2027 ICD-10-CM Diagnosis Code E51.2Wernicke's encephalopathy
ICD-10-CM Codes›E00–E89›E50-E64›E51
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
E51.2 is a billable ICD-10-CM diagnosis code for Wernicke's encephalopathy. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 640 through 641. 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 34 closely related codes. Coders also document this condition as cerebral degeneration due to beriberi. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nutritional deficiencies.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Cerebral degeneration due to beriberi
- Encephalopathy due to vitamin deficiency
- Polioencephalopathy
- Wernicke's disease
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to E51.2: its own notes plus those printed at E51, block E50-E64, and Chapter 4. A note printed at a category, block or chapter applies to every code under it.
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.
- All neoplasms, whether functionally active or not, are classified in Chapter 2. Appropriate codes in this chapter (i.e. E05.8, E07.0, E16-E31, E34.-) may be used as additional codes to indicate either functional activity by neoplasms and ectopic endocrine tissue or hyperfunction and hypofunction of endocrine glands associated with neoplasms and other conditions classified elsewhere.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name E51.2, its category, or a range that includes it.
Excludes1 3
These codes carry an Excludes1 note naming E51.2: they are not reported together with it, unless the two conditions are unrelated.
Code First 1
These codes say to code first a condition named in the note, and E51.2 is one of the conditions named.
- G63 Polyneuropathy in diseases classified elsewhere
Notes 1
These notes mention E51.2.
- E64 Sequelae of malnutrition and other nutritional deficienciesThis category is to be used to indicate conditions in categories E43, E44, E46, E50-E63 as the cause of sequelae, which are themselves classified elsewhere. The 'sequelae' include conditions specified as such; they also include the late effects of diseases classifiable to the above categories if the disease itself is no longer present names E50-E63, which includes this code
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
disease or syndrome E51.2
encephalopathy E51.2
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Wernicke Encephalopathy
an acute neurological disorder characterized by the triad of ophthalmoplegia, ataxia, and disturbances of mental activity or consciousness. eye movement abnormalities include nystagmus, external rectus palsies, and reduced conjugate gaze. thiamine deficiency and chronic alcoholism are associated conditions. pathologic features include periventricular petechial hemorrhages and neuropil breakdown in the diencephalon and brainstem. chronic thiamine deficiency may lead to korsakoff syndrome. (adams et al., principles of neurology, 6th ed, pp1139-42; davis & robertson, textbook of neuropathology, 2nd ed, pp452-3)
Patient EducationClinical
Brain Diseases
Your brain is the control center of your body. It controls your thoughts, memory, speech, and movement. It regulates the function of many organs. It's part of your nervous system, which also includes your spinal cord and peripheral nerves. The nervous system sends signals between your brain and the rest of the body.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert E51.2 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About E51.2Overview
What is the ICD-10 code for Wernicke's encephalopathy?
The ICD-10-CM code for Wernicke's encephalopathy is E51.2 (sometimes written as E512). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is E51.2 (Thiamine deficiency) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report Wernicke's encephalopathy on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does E51.2 group to?
When Wernicke's encephalopathy is the principal diagnosis on an inpatient stay, it groups to MS-DRG 641, 640, with relative weights from 0.7864 to 1.3392 depending on complications. Higher weights mean higher Medicare reimbursement.
Is E51.2 a CC or MCC?
CMS lists E51.2 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 34 closely related codes in its exclusion list.
Can E51.2 be reported with E64.8?
Not as a rule. The Excludes1 note at E51, which applies to E51.2, lists "sequelae of thiamine deficiency (E64.8)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
