Peroneal Neuropathy¶
VERSION: 1.1 CREATED: February 2, 2026 REVISED: February 2, 2026 STATUS: Validated per checker pipeline
DIAGNOSIS: Peroneal Neuropathy (Common Peroneal / Common Fibular Neuropathy)
ICD-10: G57.30 (Lesion of lateral popliteal nerve, unspecified lower limb); G57.31 (Lesion of lateral popliteal nerve, right lower limb); G57.32 (Lesion of lateral popliteal nerve, left lower limb); G57.33 (Lesion of lateral popliteal nerve, bilateral lower limbs); G57.80 (Other mononeuropathies of lower limb, unspecified); G57.90 (Unspecified mononeuropathy of lower limb, unspecified)
CPT CODES: 95907 (NCS, 1-2 studies); 95908 (NCS, 3-4 studies); 95909 (NCS, 5-6 studies); 95886 (Needle EMG, complete); 95885 (Needle EMG, limited); 76882 (Ultrasound, extremity, limited); 73721 (MRI knee without contrast); 73723 (MRI knee with and without contrast); 73720 (MRI lower extremity without contrast); 64708 (Neuroplasty, major peripheral nerve); 64712 (Neuroplasty, sciatic nerve); 27884 (Decompression fasciotomy, leg); 27690 (Transfer or transplant tendon); 95999 (Unlisted neurological procedure); 97110 (Therapeutic exercises); 97116 (Gait training); L1960 (AFO, custom molded); L4396 (AFO, prefabricated)
CLINICAL SYNONYMS: Common peroneal neuropathy, common fibular neuropathy, peroneal nerve palsy, fibular nerve palsy, peroneal nerve entrapment, foot drop neuropathy, lateral popliteal nerve lesion, peroneal nerve compression at fibular head, drop foot from peroneal injury, crossed-leg palsy, peroneal nerve injury, fibular tunnel syndrome
SCOPE: Evaluation and management of common peroneal (fibular) neuropathy at the fibular head from initial presentation through electrodiagnostic confirmation, conservative management, and surgical referral. Covers foot drop assessment, localization with EMG/NCS, differentiation from L5 radiculopathy and sciatic neuropathy, ankle-foot orthosis fitting, physical therapy, and indications for surgical decompression or tendon transfer. Settings: ED (acute foot drop evaluation), HOSP (post-surgical/post-traumatic), OPD (primary management). For deep peroneal neuropathy (anterior tarsal tunnel syndrome), refer to specialized evaluation.
PRIORITY KEY: STAT = Immediate | URGENT = Within hours | ROUTINE = Standard | EXT = Extended/atypical cases | - = Not applicable to this setting
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1. LABORATORY WORKUP¶
1A. Essential/Core Labs¶
| Test | ED | HOSP | OPD | ICU | Rationale | Target Finding |
|---|---|---|---|---|---|---|
| Fasting glucose (CPT 82947) | STAT | STAT | ROUTINE | STAT | Diabetes is the most common metabolic cause of peroneal neuropathy (increased nerve vulnerability) | <100 mg/dL |
| HbA1c (CPT 83036) | - | ROUTINE | ROUTINE | - | Screen for diabetes/prediabetes; diabetic nerves more susceptible to compression | <5.7% |
| CBC with differential (CPT 85025) | STAT | ROUTINE | ROUTINE | STAT | Infection screen (post-traumatic); anemia workup; hematologic malignancy | Normal |
| BMP (CPT 80048) | STAT | ROUTINE | ROUTINE | STAT | Electrolyte abnormalities; renal function (affects medication dosing) | Normal |
1B. Extended Workup (Second-line)¶
| Test | ED | HOSP | OPD | ICU | Rationale | Target Finding |
|---|---|---|---|---|---|---|
| ESR (CPT 85652) | - | ROUTINE | ROUTINE | - | Vasculitic neuropathy screen; inflammatory etiology | <20 mm/hr |
| CRP (CPT 86140) | - | ROUTINE | ROUTINE | - | Inflammatory marker; vasculitis, autoimmune | <3.0 mg/L |
| TSH (CPT 84443) | - | ROUTINE | ROUTINE | - | Hypothyroidism increases susceptibility to entrapment neuropathy | 0.4-4.0 mIU/L |
| Vitamin B12 (CPT 82607) | - | ROUTINE | ROUTINE | - | Concomitant peripheral neuropathy contributing to nerve vulnerability | >300 pg/mL |
| Folate (CPT 82746) | - | ROUTINE | ROUTINE | - | Nutritional neuropathy; often deficient with B12 | >7 ng/mL |
| Rheumatoid factor (CPT 86431) | - | ROUTINE | ROUTINE | - | RA-associated peroneal neuropathy (Baker cyst, synovial compression at knee) | Negative |
| ANA (CPT 86235) | - | EXT | ROUTINE | - | Connective tissue disease/vasculitic neuropathy screen | Negative |
| ANCA panel (CPT 86235/86236) | - | EXT | ROUTINE | - | Vasculitic neuropathy (mononeuritis multiplex pattern) | Negative |
| Serum protein electrophoresis (SPEP) (CPT 86335) | - | EXT | ROUTINE | - | Paraproteinemic neuropathy; myeloma with focal nerve involvement | No M-spike |
| Uric acid (CPT 84550) | - | ROUTINE | ROUTINE | - | Gout with tophi at fibular head (rare but reported cause) | Normal (3.5-7.2 mg/dL male; 2.5-6.2 mg/dL female) |
1C. Rare/Specialized (Refractory or Atypical)¶
| Test | ED | HOSP | OPD | ICU | Rationale | Target Finding |
|---|---|---|---|---|---|---|
| Anti-ganglioside antibodies (GM1, anti-MAG) (CPT 86255) | - | EXT | EXT | - | Multifocal motor neuropathy with conduction block mimicking peroneal neuropathy | Negative |
| Cryoglobulins (CPT 82784) | - | EXT | EXT | - | Cryoglobulinemic vasculitis causing mononeuropathy | Negative |
| Hepatitis B/C panel (CPT 87340/86803) | - | EXT | EXT | - | Vasculitic neuropathy associated with hepatitis (PAN, cryoglobulinemia) | Negative |
