper limb). Used as the base code for upper limb chemodenervation when 1-4 muscles are treated.

• 64646: Chemodenervation of trunk muscle(s). Used when chemodenervation is performed on trunk muscles.

• 64647: Chemodenervation of trunk muscle(s); each additional trunk muscle group (add‑on). Used as an add-on code for each additional trunk muscle group treated.

Clinical Workflow Relation:

• 64644 or 64642 are typically reported as the primary procedure for chemodenervation of 1-4 muscles in one extremity.
• 64645 is reported for each additional extremity treated (5 or more muscles), in addition to the primary code.
• 64646 and 64647 are used when trunk muscles are targeted, either alone or in combination with extremity codes, depending on the clinical scenario.
• These codes may be used together when multiple muscle groups across extremities and trunk are treated in a single session.

For CPT code 64645, the national mean rate for Medicare is $132.75, while the BUCA (average commercial) mean rate is $145.90. Commercial payers such as UnitedHealth Group and Cigna report higher mean rates, with UnitedHealth Group at $191.19 and Cigna at $178.15, compared to Medicare.

Rate dispersion, measured as the difference between the 75th and 25th percentiles, varies significantly across payers. Medicare exhibits the tightest range at $14.00, indicating relatively consistent reimbursement rates. In contrast, UnitedHealth Group shows the widest dispersion at $107.00, followed by Cigna at $97.17, reflecting greater variability in commercial reimbursement.

The table and chart below present the full breakdown of national benchmarks for CPT code 64645 across major payers.