2027 ICD-10-CM Diagnosis Code Q04.8Other specified congenital malformations of brain
ICD-10-CM Codes›Q00-Q99›Q00-Q07›Q04
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 182
- POA Exempt
- Chronic Condition
Q04.8 is a billable ICD-10-CM diagnosis code for other specified congenital malformations of brain. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 91 through 93, 791, 793. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 4 closely related codes. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nervous system congenital anomalies.
For Medicare Advantage risk adjustment, Q04.8 maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries) under the V28 model, adding a risk factor of about 0.478 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Present on Admission (POA)Billing
Q04.8 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Congenital malformations of the nervous system (Q00-Q07).
Medicare Risk Adjustment (HCC)Billing
Q04.8 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- 3C syndrome
- Abnormality of neurogenesis
- Acalvaria
- Aprosencephaly
- Aprosencephaly cerebellar dysgenesis
- Aprosencephaly/atelencephaly spectrum
- Athabaskan brainstem dysgenesis syndrome
- CEDNIK syndrome
- Central bilateral macrogyria
- Cerebellar cortical dysplasia
- Cerebellar hemangioblastomatosis
- Cerebral ventriculomegaly, cystic kidney disease
- Cerebro-facio-thoracic dysplasia
- Chiari malformation
- Chiari malformation type IV
- Coffin-Siris syndrome
- Colpocephaly
- Communicating hydrocephalus co-occurrent and due to congenital agenesis of arachnoid villi
- Congenital abnormal shape of cerebellum
- Congenital abnormal shape of cerebrum
- Congenital absence of cranial vault
- Congenital aniridia
- Congenital dysplasia of fronto-parietal cortex
- Congenital enlargement of ventricle of brain
- Congenital intrauterine infection-like syndrome
- Congenital pseudobulbar palsy
- Congenital sequelae of disorders
- Congenital superior cerebellar dysplasia
- Cortical dysplasia
- Cortical dysplasia with hemimegalencephaly
- Cystic malformation of posterior fossa
- Dandy-Walker syndrome
- Defect of telencephalic division
- Dentate dysplasia
- Diencephalic mesencephalic junction dysplasia
- Ecchordosis physaliphora
- Ectopic glial tissue
- Ectopic gray matter
- Ectopic gray matter in centrum ovale
- Exencephaly
- Focal cortical dysplasia Blumcke type I
- Focal cortical dysplasia Blumcke type Ia
- Focal cortical dysplasia Blumcke type Ib
- Focal cortical dysplasia Blumcke type Ic
- Focal cortical dysplasia Blumcke type II
- Focal cortical dysplasia Blumcke type IIa
- Focal cortical dysplasia Blumcke type IIb
- Focal cortical dysplasia Blumcke type III
- Focal cortical dysplasia Blumcke type IIIa
- Focal cortical dysplasia Blumcke type IIIb
- Focal cortical dysplasia Blumcke type IIIc
- Focal cortical dysplasia Blumcke type IIId
- Focal cortical dysplasia type I
- Focal cortical dysplasia type Ia
- Focal cortical dysplasia type Ib
- Focal cortical dysplasia type II
- Focal cortical dysplasia type IIa
- Focal cortical dysplasia type IIb
- Gelastic seizures with hypothalamic hamartoma
- Gillespie syndrome
- Hamartoma of brain
- Hamartoma of hypothalamus
- Infantile hemangioma
- Isolated focal cortical dysplasia
- Laminar heterotopia
- Localized cortical dysplasia
- Macrogyria
- MECP2 related disorder
- Microdysgenesis
- Nasal glial heterotopia
- Neuronal heterotopia
- Nodular heterotopia
- Olivary heterotopia
- Olive dysplasia
- Periventricular nodular heterotopia
- Pettigrew syndrome
- PHACE syndrome
- Posterior-predominant lissencephaly, broad flat pons and medulla-midline crossing defects syndrome
- PPM-X syndrome
- Pseudobulbar palsy
- Subcortical nodular heterotopia
- Subependymal nodular heterotopia
- Tubulinopathy-associated dysgyria
- Type 1 lissencephaly
- Ulegyria
- Upper motor neuron disease
- Ventriculomegaly
- Ventriculomegaly due to developmental anomaly
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Q04.8: its own notes plus those printed at Q04 and Chapter 17. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Arnold-Chiari syndrome, type IV
- Macrogyria
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Notes
General instructions on how these codes are used.
- Codes from this chapter are not for use on maternal records
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name Q04.8, its category, or a range that includes it.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
ventricular, ventricle (acute) (chronic) See Also: Hypertrophy, cardiac;
cerebral, congenital Q04.8
Heterotopia, heterotopic See Also: Malposition, congenital;
cerebralis Q04.8
Macrogyria (congenital) Q04.8
Malformation (congenital) See Also: Anomaly;
Ulegyria Q04.8
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Brain Malformations
Most brain malformations begin long before a baby is born. Something damages the developing nervous system or causes it to develop abnormally. Sometimes it's a genetic problem. In other cases, exposure to certain medicines, infections, or radiation during pregnancy interferes with brain development.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert Q04.8 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Q04.8Overview
What is the ICD-10 code for other specified congenital malformations of brain?
The ICD-10-CM code for other specified congenital malformations of brain is Q04.8 (sometimes written as Q048). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is Q04.8 (Other congenital malformations of brain) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report other specified congenital malformations of brain on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does Q04.8 group to?
When other specified congenital malformations of brain is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 91, 92, 93, with relative weights from 0.7783 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
Is Q04.8 a CC or MCC?
CMS lists Q04.8 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 4 closely related codes in its exclusion list.
Is Q04.8 exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for other specified congenital malformations of brain on inpatient claims. The code appears in the Congenital malformations of the nervous system (Q00-Q07) range of the CMS exempt list.
What HCC is Q04.8?
Q04.8 (other specified congenital malformations of brain) maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries), commonly written as HCC 182, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 72 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 155.
Does Q04.8 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, Q04.8 adds a risk adjustment factor of about 0.478 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.270 to 0.478 depending on the payment segment). A more severe related category (HCC 180, HCC 181, HCC 191, and HCC 192) supersedes it when both are reported. See the full factor table on the HCC 182 category page.
