G83.4

🧠 ICD-10-CM G83.4 — Cauda Equina Syndrome

Billable Code Confirmed

ICD-10-CM G83.4 is a valid, billable 4-character ICD-10-CM code for FY2026. The code is fully specified: G83 (other paralytic syndromes) + .4 (cauda equina syndrome). All four characters are required for valid reporting.

Non-Billable Parent Code — Never Submit Alone

• ❌ G83 — 3-character category header — non-billable; never submit alone

Always submit G83.4 (all 4 characters). Submitting G83 alone will result in a claim edit. The 4th character is required and available.

Traumatic vs. Non-Traumatic — Sequencing Depends on Etiology

G83.4 classifies cauda equina syndrome regardless of underlying cause. When the syndrome results from trauma, the acute spinal cord/ nerve root injury code (S34.3- with 7th character) typically sequences alongside or as principal, with G83.4 as an additional code capturing the clinical syndrome. In non-traumatic admissions (disc herniation, tumor, abscess), the underlying condition or the syndrome itself sequences as principal per UHDDS criteria — whichever was chiefly responsible for the admission.

Code Classification

ICD-10-CM Diagnosis Code — Fields for wRVU, assistant payable, and global period are not applicable. This is an organic neurological condition code used in inpatient, outpatient, and rehabilitation settings to capture the clinical syndrome arising from compression or injury of the cauda equina nerve roots in the lumbar spinal canal.

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🔍 Code Description

ICD-10-CM G83.4 classifies cauda equina syndrome (CES) — a neurological emergency arising from compression, injury, or disruption of the cauda equina: the bundle of lumbosacral nerve roots (L2 through S5) that descend through the lumbar spinal canal below the termination of the spinal cord at the conus medullaris (L1-L2).

Because the cauda equina is composed entirely of peripheral nerve roots rather than spinal cord tissue, injury here produces an exclusively lower motor neuron (LMN) syndrome — in direct contrast to the mixed UMN/LMN picture of conus medullaris syndrome (G95.81). Clinical hallmarks are flaccid, areflexic paralysis, saddle anesthesia (perineal, perianal, inner thigh sensory loss), and — most critically from a urological standpoint — areflexic neurogenic bladder presenting as painless urinary retention that the patient may not perceive due to concurrent sensory loss.

CES is a surgical emergency. Outcomes are time-dependent: early decompression (ideally within 24-48 hours of onset) is associated with significantly better neurological recovery, particularly for bladder function. The inpatient coder should recognize that cauda equina syndrome admissions typically involve urgent or emergent surgical decompression and that the surgical procedure code selection will significantly impact DRG assignment.

G83.4 is used across the full spectrum of CES — complete CES (no preserved sacral function), incomplete CES (some preserved function), acute, subacute, and chronic presentations. The code does not differentiate completeness; clinical specificity is captured in the physician’s documentation and should be preserved in the coding record.

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🌳 Code Tree / Hierarchy

G83 — Other Paralytic Syndromes ❌ Non-billable
│
├── G83.0 — Diplegia of Upper Limbs ✅ Billable
├── G83.1- — Monoplegia of Lower Limb ✅ Billable (laterality subcodes)
├── G83.2- — Monoplegia of Upper Limb ✅ Billable (laterality subcodes)
├── G83.3- — Monoplegia, Unspecified ✅ Billable (laterality subcodes)
├── G83.4 — Cauda Equina Syndrome ◀ THIS CODE ✅ Billable
├── G83.5 — Locked-In State ✅ Billable
├── G83.8- — Other Specified Paralytic Syndromes ✅ Billable
└── G83.9 — Paralytic Syndrome, Unspecified ⚠️ Avoid — query specificity

G83.4 vs. G95.81 — The Clinical Distinction That Drives Code Selection

G83.4 (cauda equina syndrome) and G95.81 (conus medullaris syndrome) are anatomically and clinically distinct — and mutually exclusive in the strict sense. Cauda equina = nerve roots only = pure LMN syndrome. Conus = cord terminus = mixed UMN/LMN syndrome. The distinction must come from physician documentation. If the record is ambiguous, a CDI query is appropriate before code assignment.

