Plexopathy - Brachial and Lumbosacral¶

VERSION: 1.1 CREATED: February 2, 2026 REVISED: February 2, 2026

STATUS: Revised per checker v1.1

DIAGNOSIS: Plexopathy - Brachial and Lumbosacral ICD-10: G54.0 (Brachial plexus disorders); G54.1 (Lumbosacral plexus disorders); G54.5 (Neuralgic amyotrophy / Parsonage-Turner syndrome); G54.9 (Nerve root and plexus disorder, unspecified); G62.0 (Drug-induced polyneuropathy, radiation plexopathy); C47.1 (Malignant neoplasm of peripheral nerves of upper limb, including shoulder); C47.2 (Malignant neoplasm of peripheral nerves of lower limb, including hip); G63 (Polyneuropathy in diseases classified elsewhere); E11.44 (Type 2 diabetes with diabetic amyotrophy) CPT CODES: 95907-95913 (NCS 1-13 studies), 95885-95887 (needle EMG limited/complete/each additional), 72141 (MRI cervical spine without contrast), 72148 (MRI lumbar spine without contrast), 72196 (MRI pelvis without contrast), 72197 (MRI pelvis with and without contrast), 73218 (MRI upper extremity without contrast), 73221 (MRI upper extremity with and without contrast), 73720 (MRI lower extremity with and without contrast), 70553 (MRI brain with and without contrast), 95886 (needle EMG complete), 95909 (NCS 5-6 studies), 36415 (venipuncture), 86235 (nuclear antigen antibody), 86200 (CCP antibody), 86038 (ANA), 88305 (surgical pathology), 20206 (needle biopsy, muscle), 64708 (neuroplasty, major peripheral nerve arm), 64712 (neuroplasty, sciatic nerve), 64713 (neuroplasty, brachial plexus), 64856 (nerve repair, suture), 64910 (nerve graft) SYNONYMS: Plexopathy, brachial plexopathy, lumbosacral plexopathy, Parsonage-Turner syndrome, neuralgic amyotrophy, brachial neuritis, idiopathic brachial plexopathy, diabetic amyotrophy, diabetic lumbosacral radiculoplexus neuropathy, DLRPN, radiation plexopathy, neoplastic plexopathy, traumatic plexopathy, obstetric brachial plexus palsy, Erb palsy, Klumpke palsy, plexus neuropathy, plexitis SCOPE: Evaluation and management of brachial and lumbosacral plexopathy in adults. Covers idiopathic/inflammatory (Parsonage-Turner syndrome / neuralgic amyotrophy), traumatic, compressive, radiation-induced, diabetic (diabetic amyotrophy / DLRPN), and neoplastic etiologies. Includes diagnostic workup with MRI plexus imaging, EMG/NCS, and laboratory evaluation. Addresses acute pain management, immunotherapy for inflammatory etiologies, rehabilitation, and surgical considerations. Excludes isolated mononeuropathies (see Carpal Tunnel Syndrome, Peroneal Neuropathy templates), cervical/lumbar radiculopathy (see Radiculopathy template), and brachial plexus birth injuries.

PRIORITY KEY: STAT = Immediate | URGENT = Within hours | ROUTINE = Standard | EXT = Extended/atypical cases | - = Not applicable to this setting

CLINICAL PEARLS: PLEXUS ANATOMY AND LOCALIZATION¶

Brachial Plexus (C5-T1)¶

Trunk/Cord	Roots	Motor Involvement	Sensory Distribution	Clinical Pattern
Upper trunk	C5-C6	Deltoid, biceps, supraspinatus, infraspinatus (shoulder abduction/ER, elbow flexion)	Lateral arm, lateral forearm	Erb palsy pattern; mimics C5-C6 radiculopathy
Middle trunk	C7	Triceps, wrist extensors, finger extensors	Middle finger, dorsal forearm	Wrist drop/finger drop
Lower trunk	C8-T1	Hand intrinsics, finger flexors, wrist flexors	Medial arm, medial forearm, ring/small fingers	Klumpke pattern; consider Pancoast tumor
Lateral cord	C5-C7	Biceps, coracobrachialis, lateral pectoral	Lateral forearm (musculocutaneous)	Lateral antebrachial cutaneous loss
Posterior cord	C5-T1	Deltoid, teres minor, latissimus dorsi, wrist/finger extensors	Posterior arm, posterior forearm, dorsal hand (radial)	Axillary + radial nerve territory
Medial cord	C8-T1	Hand intrinsics (ulnar), medial forearm flexors	Medial forearm, ring/small fingers (ulnar)	Ulnar + medial pectoral territory

Lumbosacral Plexus (L1-S3)¶

Division	Roots	Motor Involvement	Sensory Distribution	Clinical Pattern
Lumbar plexus (upper)	L1-L4	Hip flexion (iliopsoas), knee extension (quadriceps), hip adduction	Anterior thigh, medial thigh, medial leg	Femoral + obturator territory
Lumbosacral trunk	L4-L5	Ankle dorsiflexion, toe extension, hip abduction	Lateral leg, dorsum of foot	Bridge between lumbar and sacral plexus
Sacral plexus	L4-S3	Hamstrings, ankle plantarflexion, foot intrinsics	Posterior thigh, lateral/posterior leg, sole of foot	Sciatic territory (peroneal + tibial)
Pudendal plexus	S2-S4	Pelvic floor, external sphincters	Perineum, genitalia	Bowel/bladder/sexual dysfunction

KEY DISTINGUISHING FEATURES BY ETIOLOGY¶

Etiology	Onset	Pain	Distribution	Key Features	Diagnostic Clues
Parsonage-Turner (neuralgic amyotrophy)	Acute (hours to days)	Severe, precedes weakness by days-weeks	Patchy, non-anatomic trunk/cord distribution; often upper trunk	Preceded by illness/surgery/vaccination; self-limited but slow recovery (months-years)	EMG: patchy denervation; MRI: muscle denervation edema; serum anti-LRP4 rarely positive
Traumatic	Acute (immediate)	Variable	Correlates with mechanism (traction, penetrating)	Motorcycle accidents, falls, shoulder dislocations	EMG at 3-4 weeks; CT angiography for vascular injury; MR neurography for nerve continuity
Radiation-induced	Insidious (months-years post-RT)	Usually painless; paresthesias early	Upper trunk brachial (breast/lung RT); lumbosacral (pelvic RT)	Latency 6 months-20+ years post-radiation; dose >60 Gy higher risk; myokymia on EMG	EMG: myokymic discharges pathognomonic; MRI: diffuse T2 signal without mass
Neoplastic	Subacute-chronic (weeks-months)	Often severe, progressive	Lower trunk brachial (Pancoast); lumbosacral (pelvic tumors)	Weight loss; progressive course; Horner syndrome (lower trunk); palpable mass	MRI with contrast: enhancing mass; PET-CT; biopsy may be needed
Diabetic amyotrophy (DLRPN)	Subacute (weeks)	Severe thigh/hip pain	Proximal > distal; often starts unilateral then bilateral	Weight loss; T2DM (may be well-controlled); CSF protein elevated	EMG: lumbosacral plexopathy; nerve biopsy: microvasculitis; MRI: nerve/muscle enhancement
Compressive/Entrapment	Gradual or postoperative	Positional; may be painless	Relates to anatomic compression site	Post-surgical (lithotomy, retractors); hematoma; aneurysm	CT/MRI: structural lesion; EMG confirms localization