| HIV antibody/antigen (CPT 87389) | - | EXT | EXT | - | HIV-associated neuropathy; vasculitic mononeuropathy | Negative |
| Genetic testing (CMT panel) (CPT 81405) | - | - | EXT | - | Hereditary neuropathy with liability to pressure palsies (HNPP) if recurrent or bilateral | No PMP22 deletion |
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2. DIAGNOSTIC IMAGING & STUDIES¶
2A. Essential/First-line¶
| Study | ED | HOSP | OPD | ICU | Timing | Target Finding | Contraindications |
|---|---|---|---|---|---|---|---|
| Nerve conduction studies (NCS) (CPT 95907-95909) and EMG (CPT 95885-95886) | - | ROUTINE | ROUTINE | - | Gold standard for diagnosis and localization; optimal timing 2-3 weeks post-onset for denervation; NCS abnormalities may be immediate | Focal slowing or conduction block at fibular head; reduced CMAP amplitude peroneal nerve; normal superficial peroneal SNAP if at fibular head; denervation in tibialis anterior, peroneus longus, extensor digitorum brevis | Anticoagulation for needle EMG (relative) |
| Knee X-ray (CPT 73560) | URGENT | ROUTINE | ROUTINE | - | Exclude fracture of proximal fibula, osteophytes, or bony mass at fibular head | Normal; no fracture or mass at fibular head | None |
2B. Extended¶
| Study | ED | HOSP | OPD | ICU | Timing | Target Finding | Contraindications |
|---|---|---|---|---|---|---|---|
| MRI knee without contrast (CPT 73721) | - | ROUTINE | ROUTINE | - | Evaluate for mass lesion (ganglion cyst, nerve sheath tumor, Baker cyst) compressing peroneal nerve at fibular head | No mass lesion; normal peroneal nerve signal | Pacemaker; claustrophobia |
| MRI knee with and without contrast (CPT 73723) | - | ROUTINE | ROUTINE | - | If tumor or intraneural pathology suspected; post-gadolinium enhancement in nerve sheath tumor | No enhancing mass | GFR <30; pacemaker; gadolinium allergy |
| Ultrasound of peroneal nerve at fibular head (CPT 76882) | - | ROUTINE | ROUTINE | - | Point-of-care evaluation; can visualize nerve swelling, ganglion cyst, entrapment; operator-dependent | Normal nerve caliber at fibular head (<5 mm CSA typical); no cyst or mass | None |
| MRI lumbar spine without contrast (CPT 72148) | - | ROUTINE | ROUTINE | - | Rule out L5 radiculopathy if clinical localization uncertain | No L4-L5 or L5-S1 foraminal stenosis/disc herniation | Pacemaker; claustrophobia |
| MRI lumbar spine with and without contrast (CPT 72158) | - | ROUTINE | ROUTINE | - | If neoplastic or inflammatory radiculopathy suspected | No enhancing nerve root lesion | GFR <30; pacemaker; gadolinium allergy |
2C. Rare/Specialized¶
| Study | ED | HOSP | OPD | ICU | Timing | Target Finding | Contraindications |
|---|---|---|---|---|---|---|---|
| MR neurography of lower extremity (CPT 73720) | - | EXT | EXT | - | High-resolution nerve imaging if standard MRI inconclusive; can visualize nerve fascicular detail | Normal nerve signal and caliber; no intraneural or perineural pathology | Pacemaker; claustrophobia |
| CT knee without contrast (CPT 73700) | - | EXT | EXT | - | Bony pathology at fibular head not visualized on X-ray | No fracture, exostosis, or osteochondroma | Pregnancy (relative) |
| Diagnostic nerve block (peroneal at fibular head) (CPT 64450) | - | - | EXT | - | Confirm localization if clinical and electrodiagnostic data discordant | Temporary symptom improvement confirms localization | Infection; anticoagulation; allergy to local anesthetic |
| MRI pelvis (CPT 72196) | - | EXT | EXT | - | Exclude sciatic nerve lesion or pelvic mass causing proximal nerve injury | Normal sciatic nerve; no pelvic mass | GFR <30; pacemaker |
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3. TREATMENT¶
3A. Acute/Emergent¶
| Treatment | Route | Indication | Dosing | Contraindications | Monitoring | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|---|---|
| Ankle-foot orthosis (AFO) | External | First-line for foot drop regardless of etiology; prevents tripping, ankle sprains, and gait instability | Custom or prefabricated AFO :: External :: Continuous during ambulation :: Fit AFO immediately when foot drop identified; custom molded if expected >6 months; prefabricated for acute/temporary use; dorsiflexion assist type preferred | None | Skin breakdown at calf/ankle; fit adjustment; compliance | ROUTINE | ROUTINE | ROUTINE | - |
| Remove compressive cause | External | Eliminate identified external compression at fibular head | Discontinue :: External :: Immediately :: Stop leg crossing; remove tight casts, stockings, or braces; pad fibular head if bedbound; modify positioning | None | Ensure compliance; reassess nerve function | URGENT | URGENT | URGENT | URGENT |
| Weight-bearing precautions (if fracture) | External | Proximal fibula fracture associated with peroneal nerve injury | Non-weight-bearing :: External :: Until fracture healing :: Per orthopedic guidance; typically 6-8 weeks | None | Fracture healing on follow-up imaging | URGENT | URGENT | ROUTINE | - |
3B. Symptomatic Treatments¶
| Treatment | Route | Indication | Dosing | Contraindications | Monitoring | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|---|---|
