G12.21

🧠 ICD-10 CM G12.21 — Amyotrophic Lateral Sclerosis (ALS)

Billable Code Confirmed

ICD-10 CM G12.21 is a valid, billable 5-character ICD-10-CM code for FY2025. The code structure is: G12 (category — Spinal muscular atrophy and related syndromes) + .2 (subcategory — Motor neuron disease) + 1 (5th character — Amyotrophic lateral sclerosis). No 6th or 7th character is required. This code is valid for claims submission from October 1, 2024 through September 30, 2025.

⭐ HCC 73 High-Priority Capture: G12.21 maps to CMS-HCC v28 Category 73 — one of the highest-weight neurological HCC categories. This code must be documented and coded at every eligible encounter where ALS is actively managed.

Non-Billable Parent Codes — Never Submit These

• ❌ G12.2 — 4-character subcategory header — missing the specific motor neuron disease type; not billable
• ❌ G12 — 3-character category — no specificity; not billable

Always submit G12.21 (all 5 characters) for ALS. Note: if the provider documents familial or hereditary ALS, G12.24 (Familial motor neuron disease) — added in FY2022 — is the more specific code. See [!important] below.

Critical Distinction: ALS Subtype Specificity — G12.21 vs. G12.22 vs. G12.23 vs. G12.24

Effective FY2022, ICD-10-CM expanded the G12.2x subcategory to include separate codes for distinct motor neuron disease subtypes. Coding accuracy requires differentiating these conditions based on provider documentation:

Code	Description	Key Clinical Features	When to Use
G12.21	Amyotrophic lateral sclerosis	Mixed UMN + LMN degeneration; limb-onset or bulbar-onset; sporadic (~90% of all ALS)	When provider documents “ALS,” “Lou Gehrig’s disease,” or “amyotrophic lateral sclerosis” without specifying familial origin
G12.22	Progressive bulbar palsy	Predominantly bulbar motor neuron involvement; dysarthria, dysphagia, dysphonia early; LMN predominance	When provider specifically documents “progressive bulbar palsy” as a distinct diagnosis
G12.23	Primary lateral sclerosis	Pure UMN degeneration only; slowly progressive spasticity; NO lower motor neuron signs; longer survival than ALS	When provider documents “primary lateral sclerosis (PLS)” specifically
G12.24	Familial motor neuron disease	Hereditary/genetic ALS (~10%); includes SOD1-ALS, C9orf72-ALS, FUS-ALS, TDP-43-ALS; family history established	When provider documents “familial ALS,” “hereditary ALS,” or genetic mutation (SOD1, C9orf72) confirmed
G12.20	Motor neuron disease, unspecified	No specific subtype documented	Avoid if subtype is specified; use only when provider cannot clinch a specific MND diagnosis

Most Important FY2022 Change: Before FY2022, ALL ALS — both sporadic and familial — was coded as G12.21. Since FY2022, familial/hereditary ALS must be coded as G12.24. CDI teams should query the provider when genetic testing (SOD1, C9orf72) is positive and the family history is documented — this changes the code from G12.21 to G12.24.

ALS with Frontotemporal Dementia (ALS-FTD): Approximately 15% of ALS patients develop frontotemporal dementia. Code G12.21 PLUS F02.80 or F02.81 (Dementia in other diseases classified elsewhere) as an additional diagnosis when the provider documents cognitive or behavioral symptoms meeting FTD criteria.

🔍 Code Description

ICD-10-CM G12.21 classifies amyotrophic lateral sclerosis (ALS) — a relentlessly progressive, fatal neurodegenerative disease characterized by the simultaneous degeneration of both upper motor neurons (UMN) (in the motor cortex and corticospinal tract) and lower motor neurons (LMN) (in the anterior horn of the spinal cord and brainstem motor nuclei). The combined loss of both motor neuron systems produces the hallmark clinical combination of:

• UMN signs: Spasticity, hyperreflexia, clonus, Babinski sign, pseudobulbar affect
• LMN signs: Fasciculations, muscle atrophy, hyporeflexia, weakness, cramps, tongue atrophy

ALS is relentlessly progressive with a median survival of 2-5 years from symptom onset. Respiratory failure — due to diaphragm and intercostal muscle denervation — is the leading cause of death in approximately 80% of cases. Cognition, sensation, eye movements, and bladder function are spared in classic ALS, unlike many other neurodegenerative diseases.