RED FLAGS REQUIRING URGENT EVALUATION¶

Red Flag	Concern	Action
Rapidly progressive weakness (days to weeks)	Neoplastic infiltration; hemorrhage into plexus	STAT MRI plexus with contrast; oncology consult
Horner syndrome (ptosis, miosis, anhidrosis) with arm weakness	Pancoast tumor (lung apex); lower trunk involvement	STAT CT chest with contrast; MRI brachial plexus with contrast
Unexplained weight loss with plexopathy	Neoplastic infiltration; diabetic amyotrophy	MRI with contrast; PET-CT; HbA1c; malignancy workup
Severe unrelenting pain not responding to opioids	Tumor infiltration; ischemic plexopathy	MRI with contrast; vascular imaging; pain management consult
Bilateral lumbosacral plexopathy with bowel/bladder	Cauda equina or conus medullaris involvement; pelvic mass	STAT MRI lumbar/pelvis; urology consult; catheterization as needed
Post-anticoagulation with hip/thigh pain and weakness	Retroperitoneal hematoma compressing lumbosacral plexus	STAT CT abdomen/pelvis; check coags; reverse anticoagulation; surgical consult
Fever + plexopathy	Infectious plexitis; abscess	MRI with contrast; blood cultures; ESR/CRP; infectious disease consult
Post-radiation plexopathy with new pain	Radiation-induced tumor vs. recurrence	MRI with contrast; PET-CT to differentiate; biopsy if equivocal
Acute plexopathy after shoulder dislocation	Traumatic brachial plexus injury; vascular injury	CT angiography; orthopedic/trauma consult; MR neurography
Rapidly progressive bilateral plexopathy	Vasculitic neuropathy; CIDP; lymphoma	ESR/CRP; ANCA; SPEP; CSF analysis; nerve biopsy

═══════════════════════════════════════════════════════════════ SECTION A: ACTION ITEMS ═══════════════════════════════════════════════════════════════

1. LABORATORY WORKUP¶

1A. Essential/Core Labs¶

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
CBC with differential (85025)	STAT	STAT	ROUTINE	STAT	Infection screen; malignancy screen; assess for leukocytosis or anemia	Normal WBC; no anemia; no atypical cells
CMP - BMP + LFTs (80053)	STAT	STAT	ROUTINE	STAT	Baseline renal/hepatic function for medications; electrolytes; glucose	Normal electrolytes; normal glucose
HbA1c (83036)	URGENT	URGENT	ROUTINE	URGENT	Diabetes is major cause of lumbosacral plexopathy (diabetic amyotrophy); may be initial presentation	<5.7%; elevated suggests diabetic amyotrophy
ESR (85652)	URGENT	URGENT	ROUTINE	URGENT	Elevated in inflammatory, neoplastic, and infectious etiologies	<20 mm/hr (age-adjusted)
CRP (86140)	URGENT	URGENT	ROUTINE	URGENT	Acute-phase reactant for inflammatory and infectious causes	<0.5 mg/dL
Fasting glucose (82947)	URGENT	URGENT	ROUTINE	URGENT	Screen for diabetes; diabetic amyotrophy may present in pre-diabetes	<100 mg/dL

1B. Extended Workup (Second-line)¶

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
TSH (84443)	-	ROUTINE	ROUTINE	-	Thyroid disease can cause myopathy and neuropathy; confounding factor	Normal (0.4-4.0 mIU/L)
Vitamin B12 (82607)	-	ROUTINE	ROUTINE	-	B12 deficiency causes neuropathy that may overlap with plexopathy	>300 pg/mL
ANA (86038)	-	ROUTINE	ROUTINE	-	Connective tissue disease associated with vasculitic plexopathy	Negative or low titer
ANCA panel (86200, 86235)	-	ROUTINE	ROUTINE	-	Vasculitis (granulomatosis with polyangiitis, microscopic polyangiitis) causing plexopathy	Negative
SPEP with immunofixation (86335, 86334)	-	ROUTINE	ROUTINE	-	Paraproteinemia; lymphoma; amyloidosis causing plexopathy	No M-spike; no monoclonal band
Coagulation panel - PT/INR, PTT (85610, 85730)	STAT	STAT	-	STAT	If retroperitoneal hematoma suspected; pre-procedural assessment	INR <1.5; PTT normal
LDH (83615)	-	ROUTINE	ROUTINE	-	Elevated in lymphoma and other malignancies	Normal (120-246 U/L)
Uric acid (84550)	-	ROUTINE	ROUTINE	-	Tumor lysis; gout causing nerve compression (rare)	Normal (3.5-7.2 mg/dL)
Urinalysis (81001)	URGENT	ROUTINE	ROUTINE	-	UTI as confounding factor; proteinuria in vasculitis	Normal

1C. Rare/Specialized (Refractory or Atypical)¶

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
CSF analysis (89050, 89051)	-	EXT	EXT	-	Elevated protein in DLRPN/diabetic amyotrophy and neoplastic plexopathy; cytology for leptomeningeal disease	Protein <45 mg/dL; no malignant cells; normal cell count
Paraneoplastic panel (86255)	-	EXT	EXT	-	Paraneoplastic plexopathy (anti-Hu, anti-CV2/CRMP5); subacute progressive course with occult malignancy	Negative
Ganglioside antibodies - GM1, GD1a, GD1b (86255)	-	EXT	EXT	-	Multifocal motor neuropathy mimicking plexopathy; GBS variants	Negative
Anti-LRP4 antibodies (86235)	-	EXT	EXT	-	Associated with hereditary neuralgic amyotrophy (SEPT9 mutation); research use	Negative
Lyme serology (86618)	-	EXT	EXT	-	Endemic areas; Lyme can cause polyradiculoplexopathy	Negative
ACE level (82164)	-	EXT	EXT	-	Sarcoidosis with multifocal neuropathy/plexopathy	Normal
HIV serology (86703)	-	EXT	EXT	-	HIV-associated plexopathy; CMV polyradiculopathy in immunocompromised	Negative
Cryoglobulins (86157)	-	EXT	EXT	-	Cryoglobulinemic vasculitis causing plexopathy	Negative
Genetic testing - SEPT9 gene (81479)	-	-	EXT	-	Hereditary neuralgic amyotrophy (recurrent episodes, family history)	No pathogenic variant