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✅ Includes

The following clinical documentation patterns map to G83.4:

• Cauda equina syndrome NOS — complete or incomplete, when documented by physician
• CES presenting with saddle anesthesia, urinary retention, and lower extremity weakness
• Cauda equina compression syndrome — regardless of etiology
• Neurogenic bladder in the context of documented cauda equina syndrome (code N31.x additionally as a separate diagnosis)
• Post-surgical CES following lumbar spine surgery

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❌ Excludes

Excludes 2 — May Be Coded Simultaneously When Both Documented

Code	Description	Note
S34.3-	Injury of cauda equina (traumatic)	Traumatic mechanism code — report additionally with G83.4 when traumatic etiology is established; both may be coded simultaneously

No Excludes 1 at G83.4 — Dual Coding with Injury Codes Is Permitted

G83.4 does not carry Excludes 1 restrictions against traumatic injury codes. The S34.3- traumatic cauda equina injury code and G83.4 may be reported together to capture both the traumatic mechanism and the resulting clinical syndrome. Apply sequencing per UHDDS principal diagnosis criteria and Official Coding Guidelines.

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📋 Clinical Overview

Anatomy — Why the Cauda Equina Is Distinct from the Conus

The spinal cord ends at the conus medullaris (L1-L2). Below this level, the lumbar and sacral nerve roots travel as individual peripheral nerve fibers through the spinal canal — this collection is the cauda equina (Latin: “horse’s tail”). Because these are peripheral nerve roots, not spinal cord tissue, compression here produces purely LMN findings. There are no corticospinal tract fibers to injure, no UMN signs.

Feature	G83.4 — Cauda Equina Syndrome	G95.81 — Conus Medullaris Syndrome
Structure injured	Peripheral nerve roots (L2-S5)	Spinal cord terminus (L1-L2)
Motor findings	Flaccid, areflexic — LMN only	Mixed — LMN + UMN components
Reflexes	Absent / markedly diminished	Variable — absent (LMN) or hyperreflexic (UMN)
Bladder	Areflexic — painless retention	Areflexic (LMN sacral) — similar
Onset pattern	Often more gradual (disc); may be sudden	Variable by etiology
Saddle anesthesia	Present — hallmark	Present
Surgical urgency	✅ Emergency — time critical	✅ Urgent — time critical
ICD-10-CM Code	G83.4	G95.81

Etiology

Etiology	Notes	Associated Code(s)
Central disc herniation L4-L5 or L5-S1	Most common cause — large central herniation	M51.16 or M51.17 + G83.4
Lumbar spinal stenosis, severe	Gradual onset CES — stenosis-related	M48.06 + G83.4
Traumatic fracture/dislocation	Burst fracture, high-energy trauma	S34.3- + G83.4
Epidural abscess	Infectious compression — urgent decompression	G06.1 + G83.4
Epidural hematoma	Spontaneous or anticoagulation-related	G97.31 or I69.x context + G83.4
Neoplasm (primary or metastatic)	Progressive onset; leptomeningeal carcinomatosis	Neoplasm code + G83.4
Post-surgical complication	Following lumbar spine surgery	G97.32 + G83.4
Spinal AVM / epidural lipomatosis	Less common; progressive	Appropriate etiology code + G83.4

Clinical Presentation

Patients presenting with G83.4 classically exhibit:

• Saddle anesthesia — sensory loss in the perineum, genitalia, inner thighs, and perianal region (S3-S5 distribution) — the most consistent physical finding
• Urinary retention — painless, large-volume; patient may not perceive fullness due to concurrent sensory loss — this is the urological hallmark of CES and the driver of long-term morbidity
• Bowel dysfunction — reduced rectal tone, fecal incontinence, or constipation
• Lower extremity weakness — variable; may be bilateral, asymmetric, or absent if sacral roots predominate over lumbar involvement
• Absent reflexes — diminished or absent ankle jerks; absent bulbocavernosus reflex (sacral LMN)
• Sexual dysfunction — erectile dysfunction, loss of genital sensation