Epidemiology and risk factors relevant to coding:

• Incidence: ~5,000 new U.S. diagnoses annually; prevalence ~30,000
• Peak onset: 55-75 years (sporadic ALS); younger onset in familial forms
• Male:female ratio approximately 1.5:1
• Sporadic ALS (~90%): G12.21 — no family history or identified genetic cause
• Familial ALS (~10%): G12.24 — C9orf72 expansion (most common), SOD1, FUS, TDP-43 mutations

Clinical milestones driving additional diagnoses to code:

Disease Stage	Clinical Development	Additional ICD-10-CM to Capture
Early	Focal limb weakness, fasciculations, mild dysarthria	G12.21 as the only diagnosis
Moderate	Dysphagia, significant dysarthria, dyspnea on exertion	R13.10 Dysphagia; R06.09 Dyspnea
Advanced	Respiratory failure, malnutrition, PEG/trach dependent	J96.10 Chronic resp. failure; E44.0 Malnutrition
End-stage	Ventilator dependence, total paralysis, anarthria	Z99.11 Ventilator dependence; palliative codes
Any stage with FTD	Cognitive/behavioral changes (15% of patients)	F02.80 Dementia in other classified disease

Note

Tofersen (Qalsody) and SOD1-ALS Specificity: In 2023, the FDA approved tofersen (Qalsody) — the first intrathecal antisense oligonucleotide therapy approved specifically for SOD1-mutation ALS. When a patient receives tofersen, the provider must have confirmed SOD1 gene mutation. This specific genetic diagnosis should be coded as G12.24 (Familial motor neuron disease) in ICD-10-CM, not G12.21, because SOD1-ALS is a genetically defined familial/hereditary form. Documentation of the SOD1 mutation supports G12.24 coding and is essential for prior authorization of tofersen.

🌳 Code Tree / Hierarchy

G10-G14  Systemic Atrophies Primarily Affecting the Central Nervous System ❌ Block
│
└── G12  Spinal muscular atrophy and related syndromes ❌ Non-billable
    │
    ├── G12.0  Infantile spinal muscular atrophy, type I (Werdnig-Hoffmann disease) ✅
    │
    ├── G12.1  Other inherited spinal muscular atrophy ✅
    │          (Includes: Fazio-Londe disease; progressive bulbar palsy of childhood;
    │           Wohlfart-Kugelberg-Welander; distal SMA; scapuloperoneal form SMA;
    │           X-linked SMA type 2)
    │
    ├── G12.2  Motor neuron disease ❌ Non-billable subcategory header
    │   │
    │   ├── G12.20  Motor neuron disease, unspecified ✅ Billable
    │   │           (Avoid — use specific MND code when type is documented)
    │   │
    │   ├── G12.21  AMYOTROPHIC LATERAL SCLEROSIS ◀ THIS CODE ✅
    │   │           [Sporadic ALS; Lou Gehrig's disease; Charcot's disease]
    │   │           [HCC 73 — High-weight HCC; re-code every encounter]
    │   │
    │   ├── G12.22  Progressive bulbar palsy ✅ Billable
    │   │           (Distinct from ALS; bulbar-predominant LMN degeneration)
    │   │
    │   ├── G12.23  Primary lateral sclerosis ✅ Billable (added FY2022)
    │   │           (Pure UMN syndrome; much slower progression than ALS;
    │   │            NO LMN signs; may survive decades)
    │   │
    │   ├── G12.24  Familial motor neuron disease ✅ Billable (added FY2022)
    │   │           (Hereditary ALS — SOD1, C9orf72, FUS, TDP-43 mutations;
    │   │            ALSO HCC 73; use for genetic/familial ALS instead of G12.21)
    │   │
    │   └── G12.29  Other motor neuron disease ✅ Billable
    │               (Includes progressive muscular atrophy; flail arm/flail leg
    │                variants when not specifically coded elsewhere)
    │
    ├── G12.8  Other spinal muscular atrophies and related syndromes ✅
    │          (Benign focal amyotrophy; Hirayama disease)
    │
    └── G12.9  Spinal muscular atrophy, unspecified ✅
               (Avoid — use specific code)