2. DIAGNOSTIC IMAGING & STUDIES¶

2A. Essential/First-line¶

Study	ED	HOSP	OPD	ICU	Timing	Target Finding	Contraindications
MRI brachial plexus with and without contrast (73221)	URGENT	URGENT	ROUTINE	URGENT	STAT if mass suspected; within 1 week for inflammatory/traumatic	Nerve T2 hyperintensity; muscle denervation edema; enhancing mass; nerve enlargement	MRI-incompatible pacemaker; cochlear implant; GFR <30 for gadolinium
MRI lumbosacral plexus with and without contrast (72197)	URGENT	URGENT	ROUTINE	URGENT	STAT if mass suspected or retroperitoneal hematoma; within 1 week otherwise	Nerve enhancement; mass lesion; psoas hematoma; diffuse vs. focal nerve signal abnormality	MRI-incompatible device; GFR <30 for gadolinium; claustrophobia
MRI lumbar spine without contrast (72148)	URGENT	URGENT	ROUTINE	URGENT	Concurrent with plexus imaging to exclude radiculopathy	Disc herniation; foraminal stenosis; conus/cauda equina lesion	MRI-incompatible device
MRI cervical spine without contrast (72141)	URGENT	URGENT	ROUTINE	URGENT	If brachial plexopathy - exclude cervical radiculopathy	Disc herniation; foraminal stenosis; cord lesion	MRI-incompatible device
EMG/NCS - electrodiagnostic studies (95886, 95909)	-	ROUTINE	ROUTINE	-	Optimal at 3-4 weeks after symptom onset; can perform earlier for baseline	Denervation in plexus distribution crossing multiple nerve territories; myokymic discharges (radiation); conduction block (compression)	Anticoagulation (relative for needle EMG); pacemaker (relative)

2B. Extended¶

Study	ED	HOSP	OPD	ICU	Timing	Target Finding	Contraindications
CT chest with contrast (71260)	URGENT	URGENT	ROUTINE	URGENT	If Pancoast tumor suspected (lower trunk brachial plexopathy + Horner)	Lung apex mass; mediastinal lymphadenopathy	Contrast allergy; renal insufficiency (GFR <30)
CT abdomen/pelvis with contrast (74178)	STAT	STAT	ROUTINE	STAT	If retroperitoneal hematoma suspected; pelvic mass	Retroperitoneal hematoma; pelvic mass compressing lumbosacral plexus	Contrast allergy; renal insufficiency
CT angiography - upper extremity (73206) or lower extremity (73706)	STAT	URGENT	-	STAT	Post-traumatic plexopathy to assess vascular injury	Vascular compromise; pseudoaneurysm; arteriovenous fistula	Contrast allergy; renal insufficiency
Ultrasound - nerve (76881, 76882)	-	ROUTINE	ROUTINE	-	Real-time assessment of nerve continuity; guide injection	Nerve enlargement; loss of fascicular pattern; mass	None significant
PET-CT (78816)	-	EXT	ROUTINE	-	Differentiate radiation plexopathy from tumor recurrence; occult malignancy	FDG-avid mass suggests tumor recurrence; diffuse uptake may be inflammatory	Pregnancy; uncontrolled diabetes

2C. Rare/Specialized¶

Study	ED	HOSP	OPD	ICU	Timing	Target Finding	Contraindications
MR neurography - dedicated plexus protocol (73221)	-	EXT	ROUTINE	-	High-resolution nerve imaging when standard MRI equivocal	Fascicular detail; intraneural pathology; nerve continuity assessment	MRI-incompatible device; GFR <30
Nerve biopsy - typically sural or superficial peroneal (64795)	-	EXT	EXT	-	Vasculitis suspected; amyloidosis; sarcoidosis; diagnosis uncertain after non-invasive workup	Vasculitis (necrotizing); amyloid deposits; granulomas; perivascular inflammation	Coagulopathy; patient preference
Muscle biopsy (20206)	-	EXT	EXT	-	If concurrent myopathy suspected; vasculitic neuropathy confirmation	Neurogenic atrophy pattern; perifascicular atrophy (if myopathy); vasculitis	Coagulopathy; infection at site
Bone scan (78300)	-	EXT	ROUTINE	-	Suspected skeletal metastasis causing plexus compression	No increased uptake at plexus level	Pregnancy
SSEP - somatosensory evoked potentials (95925, 95926)	-	EXT	EXT	-	Pre-ganglionic vs. post-ganglionic lesion localization (traumatic)	Absent cortical response with preserved SNAPs suggests pre-ganglionic (root avulsion)	None significant

3. TREATMENT¶

3A. Acute/Emergent¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Methylprednisolone	IV	Severe acute inflammatory plexopathy (neuralgic amyotrophy with progressive weakness); neoplastic plexopathy with impending cord/nerve compromise	1000 mg :: IV :: daily x 3-5 days :: 1000 mg IV daily x 3-5 days then transition to oral prednisone taper	Active infection; uncontrolled diabetes; GI bleeding; psychosis	Glucose q6h; BP; psychiatric effects; GI prophylaxis	STAT	STAT	-	STAT
Dexamethasone	IV/PO	Acute plexopathy with severe pain and inflammation; peritumoral edema	10 mg :: IV :: once then 4 mg q6h :: 10 mg IV loading dose, then 4 mg IV/PO q6h; taper over 7-14 days	Active infection; uncontrolled diabetes; GI bleeding	Glucose; BP; psychiatric effects; insomnia	STAT	STAT	ROUTINE	STAT
Prednisone	PO	Acute inflammatory plexopathy (Parsonage-Turner); diabetic amyotrophy (controversial)	60 mg :: PO :: daily x 5-7 days :: 60 mg PO daily x 5-7 days then taper over 2-4 weeks; total course 4-6 weeks for inflammatory etiology	Active GI bleed; uncontrolled DM; active infection	Glucose; BP; mood; weight; bone density if prolonged	URGENT	URGENT	ROUTINE	-
Ketorolac	IV/IM	Acute severe plexopathy pain (short-term)	30 mg :: IV :: q6h :: 30 mg IV/IM q6h; max 5 days; reduce to 15 mg if elderly or renal impairment	CrCl <30; active GI bleed; aspirin allergy; post-CABG	Renal function; GI bleeding	STAT	STAT	-	STAT
Morphine	IV	Severe acute plexopathy pain unresponsive to non-opioids	2-4 mg :: IV :: q2-4h PRN :: 2-4 mg IV q2-4h PRN severe pain; titrate to effect	Respiratory depression; severe asthma; paralytic ileus	Respiratory status; sedation; pain scores	STAT	STAT	-	STAT
Hydromorphone	IV	Severe acute plexopathy pain (alternative to morphine)	0.5-1 mg :: IV :: q2-4h PRN :: 0.5-1 mg IV q2-4h PRN; titrate to effect	Respiratory depression; severe asthma; paralytic ileus	Respiratory status; sedation; pain scores	STAT	STAT	-	STAT

