Cubital Tunnel Syndrome - Hand

Summary

Cubital Tunnel Syndrome is a common compressive neuropathy of the ulnar nerve usually caused by anatomic compression in the elbow region.
The condition typically presents with numbness, tingling, and sensory changes of the ring and little finger that progresses slowly over time.
Treatment may be nonoperative modalities such as bracing or surgical decompression depending the the severity and duration of symptoms, and success of nonoperative treatment.

Introduction

Epidemiology
- 19-25 cases per 100,000 person-years
- patients with cubital tunnel syndrome present at a more advanced disease state than those with carpal tunnel syndrome
- second most common compression neuropathy of upper extremity
Pathophysiology
- Cubital tunnel syndrome results from compression and traction on the ulnar nerve about the elbow
Associated conditions
- cubitus varus or valgus deformities
- medial epicondylitis
- burns
- elbow contracture release

Anatomy

Ulnar nerve
- pierces intramuscular septum at arcade of Struthers 8 cm proximal to the medial epicondyle as it passes from the anterior to posterior compartment of the arm
- enters cubital tunnel
Cubital tunnel
- roof
  - formed by FCU fascia and Osborne's ligament (travels from the medial epicondyle to the olecranon)
- floor
  - formed by posterior and transverse bands of MCL and elbow joint capsule
- walls
  - formed by medial epicondyle and olecranon
Sites of entrapment
- most common
  - between the two heads of FCU/aponeurosis (most common site)
  - within arcade of Struthers (hiatus in medial intermuscular septum)
  - between Osborne's ligament and MCL
- less common sites of compression include
  - medial head of triceps
  - medial intermuscular septum
  - medial epicondyle
  - fascial bands within FCU
  - anconeus epitrochlearis (anomalous muscle from the medial olecranon to the medial epicondyle)
  - aponeurosis of FDS proximal edge
- external sources of compression
  - fractures and medial epicondyle nonunions
  - osteophytes
  - heterotopic ossification
  - tumors and ganglion cysts

Classification

McGowan and Dellon
Type 1	Subjective sensory symptoms without objective loss of two-point sensibility or muscular atrophy
Type 2A	Sensory symptoms + weakness on pinch and grip without atrophy
Type 2B	Sensory symptoms + atrophy and intrinsic muscle strength ≤ 3
Type 3	Profound muscular atrophy and sensory disturbance

Presentation

Symptoms
- paresthesias of small finger, ulnar half of ring finger, and ulnar dorsal hand
  - exacerbating activities include
    - cell phone use (excessive flexion)
    - occupational or athletic activities requiring repetitive elbow flexion and valgus stress
- night symptoms
  - caused by sleeping with arm in flexion
Physical exam
- inspection and palpation
  - interosseous and first web space atrophy
  - ring and small finger clawing
  - observe ulnar nerve subluxation over the medial epicondyle as the elbow moves through a flexion-extension arc
- sensory
  - decreased sensation in ulnar 1-1/2 digits
- motor
  - loss of the ulnar nerve results in paralysis of intrinsic muscles (adductor pollicis, deep head FPB, interossei, and lumbricals 4 and 5) which leads to
    - weakened grasp
      - from loss of MP joint flexion power
    - weak pinch
      - from loss of thumb adduction (as much as 70% of pinch strength is lost)
    - Froment sign
      - compensatory thumb IP flexion by FPL (AIN) during key pinch
        
        compensates for the loss of MCP flexion by adductor pollicis (ulna n.)
        
        adductor pollicis muscle normally acts as a MCP flexor, first metacarpal adductor, and IP extensor
    - Jeanne sign
      - compensatory thumb MCP hyperextension and thumb adduction by EPL (radial n.) with key pinch
        
        compensates for loss of IP extension and thumb adduction by adductor pollicis (ulna n.)
    - Wartenberg sign
      - persistent small finger abduction and extension during attempted adduction secondary to weak 3rd palmar interosseous and small finger lumbrical
    - Masse sign
      - palmar arch flattening and loss of ulnar hand elevation secondary to weak opponens digiti quinti and decreased small finger MCP flexion
- extrinsic weakness
  - Pollock's sign
    - inability to flex DIPJ of ring and small fingers (weak FDP)
- provocative tests
  - Tinel sign positive over cubital tunnel
  - elbow flexion test
    - positive when flexion of the elbow for > 60 seconds reproduces symptoms
  - direct cubital tunnel compression exacerbates symptoms