✅ Includes

The following clinical terms and documentation phrases are captured by G12.21:

• Amyotrophic lateral sclerosis (ALS) — sporadic type
• Lou Gehrig’s disease (eponymous reference; alphabetic index directs to G12.21)
• Charcot’s disease — when used in the context of ALS (not Charcot-Marie-Tooth disease, which is G60.0)
• Motor neuron disease — amyotrophic type
• Limb-onset ALS (arm or leg onset with later bulbar involvement)
• Bulbar-onset ALS (speech/swallowing onset with later limb involvement; distinct from progressive bulbar palsy G12.22)
• Classical ALS (both UMN and LMN involvement, non-familial)
• ALS with pseudobulbar affect (emotional lability from UMN involvement; code ALS only; pseudobulbar affect is a manifestation, not separately coded unless explicitly separately managed)
• ALS with cognitive impairment (code F02.80/F02.81 additionally when FTD is documented)

❌ Excludes

Excludes at G12 Category Level — Cannot be Coded Instead of G12.21

The following conditions at the G12 category have no explicit Excludes1/Excludes2 notes that would prevent their co-coding with G12.21, but they represent distinct diagnoses that should NOT be assigned as alternatives or equivalents:

• G12.22 — Progressive bulbar palsy: When provider documents this specific variant, G12.22 is correct — NOT G12.21; these may coexist in a single patient if both lower bulbar LMN disease AND spinal ALS are documented
• G12.23 — Primary lateral sclerosis: Pure UMN syndrome; absence of LMN signs is diagnostic; do NOT use G12.21 when provider explicitly documents PLS
• G12.24 — Familial motor neuron disease: Effective FY2022, hereditary/genetic ALS must be coded here, NOT as G12.21; failure to update from G12.21 to G12.24 when genetic confirmation is documented constitutes under-coding

Key Differential Diagnoses — Do Not Substitute These for G12.21

• G60.0 — Hereditary motor and sensory neuropathy (Charcot-Marie-Tooth): “Charcot’s disease” can refer to either ALS or CMT; context and provider intent determine the code; confirm with provider before assigning
• G35.- — Multiple sclerosis: May mimic ALS early; once ALS is confirmed, G12.21 is correct; do NOT use G35.- unless provider explicitly documents MS
• G71.00-G71.09 — Muscular dystrophies: Distinct neuromuscular conditions; progressive muscle weakness with different pathophysiology

Conditions That Should Be Coded IN ADDITION to G12.21

The following are NOT Excludes — they represent common, codeable complications and comorbidities of ALS that must be separately captured:

Additional ICD-10-CM	Clinical Scenario	Code Type
J96.10	Chronic respiratory failure without hypoxia	Secondary — respiratory muscle weakness
J96.11	Chronic respiratory failure with hypoxia	Secondary — advanced respiratory involvement
J96.00	Acute respiratory failure without hypoxia	Secondary/Principal — acute decompensation
J69.0	Pneumonitis due to inhalation of food/vomit (aspiration pneumonia)	Secondary — dysphagia complication
R13.10	Dysphagia, unspecified	Secondary — bulbar ALS involvement
E44.0, E44.1	Moderate/Mild protein-calorie malnutrition	Secondary — dysphagia-related weight loss
Z99.11	Dependence on respirator (ventilator)	Secondary — when mechanically ventilated
F02.80, F02.81	Dementia in other diseases classified elsewhere	Secondary — ALS-FTD; ~15% of ALS patients
G12.24	Familial motor neuron disease	Replace G12.21 entirely when familial
Z86.19	Personal history of other infectious and parasitic diseases	As contextually appropriate

🛠️ CPT Procedural Crosswalk — wRVU & Assistant Payable Status

ALS management is multidisciplinary. Diagnostic workup uses EMG/NCS to confirm the clinical diagnosis; ongoing management involves neurology, pulmonology (respiratory monitoring), gastroenterology (PEG), SLP (swallowing, communication), and palliative care. Three disease-modifying drugs are FDA-approved as of 2026.