3B. Symptomatic Treatments - Pain Management¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Gabapentin	PO	Neuropathic pain from plexopathy (first-line)	300 mg :: PO :: qHS :: Start 300 mg qHS; increase by 300 mg q1-3 days; target 900-1800 mg TID; max 3600 mg/day	Renal impairment (adjust: CrCl 30-59 max 1400 mg/day; CrCl 15-29 max 600 mg/day; CrCl <15 max 300 mg/day)	Sedation; dizziness; edema; taper to discontinue	ROUTINE	ROUTINE	ROUTINE	ROUTINE
Pregabalin	PO	Neuropathic pain from plexopathy (first-line alternative)	75 mg :: PO :: BID :: Start 75 mg BID; increase to 150 mg BID after 1 week; max 300 mg BID (600 mg/day)	Renal impairment (adjust per CrCl); Class V controlled	Sedation; weight gain; edema; dizziness	-	ROUTINE	ROUTINE	ROUTINE
Duloxetine	PO	Neuropathic pain with depression/anxiety; diabetic amyotrophy pain	30 mg :: PO :: daily :: Start 30 mg daily x 1 week; increase to 60 mg daily; max 120 mg/day	Hepatic impairment; CrCl <30; MAOIs; narrow-angle glaucoma	Nausea; BP; discontinuation syndrome (taper over 2+ weeks)	-	ROUTINE	ROUTINE	-
Amitriptyline	PO	Neuropathic pain (second-line; helps with sleep disruption from pain)	10 mg :: PO :: qHS :: Start 10-25 mg qHS; increase by 10-25 mg weekly; max 150 mg qHS	Cardiac conduction abnormality; recent MI; urinary retention; glaucoma; elderly (anticholinergic)	ECG if dose >100 mg/day; anticholinergic effects; sedation	-	ROUTINE	ROUTINE	-
Nortriptyline	PO	Neuropathic pain (second-line; less sedating than amitriptyline)	10 mg :: PO :: qHS :: Start 10-25 mg qHS; increase by 10-25 mg weekly; max 150 mg qHS	Cardiac conduction abnormality; recent MI; urinary retention; glaucoma	ECG if dose >100 mg/day; fewer anticholinergic effects	-	ROUTINE	ROUTINE	-
Ibuprofen	PO	Mild-moderate plexopathy pain; anti-inflammatory (adjunct)	400 mg :: PO :: TID :: 400-800 mg TID with food; max 3200 mg/day; short-term use preferred	CrCl <30; active GI bleed; aspirin allergy; third trimester pregnancy	GI symptoms; renal function with prolonged use	ROUTINE	ROUTINE	ROUTINE	-
Naproxen	PO	Mild-moderate plexopathy pain (longer duration NSAID)	250 mg :: PO :: BID :: 250-500 mg BID with food; max 1500 mg/day	CrCl <30; active GI bleed; aspirin allergy; third trimester pregnancy	GI symptoms; renal function with prolonged use	ROUTINE	ROUTINE	ROUTINE	-
Acetaminophen	PO	Mild pain (adjunct; avoid hepatotoxicity)	650 mg :: PO :: q6h :: 650-1000 mg q6h; max 3000 mg/day (2000 mg/day if liver disease)	Severe hepatic impairment; chronic alcohol use	LFTs with prolonged use	ROUTINE	ROUTINE	ROUTINE	ROUTINE
Lidocaine patch 5%	TOP	Localized plexopathy pain (shoulder, hip region)	1-3 patches :: TOP :: 12h on/12h off :: Apply 1-3 patches to affected area for 12h on, 12h off	Severe hepatic impairment; broken skin	Minimal systemic absorption; local skin irritation	-	ROUTINE	ROUTINE	ROUTINE
Capsaicin cream 0.075%	TOP	Localized neuropathic pain (adjunct)	Apply thin layer :: TOP :: TID-QID :: Apply TID-QID to affected area; takes 2-4 weeks for effect	Open wounds; avoid eyes/mucous membranes	Initial burning (decreases with use); wash hands after	-	-	ROUTINE	-
Cyclobenzaprine	PO	Muscle spasm associated with plexopathy (short-term)	5 mg :: PO :: TID :: 5-10 mg TID; max 30 mg/day; limit to 2-3 weeks	Arrhythmia; heart failure; MAOIs within 14 days; hyperthyroidism	Sedation; anticholinergic effects; dry mouth	ROUTINE	ROUTINE	ROUTINE	-
Baclofen	PO	Muscle spasm refractory to cyclobenzaprine	5 mg :: PO :: TID :: Start 5 mg TID; increase by 5 mg/dose q3d; max 80 mg/day	Withdrawal risk if stopped abruptly; renal impairment	Sedation; weakness; must taper to discontinue (seizure risk)	-	ROUTINE	ROUTINE	-

3C. Disease-Specific / Immunotherapy¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
IVIg (intravenous immunoglobulin)	IV	Severe/refractory neuralgic amyotrophy; diabetic amyotrophy (DLRPN) with vasculitic features; atypical inflammatory plexopathy	0.4 g/kg :: IV :: daily x 5 days :: 0.4 g/kg/day IV x 5 days (total 2 g/kg); repeat q4 weeks x 3-6 months if responsive	IgA deficiency (anaphylaxis risk); renal insufficiency; hypercoagulable state	Renal function; IgA level before first dose; infusion reaction vitals q15 min; headache (aseptic meningitis); thrombotic events	-	URGENT	ROUTINE	URGENT
Plasma exchange (PLEX)	IV	Severe inflammatory plexopathy refractory to steroids and IVIg; CIDP-like plexopathy	5 exchanges :: IV :: q other day x 10-14 days :: 5-7 exchanges over 10-14 days; 1-1.5 plasma volumes per exchange	Hemodynamic instability; severe coagulopathy; poor IV access	BP during exchange; electrolytes (Ca, K, Mg); fibrinogen; coags; line site infection	-	URGENT	-	URGENT
Methotrexate	PO	Steroid-sparing agent for chronic inflammatory plexopathy	7.5 mg :: PO :: weekly :: Start 7.5 mg weekly; increase by 2.5 mg q2-4 weeks; max 25 mg weekly; add folic acid 1 mg daily	Pregnancy; severe hepatic/renal impairment; active infection; bone marrow suppression	CBC, LFTs, creatinine q2-4 weeks x 3 months then q3 months; folic acid supplementation	-	EXT	ROUTINE	-
Azathioprine	PO	Steroid-sparing agent for chronic relapsing plexopathy	50 mg :: PO :: daily :: Start 50 mg daily; titrate to 2-3 mg/kg/day over 4-6 weeks; check TPMT before starting	TPMT deficiency; pregnancy; concurrent allopurinol (dose reduction required)	TPMT genotype before starting; CBC q2 weeks x 2 months then q3 months; LFTs	-	EXT	ROUTINE	-
Mycophenolate mofetil	PO	Steroid-sparing for chronic inflammatory plexopathy (alternative)	500 mg :: PO :: BID :: Start 500 mg BID; increase to 1000 mg BID over 2-4 weeks; max 3000 mg/day	Pregnancy (teratogenic); active infection	CBC q2 weeks x 3 months then monthly; GI symptoms; opportunistic infections	-	EXT	ROUTINE	-
Glycemic optimization (insulin/OHAs)	Variable	Diabetic amyotrophy - tight glucose control is cornerstone of management	Per protocol :: Variable :: per diabetes team :: Target HbA1c <7%; avoid rapid glucose reduction (risk of treatment-induced neuropathy if HbA1c drops >2% in 3 months)	Hypoglycemia; individualize targets in elderly	HbA1c q3 months; daily glucose monitoring; hypoglycemic events	ROUTINE	ROUTINE	ROUTINE	ROUTINE