Documentation Requirements

For accurate assignment of G83.4, physician documentation should include:

1. Explicit diagnosis — “cauda equina syndrome” stated by the physician or surgeon; coders should not infer CES from symptom description alone
2. Completeness — complete vs. incomplete CES when documented; affects prognosis and surgical decision-making
3. Etiology — disc herniation, trauma, tumor, infection — drives sequencing and additional code selection
4. Bladder/bowel status — urinary retention, neurogenic bladder, bowel dysfunction — supports separate coding of N31.x, K59.3x
5. Surgical indication and timing — documentation of surgical urgency supports medical necessity for emergent/urgent decompression coding

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💰 HCC Risk Adjustment (CMS-HCC v28)

Field	Detail
CMS-HCC Model Version	v28 (2024-2025 Implementation)
HCC Assignment	✅ HCC 72 — Paraplegia
HCC Category	HCC 72
RAF Coefficient	High — verify current v28 coefficient tables
RxHCC Assignment	Review current RxHCC mappings

G83.4 maps to HCC 72 (Paraplegia) under CMS-HCC v28. This is a high-weight HCC reflecting the long-term functional impact and resource intensity associated with cauda equina syndrome. Capture at every encounter where CES is documented, active, and managed.

Capture All Associated HCC-Bearing Comorbidities

The comorbidities accompanying G83.4 frequently carry independent HCC weight:

• Neurogenic bladder (N31.2 — flaccid) — separately codeable
• Pressure injuries (L89.x) — Stage III/IV are MCCs; HCC-mapped
• Recurrent UTI (N39.0) — extremely common in CIC/catheter patients
• Major depressive disorder (F33.x) — HCC-mapped if documented
• Chronic pain — review for appropriate pain coding

Thorough comorbidity capture in this population is essential for accurate RAF representation and DRG optimization.

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🏥 MS-DRG Assignment

MDC 01 — Diseases and Disorders of the Nervous System

DRG	Title	Est. Relative Weight*
DRG 091	Other Disorders of Nervous System with MCC	~1.40-1.80
DRG 092	Other Disorders of Nervous System with CC	~0.90-1.20
DRG 093	Other Disorders of Nervous System without CC/MCC	~0.65-0.85

*Approximate. Verify against IPPS FY2026 Final Rule tables.

Surgical Admissions — DRG May Shift Based on Principal Dx and Procedure

When the principal diagnosis is the underlying structural cause (e.g., M51.16 — disc herniation at L4-L5) and a surgical decompression is performed, the admission may group to a surgical DRG in MDC 08 (musculoskeletal) rather than MDC 01. When G83.4 sequences as principal in a non-surgical or non-traumatic neurological admission, MDC 01 / DRG 091-093 applies. Always verify MDC/DRG assignment against the actual principal diagnosis and procedure combination in your facility’s grouper.

CC/MCC Tier — This Population Has High Comorbidity Burden

UTI (extremely common with neurogenic bladder), pressure injuries, sepsis, and respiratory complications are common MCCs/CCs in CES patients. Complete comorbidity documentation and capture directly impacts DRG relative weight.