Diagnostic Procedures

CPT / HCPCS	Description	wRVU (Facility)	Asst. Payable?	Co-Surgeon?
95864	Needle electromyography (EMG); 4 extremities — cornerstone electrodiagnostic study for ALS diagnosis; confirms LMN degeneration in multiple spinal cord regions per El Escorial/Gold Coast criteria	2.17	❌ No	❌ No
95860	Needle EMG; 1 extremity	1.20	❌ No	❌ No
95866	Needle EMG; thoracic paraspinal muscles — critical for demonstrating thoracic region involvement in ALS diagnosis	0.50	❌ No	❌ No
95865	Needle EMG; larynx — bulbar involvement assessment	0.60	❌ No	❌ No
95913	Nerve conduction studies (NCS); 7 or more studies — to exclude mimics (multifocal motor neuropathy, Kennedy disease)	2.09	❌ No	❌ No
94010	Spirometry — forced vital capacity (FVC) monitoring; critical for respiratory management decisions (BiPAP initiation at FVC <50%); recommended every 3 months	0.25	❌ No	❌ No
94150	Vital capacity (absolute) — simpler respiratory measure in patients unable to perform full spirometry	0.17	❌ No	❌ No

FDA-Approved Treatments & Drug Codes

CPT / HCPCS	Description	wRVU	Notes
96365	IV infusion, therapeutic; initial hour — for edaravone (Radicava) or tofersen (Qalsody) infusion administration	0.17	❌ No
96366	IV infusion; each additional hour (add-on to 96365)	0.10	❌ No
J3262	Injection, edaravone, 1 mg — FDA-approved disease-modifying therapy; standard dose 60 mg (60 units of J3262) IV infusion; report units per mg administered	N/A (drug)	—
J3590	Unclassified drugs — for tofersen (Qalsody) until a specific HCPCS J-code is assigned; intrathecal antisense oligonucleotide; approved 2023 for SOD1-ALS only; requires G12.24 as diagnosis, not G12.21	N/A (drug)	—

⚠️ Riluzole (Rilutek/Exservan) Billing Note: Riluzole is an oral medication (tablet or oral film) and has no infusion J-code. It is covered under the Medicare Part D pharmacy benefit and commercial pharmacy benefit — not Part B. No CPT or HCPCS administration code applies to oral riluzole. It is NOT billed by the physician office as a drug infusion.

⚠️ Tofersen Diagnosis Code Alert: Tofersen (Qalsody) is FDA-approved only for SOD1-mutation ALS. When billing J3590 for tofersen, the primary diagnosis code must be G12.24 (Familial motor neuron disease, reflecting the SOD1 genetic etiology) — NOT G12.21. Using G12.21 for a tofersen claim will likely result in a coverage denial and/or a payer audit.

Procedural / Interventional Procedures

CPT / HCPCS	Description	wRVU (Facility)	Asst. Payable?	Co-Surgeon?
43246	Upper GI endoscopy with placement of percutaneous gastrostomy tube (PEG) — indicated when dysphagia leads to weight loss or aspiration risk; recommended at FVC ≥50% for safety	4.22	❌ No (Indicator 0)	❌ No
92610	Evaluation of oral and pharyngeal swallowing function (MBSS/clinical evaluation) — SLP assessment for dysphagia in ALS	0.98	❌ No	❌ No
92526	Treatment of swallowing dysfunction — SLP dysphagia treatment	0.98	❌ No	❌ No
94660	Continuous positive airway pressure ventilation (CPAP) initiation — or BiPAP initiation for respiratory muscle weakness	0.45	❌ No	❌ No
31600	Tracheostomy, emergency — for acute airway loss or long-term ventilator dependence	8.25	✅ Yes (Indicator 1)	❌ No
99291	Critical care, first 30-74 minutes — for acute respiratory failure/aspiration pneumonia in ALS	4.50	❌ No	❌ No
99292	Critical care, each additional 30 minutes	2.25	❌ No	❌ No

E/M and Multidisciplinary Coordination

CPT	Description	wRVU	Notes
99215	Office visit, high complexity — multidisciplinary ALS clinic visit; complex decision-making with multiple systems involved	2.11	—
99214	Office visit, moderate complexity — established ALS patient follow-up	1.50	—
99497	Advance care planning, first 30 minutes — essential component of ALS care; AAN quality measure	1.50	—
99498	Advance care planning, each additional 30 minutes (add-on to 99497)	1.40	—

