4A0004Z ICD-10-PCS Code: Measurement of Central Nervous Electrical Activity, Open Approach
Measurement of CNS Electr Activity, Open Approach
Axis Breakdown
Every ICD-10-PCS code is exactly seven characters, one per axis. Each character's meaning is defined by its position in the code.
| Position | Value | Meaning |
|---|---|---|
| 1 | Section4 | Measurement and Monitoring |
| 2 | Body SystemA | Physiological Systems |
| 3 | Root Operation0 | Measurement Determining the level of a physiological or physical function at a point in time |
| 4 | Body System0 | Central Nervous |
| 5 | Approach0 | Open |
| 6 | Function / Device4 | Electrical Activity |
| 7 | QualifierZ | No Qualifier |
Related Codes
Same operation — other Body System
Same table and root operation, differing only in the body system character.
4A0104Z — Measurement of Peripheral Nervous Electrical Activity, Open Approach, 4A0204Z — Measurement of Cardiac Electrical Activity, Open Approach
Same operation — other Approach
Same table and root operation, differing only in the approach character.
4A0034Z — Measurement of Central Nervous Electrical Activity, Percutaneous Approach, 4A0074Z — Measurement of Central Nervous Electrical Activity, Via Natural or Artificial Opening, 4A0084Z — Measurement of Central Nervous Electrical Activity, Via Natural or Artificial Opening Endoscopic, 4A00X4Z — Measurement of Central Nervous Electrical Activity, External Approach
Same operation — other Function / Device
Same table and root operation, differing only in the function / device character.
4A0002Z — Measurement of Central Nervous Conductivity, Open Approach, 4A000BZ — Measurement of Central Nervous Pressure, Open Approach
Same procedure category (CCSR), other tables
AHRQ's Clinical Classifications Software Refined groups these ICD-10-PCS procedures with this one under Electroencephalogram (EEG) (Measurement and Monitoring); listed here are the members in other PCS tables. Source: Clinical Classifications Software Refined (CCSR), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, November 2025.
4A1004G — Monitoring of Central Nervous Electrical Activity, Intraoperative, Open Approach, 4A1004Z — Monitoring of Central Nervous Electrical Activity, Open Approach, 4A1034G — Monitoring of Central Nervous Electrical Activity, Intraoperative, Percutaneous Approach, 4A1034Z — Monitoring of Central Nervous Electrical Activity, Percutaneous Approach, 4A1074G — Monitoring of Central Nervous Electrical Activity, Intraoperative, Via Natural or Artificial Opening, 4A1074Z — Monitoring of Central Nervous Electrical Activity, Via Natural or Artificial Opening, 4A1084G — Monitoring of Central Nervous Electrical Activity, Intraoperative, Via Natural or Artificial Opening Endoscopic, 4A1084Z — Monitoring of Central Nervous Electrical Activity, Via Natural or Artificial Opening Endoscopic, 4A10X4G — Monitoring of Central Nervous Electrical Activity, Intraoperative, External Approach, 4A10X4Z — Monitoring of Central Nervous Electrical Activity, External Approach, XX20X89 — Monitoring of Brain Electrical Activity, Computer-aided Detection and Notification, New Technology Group 9, XXE0X48 — Measurement of Brain Electrical Activity, Computer-aided Semiologic Analysis, New Technology Group 8
Contextual Map
Every relationship of 4A0004Z in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.
PCS table
- 4A0[PCS table]— CMS ICD-10-PCS tables
- Measurement and Monitoring — Section: Measurement and Monitoring[Section]: “Measurement and Monitoring”— CMS ICD-10-PCS tables
- Physiological Systems — Body System: Physiological Systems[Body System]: “Physiological Systems”— CMS ICD-10-PCS tables
- Measurement — Operation: Measurement[Operation]: “Measurement”— CMS ICD-10-PCS tables
Clinical classification (CCSR)
- MAM011 — Electroencephalogram (EEG)[CCSR category]: “Electroencephalogram (EEG) — Measurement and Monitoring”— AHRQ CCSR for ICD-10-PCS Procedures (HCUP) · v2026.1
Nearest codes
- 4A0002Z — Measurement of Central Nervous Conductivity, Open Approach[One axis away]— CMS ICD-10-PCS tables
- 4A000BZ — Measurement of Central Nervous Pressure, Open Approach[One axis away]— CMS ICD-10-PCS tables
- 4A0034Z — Measurement of Central Nervous Electrical Activity, Percutaneous Approach[One axis away]— CMS ICD-10-PCS tables
- 4A0074Z — Measurement of Central Nervous Electrical Activity, Via Natural or Artificial Opening[One axis away]— CMS ICD-10-PCS tables
- 4A0084Z — Measurement of Central Nervous Electrical Activity, Via Natural or Artificial Opening Endoscopic[One axis away]— CMS ICD-10-PCS tables
- 4A00X4Z — Measurement of Central Nervous Electrical Activity, External Approach[One axis away]— CMS ICD-10-PCS tables
- 4A0104Z — Measurement of Peripheral Nervous Electrical Activity, Open Approach[One axis away]— CMS ICD-10-PCS tables
- 4A0204Z — Measurement of Cardiac Electrical Activity, Open Approach[One axis away]— CMS ICD-10-PCS tables
Change history
No changes recorded for this code. This ledger tracks additions, deletions and description changes from FY2026 (April) onward. Note changes are not tracked.
Read from: CMS ICD-10-PCS code tables, index and definitions — FY2026 (April); CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43; AHRQ HCUP Clinical Classifications Software Refined for ICD-10-PCS Procedures (hcup-us.ahrq.gov/toolssoftware/ccsr/PRCCSR_v2026-1.zip) — v2026.1. All data sources · How to read the labels