3D. Surgical/Procedural Treatments (Specialist Decision)¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Surgical decompression of hematoma	Surgical	Retroperitoneal hematoma compressing lumbosacral plexus; expanding hematoma despite reversal of anticoagulation	N/A :: Surgical :: emergent :: Emergent or urgent depending on progression; coordinate with vascular/general surgery	Uncontrolled coagulopathy (correct first); hemodynamic instability (stabilize first)	Post-op neuro checks; coagulation status; hemoglobin; drain output	STAT	STAT	-	STAT
Brachial plexus exploration and nerve repair (64713, 64856)	Surgical	Traumatic brachial plexus injury with no recovery by 3-6 months; sharp/penetrating injuries (early repair)	N/A :: Surgical :: planned :: Timing depends on mechanism: sharp injuries repair early (days-weeks); closed traction injuries explore at 3-6 months if no EMG recovery	Active infection; patient factors precluding prolonged surgery	Post-op neuro exam; wound; serial EMG at 3-6 month intervals to assess reinnervation	-	EXT	ROUTINE	-
Nerve transfer	Surgical	Proximal brachial plexus injury (root avulsion) where direct repair not possible	N/A :: Surgical :: planned :: Transfer of expendable donor nerve to target nerve; best results within 6-12 months of injury	Active infection; poor donor nerve options; extensive pan-plexus injury	Serial clinical and EMG evaluation; recovery takes 6-18 months	-	EXT	ROUTINE	-
Nerve graft (64910)	Surgical	Gap in nerve continuity after traumatic injury or tumor resection	N/A :: Surgical :: planned :: Sural nerve or other donor nerve graft to bridge gap; best results with gaps <6 cm	Active infection; severe medical comorbidities; poor regenerative potential	Serial EMG; clinical exam q3 months; donor site sensory deficit expected	-	EXT	ROUTINE	-
Tumor resection	Surgical	Neoplastic plexopathy - resectable tumor compressing plexus	N/A :: Surgical :: planned or urgent :: Coordinate with oncology and nerve surgery; intraoperative monitoring recommended	Unresectable tumor (radiation instead); poor surgical candidate	Post-op neuro exam; oncology follow-up; adjuvant therapy per oncology	-	URGENT	ROUTINE	-
Radiation therapy	External beam	Neoplastic plexopathy (Pancoast tumor, lymphoma, metastatic disease)	Per protocol :: External beam :: per radiation oncology :: Dose and fractionation per tumor type and radiation oncology plan	Prior radiation to same field (cumulative dose limits); pregnancy	Radiation plexopathy monitoring (may develop months-years later); skin integrity; CBC	-	ROUTINE	ROUTINE	-
Epidural steroid injection / nerve root block	Fluoroscopic	Plexopathy with concurrent radicular component; diagnostic block to differentiate radiculopathy from plexopathy	Per protocol :: Fluoroscopic :: q2-4 weeks x 3 :: Fluoroscopic-guided transforaminal approach; diagnostic and therapeutic	Coagulopathy (INR >1.5, plt <100k); infection at site; allergy to contrast/steroids	Post-procedure neuro exam; glucose (diabetics); headache	-	EXT	ROUTINE	-

4. OTHER RECOMMENDATIONS¶

4A. Referrals & Consults¶

Recommendation	ED	HOSP	OPD	ICU
Neurology consult for all suspected plexopathy (confirmation of diagnosis, localization, etiology determination)	URGENT	URGENT	ROUTINE	URGENT
EMG/NCS referral for electrodiagnostic confirmation and localization (optimal timing 3-4 weeks after onset; earlier if needed for baseline)	-	ROUTINE	ROUTINE	-
Oncology consult STAT for suspected neoplastic plexopathy (Pancoast tumor, pelvic malignancy, lymphoma)	STAT	STAT	URGENT	STAT
Surgical consult (neurosurgery or peripheral nerve surgery) for traumatic plexopathy with no recovery, expanding hematoma, or nerve repair candidacy	URGENT	URGENT	ROUTINE	URGENT
Radiation oncology consult for radiation-induced plexopathy management and for neoplastic plexopathy treatment	-	ROUTINE	ROUTINE	-
Pain management/Interventional pain for refractory neuropathic pain; nerve blocks; neuromodulation	-	ROUTINE	ROUTINE	-
Endocrinology for diabetic amyotrophy (glycemic optimization and diabetic complication management)	-	ROUTINE	ROUTINE	-
Rheumatology for suspected vasculitic plexopathy (systemic vasculitis workup and immunosuppressive management)	-	ROUTINE	ROUTINE	-
Physical therapy for shoulder/hip stabilization, progressive strengthening, ROM maintenance, and adaptive equipment training	-	ROUTINE	ROUTINE	-
Occupational therapy for upper extremity plexopathy (ADL training, splinting, adaptive devices, ergonomic modifications)	-	ROUTINE	ROUTINE	-
PM&R (Physical Medicine & Rehabilitation) for comprehensive neurorehabilitation program	-	ROUTINE	ROUTINE	-
Vascular surgery consult if vascular injury suspected (traumatic plexopathy with limb ischemia)	STAT	STAT	-	STAT
Psychology/Pain psychology for chronic pain management, coping strategies, CBT for neuropathic pain	-	-	ROUTINE	-
Social work for disability assistance, return-to-work planning, and insurance navigation	-	ROUTINE	ROUTINE	-

