M99.77 identifies narrowing of the intervertebral foramina of the upper extremity region caused by connective tissue changes or disc pathology — classified as a biomechanical lesion not elsewhere classified.
Verified May 8, 2026 · 4 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 10
- Region
- Shoulder
Documentation tips
What should appear in the chart to support M99.77.
Source · Editorial brief grounded in 4 cited references ↓
- Specify whether the foraminal narrowing is disc-mediated, connective tissue-mediated, or both — M99.77 requires one of those etiologies; pure bony stenosis belongs under M99.67.
- Record the affected cervical or upper thoracic level (e.g., C5-C6, C6-C7) and the corresponding symptomatic upper extremity dermatome or myotome.
- Note imaging findings that confirm foraminal narrowing — MRI signal changes, disc protrusion into foramen, or ligamentous hypertrophy — to support medical necessity at payer audit.
- Document upper extremity symptom laterality (right arm, left arm, bilateral) even though M99.77 does not carry a laterality character itself; this supports any co-assigned radiculopathy or neurological deficit codes.
- If conservative care has been rendered, record the treatment history (manipulation, physical therapy, injections) to substantiate ongoing or escalating management decisions.
Related CPT procedures
Procedure codes commonly billed with M99.77. Linking the right diagnosis to the right procedure is what establishes medical necessity.
Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis
Common coding pitfalls
The recurring mistakes coders make with M99.77 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Confusing M99.77 with M99.67 (osseous stenosis of intervertebral foramina, upper extremity) — use M99.77 only when the stenosis source is disc or connective tissue, not bone.
- Assigning M99.77 without co-documenting the symptomatic condition — payers may deny a standalone biomechanical lesion code if no radiculopathy, myelopathy, or upper extremity deficit code accompanies it.
- Using M99.77 when a more specific cervical disc code (M50.0–M50.3x) fully captures the documented diagnosis — M99 codes are 'not elsewhere classified' and should yield to more specific categories when applicable.
- Omitting laterality-specific neurological deficit codes (e.g., cervical radiculopathy M54.12/M54.13) that would strengthen the claim and clarify which extremity is affected, since M99.77 itself has no laterality character.
Clinical context
Source · Editorial summary grounded in 4 cited references ↓
M99.77 sits within the M99.7x subcategory (connective tissue and disc stenosis of intervertebral foramina) and specifically targets the upper extremity region. Use it when clinical or imaging evidence supports foraminal narrowing attributable to connective tissue thickening or disc encroachment at the cervical or upper thoracic segments that manifests with upper extremity symptoms — radicular pain, paresthesia, or neurogenic weakness in the arm, forearm, or hand.
This code is commonly assigned in chiropractic, osteopathic manipulative medicine, physical medicine and rehabilitation, and spine surgery settings. It pairs appropriately with cervical radiculopathy coding sequences when the foraminal stenosis is the documented structural cause. If the stenosis is purely osseous (bony foraminal narrowing), consider M99.67 (osseous stenosis of intervertebral foramina, upper extremity) instead — the M99.77 axis specifically requires connective tissue or disc etiology.
Because M99.77 lives in Chapter 13 under biomechanical lesions, it does not carry 7th-character injury extensions. Document the structural finding, the causative tissue type (disc vs. connective tissue), and the symptomatic upper extremity distribution to distinguish this from unspecified cervical disc or stenosis codes in the M50 category.
Sibling codes
Other billable codes under M99.7 (laterality / anatomic variants).
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 4 cited references ↓
01What is the difference between M99.77 and M99.67?
02Does M99.77 require a 7th-character extension?
03Can M99.77 be used as a primary diagnosis on a chiropractic claim?
04Should M99.77 be coded alongside a cervical radiculopathy code?
05Is M99.77 appropriate when MRI shows a disc herniation at C6-C7 compressing the foramen?
06Does M99.77 have laterality built into the code?
Sources & references
Editorial content was developed using the following public sources. Last verified May 8, 2026.
Mira AI Scribe
Mira's AI scribe captures the foraminal narrowing etiology (disc vs. connective tissue), the affected spinal level, and the patient's upper extremity symptom pattern — radicular pain distribution, dermatomal paresthesia, grip weakness — directly from the encounter note. That specificity prevents claim downcoding to an unspecified biomechanical lesion and blocks payer queries about whether osseous stenosis (M99.67) was the correct code instead.
See how Mira captures M99.77 documentation