Neurology ICD-10-CM codes

Migraine codes encode three axes: aura status, intractability, and status migrainosus. G43.909 (unspecified, not intractable, without status migrainosus) is the default, and G43.709 covers chronic migraine without aura; document intractability explicitly because the intractable codes support CGRP inhibitor and Botox authorization. Tension-type headache is G44.209 and undifferentiated headache R51.9.

Parkinson's disease is no longer coded G20 alone: the FY2024 expansion requires the dyskinesia and fluctuation status, with G20.A1 (without dyskinesia, without fluctuations) the most common and G20.B1 when dyskinesia is present. Multiple sclerosis was similarly expanded for FY2026: G35 itself is no longer billable, so report the documented course, G35.A for relapsing-remitting or G35.D when the type is unspecified. Claims still carrying the old parent codes will reject.

Stroke coding separates the acute event (I63.9 during the admission), the TIA (G45.9), the history without residual deficit (Z86.73), and the sequela codes in I69 for lasting deficits, such as I69.351 for hemiplegia affecting the right dominant side. Never code I63.9 on an office follow-up after discharge; use I69 or Z86.73. Epilepsy defaults to G40.909 (unspecified, not intractable, without status epilepticus) with R56.9 for unspecified convulsions before an epilepsy diagnosis is made.

Cognitive and neuropathy volume rounds out the clinic: G30.9 for Alzheimer's disease with an additional F02 or F03 dementia code, G31.84 for mild cognitive impairment, and R41.81 or R41.3 for age-related decline and memory complaints short of MCI. Peripheral neuropathy is G62.9 when idiopathic but E11.42 when diabetic; carpal tunnel (G56.01, G56.02) and radiculopathy (M54.12, M54.16) carry site and side.