4B. Patient Instructions¶

Recommendation	ED	HOSP	OPD
Return to ED IMMEDIATELY if rapid worsening of weakness, loss of ability to use arm/hand or walk, or new bowel/bladder dysfunction	STAT	STAT	STAT
Return to ED if fever develops with worsening neurological symptoms (may indicate infection)	STAT	STAT	STAT
Return if new onset of drooping eyelid with arm weakness (Horner syndrome - may indicate Pancoast tumor)	STAT	STAT	STAT
Parsonage-Turner syndrome (neuralgic amyotrophy) has a prolonged recovery course (months to 2-3 years); improvement is expected but slow	ROUTINE	ROUTINE	ROUTINE
Protect the weak limb from injury: avoid carrying heavy objects with affected arm; use assistive devices for walking if leg is weak	ROUTINE	ROUTINE	ROUTINE
For shoulder plexopathy: avoid sleeping on the affected side; use a sling only as directed (prolonged sling use causes frozen shoulder)	ROUTINE	ROUTINE	ROUTINE
Perform prescribed physical therapy exercises daily at home to maintain range of motion and prevent contractures	-	ROUTINE	ROUTINE
Do not stop gabapentin/pregabalin abruptly - taper under medical guidance to avoid withdrawal	-	ROUTINE	ROUTINE
Neuropathic pain medications (gabapentin, pregabalin, duloxetine) take 2-4 weeks to reach full effect; do not stop prematurely	-	ROUTINE	ROUTINE
If diabetic: tight glucose control is essential for recovery; monitor blood sugars as directed and follow up with endocrinology	-	ROUTINE	ROUTINE
Report any new lumps, unexplained weight loss, or night sweats to your physician (may indicate malignancy)	ROUTINE	ROUTINE	ROUTINE
Do not drive while taking opioids or sedating medications	ROUTINE	ROUTINE	ROUTINE
Follow up with neurology in 2-4 weeks for clinical and EMG reassessment	ROUTINE	ROUTINE	ROUTINE

4C. Lifestyle & Prevention¶

Recommendation	ED	HOSP	OPD
Smoking cessation to improve nerve healing and reduce vascular risk (smoking impairs peripheral nerve regeneration)	ROUTINE	ROUTINE	ROUTINE
Weight management to reduce mechanical stress on plexus and improve surgical outcomes if needed	-	ROUTINE	ROUTINE
Glycemic control if diabetic (HbA1c <7%) to prevent diabetic amyotrophy recurrence and facilitate nerve recovery	-	ROUTINE	ROUTINE
Avoid rapid glucose reduction (HbA1c drop >2% in 3 months) which can paradoxically worsen neuropathy (treatment-induced neuropathy of diabetes)	-	ROUTINE	ROUTINE
Ergonomic workstation modifications if plexopathy affects work capacity; adjustable desk, ergonomic keyboard	-	-	ROUTINE
Use shoulder/arm sling as directed for brachial plexopathy but remove regularly for ROM exercises to prevent frozen shoulder	-	ROUTINE	ROUTINE
Avoid repetitive overhead activities during recovery from brachial plexopathy	-	ROUTINE	ROUTINE
Fall prevention measures if lower extremity weakness present (remove loose rugs, install grab bars, use assistive devices)	-	ROUTINE	ROUTINE
Maintain range of motion with daily passive and active exercises to prevent contractures	-	ROUTINE	ROUTINE
Adequate nutrition (protein, vitamin B complex) to support nerve regeneration	-	ROUTINE	ROUTINE
Manage stress and ensure adequate sleep as chronic pain worsens with fatigue and stress	-	ROUTINE	ROUTINE
Alcohol moderation (excessive alcohol impairs nerve regeneration and compounds neuropathy risk)	-	ROUTINE	ROUTINE

═══════════════════════════════════════════════════════════════ SECTION B: REFERENCE ═══════════════════════════════════════════════════════════════

5. DIFFERENTIAL DIAGNOSIS¶

Alternative Diagnosis	Key Distinguishing Features	Tests to Differentiate
Cervical radiculopathy	Dermatomal distribution (single root); neck pain with Spurling test positive; symptoms follow one root territory	MRI cervical spine shows disc/foraminal pathology; EMG limited to one myotome; no abnormal SNAP (pre-ganglionic)
Lumbar radiculopathy	Dermatomal distribution; positive straight leg raise; back pain radiating in single root territory	MRI lumbar spine shows disc herniation/stenosis; EMG limited to one myotome
Mononeuropathy (single nerve)	Deficit restricted to single nerve territory (e.g., axillary, suprascapular, femoral, obturator)	EMG/NCS isolated to single nerve; plexopathy affects multiple nerves from same plexus
Rotator cuff tear	Shoulder pain with weakness in specific rotator cuff muscles; positive impingement signs	MRI shoulder shows tendon tear; EMG normal (no denervation)
Cervical myelopathy	Upper motor neuron signs (hyperreflexia, Babinski, spasticity); gait ataxia; bilateral symptoms	MRI cervical spine shows cord compression/signal change; EMG may be normal
Polymyositis/Dermatomyositis	Proximal symmetric weakness; elevated CK; skin changes (dermatomyositis); no sensory loss	Elevated CK; EMG shows myopathic pattern; muscle biopsy; myositis-specific antibodies
Motor neuron disease (ALS)	Progressive weakness without sensory loss; upper + lower motor neuron signs; fasciculations	EMG shows widespread denervation in multiple regions; no sensory nerve abnormalities
Multifocal motor neuropathy (MMN)	Asymmetric distal > proximal weakness; no sensory loss; slowly progressive	NCS shows conduction block; anti-GM1 IgM antibodies; responds to IVIg
CIDP	Symmetric proximal and distal weakness; areflexia; sensory loss; progressive >8 weeks	NCS shows demyelinating pattern; CSF elevated protein; nerve biopsy shows demyelination
Guillain-Barre syndrome	Ascending weakness; areflexia; often post-infectious; acute onset (<4 weeks)	NCS shows demyelinating or axonal pattern; CSF albuminocytologic dissociation
Vasculitic neuropathy	Mononeuritis multiplex pattern (stepwise); systemic symptoms; weight loss; rash	ESR/CRP elevated; ANCA positive; nerve biopsy shows necrotizing vasculitis
Hereditary neuropathy (HNPP)	Recurrent pressure palsies; family history; generalized slowing on NCS	NCS shows diffuse conduction slowing; genetic testing (PMP22 deletion); tomaculous neuropathy on biopsy
Thoracic outlet syndrome	Positional arm symptoms (overhead); vascular compromise (venous, arterial); neurogenic TOS rare	Provocative maneuvers (Adson, Wright); NCS (medial antebrachial cutaneous SNAP reduced); MRA/MRV
Meralgia paresthetica	Isolated lateral thigh numbness/burning (lateral femoral cutaneous nerve); no weakness	Normal EMG; abnormal lateral femoral cutaneous NCS; MRI plexus normal
Lumbosacral radiculoplexus neuropathy (non-diabetic)	Identical to diabetic amyotrophy but in non-diabetic; weight loss; severe pain	EMG shows lumbosacral plexopathy; nerve biopsy: microvasculitis; HbA1c normal
Cauda equina syndrome	Saddle anesthesia; bowel/bladder dysfunction; bilateral leg symptoms	MRI shows large central disc or mass compressing cauda equina
Spinal cord tumor	Progressive myelopathic symptoms; pain worse at night; specific level on exam	MRI with contrast shows enhancing intramedullary or extramedullary mass
Retroperitoneal mass (non-neoplastic)	Compressive lumbosacral plexopathy from abscess, fibrosis, endometriosis, aneurysm	CT/MRI pelvis shows structural cause; ESR/CRP if infectious; biopsy if mass

6. MONITORING PARAMETERS¶

Venue column indicates where monitoring is typically ordered/initiated. Most monitoring continues in outpatient setting.