| Gabapentin | PO | Neuropathic pain/dysesthesia along lateral leg or dorsal foot | 300 mg :: PO :: TID :: Start 300 mg qHS; increase by 300 mg q3-7d as tolerated; target 900-1800 mg/day divided TID; max 3600 mg/day | Renal impairment (dose adjust per CrCl) | Sedation, dizziness, peripheral edema | - | ROUTINE | ROUTINE | - |
| Pregabalin | PO | Neuropathic pain (alternative to gabapentin) | 75 mg :: PO :: BID :: Start 75 mg BID; increase to 150 mg BID after 1 week; max 300 mg/day for neuropathic pain | Renal impairment; Class V controlled | Sedation, weight gain, edema | - | ROUTINE | ROUTINE | - |
| Duloxetine | PO | Neuropathic pain with comorbid depression/anxiety | 30 mg :: PO :: daily :: Start 30 mg daily; increase to 60 mg after 1 week; max 120 mg/day | Hepatic impairment; CrCl <30; MAOIs; narrow-angle glaucoma | Nausea, BP; taper to discontinue | - | ROUTINE | ROUTINE | - |
| Amitriptyline | PO | Nocturnal neuropathic pain (second-line) | 10 mg :: PO :: qHS :: Start 10 mg qHS; increase by 10 mg weekly; max 75 mg qHS | Cardiac conduction abnormality; urinary retention; glaucoma; elderly | ECG if >50 mg; anticholinergic effects | - | - | ROUTINE | - |
| Ibuprofen | PO | Acute pain/inflammation at injury site | 400 mg :: PO :: TID :: Ibuprofen 400 mg TID with food; short course 7-14 days; not for chronic neuropathic pain | GI bleeding; renal impairment; cardiovascular disease; third trimester pregnancy | GI symptoms; renal function | ROUTINE | ROUTINE | ROUTINE | - |
| Naproxen | PO | Acute pain/inflammation (alternative NSAID) | 500 mg :: PO :: BID :: Naproxen 500 mg BID with food; short course 7-14 days | GI bleeding; renal impairment; cardiovascular disease | GI symptoms; renal function | ROUTINE | ROUTINE | ROUTINE | - |
| Topical lidocaine 5% patch | TOP | Localized neuropathic pain over lateral leg/dorsal foot | 1 patch :: TOP :: 12h on/12h off :: Apply over painful area 12h on, 12h off; up to 3 patches simultaneously | Broken skin; severe hepatic impairment | Minimal systemic absorption; local skin irritation | - | - | ROUTINE | - |
3C. Rehabilitative/Conservative¶
| Treatment | Route | Indication | Dosing | Contraindications | Monitoring | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|---|---|
| Physical therapy (CPT 97110/97116) | External | Core rehabilitation for foot drop; nerve recovery optimization; gait training | PT prescription :: External :: 2-3x/week :: Ankle dorsiflexion/eversion strengthening; gait training with AFO; balance exercises; nerve gliding; electrical stimulation (NMES) to tibialis anterior | Acute fracture (modify program) | Muscle strength grading (MRC scale); gait quality; functional improvement | - | ROUTINE | ROUTINE | - |
| Neuromuscular electrical stimulation (NMES) | External | Prevent muscle atrophy during reinnervation; maintain ankle dorsiflexor mass | NMES device :: External :: Daily :: Apply to tibialis anterior; 20-30 minutes daily; per PT protocol; during period of denervation/reinnervation | Pacemaker/defibrillator; over open wound; deep vein thrombosis | Muscle bulk; contraction quality; skin irritation | - | ROUTINE | ROUTINE | - |
| Fibular head padding/protection | External | Prevent further compression in hospitalized or bedbound patients | Foam pad :: External :: Continuous while in bed :: Place foam pad at lateral knee/fibular head; avoid leg crossing; reposition every 2 hours | None | Skin integrity; compliance | - | ROUTINE | ROUTINE | URGENT |
| Vitamin B complex supplementation | PO | Nutritional support for nerve recovery (adjunctive) | B-complex :: PO :: daily :: One B-complex tablet daily; ensure adequate B1, B6, B12; not evidence-based as monotherapy for recovery | B6 >200 mg/day causes neuropathy | None specific | - | - | ROUTINE | - |
3D. Surgical Treatment¶
| Treatment | Route | Indication | Dosing | Contraindications | Monitoring | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|---|---|
| Peroneal nerve decompression at fibular head (CPT 64708) | Surgical | Entrapment neuropathy with identifiable compression (fibrous band, tight peroneal tunnel); failed conservative management 3-6 months; progressive weakness | Surgical decompression :: Outpatient surgery :: Single procedure :: Release of peroneal tunnel (fascial arch of peroneus longus); neurolysis of common peroneal nerve at fibular head; typically outpatient | Active infection; severe medical comorbidity; complete nerve transection (requires repair instead) | Post-op motor/sensory exam; wound healing; EMG at 3-6 months post-op | - | - | ROUTINE | - |
| Peroneal nerve repair/grafting (CPT 64712) | Surgical | Complete nerve transection from trauma (laceration, fracture); no recovery on serial EMG at 3-6 months with absent motor units on voluntary activation | Nerve repair or cable graft :: Inpatient surgery :: Single procedure :: Direct repair if gap <2 cm; sural nerve cable graft if gap >2 cm; timing optimal within 6 months of injury | Severe medical comorbidity; poor surgical candidate; gap too large for grafting (>6-8 cm) | Serial EMG q3 months; motor function; reinnervation signs | - | ROUTINE | ROUTINE | - |