💊 Coding Scenarios

Scenario 1 — New ALS Diagnosis, Outpatient Neurology

Clinical Vignette: A 62-year-old male is referred to neurology for 8 months of progressive right hand weakness, muscle twitching, and slurred speech. On examination: fasciculations in bilateral upper extremities, tongue; hyperreflexia in all four limbs with Babinski sign bilaterally; and right thenar atrophy. EMG demonstrates active and chronic denervation in 3 spinal cord regions plus bulbar region. MRI brain and spine are unremarkable. Neurologist documents “Amyotrophic lateral sclerosis — sporadic, limb and bulbar onset.” Riluzole 50 mg BID is initiated.

CPT / HCPCS Codes:

• 99215 — Office visit, high complexity (new ALS diagnosis with complex multi-system findings and management)
• 95864 — Needle EMG, 4 extremities (electrodiagnostic confirmation)
• 95866 — Needle EMG, thoracic paraspinal (3rd spinal region documentation for El Escorial/Gold Coast criteria)
• 95913 — NCS, 7+ studies (to exclude multifocal motor neuropathy and Kennedy disease)
• 94010 — Spirometry (baseline FVC for respiratory monitoring plan)
• 99497 — Advance care planning, 30 minutes (AAN ALS quality measure — initiate goals of care discussion at diagnosis)

ICD-10-CM:

• G12.21 — Amyotrophic lateral sclerosis (confirmed new diagnosis; sporadic; no family history)

🏥 Outpatient Coder Tip: G12.21 maps to HCC 73 and must be coded at this encounter. All subsequent office visits, therapy evaluations, pulmonary assessments, and home health/hospice episodes should also carry G12.21 — this is a chronic, progressive condition that should be re-documented and re-coded at every eligible encounter to ensure continuous HCC capture. Riluzole is billed through pharmacy/Part D and does not generate a facility CPT/HCPCS claim.

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Scenario 2 — ALS Inpatient Admission: Acute Respiratory Failure

Clinical Vignette: A 67-year-old female with known ALS (FVC 38% at last visit 6 weeks ago) is admitted by EMS after worsening dyspnea and hypoxia (O2 sat 82%). She is placed on BiPAP; ABG shows pH 7.28, PaCO2 72 mmHg. She was previously refusing intubation per her advance directive; her POLST indicates BiPAP acceptable, intubation declined. The attending documents “Acute hypercapnic respiratory failure due to ALS; patient on NIV per advance directive.”

CPT / HCPCS Codes (facility/UB-04):

• 94660 — BiPAP initiation
• 99291 — Critical care, first 30-74 minutes (acute respiratory failure with hypoxia/hypercapnia)
• 99292 × 3 — Additional critical care time (90 additional minutes)
• 94010 × 3 — Serial spirometry during admission for respiratory monitoring

ICD-10-CM (UB-04):

• Principal Dx: J96.01 — Acute respiratory failure with hypoxia (the condition, after study, responsible for admission)
• Secondary Dx: G12.21 — Amyotrophic lateral sclerosis (CC status — elevates DRG; underlying cause of respiratory failure)
• Secondary Dx: Z66 — Do not resuscitate (DNR) status (POLST/advance directive documented)
• Secondary Dx: Z99.89 — Dependence on other enabling machines and devices (NIV/BiPAP dependence per advance directive)

🏥 Inpatient Coder Tip: Sequence J96.01 (acute respiratory failure) as principal — it is the condition driving the admission per UHDDS. G12.21 is an essential secondary diagnosis both for clinical accuracy AND because it carries CC status in MS-DRG v41, helping support DRG assignment. Failure to include G12.21 as a secondary diagnosis misrepresents the clinical burden and risks DRG under-capture. Z66 (DNR) should be coded per OGCRs when documented, reflecting the patient’s advance directive status.

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Scenario 3 — Familial ALS Coding Change: G12.21 vs. G12.24 + Tofersen Eligibility

Clinical Vignette: A 49-year-old male with a 2-year history of ALS was previously coded as G12.21. At this visit, genetic testing returns positive for SOD1 p.A5V mutation. His father also had ALS. The neurologist documents “ALS confirmed SOD1 mutation — familial motor neuron disease; tofersen (Qalsody) candidacy evaluation initiated.” Tofersen intrathecal injection is ordered.

