01Approach to the Critical Patient/attcp40

Immediate priorities

›Alarm features requiring urgent action

›Open wound over ulnar nerve course

›Sharp laceration at wrist or forearm suggests neurotmesis

›Immediate surgical exploration required

›Complete motor and sensory loss with sharp mechanism

›Urgent hand surgery or peripheral nerve specialist consultation

›Do not delay beyond emergency department evaluation

›Associated vascular injury

›Absent ulnar pulse

›Expanding hematoma at wrist or elbow

›Pallor or cyanosis of digits 4 and 5

›Compartment syndrome signs

›Tense forearm compartments

›Pain with passive extension of fingers

›Escalate immediately to surgical team

›Fracture-dislocation of the elbow with nerve deficit

›High risk of concurrent ulnar nerve injury

›Orthopedic consultation within the same encounter

Monitoring and targets

›Neurologic monitoring priorities

›Serial motor strength assessment in ED

›Finger abduction MRC grade at presentation and post-intervention

›Froment sign change with time

›Vascular monitoring

›Ulnar pulse by Doppler if manually absent

›Capillary refill of 4th and 5th digits

›Wound surveillance

02History/hx55

Mechanism and onset

›Injury mechanism

›Direct trauma

›Laceration at wrist or elbow

›Fracture of distal humerus, olecranon, or medial epicondyle

›Elbow dislocation

›Compression

›Prolonged anesthesia or coma with elbow pressure

›Habitual leaning on hard surface

›Wheelchair use with armrest pressure

›Traction injury

›Forceful elbow or shoulder distraction

›Sports related overhead throwing mechanism

›Crush mechanism

›Industrial machinery

›Motor vehicle collision

›Symptom timing

›Sudden onset with laceration or fracture

›Hours after compression event (Saturday night palsy equivalent)

›Worsening with elbow flexion suggests cubital tunnel pathology

Symptom characterization

›Sensory symptoms

›Numbness or tingling in 5th digit and ulnar half of 4th digit

›Pain at medial elbow radiating distally into hand

›Dorsal ulnar hand involvement localizes lesion to elbow or proximal

›Motor symptoms

›Hand weakness or clumsiness

›Difficulty with grip strength and key pinch

03Physical Exam/exam63

Inspection and general

›Ulnar claw hand deformity

›Hyperextension at MCP joints of 4th and 5th digits

›Flexion at IP joints of 4th and 5th digits

›Indicates significant motor axon loss at presentation

›Muscle atrophy

›Hypothenar eminence wasting

›Interosseous muscle wasting with visible dorsal guttering

›First dorsal interosseous (FDI) atrophy most visible

›Wound and skin

›Laceration over medial elbow, forearm, or wrist

›Expanding hematoma

›Ecchymosis pattern suggesting fracture

Provocative and palpation tests

›Tinel sign

›Percussion over cubital tunnel reproduces paresthesias in 4th and 5th digits

›Positive in cubital tunnel syndrome

›Elbow flexion test

›Sustained elbow flexion beyond 60 seconds reproduces symptoms

›Positive suggests cubital tunnel pathology

›Froment sign

›Thumb IP joint flexion when pinching paper between thumb and index finger

›Compensatory FPL activation due to adductor pollicis weakness

›Positive indicates intrinsic weakness

›Wartenberg sign

›Involuntary abduction of 5th digit at rest

›Due to weak 3rd palmar interosseous

›Ulnar nerve palpation

04Differential Diagnosis/ddx44

Peripheral nerve localization

›Ulnar neuropathy at the elbow (cubital tunnel)

›ICD-10 G56.2

›Most common site of ulnar nerve entrapment

›FCU and FDP involved; dorsal ulnar hand sensation involved

›Ulnar neuropathy at the wrist (Guyon's canal)