| Posterior tibial tendon transfer (CPT 27690) | Surgical | Irreversible foot drop; no EMG evidence of reinnervation at 12-18 months; functional deficit despite AFO | Tendon transfer :: Inpatient surgery :: Single procedure :: Transfer of posterior tibialis tendon to dorsum of foot to restore dorsiflexion; requires intact posterior tibial nerve | Active infection; non-ambulatory patient; insufficient posterior tibial muscle | Post-op immobilization 6-8 weeks; PT for retraining; gait analysis | - | ROUTINE | ROUTINE | - |
| Ganglion cyst excision (CPT 27347) | Surgical | Ganglion cyst at fibular head compressing peroneal nerve; identified on MRI or ultrasound | Surgical excision :: Outpatient surgery :: Single procedure :: Excise cyst with capsular base; decompress nerve simultaneously | Active infection; asymptomatic cyst | Recurrence (10-15%); nerve function post-op | - | - | ROUTINE | - |
Surgical Indications (Absolute): - Complete foot drop with no recovery at 3-6 months and identifiable compressive lesion - Progressive weakness despite removal of compressive factors - Mass lesion (ganglion cyst, tumor) confirmed on imaging - Nerve transection from acute trauma (laceration, open fracture)
Surgical Indications (Relative): - Partial foot drop failing conservative therapy for 3-6 months - EMG showing axonal loss without reinnervation at 4-6 months - Occupational requirement for normal ankle dorsiflexion - Patient preference after informed discussion
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4. OTHER RECOMMENDATIONS¶
4A. Referrals & Consults¶
| Recommendation | ED | HOSP | OPD | ICU |
|---|---|---|---|---|
| Electrodiagnostic medicine/neurology for NCS/EMG to confirm diagnosis, localize lesion, and assess severity; optimal timing 2-3 weeks post-onset | ROUTINE | ROUTINE | ROUTINE | - |
| Orthopedic surgery or peripheral nerve surgery referral if mass lesion, fracture, or failed conservative management >3-6 months | - | ROUTINE | ROUTINE | - |
| Physical medicine and rehabilitation (PM&R) for comprehensive foot drop rehabilitation program and AFO fitting | - | ROUTINE | ROUTINE | - |
| Physical therapy for gait training, ankle strengthening, balance exercises, and NMES program | - | ROUTINE | ROUTINE | - |
| Orthotics/prosthetics for custom AFO fitting if foot drop expected to persist >6 months | - | ROUTINE | ROUTINE | - |
| Neurosurgery consultation if sciatic nerve or proximal lesion suspected on imaging | - | ROUTINE | ROUTINE | - |
| Endocrinology for diabetes optimization if contributing to nerve vulnerability | - | ROUTINE | ROUTINE | - |
| Podiatry if secondary foot deformity developing (equinovarus contracture) | - | - | ROUTINE | - |
| Occupational medicine for workplace modification if occupational factors contributed to compression | - | - | ROUTINE | - |
| Genetics referral if HNPP suspected (recurrent pressure palsies, family history) | - | - | EXT | - |
4B. Patient Instructions¶
| Recommendation | ED | HOSP | OPD | ICU |
|---|---|---|---|---|
| Wear ankle-foot orthosis (AFO) during all walking to prevent tripping and ankle injury; remove only for bathing and sleeping | ROUTINE | ROUTINE | ROUTINE | - |
| Do not cross legs while sitting as this compresses the peroneal nerve at the fibular head and worsens injury | ROUTINE | ROUTINE | ROUTINE | - |
| Avoid prolonged squatting, kneeling, or positions that put pressure on the outer knee area | ROUTINE | ROUTINE | ROUTINE | - |
| Perform ankle dorsiflexion and eversion exercises as instructed by physical therapist to maintain muscle strength during recovery | - | ROUTINE | ROUTINE | - |
| Check lateral leg and foot daily for skin breakdown, especially if sensation is reduced; report any sores or ulcers | - | ROUTINE | ROUTINE | - |
| Report worsening weakness (new difficulty lifting toes), spreading numbness, or pain to physician as this indicates progression requiring urgent re-evaluation | ROUTINE | ROUTINE | ROUTINE | - |
| Nerve recovery is slow (approximately 1 inch per month); improvement takes 6-12 months; maintain therapy and AFO use during this period | - | ROUTINE | ROUTINE | - |
| Avoid tight boots, stockings, or knee braces that compress the area below the outer knee | ROUTINE | ROUTINE | ROUTINE | - |
| Use caution on stairs and uneven surfaces; the AFO helps but does not fully replace normal ankle function | ROUTINE | ROUTINE | ROUTINE | - |
| If diabetic, maintain strict blood sugar control as elevated glucose impairs nerve recovery | - | ROUTINE | ROUTINE | - |
| Pad the lateral knee area when sleeping on the side; place a pillow between the legs | - | ROUTINE | ROUTINE | - |
4C. Lifestyle & Prevention¶
| Recommendation | ED | HOSP | OPD | ICU |
|---|---|---|---|---|
| Lose weight if overweight/obese; excess weight increases pressure on peripheral nerves and slows recovery | - | ROUTINE | ROUTINE | - |
| Avoid habitual leg crossing; this is the most common compressive cause of peroneal neuropathy ("crossed-leg palsy") | ROUTINE | ROUTINE | ROUTINE | - |
| Optimize glycemic control (HbA1c <7%) as diabetes impairs nerve recovery and increases vulnerability to compression | - | ROUTINE | ROUTINE | - |
| Stop smoking to improve microvascular circulation and nerve healing | - | ROUTINE | ROUTINE | - |
| Maintain adequate nutrition including B vitamins, protein, and micronutrients for nerve repair | - | ROUTINE | ROUTINE | - |
