ICD-10 Code G35.B – Primary progressive multiple sclerosis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G35.B – Primary progressive multiple sclerosis
What it is
This code identifies primary progressive multiple sclerosis, a form of MS marked by gradual neurological worsening from onset. It is used when the record specifically documents a progressive course without distinct relapses.
Clinical signs
Clinical features vary; refer to documentation. Commonly documented findings include steadily worsening weakness, gait difficulty, spasticity, balance problems, or sensory changes over time, with no clear remission pattern.
When to use this code
Use G35.B when the clinician documents primary progressive multiple sclerosis or a progressive MS course from the outset. Apply it when the record clearly distinguishes this subtype from relapsing-remitting, secondary progressive, or other demyelinating conditions.
If the note only says “multiple sclerosis” without subtype, check documentation before coding. Use the code only when the provider’s diagnosis supports primary progressive disease.
Do not use for
Do not use this code for relapsing-remitting MS, secondary progressive MS, or nonspecific demyelinating disease. If the subtype is unclear, check documentation.
Coding tip
Confirm the exact MS subtype in the assessment or problem list before assigning G35.B.