ICD-10-CM — Code Change Required at This Encounter:

• Remove G12.21 from this visit forward
• Add G12.24 — Familial motor neuron disease (SOD1-confirmed hereditary ALS; effective FY2022)

CPT / HCPCS for Tofersen Administration Visit:

• 96365 — IV/intrathecal infusion administration, initial hour
• J3590 — Unclassified drug (tofersen/Qalsody until specific J-code assigned; document drug name and dose in narrative)
• 99214 — Office visit, moderate complexity

ICD-10-CM for Tofersen Claim:

• G12.24 — Familial motor neuron disease (required for tofersen coverage; G12.21 will result in denial)

🏥 CDI/Coding Tip: This is one of the most important post-FY2022 ALS coding updates. Any ALS patient with a confirmed genetic mutation (SOD1, C9orf72, FUS, TDP-43, TARDBP) and/or documented family history of ALS should be coded as G12.24, not G12.21. This transition also has prior authorization implications — tofersen requires G12.24 (or specific SOD1 mutation documentation) for payer approval. A CDI query should be initiated whenever genetic testing results are in the chart but the diagnosis code remains G12.21.

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Scenario 4 — ALS with FTD and PEG Placement, Inpatient

Clinical Vignette: A 71-year-old male with ALS is admitted for percutaneous gastrostomy (PEG) tube placement due to dysphagia and 18 lb weight loss over 3 months. FVC is 60% (above the 50% cutoff — safe for PEG). His wife notes increasing personality changes and disinhibition over the past year. The neurologist and gastroenterologist jointly document “ALS with ALS-FTD behavioral variant; dysphagia due to ALS; moderate protein-calorie malnutrition; PEG placement for nutritional support.”

CPT / HCPCS:

• 43246 — Upper GI endoscopy with PEG tube placement (primary procedure)
• 92610 — Evaluation of oral and pharyngeal swallowing function (SLP pre-procedure assessment)
• 94010 — Spirometry (pre-procedure FVC)

ICD-10-CM (UB-04):

• Principal Dx: G12.21 — Amyotrophic lateral sclerosis (the underlying reason for all procedures)
• Secondary Dx: F02.81 — Dementia in other diseases classified elsewhere, with behavioral disturbance (ALS-FTD with behavioral variant; behavioral disturbance = disinhibition)
• Secondary Dx: R13.10 — Dysphagia, unspecified (the specific complication prompting PEG)
• Secondary Dx: E44.0 — Moderate protein-calorie malnutrition (18 lb weight loss; should be further specified as moderate or mild per provider documentation)

🏥 Inpatient Coder Tip: The combination of G12.21 + F02.81 (ALS-FTD with behavioral disturbance) is a critically important pairing. F02.81 carries MCC status in MS-DRG v41 — adding it to this claim could elevate the DRG from 057 to 056 (Degenerative Nervous System Disorders with MCC), significantly increasing reimbursement. Always query the provider when cognitive or behavioral changes are documented in an ALS patient — ALS-FTD is clinically recognized, codeable, and MCC-bearing. E44.0 (moderate malnutrition) may also carry CC/MCC status depending on the severity specified — always confirm malnutrition severity with the treating team or dietitian.

