Active primary progressive multiple sclerosis

This code signifies a diagnosis of primary progressive multiple sclerosis (PPMS) that is currently active. PPMS is a form of multiple sclerosis characterized by a steady, gradual worsening of neurological function from the onset, without distinct relapses or remissions, and the "active" designation indicates ongoing disease activity, often evidenced by new lesions on MRI or clinical progression.

Use this code when documentation explicitly states a diagnosis of "active primary progressive multiple sclerosis." This typically applies to patients experiencing continuous neurological decline without periods of improvement, and where imaging or clinical assessment confirms ongoing disease activity. Support for this code comes from neurologist notes, MRI reports indicating new or enhancing lesions, and clinical assessments detailing progressive neurological deficits.

• Ensure documentation specifies "active" PPMS; otherwise, consider G35.B0 (Primary progressive multiple sclerosis, unspecified activity).
• Distinguish from other MS types like relapsing-remitting (G35.A) or secondary progressive (G35.C) based on the disease course described.
• Always sequence this code as the primary diagnosis when it is the reason for the encounter, unless another condition is clearly the primary focus of treatment.