| Wear appropriate footwear: avoid high-top boots or tight lace-up shoes that compress the dorsal foot (deep peroneal branch) | - | ROUTINE | ROUTINE | - |
| For hospitalized patients: apply fibular head padding, reposition frequently, and avoid external compression to prevent iatrogenic peroneal neuropathy | - | ROUTINE | ROUTINE | - |
| Implement fall prevention measures at home: remove loose rugs, ensure adequate lighting, install grab bars if balance impaired | - | ROUTINE | ROUTINE | - |
| Notify surgical team of peroneal neuropathy risk during any planned lower extremity surgery, especially knee replacement or proximal fibula procedures | - | ROUTINE | ROUTINE | - |
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5. DIFFERENTIAL DIAGNOSIS¶
| Alternative Diagnosis | Key Distinguishing Features | Tests to Differentiate |
|---|---|---|
| L5 radiculopathy | Back pain radiating to leg; weakness includes hip abduction (gluteus medius) and toe extension; inversion weakness (tibialis posterior - L5 innervated but tibial nerve); positive straight leg raise; reflex usually normal (no L5 reflex); sensory loss extends to medial foot | MRI lumbar spine (L4-L5 disc, foraminal stenosis); EMG shows denervation in L5 myotome including non-peroneal muscles (tibialis posterior, gluteus medius); normal peroneal NCS across fibular head |
| Sciatic neuropathy | Weakness involves both peroneal AND tibial nerve distributions (plantar flexion weakness); hamstring weakness possible; hip/buttock pain; history of hip surgery, injection, or trauma | EMG shows denervation in tibial-innervated muscles (gastrocnemius, tibialis posterior); abnormal tibial NCS; short head biceps femoris (peroneal division) vs long head (tibial division) helps localize within sciatic |
| Lumbosacral plexopathy | Involves multiple nerve distributions (femoral + peroneal + tibial); hip flexion and knee extension weakness possible; pelvic pain; diabetes, malignancy, or radiation history | EMG shows denervation across L2-S1 myotome; MRI pelvis/plexus; CT abdomen/pelvis for mass |
| Hereditary neuropathy with liability to pressure palsies (HNPP) | Recurrent, episodic pressure palsies at multiple sites; family history; young onset; disproportionate slowing on NCS at compression sites | Genetic testing for PMP22 deletion; NCS shows diffuse conduction slowing at entrapment sites; nerve biopsy shows tomaculous neuropathy |
| Anterior horn cell disease (ALS) | Progressive weakness without sensory loss; fasciculations; upper motor neuron signs (hyperreflexia, Babinski); bulbar symptoms in advanced disease | EMG shows widespread denervation/reinnervation in 3+ regions; normal sensory NCS; no conduction block at fibular head |
| Multifocal motor neuropathy with conduction block (MMN) | Asymmetric distal weakness (often upper limb first); no sensory loss; conduction block outside typical entrapment sites; may mimic peroneal neuropathy | Anti-GM1 antibodies; NCS shows motor conduction block in non-entrapment sites; normal sensory studies |
| Deep peroneal neuropathy (anterior tarsal tunnel) | Weakness limited to EDB; sensory loss confined to first web space; foot dorsiflexion preserved; compression at ankle (tight shoes, trauma) | EMG/NCS localizes to ankle; fibular head conduction normal; selective EDB denervation only |
| Compartment syndrome (anterior compartment) | Acute onset with trauma; severe pain, tense compartment; pain with passive stretch of toes; late finding: foot drop | Compartment pressure measurement (>30 mmHg or within 30 mmHg of diastolic); clinical diagnosis; surgical emergency |
| Mononeuritis multiplex (vasculitic) | Stepwise involvement of multiple nerves; systemic symptoms (fever, weight loss, rash); painful | ESR, CRP, ANCA, hepatitis panel; nerve biopsy shows vasculitis; multifocal EMG abnormalities |
| Superficial peroneal neuropathy | Sensory loss over lateral leg and dorsal foot; no motor weakness (unless proximal injury); lateral leg pain; injury at mid-leg fascial defect | EMG/NCS: abnormal superficial peroneal SNAP; normal deep peroneal motor; normal tibialis anterior on EMG |
| Functional (psychogenic) foot drop | Inconsistent weakness on formal testing; give-way weakness; Hoover sign positive; no EMG abnormalities; foot dragged but toe clears ground on distraction | Normal NCS/EMG; inconsistent exam; psychiatric comorbidity; symptom onset with psychosocial stressor |
| Peroneal intraneural ganglion cyst | Progressive foot drop; palpable fullness at fibular head; ascending weakness pattern follows articular branch from superior tibiofibular joint | MRI shows intraneural cyst with tubular extension along articular branch; ultrasound shows cystic structure within nerve |
| Knee dislocation/proximal fibula fracture | Acute traumatic onset; significant knee instability; vascular injury risk (popliteal artery); high-energy mechanism | X-ray/CT shows fracture or dislocation; vascular assessment (ABI, CTA); NCS after acute phase |
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6. MONITORING PARAMETERS¶
Venue column indicates where monitoring is typically ordered/initiated.