›ICD-10 G56.2

›Dorsal ulnar cutaneous sensation spared

›FCU and FDP spared

›Associated with cyclist's palsy or hook of hamate fracture

›Traumatic neurotmesis of ulnar nerve

›ICD-10 S54.0

›Complete loss of all ulnar-innervated function

›Requires surgical repair for recovery

Proximal nerve and plexus lesions

›C8 to T1 radiculopathy

›Sensory loss extends to medial forearm (not typical of ulnar neuropathy)

›Weakness includes non-ulnar muscles (flexor pollicis longus, extensor indicis proprius, APB)

›Neck pain commonly present

›Differentiate with EMG and MRI cervical spine

›Lower trunk or medial cord brachial plexopathy

›Involves both ulnar and median-innervated hand muscles

›APB and opponens pollicis weak

›Horner syndrome if preganglionic

›Associated with Pancoast tumor or traumatic avulsion

›Thoracic outlet syndrome

›Positional symptoms

›Vascular changes in arm

05Laboratory Tests/lt23

Routine labs

›Standard labs not required for isolated traumatic ulnar nerve injury

›No specific hematologic or metabolic marker for peripheral nerve injury

›Reserve for suspected systemic etiology or comorbidity screening

Metabolic and systemic screening

›Diabetes evaluation when risk factors present

›Fasting glucose for acute screening

›HbA1c for chronic glycemic control assessment

›Diabetes increases risk for compressive neuropathy and slows recovery

›Thyroid function

›TSH when hypothyroidism suspected

›Hypothyroidism associated with entrapment neuropathies

›Inflammatory markers when autoimmune etiology suspected

›ESR and CRP for inflammatory conditions

›Rheumatoid factor and ANA if rheumatoid arthritis or connective tissue disease

›CBC for infectious or hematologic concern

›Nutritional assessment

›B12 and folate for nutritional neuropathy overlap

›Relevant in alcohol use disorder context

Point of care considerations

›Glucose point of care testing

›Rapid screening in trauma patients with altered status

›Hypoglycemia mimics or exacerbates neurologic symptoms

›Coagulation studies when anticoagulation or coagulopathy suspected

›INR and PTT if hematoma expanding

›Guides surgical timing

06Diagnostic Tests/dt88

Scoring Systems

›Sunderland classification of nerve injury severity

›Grade 1 (neurapraxia): focal demyelination, full recovery expected

›Conduction block on NCS without axon loss

›Recovery within weeks to 3 months

›Grade 2 (axonotmesis): axon disruption, endoneurium intact

›Wallerian degeneration distal to injury

›Recovery rate approximately 1 mm per day from injury site

›Grade 3: axon and endoneurium disrupted, perineurium intact

›Variable and incomplete recovery

›Grade 4: all structures disrupted except epineurium

›Poor spontaneous recovery, surgery often needed

›Grade 5 (neurotmesis): complete nerve transection

›No recovery without surgical repair

›McGowan grading for ulnar neuropathy at elbow

›Grade 1: paresthesias only, no motor deficit

›Grade 2: weakness of interossei with or without sensory changes

›Grade 3: severe weakness and atrophy

›Guides conservative versus surgical decision

›Electrodiagnostic grading system (Zeidman and Pandey 2020)

