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ICD-10 Guide
DiagnosesAmyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis

ICD-10 Coding for Amyotrophic Lateral Sclerosis(G12.21)

PRIMARY SPECIALTYNeurology
COMPLEXITYHigh
LAST UPDATED09/15/2025
Sam Tuffun, PT, DPT
Physical Therapist | Medical Coding & Billing Contributor

Diagnosis Overview

What is Amyotrophic Lateral Sclerosis?
Essential facts and insights about Amyotrophic Lateral Sclerosis

Key Clinical Considerations:

  • Progressive muscle weakness and atrophy, typically starting in the hands or feet.
  • Electromyography (EMG) findings showing denervation and reinnervation.
  • Physical examination may reveal muscle fasciculations, spasticity, and hyperreflexia.
  • MRI may be used to rule out other conditions but is not diagnostic for ALS.
  • Severity is often assessed using the ALS Functional Rating Scale (ALSFRS).

Clinical Information

Clinical Criteria & Documentation Requirements

  • Complete medical history including onset and progression of symptoms.
  • Specific terminology such as 'upper motor neuron signs' and 'lower motor neuron signs' must be documented.
  • Examples include documenting muscle strength testing results and EMG findings.
  • Medical necessity must be established through documentation of functional impairments.
  • Quality measures may include tracking progression and treatment response.

Coding Guidelines

Usage Guidelines & Examples

  • Use G12.21 for patients with confirmed ALS with progressive symptoms.
  • Do not use this code for patients with other motor neuron diseases like primary lateral sclerosis (G12.22).
  • Compare with G12.22 (Primary lateral sclerosis) and G12.23 (Progressive muscular atrophy).
  • Common errors include misclassifying ALS with other neurological disorders; ensure clear documentation.
  • In complex cases, consider the patient's full clinical picture and consult coding guidelines.

Code Exclusions

Important Exclusions

  • Excludes other motor neuron diseases such as G12.22 (Primary lateral sclerosis).
  • Alternative codes for excluded conditions include G12.23 for Progressive muscular atrophy.
  • Conditions are excluded due to differing pathophysiology and treatment approaches.
  • Common mistakes include using G12.21 for patients with other neurological disorders; ensure accurate diagnosis.
  • Related but distinct conditions include myopathy and peripheral neuropathy.

Related ICD-10 Codes

Primary Codes
G12.21
Amyotrophic lateral sclerosis
G12.22
Primary lateral sclerosis
Ancillary Codes
R29.818
R25.8
Differential Codes
G12.23
G12.24

Related CPT Codes

CPT codes will be available in a future update.

Specialty Focus

Primary Specialty

Neurology

Specialty Applications

  • Patients diagnosed with ALS, typically adults aged 40-70.
  • Higher prevalence in males than females.
  • Clinical settings include neurology clinics, inpatient rehabilitation, and outpatient care.
  • Specialty-specific applications in neurology and palliative care.
  • Treatment contexts include symptom management and multidisciplinary care.

Coding Complexity

High Complexity

This diagnosis requires careful attention to:

  • Comprehensive clinical documentation
  • Accurate code selection based on clinical criteria
  • Proper exclusion considerations
  • Specialty-specific coding guidelines

Documentation

Documentation Templates

Template 1

Template: 'Patient diagnosed with amyotrophic lateral sclerosis based on clinical findings of muscle weakness and EMG results.'

Template 2

Template: 'Clinical presentation consistent with ALS including progressive muscle atrophy and fasciculations.'

Template 3

Template: 'Diagnostic criteria for ALS met as evidenced by EMG findings of denervation.'

Template 4

Template: 'Treatment plan initiated for ALS with multidisciplinary interventions including physical therapy.'

Template 5

Template: 'Follow-up care for ALS including monitoring of respiratory function and nutritional status.'

Billing Information

Billing Considerations

  • Ensure proper documentation for billing
  • Verify code specificity requirements
  • Check for any additional codes needed
  • Review payer-specific guidelines

Common Issues

  • Insufficient clinical documentation
  • Incorrect code selection
  • Missing supporting diagnoses
  • Timing and frequency documentation

Frequently Asked Questions

What documentation is required for this diagnosis?

Document clinical findings, EMG results, and progression of symptoms.

How does this differ from similar diagnoses?

ALS involves both upper and lower motor neuron signs, while primary lateral sclerosis involves only upper motor neuron signs.

What are common billing considerations?

Ensure medical necessity is documented and consider the use of modifiers for associated services.

What procedures are typically associated?

CPT codes for EMG, nerve conduction studies, and multidisciplinary evaluations.

Are there any quality reporting implications?

Quality measures may include tracking functional decline and adherence to treatment protocols.