| Parameter | Frequency | Target/Threshold | Action if Abnormal | ED | HOSP | OPD | ICU |
|---|---|---|---|---|---|---|---|
| Ankle dorsiflexion strength (MRC grade) | Each visit | Improvement from baseline; target MRC 4+/5 or better | If no improvement at 3 months, repeat EMG; if worsening, expedite surgical referral | ROUTINE | ROUTINE | ROUTINE | - |
| Ankle eversion strength | Each visit | Improvement or stable | Eversion loss suggests superficial peroneal involvement; reassess localization | - | ROUTINE | ROUTINE | - |
| Toe extension strength | Each visit | Improvement from baseline | If isolated loss, evaluate for deep peroneal branch lesion | - | ROUTINE | ROUTINE | - |
| Sensory exam (lateral leg, dorsal foot) | Each visit | Return of sensation; no expansion of deficit | Expanding sensory loss suggests progression or alternative diagnosis | ROUTINE | ROUTINE | ROUTINE | - |
| Gait assessment | Each visit | Improved gait pattern; reduced foot slap/steppage | Adjust AFO; modify PT program; assess surgical candidacy if no improvement | - | ROUTINE | ROUTINE | - |
| EMG/NCS (follow-up) | 3-6 months post-onset; then q6 months if not recovering | Reinnervation potentials; improved CMAP amplitude; reduced denervation | If no reinnervation at 6 months, pursue surgical exploration; if reinnervation present, continue conservative management | - | - | ROUTINE | - |
| AFO fit and compliance | Each visit | Proper fit; wearing during ambulation | Refit if needed; address compliance barriers | - | ROUTINE | ROUTINE | - |
| HbA1c (diabetic patients) | Every 3 months | <7% or individualized | Intensify diabetes management for nerve recovery optimization | - | ROUTINE | ROUTINE | - |
| Skin integrity (lateral leg, foot) | Each visit; daily if inpatient | No breakdown; no ulceration | Initiate wound care; adjust AFO/padding; podiatry referral | - | ROUTINE | ROUTINE | ROUTINE |
| Fall assessment | Each visit | No falls; safe ambulation with AFO | Modify PT program; home safety evaluation; add assistive device | - | ROUTINE | ROUTINE | - |
| Post-surgical motor/sensory function | 2 weeks, 6 weeks, 3 months, 6 months, 12 months post-op | Progressive motor improvement | If no improvement by 6 months post-decompression, repeat EMG and evaluate for revision or tendon transfer | - | ROUTINE | ROUTINE | - |
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7. DISPOSITION CRITERIA¶
| Disposition | Criteria |
|---|---|
| Discharge home | Foot drop identified; AFO fitted; able to ambulate safely with AFO; outpatient neurology/EMG follow-up arranged; no progressive deficit; no compartment syndrome |
| Admit to floor | Acute traumatic peroneal nerve injury requiring surgical evaluation; post-knee surgery with new foot drop; compartment syndrome requiring fasciotomy; progressive mononeuropathy multiplex requiring inpatient workup |
| Admit to ICU | Compartment syndrome with vascular compromise; polytrauma with peroneal nerve injury; not typical for isolated peroneal neuropathy |
| Urgent surgical referral | Suspected compartment syndrome; mass lesion causing acute progressive nerve compression; complete nerve transection from open injury; rapidly progressive foot drop with no identifiable compressive cause |
| Routine surgical referral | Failed conservative therapy at 3-6 months; ganglion cyst or mass at fibular head; no EMG evidence of reinnervation at 6 months; chronic complete foot drop for tendon transfer evaluation |
| Outpatient follow-up | Most patients; initial evaluation with EMG at 2-3 weeks; repeat EMG at 3-6 months; PT prescription; AFO fitting; reassess at 4-6 week intervals |
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8. EVIDENCE & REFERENCES¶
| Recommendation | Evidence Level | Source |
|---|---|---|
| Common peroneal neuropathy is the most common mononeuropathy of the lower extremity; fibular head is the most frequent compression site | Class II, Level B | Stewart JD. Neurology 2008 |
| EMG/NCS is the gold standard for diagnosis and localization of peroneal neuropathy; conduction block at fibular head distinguishes demyelinating from axonal lesion | Class II, Level B | Katirji B et al. Neurology 1988 |
| Habitual leg crossing is the most common identifiable cause of peroneal neuropathy at the fibular head | Class III, Level C | Aprile I et al. Neurol Sci 2005 |
| Weight loss >10 kg is a significant risk factor for peroneal neuropathy (loss of protective fat pad at fibular head) | Class III, Level C | Sotaniemi KA. J Neurol Neurosurg Psychiatry 1984 |
| Diabetes mellitus increases susceptibility to focal compression neuropathies including peroneal nerve | Class II, Level B | Pourmemari MH et al. Acta Neurol Scand 2018 |