›Mild: slowing across elbow only, no denervation

›Moderate: reduced amplitudes with slowing

›Severe: absent responses or fibrillations on EMG

›Guides prognosis and surgical timing

MRI

›MRI indications for ulnar nerve injury

›Space-occupying lesion evaluation

›Ganglion cyst at Guyon's canal or cubital tunnel

›Lipoma or other soft tissue mass

›When ultrasound is non-diagnostic

›Complex anatomy after prior surgery

›Suspected intraneural pathology

›Nerve characterization

›Nerve thickening and T2 hyperintensity along ulnar nerve

›Denervation edema in ulnar-innervated hand muscles

›MRI protocol considerations

›High-resolution coil and thin-slice sequences for peripheral nerve

›3T preferred over 1.5T for peripheral nerve imaging

›MRI limitations

›Limited availability in acute setting

›Motion artifact risk

›Does not replace electrodiagnostic testing for functional severity

CT

›CT indications in ulnar nerve injury

›Complex fracture characterization

›Distal humerus or olecranon fractures with comminution

›Medial epicondyle avulsion fracture detail

›Bony deformity assessment

›Old healed fractures with delayed ulnar neuropathy

›Heterotopic ossification in the cubital tunnel

›CT angiography when vascular injury suspected

›Ulnar artery occlusion or pseudoaneurysm

›Hypothenar hammer syndrome at Guyon's canal

›CT limitations

›Poor soft tissue contrast for nerve visualization

›Use plain X-ray first for bony injury

Ultrasound

›Nerve ultrasound for ulnar nerve injury

›Nerve cross-sectional area (CSA) measurement

›CSA greater than 8 to 11 mm2 at elbow is abnormal

›Sensitivity 64 to 81%, specificity 60 to 91% for ulnar neuropathy at elbow

›Nerve subluxation detection

›Dynamic assessment with elbow flexion and extension

›Identifies nerve instability predisposing to injury

›Space-occupying lesion identification

›Ganglion, lipoma, anomalous muscle

›Vascularity on Doppler for vascular lesions

›Expert consensus supports ultrasound as complement to electrodiagnostics

›Clinical Neurophysiology consensus 2021

›Adds structural information NCS/EMG cannot provide

›Vascular ultrasound

›Doppler assessment of ulnar artery when pulse absent

›Allen test confirmation with Doppler

›Pseudoaneurysm or thrombosis at Guyon's canal

Electrodiagnostic testing

›NCS and EMG as gold standard for acute ulnar nerve injury

›Motor NCS across elbow with recording from ADM and FDI

›Recording from both ADM and FDI increases sensitivity to approximately 85%

›Conduction velocity less than 50 m/s across elbow is abnormal

›Sensory NCS

›Ulnar SNAP normal in pure demyelination (neurapraxia)