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🔗 Related ICD-10-CM Codes

G83 Category Sibling Codes

Code	Description
G83.0	Diplegia of upper limbs
G83.1-	Monoplegia of lower limb
G83.4	Cauda equina syndrome ← This Code
G83.5	Locked-in state
G83.9	Paralytic syndrome, unspecified ⚠️ Avoid

Clinically Related Spinal Codes

Code	Description	Distinction
G95.81	Conus medullaris syndrome	Mixed UMN/LMN — cord terminus; distinct from pure LMN cauda equina
G54.4	Lumbosacral root disorders, NEC	Alternate code path for nerve root lesions — see G54.4 note; distinct from full CES
S34.3-	Injury of cauda equina (traumatic)	Traumatic mechanism — report with G83.4 when applicable
G06.1	Intraspinal abscess and granuloma	Infectious etiology compressing cauda equina
M51.16	Intervertebral disc degeneration, lumbar region	Most common structural cause of CES
M51.17	Intervertebral disc degeneration, lumbosacral	L5-S1 disc — common CES etiology

Commonly Associated Additional Diagnoses

Code	Description	Coding Relevance
N31.2	Flaccid neuropathic bladder, NEC	Neurogenic bladder — hallmark of CES; always code separately
N31.9	Neuromuscular dysfunction of bladder, unspecified	Use when bladder type not specified as flaccid/spastic
R33.9	Retention of urine, unspecified	Acute urinary retention — code when documented as presenting symptom
K59.31	Functional constipation	Neurogenic bowel — code when documented
L89.x	Pressure injury	Stage-specific; III/IV are MCCs — critical for DRG
N39.0	Urinary tract infection, site not specified	Extremely common in CIC/catheter-dependent CES patients
G97.32	Intraoperative injury — spinal cord/nerve	Post-surgical CES when iatrogenic
Z99.89	Dependence on other enabling machines and devices	Catheter-dependent patients — document dependency

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🛠️ Commonly Associated CPT Codes (Outpatient/Physician Context)

Outpatient and Physician Setting Context

The CPT codes below are associated with evaluation and management of cauda equina syndrome in outpatient, neurosurgery, and rehabilitation settings. In the inpatient setting, ICD-10-PCS procedure codes govern procedural reporting.

CPT Code	Description	Clinical Application
99223	Initial hospital care, high complexity	Admission H&P for new or acute CES presentation
99233	Subsequent hospital care, high complexity	Complex daily inpatient management
63047	Laminectomy for spinal stenosis, lumbar	Surgical decompression — most common CES intervention
63048	Laminectomy, additional interspace, lumbar	Add-on per additional level decompressed
63056	Transpedicular decompression, lumbar	Alternative decompressive approach
22630	Lumbar arthrodesis, posterior interbody	Fusion at time of decompression when indicated
72148	MRI lumbar spine without contrast	Primary imaging modality for CES diagnosis
72149	MRI lumbar spine with contrast	Contrast-enhanced — infection, tumor, post-surgical
72158	MRI lumbar spine with and without contrast	Comprehensive MRI protocol
51702	Insertion of temporary indwelling bladder catheter	Urinary retention management — standard initial intervention
51703	Insertion of temporary indwelling bladder catheter, complicated	Complex catheterization
95913	Nerve conduction studies; 13 or more studies	Comprehensive NCS for neurophysiological characterization

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🔬 ICD-10-PCS Crosswalk (Inpatient Procedures)

When G83.4 is an inpatient diagnosis and a procedure is performed, the following ICD-10-PCS sections are relevant. Full PCS codes require all seven characters — consult PCS tables for FY2026.

PCS Section	Body System	Root Operation	Clinical Application
0 (Medical & Surgical)	0 (Central Nervous System)	N (Release)	Spinal decompression / laminectomy — 00NX0ZZ (open, lumbar cord)
0 (Medical & Surgical)	Q (Lower Bones)	N (Release)	Laminectomy — bone removal component; code both nerve release and bone procedure
0 (Medical & Surgical)	0 (Central Nervous System)	9 (Drainage)	Lumbar drain; lumbar puncture for CSF analysis — 009U3ZX
B (Imaging)	3 (Lumbar Spine)	3 (MRI)	MRI lumbar spine — B031ZZZ (with contrast)
F (Physical Rehabilitation)	0 (Rehabilitation)	7 (Motor Treatment)	PT — lower extremity rehabilitation, transfer training, ambulation
T (Urinary System)	T (Urinary)	7 (Dilation) / 9 (Drainage)	Urinary catheterization procedures — review PCS table for drainage root operation