⚠️ Coding Pitfalls and Tips

	Pitfall or Tip
❌	Do not code G12.21 for familial/hereditary ALS since FY2022. When the provider documents family history of ALS, positive genetic testing (SOD1, C9orf72, etc.), or “hereditary ALS,” the correct code is G12.24 (Familial motor neuron disease) — a FY2022 addition that many coders and systems have not yet adopted. Continued use of G12.21 for confirmed genetic ALS is a coding inaccuracy that also jeopardizes tofersen prior authorization
❌	Do not confuse “bulbar ALS” with G12.22 (progressive bulbar palsy). Bulbar-onset ALS — where early symptoms involve speech and swallowing — is still coded G12.21 because it has both UMN and LMN involvement. G12.22 (progressive bulbar palsy) is a distinct diagnosis with predominantly LMN bulbar involvement and no limb UMN signs, documented specifically by the provider
❌	Do not use G12.21 for tofersen (Qalsody) claims. Tofersen is approved only for SOD1-ALS, which is familial G12.24 — submitting G12.21 with a tofersen drug claim will likely result in denial or audit
❌	Do not miss ALS-FTD coding. Approximately 15% of ALS patients develop frontotemporal dementia. When provider documents cognitive or behavioral changes, query for ALS-FTD and code F02.80 or F02.81 (with or without behavioral disturbance) alongside G12.21. F02.81 carries MCC status — a critical DRG escalation opportunity
❌	Do not overlook malnutrition coding in ALS. Dysphagia leads to significant weight loss in ALS; malnutrition (E44.0-E41) is commonly undercoded. Malnutrition carries CC or MCC status depending on severity and is a high-priority CDI opportunity in ALS admissions
✅	Re-code G12.21 at EVERY encounter. ALS is a lifelong diagnosis that should appear on every outpatient visit, inpatient admission, home health episode, hospice claim, and SNF stay where it is documented and monitored. HCC 73 is only captured for the payment year if coded during that year’s data period — continuous re-documentation is essential for Medicare Advantage risk adjustment
✅	Code respiratory failure (J96.xx) separately from G12.21. As ALS progresses, respiratory muscle weakness causes respiratory failure — this is a separately codeable and separately reimbursable secondary diagnosis that carries MCC/CC status depending on type and should always be captured when documented
✅	Code advance care planning CPT 99497/99498 at every ALS visit. This is both a billable service and an AAN ALS Quality Measure. Goals of care and advance directive discussions are standard of care throughout the ALS disease course and should be documented and billed consistently
✅	Document and code dysphagia (R13.10) separately. Dysphagia is a manifestation of bulbar ALS and is a separately codeable condition that supports medical necessity for SLP services, swallowing studies, PEG placement, and nutritional interventions

📚 Sources

1. CMS/NCHS. ICD-10-CM Official Guidelines for Coding and Reporting, FY2025. Tabular List — G12.21 Amyotrophic lateral sclerosis; FY2022 addenda — G12.23, G12.24 additions; Section I.C.6 — Diseases of the Nervous System.

2. World Health Organization / CMS. ICD-10-CM Tabular List of Diseases and Injuries, FY2025 Release. Category G12 — Spinal muscular atrophy and related syndromes; G12.2 Motor neuron disease subcategory; FY2022 code expansion with G12.23-G12.24.

3. Centers for Medicare & Medicaid Services. MS-DRG v41 (FY2025) Definitions Manual. MDC 01 — Diseases and Disorders of the Nervous System; DRG 056-057 Degenerative Nervous System Disorders; CC/MCC designation for G12.21 as secondary diagnosis.

4. CMS. CMS-HCC v28 Model: HCC Category 73 — Amyotrophic Lateral Sclerosis and Other Motor Neuron Disease. RAF weight reference; applicable to Medicare Advantage risk adjustment for 2024+ payment years. AAPC/Memorial Health Network HCC Quick Reference 2025.

5. American Academy of Neurology (AAN). ALS Quality Measurement Set 2022 Update. Clinical documentation standards; mandatory quality measures including advance care planning (99497/99498), FVC monitoring (94010), dysphagia assessment (92610), and multidisciplinary care.

6. FDA / Mitsubishi Tanabe Pharma. Radicava (edaravone) Prescribing Information. HCPCS J3262 billing; 60 mg IV infusion dosing protocol.

7. FDA / Biogen. Qalsody (tofersen) Prescribing Information. 2023 FDA approval for SOD1-ALS; intrathecal administration; J3590 billing until specific J-code assigned; requires G12.24 diagnosis documentation.

8. American Medical Association (AMA). CPT 2024/2025 Professional Edition. EMG/NCS codes 95860-95913; infusion codes 96365-96366; PEG placement 43246; advance care planning 99497-99498.

9. PMC/NCBI. Assessment of Therapeutic Response of Edaravone and Riluzole in ALS. Clinical context for ALS disease-modifying drug billing and ICD-10-CM documentation requirements.

10. AAPC. ICD-10-CM Code G12.21 — Amyotrophic Lateral Sclerosis. Codify reference; FY2025 code validation.