›Reduced or absent SNAP indicates axonal loss

›Inching technique

›Short-segment stimulation in 1-inch increments

›Precisely localizes the lesion within the cubital tunnel

›Needle EMG

›Evaluate FDI, ADM, FDP, FCU for denervation

›Evaluate non-ulnar C8/T1 muscles to exclude radiculopathy or plexopathy

›Timing considerations

›NCS can be performed immediately to assess for conduction block

›Wallerian degeneration manifests on NCS at 7 to 10 days

›Fibrillations appear on needle EMG at 2 to 3 weeks

›Repeat testing at 3 to 4 weeks provides more complete prognostic information

07Disposition/dispo36

Urgent surgical or admission indications

›Immediate surgical consultation required

›Open nerve laceration

›Sharp mechanism over nerve course

›No recovery expected without operative repair

›Complete motor and sensory loss with sharp mechanism

›Neurotmesis until proven otherwise

›Operative exploration and repair within hours to days

›Associated vascular injury requiring operative repair

›Ulnar artery laceration or pseudoaneurysm

›Limb-threatening ischemia

›Compartment syndrome

›Urgent fasciotomy

›Nerve decompression at same setting if indicated

›Admission indications

›Polytrauma with ulnar nerve involvement

›Post-surgical monitoring after acute repair

›Significant soft tissue or vascular injury requiring observation

Outpatient referral and discharge

›Closed injuries without complete deficit

›Discharge with early hand surgery referral within 1 to 2 weeks

›Neurology or physiatry referral for electrodiagnostic testing at 3 to 4 weeks

›Splinting and activity modification before follow-up

›Elbow extension splint at night to reduce cubital tunnel pressure

›Activity restriction to avoid prolonged elbow flexion

›Imaging before discharge when fracture suspected

›Plain X-ray of elbow before discharge

›Hook of hamate view when Guyon's canal injury with cyclist mechanism

08Treatment/t65

Immediate emergency department management

›Wound care for open injuries

›Irrigation and debridement of contaminated wounds

›Primary wound closure when clean and uncontaminated

›Do not primarily repair nerve in contaminated field

›Tag nerve ends with non-absorbable suture for delayed repair

›Delayed repair at 3 to 7 days in contaminated wounds

›Tetanus prophylaxis per wound guidelines

›Fracture management

›Reduction of displaced fracture or dislocation

›Orthopedic consultation for operative fixation planning

›Reassess nerve function post-reduction

›Splinting in position of function when fracture present

›Elbow at 90 degrees, wrist neutral, digits in intrinsic-plus position

Surgical indications and timing

›Acute surgical repair indications

›Sharp complete transection (neurotmesis)

›Primary epineural repair when tension-free anastomosis achievable

›Nerve grafting when gap exceeds 1 to 2 cm

›Class I recommendation for early repair of complete sharp transections

›Nerve injury with fracture requiring operative fixation

›Address fracture first

›Explore nerve at same sitting if complete deficit persists post-reduction

›Vascular injury with nerve involvement

›Restore perfusion first

›Nerve repair or grafting at same or staged setting

›Conservative observation indications

›Closed blunt injury without complete deficit

09Special Populations/sp76

Pregnancy

›Physiologic changes affecting nerve injury

›Fluid retention increases compartment pressures

›Higher risk of compression neuropathy in third trimester

›De Quervain and carpal tunnel more common but ulnar also affected

›Positional factors during labor and delivery

›Prolonged lithotomy position with elbow pressure

›Brachial plexus stretch with arm board malposition

›Medication safety in pregnancy

›NSAIDs relatively contraindicated after 20 weeks gestation

›Risk of premature closure of ductus arteriosus

›Acetaminophen preferred for analgesia

›Gabapentin and pregabalin

›Limited safety data in pregnancy

›Use only if benefits outweigh risks after specialist consultation

›Imaging in pregnancy

›Plain X-ray with abdominal shielding when fracture must be excluded

›Ultrasound of nerve preferred imaging modality in pregnancy

›MRI without contrast acceptable in second and third trimester

›CT with radiation dose concern, use only when critical

›Electrodiagnostic testing

›Safe throughout pregnancy

›No radiation exposure

›Preferred investigation when diagnosis uncertain

Geriatric

›Increased vulnerability to nerve injury

›Reduced nerve regeneration capacity with age

›Slower recovery and less complete reinnervation expected

›Earlier surgical evaluation warranted for significant deficits

›Higher prevalence of comorbidities

›Diabetes mellitus impairs axonal regeneration

›Renal impairment requires dose adjustment of gabapentin and pregabalin

›Osteoporosis increases fracture risk with minor trauma

›Lower threshold for X-ray in elbow injury

›Medication considerations in older adults

›NSAIDs with increased GI and renal risk

›Add proton pump inhibitor if NSAID required

›Monitor renal function with NSAID use

›Gabapentin and pregabalin with fall risk

›Increased sedation and dizziness in older adults

›Start at lowest dose and titrate slowly

›Acetaminophen preferred analgesic in older adults

›Maximum 2000 mg per day in frail or malnourished patients

›Functional recovery expectations

›Intrinsic hand muscle reinnervation may be incomplete

›Long regeneration distances disadvantage distal muscles

›Tendon transfer options for persistent clawing should be discussed early

Pediatrics

›Mechanism differences in children

›Supracondylar humerus fracture is the most common pediatric elbow fracture

›Primarily associated with anterior interosseous nerve injury but ulnar nerve also at risk