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💊 Coding Scenarios and Examples

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Scenario 1 — Acute CES, Emergency Lumbar Disc Herniation (Inpatient)

Clinical Vignette: A 44-year-old male presents to the ED with acute-onset saddle anesthesia, inability to void, and bilateral leg weakness following heavy lifting. MRI L-spine: massive central L4-L5 disc herniation with near-complete canal occlusion. Neurosurgery documents: “Cauda equina syndrome — acute, secondary to L4-L5 central disc herniation. Emergency microdiscectomy performed.” Foley catheter placed in ED; urinary retention documented.

Principal Diagnosis:

• M51.16 — Intervertebral disc degeneration, lumbar region (structural cause driving the emergency admission and surgical intervention)

Secondary Diagnoses:

• G83.4 — Cauda equina syndrome (clinical syndrome — additional code)
• N31.2 — Flaccid neuropathic bladder (neurogenic bladder — separately codeable)
• R33.9 — Retention of urine (acute presenting symptom — code if not captured by N31.2)

ICD-10-PCS:

• 00BX0ZZ — Excision, Lumbar Spinal Cord, Open (microdiscectomy — verify root operation with operative report; Release [00NX0ZZ] may be more accurate depending on operative documentation)

Disc Herniation Sequences as Principal in Surgical Admission

The structural cause of CES (M51.16) sequences as principal when it drove the admission and the surgical intervention. G83.4 is captured as secondary to document the neurological syndrome. The neurogenic bladder (N31.2) is separately codeable and represents a CC — do not omit it.

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Scenario 2 — Chronic CES, Established Neurogenic Bladder (Inpatient Rehab)

Clinical Vignette: A 38-year-old female with cauda equina syndrome from a prior L3-L4 fracture is admitted for inpatient rehabilitation. She has a chronic flaccid neurogenic bladder managed with clean intermittent catheterization, neurogenic bowel, and incomplete bilateral lower extremity weakness. Physiatrist documents: “Cauda equina syndrome, chronic — admitted for comprehensive inpatient rehabilitation. Goals: optimize CIC program, bowel regimen, lower extremity strengthening.”

Principal Diagnosis:

• G83.4 — Cauda equina syndrome (established chronic condition — reason for rehab admission; sequences as principal)

Secondary Diagnoses:

• N31.2 — Flaccid neuropathic bladder
• K59.31 — Functional constipation (neurogenic bowel)

Rehab Admission — G83.4 May Sequence as Principal

In a rehabilitation admission where CES itself is the reason for admission and no acute underlying condition is the focus, G83.4 correctly sequences as principal. IRF admissions use CMG/IRF-PAI logic; acute inpatient admissions use MS-DRG grouper — confirm the applicable reimbursement system for your facility type.

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Scenario 3 — CES, Epidural Abscess, MRSA (Inpatient Surgical Emergency)

Clinical Vignette: A 61-year-old male with diabetes and recent lumbar epidural steroid injection presents with fever, severe low back pain, and new onset urinary retention and perianal numbness. MRI: L3-L4 epidural abscess with cauda equina compression. Neurosurgery documents: “Cauda equina syndrome secondary to epidural abscess — emergent decompressive laminectomy performed.” Blood cultures: MRSA.

Principal Diagnosis:

• G06.1 — Intraspinal abscess and granuloma (infectious cause of CES — drove the admission and emergency surgery)

Secondary Diagnoses:

• G83.4 — Cauda equina syndrome
• B95.62 — MRSA as cause of diseases classified elsewhere
• N31.2 — Flaccid neuropathic bladder
• E11.9 — Type 2 diabetes mellitus without complications (documented comorbidity)

Infectious Etiology — Underlying Cause Sequences as Principal

When CES is caused by an epidural abscess, the infectious process (G06.1) sequences as principal — it was the condition chiefly responsible for the admission. G83.4 captures the neurological syndrome as a secondary code. Both are necessary for complete clinical documentation.