Parameter	Frequency	Target/Threshold	Action if Abnormal	ED	HOSP	OPD	ICU
Motor strength (MRC grading)	Each visit; weekly if inpatient	Stable or improving; >=4/5 target	Progressive weakness: repeat imaging; escalate immunotherapy; surgical consult	STAT	STAT	ROUTINE	STAT
Pain scores (0-10 NRS)	Each visit	50% reduction from baseline	Escalate neuropathic pain regimen; interventional pain referral	ROUTINE	ROUTINE	ROUTINE	ROUTINE
Sensory exam (plexus distribution)	Each visit	Stable or improving	Document progression; correlate with repeat EMG	ROUTINE	ROUTINE	ROUTINE	ROUTINE
Deep tendon reflexes	Each visit	Appropriate for plexus level (usually reduced/absent)	New hyperreflexia suggests central lesion: MRI spine	ROUTINE	ROUTINE	ROUTINE	ROUTINE
EMG/NCS follow-up	Baseline (3-4 weeks), then q3-6 months	Evidence of reinnervation (nascent MUPs, increased recruitment)	No reinnervation by 3-6 months in traumatic: surgical exploration	-	ROUTINE	ROUTINE	-
Repeat MRI plexus	3-6 months or if clinical change	Resolving edema/enhancement; no new mass	New or enlarging mass: biopsy; escalate treatment	-	ROUTINE	ROUTINE	-
HbA1c (diabetic amyotrophy)	q3 months	<7% (individualized)	Adjust diabetes management; endocrinology optimization	-	ROUTINE	ROUTINE	-
CBC/LFTs (if on immunosuppression)	q2-4 weeks initially, then q3 months	Normal	Leukopenia or elevated LFTs: hold or reduce immunosuppressant; hematology consult	-	ROUTINE	ROUTINE	-
Renal function (if on NSAIDs >2 weeks)	Baseline, then q3 months	Stable creatinine	Decline: discontinue NSAIDs; switch to acetaminophen/other	-	ROUTINE	ROUTINE	-
Glucose (if on steroids)	Daily if inpatient; before/after procedures	<180 mg/dL (diabetics)	Adjust diabetes medications; limit steroid duration	ROUTINE	ROUTINE	ROUTINE	ROUTINE
Functional status (grip strength, timed walk, disability scales)	Baseline, 6 weeks, 3 months, 6 months, 12 months	Improving scores	Not improving: reassess treatment; surgical options; adjust rehabilitation	-	ROUTINE	ROUTINE	-
Respiratory function (if phrenic nerve involved - C3-C5)	Each visit if suspected	FVC >80% predicted; no orthopnea	Declining FVC: pulmonology consult; sleep study for nocturnal desaturation; phrenic nerve pacing	-	ROUTINE	ROUTINE	ROUTINE

7. DISPOSITION CRITERIA¶

Disposition	Criteria
Discharge home	Pain controlled with oral medications; stable or slowly improving neurologic exam; no red flags; able to perform basic ADLs (possibly with modifications); reliable outpatient follow-up with neurology in 2-4 weeks; physical/occupational therapy arranged
Admit to floor	Severe pain requiring IV analgesia; rapidly progressive weakness requiring close monitoring; need for IV immunotherapy (IVIg, methylprednisolone pulse); suspected neoplastic plexopathy requiring urgent workup; suspected retroperitoneal hematoma; inability to perform basic ADLs safely
Admit to ICU	Respiratory compromise from phrenic nerve involvement (bilateral brachial plexopathy); hemodynamic instability from retroperitoneal hemorrhage; post-surgical monitoring after complex plexus surgery; concurrent autonomic instability
Emergent surgery consult	Expanding retroperitoneal hematoma with progressive lumbosacral plexopathy; traumatic plexopathy with vascular compromise; acute nerve compression from hematoma or abscess
Transfer to higher level	Peripheral nerve surgery expertise not available; MR neurography/dedicated plexus imaging not available; need for specialized EMG by neuromuscular specialist not available locally

8. EVIDENCE & REFERENCES¶

Recommendation	Evidence Level	Source
Neuralgic amyotrophy is the most common non-traumatic brachial plexopathy; annual incidence 1-3/100,000	Class II, Level B	van Alfen N, van Engelen BG. Brain 2006
MRI with STIR sequences is essential for plexus evaluation; detects denervation muscle edema and nerve signal abnormalities	Class II, Level B	Stable-Delma A et al. Skeletal Radiol 2021
EMG/NCS is the gold standard for confirming and localizing plexopathy; optimal timing 3-4 weeks post-onset	Class I, Level A	Ferrante MA. Continuum (Minneap Minn) 2014
Diabetic lumbosacral radiculoplexus neuropathy (DLRPN) is caused by microvasculitis; immunotherapy may help	Class II, Level B	Dyck PJB et al. Brain 1999
IVIg did not show significant benefit over placebo in DLRPN in a randomized trial but may help selected severe cases	Class I, Level B	Dyck PJB et al. Neurology 2006
Corticosteroids are commonly used for acute neuralgic amyotrophy but evidence is limited to retrospective/observational data	Class III, Level C	van Alfen N et al. Neurology 2009
Radiation-induced plexopathy: myokymic discharges on EMG are pathognomonic; differentiates from tumor recurrence	Class II, Level B	Harper CM et al. Neurology 1989
PET-CT helps differentiate radiation plexopathy from tumor recurrence (FDG-avid suggests recurrence)	Class II, Level B	Basu S et al. Mol Imaging Biol 2011
Gabapentin/pregabalin are first-line for neuropathic pain including plexopathy-related neuropathic pain	Class I, Level A	Finnerup NB et al. Lancet Neurol 2015
Early nerve repair (within 6 months) for traumatic brachial plexus injury improves outcomes	Class II, Level B	Terzis JK, Kostopoulos VK. Plast Reconstr Surg 2007
Nerve transfer procedures improve functional outcomes for proximal brachial plexus injuries with root avulsion	Class II, Level B	Bertelli JA, Ghizoni MF. J Neurosurg 2004
Tight glycemic control is cornerstone of management for diabetic amyotrophy; avoid rapid HbA1c reduction >2% in 3 months	Class II, Level B	Gibbons CH, Freeman R. Ann Neurol 2015
Hereditary neuralgic amyotrophy (SEPT9 mutations) in recurrent episodes or family history	Class III, Level C	Kuhlenbäumer G et al. Nat Genet 2005
Duloxetine is effective for diabetic neuropathic pain and benefits plexopathy-related neuropathic pain	Class I, Level A	Lunn MPT et al. Cochrane 2014
Retroperitoneal hematoma causing lumbosacral plexopathy requires urgent CT and anticoagulation reversal	Class III, Level C	Patel A et al. Am J Emerg Med 2019
Physical therapy and occupational therapy improve functional outcomes in plexopathy rehabilitation	Class II, Level B	Merrell GA et al. Hand Clin 2005