›Post-reduction nerve assessment mandatory

›Medial epicondyle avulsion fracture in adolescents

›High risk of ulnar nerve entrapment in fracture fragment

›Requires operative exploration if nerve deficit present

›Birth-related injury

›Traction during delivery

›Part of brachial plexus birth palsy spectrum

›Pediatric examination adaptations

›Age-appropriate sensory testing

›Younger children may not accurately report paresthesias

›Two-point discrimination testing when cooperative

›Grip dynamometry age-normative values required for interpretation

›Medication dosing in children

›Ibuprofen 5 to 10 mg/kg orally every 6 to 8 hours

›Maximum 40 mg/kg per day

›Avoid under 6 months of age

›Acetaminophen 10 to 15 mg/kg orally every 4 to 6 hours

›Maximum 75 mg/kg per day, not exceeding 4000 mg per day

›Gabapentin in children 3 years and older

›Starting dose 10 mg/kg per day divided three times daily

›Titrate to effect under specialist guidance

›Recovery expectations in children

›Generally better regeneration capacity than adults

›Neurapraxia in children resolves reliably

›Axonotmesis recovery often more complete than adult counterpart

›Monitoring for growth-related issues

›Cubitus valgus deformity after medial epicondyle fracture predisposes to delayed ulnar neuropathy

›Long-term orthopedic follow-up recommended

10Background/b73

Epidemiology

›Incidence and prevalence

›Ulnar nerve is the second most commonly injured peripheral nerve in the upper extremity

›Mean annual incidence of 24.7 per 100,000 person-years

›Cochrane systematic review 2025

›Ulnar neuropathy at the elbow is the second most common entrapment neuropathy

›After carpal tunnel syndrome

›Incidence approximately 20.9 per 100,000 person-years

›Demographic distribution

›Male predominance in occupational and sports-related injury

›Older adults at higher risk for compression during anesthesia or hospitalization

›Athletes and manual laborers overrepresented in acute cases

›Injury mechanism distribution

›Elbow fracture and dislocation are the most common traumatic causes

›Compression during anesthesia or prolonged bed rest is the most common iatrogenic cause

›Cyclist's palsy accounts for a subset of wrist-level acute cases

Pathophysiology

›Ulnar nerve anatomy and vulnerability

›Nerve root origin C8 to T1 from medial cord of brachial plexus

›Most vulnerable sites due to superficial course

›Cubital tunnel at the medial elbow

›Retroepicondylar groove behind medial epicondyle

›Guyon's canal at the wrist between pisiform and hamate

›Mechanisms of injury

›Neurapraxia (Sunderland Grade 1)

›Focal demyelination from compression or traction

›Axonal continuity preserved

›Conduction block on NCS

›Full recovery within weeks to 3 months

›Axonotmesis (Sunderland Grade 2 and 3)

›Axon disrupted with Wallerian degeneration distal to injury

›Endoneurium variably intact guiding regeneration

›Recovery at approximately 1 mm per day from injury site to target muscle

›Recovery may be incomplete especially for distal intrinsics

›Neurotmesis (Sunderland Grade 5)

›Complete nerve transection

›No recovery without surgical repair

›Results from sharp laceration or severe traction

›Cubital tunnel pathomechanics

›Canal volume decreases by 55% with elbow flexion

›Pressure within tunnel increases 6-fold from extension to flexion

›Explains worsening with sustained elbow flexion

›Anconeus epitrochlearis muscle when present narrows the canal further

Therapeutic Considerations

›Conservative versus surgical decision framework

›Neurapraxia without open wound

›Conservative management with activity modification and splinting

›Observe 3 months for spontaneous recovery before surgical consideration

›Complete deficit with sharp laceration

›Surgical exploration and primary repair as soon as feasible

›Delayed repair acceptable in contaminated wounds at 3 to 7 days

›Incomplete deficit with fracture

›Observe after fracture stabilization

›Surgical exploration if no recovery at 3 months

›Electrodiagnostic severity guides timing

›Conduction block (neurapraxia): conservative observation

›Wallerian degeneration with intact distal stump: explore early

›Absent responses without trauma history: earlier intervention

›Nerve repair principles

›Primary epineural repair when tension-free anastomosis achievable

›Nerve grafting with sural nerve graft when gap exceeds 1 to 2 cm

›Nerve conduit as alternative for short gaps less than 3 cm

›Rehabilitation principles

›Sensory re-education supports cortical reorganization

›Splinting prevents contracture during recovery

›Tendon transfer considered for persistent intrinsic weakness after failed reinnervation