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Scenario 4 — Post-Surgical CES (Complication of Lumbar Surgery)

Clinical Vignette: A 55-year-old female undergoes elective L4-L5 laminectomy. Post-operatively, she develops new saddle anesthesia and inability to void not present pre-operatively. MRI reveals epidural hematoma with cauda equina compression. Neurosurgery documents: “Post-surgical epidural hematoma with cauda equina syndrome — emergent hematoma evacuation performed.”

Principal Diagnosis:

• G97.31 — Intraoperative hemorrhage and hematoma of a nervous system organ or structure complicating a nervous system procedure (complication code sequences first)

Secondary Diagnoses:

• G83.4 — Cauda equina syndrome (clinical result of the complication)
• N31.2 — Flaccid neuropathic bladder

Post-Surgical CES — Complication Code Must Sequence First

When CES arises as a complication of surgery, the appropriate G97.x complication code sequences first. Coding only G83.4 without the complication code fails to capture the patient safety event and is incomplete. Both codes are required for an accurate and complete record.

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⚠️ Coding Pitfalls and Tips

	Pitfall or Tip
❌	Do not submit G83 alone (3 characters) — non-billable parent; always submit G83.4
❌	Do not confuse G83.4 with G95.81 (conus medullaris syndrome) — clinically and anatomically distinct; query if documentation is ambiguous
❌	Do not confuse G83.4 with G54.4 (lumbosacral root disorders NEC) — G83.4 is the appropriate code when cauda equina syndrome is explicitly documented
❌	Do not omit neurogenic bladder coding — N31.2 or N31.9 is separately codeable, commonly a CC, and reflects the most clinically significant complication of CES
❌	Do not sequence G83.4 as principal in a surgical admission when the structural etiology (disc herniation, abscess, fracture) drove the admission — the underlying cause sequences as principal per UHDDS criteria
✅	G83.4 maps to HCC 72 (Paraplegia) — capture at every encounter where CES is active and managed
✅	CES is a surgical emergency — documentation of emergent/urgent surgical decompression supports medical necessity and DRG complexity
✅	Every CES inpatient record is a CC/MCC mining opportunity — UTI, pressure injuries, sepsis, acute kidney injury are common and impactful
✅	Post-surgical CES requires G97.x complication code — do not code only G83.4 when an intraoperative or post-procedural complication is the etiology
✅	Query for completeness of CES (complete vs. incomplete) when not documented — affects prognosis documentation and supports clinical completeness
✅	Neurogenic bladder in CES is N31.2 (flaccid) — not N31.9 (unspecified) — when documentation supports the flaccid/areflexic pattern, use the more specific code

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📚 Sources

1. CMS/NCHS. ICD-10-CM Official Guidelines for Coding and Reporting, FY2026. Tabular List — G83.4; G83 category notes; Chapter 6 nervous system guidelines; Section II principal diagnosis guidelines.

2. AMA. CPT Professional Edition 2026. Neurosurgery subsection (63001-63746); Evaluation and Management guidelines.

3. CMS. 2025-2026 Medicare Advantage Risk Adjustment — CMS-HCC Model v28 ICD-10-CM Mappings. HCC 72 — Paraplegia mapping tables. Baltimore, MD: Centers for Medicare & Medicaid Services.

4. CMS. IPPS Final Rule FY2026 — MS-DRG Definitions Manual v43. MDC 01 logic tables — Other Disorders of Nervous System DRG grouping.

5. CMS. ICD-10-PCS Reference Manual FY2026. Section 0 (Medical & Surgical), Body Systems 0 (Central Nervous System), Q (Lower Bones); Section B (Imaging).

6. AMA. CPT Professional Edition 2026. Radiology — Diagnostic Imaging, spine subsection; Surgery — Nervous System.

7. CMS. NCCI Policy Manual for Medicare Services, current version. Neurosurgery chapter and general correct coding principles.