APPENDIX A: IMAGING DECISION ALGORITHM¶

When to Image the Plexus¶

Immediate MRI Plexus with Contrast (STAT): - Suspected neoplastic plexopathy (progressive weakness, weight loss, known cancer history) - Horner syndrome with brachial plexopathy (Pancoast tumor) - Post-traumatic plexopathy with suspected vascular injury - Rapidly progressive weakness without clear etiology - Suspected retroperitoneal hematoma (add CT abdomen/pelvis)

Urgent MRI Plexus (within 1-2 weeks): - Acute plexopathy with significant motor deficit - Clinical diagnosis of neuralgic amyotrophy (confirm with imaging; rule out structural cause) - Diabetic amyotrophy (assess for nerve enhancement, exclude mass) - Post-radiation patient with new plexopathy symptoms

Routine MRI Plexus (within 4-6 weeks): - Subacute plexopathy with stable deficits undergoing EMG evaluation - Chronic plexopathy for baseline documentation - Pre-surgical planning for nerve reconstruction

No MRI Needed: - Classic Parsonage-Turner presentation with typical EMG findings and improving course - Mild sensory-only symptoms with clear positional/compressive etiology resolving with conservative care

CT Indications¶

STAT CT abdomen/pelvis: Suspected retroperitoneal hematoma (anticoagulated patient + lumbosacral plexopathy)
CT chest with contrast: Suspected Pancoast tumor
CT angiography: Traumatic plexopathy with suspected vascular injury

APPENDIX B: EMG/NCS INTERPRETATION IN PLEXOPATHY¶

Key Electrodiagnostic Findings¶

Finding	Interpretation	Differential Consideration
Reduced SNAP amplitudes in plexus distribution	Post-ganglionic lesion (plexopathy)	Distinguishes from radiculopathy (SNAPs preserved in radiculopathy because lesion is pre-ganglionic)
Denervation in multiple nerves from same plexus	Confirms plexopathy (not single nerve or root)	Multiple roots/trunks/cords involved differentiates from radiculopathy or mononeuropathy
Myokymic discharges	Highly suggestive of radiation plexopathy	Nearly pathognomonic for radiation injury; absent in neoplastic plexopathy
Conduction block at plexus level	Demyelinating component; compression; tumor encasement	Compressive etiology; CIDP affecting plexus
Fibrillation potentials + positive sharp waves	Active denervation	Seen in all axonal plexopathies 2-3 weeks after onset
Reduced recruitment without fibrillations (early)	Recent injury (<2-3 weeks) or conduction block	Re-study at 3-4 weeks if initial study early
Nascent motor unit potentials	Early reinnervation (positive prognostic sign)	Earliest sign of recovery; may appear 2-4 months after injury

Timing of EMG Studies¶

Baseline: Perform early for urgent clinical questions but fibrillations not yet present
Optimal initial study: 3-4 weeks after symptom onset (allows fibrillation potentials to develop)
Follow-up study: 3-6 months to assess reinnervation
Pre-surgical study: Before nerve repair/transfer to confirm viable targets

APPENDIX C: REHABILITATION APPROACH¶

Phase 1: Acute (Week 1-4)¶

Pain management optimization
Gentle passive range of motion to prevent contractures
Shoulder/hip positioning and protection
Edema management
Splinting as needed (wrist drop, foot drop)

Phase 2: Active Assisted (Week 4-12)¶

Active assisted range of motion as pain allows
Isometric strengthening of intact muscles
Neuromuscular electrical stimulation (NMES) to denervated muscles (controversial; prevents atrophy)
Sensory re-education
Adaptive equipment training (OT)

Phase 3: Strengthening (Month 3-12)¶

Progressive resistive exercises as reinnervation occurs
Functional task training
Work conditioning and ergonomic modifications
Ongoing pain management
Serial clinical and EMG monitoring to guide exercise progression

Phase 4: Maintenance (Ongoing)¶

Independent home exercise program
Continued adaptive strategies if residual deficit
Vocational rehabilitation if unable to return to prior work
Psychological support for chronic pain and disability
Annual neurology follow-up for monitoring

CHANGE LOG¶

v1.1 (February 2, 2026) - Removed ICU column from Section 4B (Patient Instructions) per C1 - spec requires 4 columns only (Recommendation | ED | HOSP | OPD) - Removed ICU column from Section 4C (Lifestyle & Prevention) per C2 - spec requires 4 columns only (Recommendation | ED | HOSP | OPD) - Changed labs table headers from Test (CPT) to Test per R4 for canonical format consistency (CPT codes remain in individual cell values) - Replaced --- section dividers between SECTION A and SECTION B with ═══ format per C3 - Changed SECTION A and SECTION B from H2 markdown headers to plain text labels inside ═══ dividers - Removed weak/suggestive language: "consider catheterization" changed to "catheterization as needed"; "consider interventional pain referral" changed to "interventional pain referral"; "consider neuromodulation" changed to "neuromodulation"; "should be considered" changed to directive statements in references per R3 - Updated version from 1.0 to 1.1 in frontmatter and body - Added REVISED date - Updated STATUS to "Revised per checker v1.1"

v1.0 (February 2, 2026) - Initial creation - Comprehensive brachial and lumbosacral plexus anatomy tables - Etiology-specific distinguishing features table (Parsonage-Turner, traumatic, radiation, neoplastic, diabetic, compressive) - Red flag checklist with required actions for 10 urgent scenarios - Full laboratory workup (1A-1C) with CPT codes including specialized tests for inflammatory and neoplastic etiologies - Imaging section (2A-2C) with MRI plexus protocols, CT indications, PET-CT, and MR neurography - EMG/NCS guidance for diagnosis, timing, and follow-up - Treatment sections (3A-3D) with structured dosing for acute pain management, neuropathic pain medications, immunotherapy (IVIg, PLEX, steroid-sparing agents), and surgical/procedural treatments - Disease-specific treatment section including immunotherapy options for inflammatory plexopathy and glycemic optimization for diabetic amyotrophy - Surgical treatment section with nerve repair, nerve transfer, nerve graft, and tumor resection indications - Comprehensive referral section covering 14 specialty referrals - Patient instructions specific to plexopathy recovery expectations - Differential diagnosis including 18 alternative diagnoses with distinguishing features - Evidence-based references with PubMed links (16 references) - Appendix A: Imaging decision algorithm for plexus evaluation - Appendix B: EMG/NCS interpretation guide specific to plexopathy - Appendix C: Four-phase rehabilitation approach