| AFO use improves gait mechanics and reduces fall risk in patients with foot drop | Class II, Level B | Alam M et al. Prosthet Orthot Int 2014 |
| Surgical decompression of peroneal nerve at fibular head shows good outcomes in selected entrapment cases | Class III, Level C | Mont MA et al. Clin Orthop Relat Res 1996 |
| Peroneal intraneural ganglion cysts originate from the superior tibiofibular joint via the articular branch; surgical disconnection of articular branch prevents recurrence | Class III, Level C | Spinner RJ et al. J Neurosurg 2003 |
| Posterior tibial tendon transfer provides durable functional improvement in irreversible foot drop | Class III, Level C | Vigasio A et al. J Bone Joint Surg Am 2008 |
| MRI and ultrasound are complementary for evaluating structural causes of peroneal neuropathy | Class III, Level C | Visser LH. Muscle Nerve 2006 |
| HNPP (PMP22 deletion) should be suspected in recurrent or bilateral peroneal neuropathy, especially with family history | Class III, Level C | Mouton P et al. Brain 1999 |
| Neuromuscular electrical stimulation helps maintain muscle bulk during denervation period but evidence is limited | Class III, Level C | Kern H et al. Eur J Transl Myol 2014 |
| Short head of biceps femoris EMG helps differentiate peroneal neuropathy at fibular head from sciatic neuropathy (peroneal division) | Class II, Level B | Marciniak C et al. PM R 2013 |
| AANEM practice parameter: electrodiagnostic evaluation of patients with suspected peroneal neuropathy at the knee | Guideline | Katirji B. Muscle Nerve 2005 |
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CPT CODE QUICK REFERENCE¶
Laboratory CPT Codes¶
| Test | CPT Code | Description |
|---|---|---|
| Fasting glucose | 82947 | Glucose, quantitative |
| HbA1c | 83036 | Hemoglobin A1c |
| CBC with differential | 85025 | Complete blood count |
| BMP | 80048 | Basic metabolic panel |
| ESR | 85652 | Sedimentation rate, Westergren |
| CRP | 86140 | C-reactive protein |
| TSH | 84443 | Thyroid stimulating hormone |
| Vitamin B12 | 82607 | Cyanocobalamin |
| Folate | 82746 | Folic acid, serum |
| Rheumatoid factor | 86431 | Rheumatoid factor, quantitative |
| ANA | 86235 | Nuclear antigen antibody |
| ANCA | 86235/86236 | Antineutrophil cytoplasmic antibody |
| SPEP | 86335 | Protein electrophoresis, serum |
| Uric acid | 84550 | Uric acid, blood |
| Anti-ganglioside antibodies | 86255 | Antibody, fluorescent |
| Cryoglobulins | 82784 | Gammaglobulin, qualitative |
| Hepatitis B surface antigen | 87340 | HBsAg |
| Hepatitis C antibody | 86803 | Hepatitis C antibody |
| HIV antibody/antigen | 87389 | HIV-1/HIV-2 combination |
| Genetic testing (PMP22/CMT) | 81405 | Molecular pathology, Level 6 |
Diagnostic Studies CPT Codes¶
| Study | CPT Code | Description |
|---|---|---|
| NCS, 1-2 studies | 95907 | Nerve conduction, 1-2 studies |
| NCS, 3-4 studies | 95908 | Nerve conduction, 3-4 studies |
| NCS, 5-6 studies | 95909 | Nerve conduction, 5-6 studies |
| Needle EMG, limited | 95885 | EMG, limited (1 extremity) |
| Needle EMG, complete | 95886 | EMG, complete (2+ extremities) |
| Knee X-ray, 2 views | 73560 | Radiologic exam, knee, 1-2 views |
| MRI knee without contrast | 73721 | MRI, lower extremity joint, without contrast |
| MRI knee with and without contrast | 73723 | MRI, lower extremity joint, with and without contrast |
| MRI lower extremity (MR neurography) | 73720 | MRI, lower extremity, without contrast |
| Ultrasound, extremity | 76882 | Ultrasound, extremity, limited |
| MRI lumbar spine without contrast | 72148 | MRI lumbar spine without contrast |
| MRI lumbar spine with and without contrast | 72158 | MRI lumbar spine with and without contrast |
| CT knee without contrast | 73700 | CT, lower extremity, without contrast |
| MRI pelvis with contrast | 72196 | MRI pelvis with contrast |
Treatment/Procedure CPT Codes¶
| Procedure | CPT Code | Description |
|---|---|---|
| Neuroplasty, major peripheral nerve | 64708 | Neuroplasty/transposition, major peripheral nerve |
| Neuroplasty, sciatic nerve | 64712 | Neuroplasty, sciatic nerve |
| Tendon transfer, foot | 27690 | Transfer or transplant of single tendon |
| Fasciotomy, leg | 27884 | Decompression fasciotomy, leg |
| Ganglion cyst excision, knee | 27347 | Excision of lesion of meniscus or capsule, knee |
| Diagnostic nerve block | 64450 | Injection, anesthetic agent, other peripheral nerve |
| Therapeutic exercises | 97110 | Therapeutic procedure, 15 min |
| Gait training | 97116 | Gait training, 15 min |
| AFO, custom molded | L1960 | Ankle-foot orthosis, custom molded |
| AFO, prefabricated | L4396 | Ankle-foot orthosis, prefabricated |
Note: CPT codes are updated annually. Verify codes against current CMS fee schedule.