›Ring and little finger clawing addressed with lasso procedure

›FDS ring finger lasso most common transfer

›Prognostic factors

›Age is most important modifiable prognostic factor for recovery

›Time to repair influences outcome

›Earlier repair yields better functional recovery

›Chronic denervation reduces motor endplate viability

›Injury level affects recovery

›Distal injuries recover faster than proximal injuries

›Longer regeneration distances mean delayed and less complete reinnervation of intrinsics

11Patient Discharge Instructions/pdi27

copy discharge instructions

›Ulnar nerve injury home care

›Wear your elbow splint at night as directed to avoid bending the elbow during sleep

›Avoid leaning or resting your elbow on hard surfaces such as armrests or tables

›Do not carry heavy objects with the injured arm until cleared by your doctor

›Take prescribed pain medications as directed

›Ice the elbow for 15 to 20 minutes several times per day if swollen

›Activity guidance

›Avoid activities requiring prolonged elbow bending such as phone use or cycling

›For wrist injuries, avoid direct pressure over the outer wrist

›Gentle range of motion exercises are encouraged unless told otherwise

›Return to work restrictions depend on injury severity and job demands

›Return immediately to the emergency department for

›Increasing weakness or new paralysis of hand or fingers

›Spreading numbness beyond the ring and little fingers into the forearm

›Cold, pale, or blue color of the fingers

›Expanding swelling or bruising at the elbow or wrist

›Signs of wound infection including redness spreading from wound, pus, fever

›Severe pain not controlled with prescribed medications

›Follow-up appointments

›Hand surgery or nerve specialist within 1 to 2 weeks

›Nerve conduction study at 3 to 4 weeks after injury as arranged

›Occupational therapy referral for hand exercises and splint fitting

›Recovery expectations

›Minor compression injuries often recover fully within 4 to 12 weeks

›Injuries with nerve damage take months to recover and may be incomplete

›Sensation usually returns before strength

›Full recovery of small hand muscle strength is not always possible for severe injuries

12References/r17

Guidelines and key sources

›Cochrane and systematic reviews

›Caliandro P et al, Treatment for Ulnar Neuropathy at the Elbow, Cochrane Database Systematic Reviews 2025

›Zeidman LA, Pandey DK, An electrodiagnostic grading system for ulnar neuropathy at the elbow, Muscle and Nerve 2020

›Pompe SM et al, In situ decompression vs conservative treatment for mild ulnar neuropathy at the elbow, Muscle and Nerve 2020

›Clinical guidelines

›Hegmann KT et al, ACOEM Practice Guidelines: Elbow Disorders, Journal of Occupational and Environmental Medicine 2013

›Pelosi L et al, Expert Consensus on Combined Investigation of Ulnar Neuropathy at the Elbow Using Electrodiagnostic Tests and Nerve Ultrasound, Clinical Neurophysiology 2021

›Review articles and landmark sources

›Robinson LR, Traumatic injury to peripheral nerves, Muscle and Nerve 2022

›Bateman EA et al, Assessment management and rehabilitation of traumatic peripheral nerve injuries for non-surgeons, Muscle and Nerve 2025

›Silver S et al, Peripheral Nerve Entrapment and Injury in the Upper Extremity, American Family Physician 2021

›Dawson DM, Entrapment Neuropathies of the Upper Extremities, New England Journal of Medicine 1993

›Cambon-Binder A, Ulnar Neuropathy at the Elbow, Orthopaedics and Traumatology Surgery and Research 2021

›Coding references

›ICD-10 G56.2 lesion of ulnar nerve

›ICD-10 S54.0 injury of ulnar nerve at forearm level

›SNOMED CT ulnar nerve structure concept

Evidence & Review

Evidence & Review