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APPENDIX A: Clinical Examination for Peroneal Neuropathy¶
Motor Assessment¶
Ankle Dorsiflexion (Deep Peroneal Nerve, L4-L5) - Technique: Patient dorsiflexes ankle against resistance - MRC Grading: 0 = no contraction; 1 = flicker; 2 = movement with gravity eliminated; 3 = against gravity; 4 = against resistance; 5 = normal - Clinical significance: Weakness confirms foot drop; degree helps grade severity
Ankle Eversion (Superficial Peroneal Nerve, L5-S1) - Technique: Patient everts foot against resistance - Clinical significance: Weakness of eversion plus dorsiflexion = common peroneal nerve at or above fibular head; preserved eversion with dorsiflexion weakness = deep peroneal branch only
Toe Extension (Deep Peroneal Nerve, L5) - Technique: Patient extends toes (especially great toe via extensor hallucis longus) against resistance - Clinical significance: Weakness in peroneal neuropathy and L5 radiculopathy; helps with localization combined with other findings
Ankle Inversion (Tibial Nerve, L4-L5) - Technique: Patient inverts foot against resistance (tibialis posterior) - Clinical significance: PRESERVED in peroneal neuropathy; WEAK in L5 radiculopathy (tibialis posterior receives L5 via tibial nerve); key differentiating test
Hip Abduction (Superior Gluteal Nerve, L5) - Technique: Patient abducts hip against resistance (gluteus medius) - Clinical significance: PRESERVED in peroneal neuropathy; WEAK in L5 radiculopathy; key differentiating test
Sensory Assessment¶
Lateral Leg (Superficial Peroneal Nerve) - Distribution: Lateral leg below knee - Clinical significance: Involved in common peroneal neuropathy; spared in deep peroneal neuropathy
Dorsal Foot (Superficial Peroneal Nerve) - Distribution: Dorsum of foot except first web space - Clinical significance: Involved in common peroneal neuropathy
First Web Space (Deep Peroneal Nerve) - Distribution: Small patch between first and second toes - Clinical significance: Only sensory territory of deep peroneal nerve; isolated loss suggests deep peroneal branch lesion
Tinel Sign at Fibular Head¶
- Technique: Tap over common peroneal nerve at the fibular head (posterolateral to fibular neck)
- Positive: Tingling or electric sensation radiating to lateral leg or dorsal foot
- Clinical significance: Suggests focal lesion at fibular head; helps localize compression site
Key Differentiating Examination Findings¶
| Finding | Peroneal Neuropathy | L5 Radiculopathy | Sciatic Neuropathy |
|---|---|---|---|
| Ankle dorsiflexion | Weak | Weak | Weak |
| Ankle eversion | Weak | May be weak | Weak |
| Ankle inversion | Normal | Weak | May be weak |
| Hip abduction | Normal | Weak | Normal |
| Plantar flexion | Normal | Normal | Weak |
| Knee flexion (hamstrings) | Normal | Normal | May be weak |
| Tinel at fibular head | Positive | Negative | Negative |
| Straight leg raise | Negative | May be positive | May be positive |
| Back pain | Absent | Present | May be present |
| Ankle reflex | Normal | Normal | May be reduced |
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APPENDIX B: Electrodiagnostic Criteria for Peroneal Neuropathy¶
Nerve Conduction Studies Protocol¶
Motor Studies - Peroneal motor nerve: Record EDB; stimulate ankle, below fibular head, above fibular head, popliteal fossa - Key finding: Conduction block or focal slowing across fibular head segment (>10 m/s drop or >50% amplitude drop) - Tibial motor nerve: Record abductor hallucis; stimulate ankle, popliteal fossa (should be normal; rules out sciatic/plexus)
Sensory Studies - Superficial peroneal sensory: Record lateral leg; stimulate calf - Key finding: Normal SNAP amplitude in demyelinating lesion at fibular head; reduced/absent in axonal lesion or more distal lesion - Sural sensory: Record lateral ankle (should be normal; rules out polyneuropathy)
Electrodiagnostic Classification¶
| Severity | Motor NCS | Sensory NCS | EMG |
|---|---|---|---|
| Mild (demyelinating) | Focal slowing or partial conduction block at fibular head; normal CMAP amplitude at ankle | Normal superficial peroneal SNAP | Normal or minimal denervation |
| Moderate (mixed) | Reduced CMAP amplitude at ankle; conduction block at fibular head | May be reduced | Denervation in peroneal-innervated muscles (tibialis anterior, peroneus longus) |
| Severe (axonal) | Absent or very low CMAP amplitude | Reduced or absent superficial peroneal SNAP | Active denervation (fibrillations, positive sharp waves) in tibialis anterior, peroneus longus, EDB; chronic changes |
Key Electrodiagnostic Localizing Points¶
Common Peroneal Neuropathy at Fibular Head: - Abnormal: Peroneal motor conduction across fibular head; tibialis anterior, peroneus longus, EDB on needle EMG - Normal: Short head biceps femoris; tibialis posterior; gluteus medius; paraspinal muscles - Normal: Tibial motor and sural sensory studies
Sciatic Neuropathy (Peroneal Division): - Abnormal: Same as above PLUS short head biceps femoris on needle EMG - Normal: Tibialis posterior; gluteus medius; paraspinal muscles
L5 Radiculopathy: - Abnormal: Tibialis anterior, peroneus longus, tibialis posterior, gluteus medius; L5 paraspinal denervation possible - Normal: Peroneal motor conduction across fibular head; peroneal SNAP - Key distinguishing finding: Tibialis posterior and gluteus medius abnormal in L5 radiculopathy, NORMAL in peroneal neuropathy
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CHANGE LOG¶
v1.1 (February 2, 2026)
- Validated per checker pipeline (v1.1 rebuild)
- Replaced markdown blockquote draft banner with standard HTML div format
- Replaced all --- section dividers with ═══ dividers throughout document
- Formatted SECTION A and SECTION B headers with ═══ wrapper lines
- Added ICU column to Section 4B (Patient Instructions) table
- Added ICU column to Section 4C (Lifestyle & Prevention) table
- Strengthened directive language throughout: removed "may" phrasing in patient instructions and monitoring actions
- Standardized Section 6 monitoring action language to direct imperatives (e.g., "pursue surgical exploration" instead of "consider")
- Updated VERSION from 1.0 to 1.1
- Added REVISED date
- Updated STATUS to "Validated per checker pipeline"
v1.0 (February 2, 2026)
- Initial creation
- Comprehensive plan for common peroneal (fibular) neuropathy at fibular head
- Foot drop evaluation with detailed motor/sensory examination guidance
- EMG/NCS protocol for localization with electrodiagnostic classification
- Full differential diagnosis table (13 diagnoses) with focus on L5 radiculopathy, sciatic neuropathy, HNPP, and compartment syndrome
- Conservative management: AFO fitting, physical therapy, NMES, neuropathic pain medications
- Surgical indications: decompression, nerve repair/grafting, tendon transfer, ganglion cyst excision
- Key differentiating examination findings table (Appendix A)
- Electrodiagnostic criteria and localizing points (Appendix B)
- All treatment dosing in structured format with :: delimiter
- CPT code reference for laboratory, diagnostic, and procedural billing
- 12 clinical synonyms for search optimization
- Settings: ED (acute foot drop), HOSP (post-traumatic/post-surgical), OPD (primary management)