Studies

EMG / NCV
- helpful in establishing diagnosis and prognosis
- threshold for diagnosis
  - conduction velocity <50 m/sec across elbow
  - low amplitudes of sensory nerve action potentials and compound muscle action potentials

Differential

Ulnar Tunnel Syndrome
- key findings that differentiate cubital tunnel syndrome from ulnar tunnel syndrome
  - found with cubital tunnel syndrome
    - less clawing
    - sensory deficit to dorsum of the hand
    - motor deficit to ulnar-innervated extrinsic muscles
    - Tinel sign at the elbow
    - positive elbow flexion test
C8 radiculopathy
- key finding that differentiate cubital tunnel syndrome from a C8 radiculpathy
  - found with cubital tunnel syndrome
    - weakness to distal phalanx flexion of middle and index finger (difficulty with fine motor function)
    - paresthesias in ring and little finger
  - found with C8 radiculopathy
    - symptoms improve with should abduction

Treatment

Nonoperative
- NSAIDs, activity modification, and nighttime elbow extension splinting
  - indications
    - first line of treatment with mild symptoms
  - outcomes
    - management is effective in ~50% of cases
Operative
- in situ ulnar nerve decompression without transposition
  - indications
    - when nonoperative management fails
    - before motor denervation occurs
  - outcomes
    - meta-analyses have shown similar clinical results with significantly fewer complications compared to decompression with transposition
    - 80-90% good results when symptoms are intermittent and denervation has not yet occurred
    - poor prognosis correlates most with intrinsic muscle atrophy
- ulnar nerve decompression and anterior transposition
  - indications
    - failed in situ release
    - throwing athlete
    - patient with poor ulnar nerve bed from tumor, osteophyte, or heterotopic bone
  - outcomes
    - similar outcomes to in situ release but increased risk of creating a new point of compression
    - Improved outcomes with unstable nerves in the pediatric population
- medial epicondylectomy
  - indications
    - visible and symptomatic subluxating ulnar nerve
    - thin patients with inadequate subcutaneous tissue to perform a transposition
  - outcomes
    - risk of destabilizing the medial elbow by damaging the medial ulnar collateral ligament

Overview

X condition is traumatic condition characterized by X, that is [rare; incidnece] and seen in [demographic].

treatment is usually.....x

Epidemiology

incidence

US incidence

demographics

male : female ratio

age bracket

location

where in the body/bone

risk factors

smoking etc.

Pathophysiology

mechanism of injury (trauma)

this is the mechanism of injury (valgus force on knee)

pathophysiology

this is the physiology (hormone feedback loop)

pathobiology

this is the molecular or cell biology of disease

pathoantomy

this is the anatomic cascade of disease

Genetics

inheritance pattern

autosomal dominant

mutations

chromosome

gene

protein encoded for

Associated conditions

orthopaedic conditions

condition a

condition b

medical conditions & comorbidities

condition a

Prognosis

natural history of disease

prognostic variable

favorable

negative

survival with treatment

Anatomy

Osteology

x

Muscles

muscles a

Ligament

ligament a

Blood Supply

x

Biomechanics

x

Classification

Classification A

Type A

• Characteristic A • Characteristic A

Type B

• Characteristic B • Characteristic B

Type C

• Characteristic C

Type D

• Characteristic D

Presentation

History (optional)

this is a specific event the patient cites. "Heard a pop"

Symptoms

common symptoms

location

duration

severity

aggrevating / aleiving factors

Physical exam

inspection

varus or valgus deformity

ecchymosis & swelling

diffuse tenderness

motion

document flexion-extension and pronation-supination

crepitus should be noted

varus/valgus instability stress test

challenging but important for an accurate diagnosis

neurovascular

provocative tests

Imaging

Radiographs

recommended views

xrays that should alwasy be obtained on evaluation

optional views

secondary views that might give additional information

findings

disc space narrowing

measuerment

measurement A (Cobb angle)

measurement A (pelvic incidence)

criteria dictating treatment

> 3mm step of dictates operative treatment

sensitivity and specificity

CT

indications

when do you order

views

best seen on sagital

findings

sensitivity and specificity

MRI

indications

when do you order

views

best seen on T2 axial

sensitivity and specificity

Bone scan

indications

when do you order

sensitivity and specificity

Studies

Labs

serum

urine

surface (nasal swab, sputum)

Invasive studies

Histology

gross anatomy

histology

immunostaining

Tested Differential (if nothing or NOT and important teaching point, leave blank)

Frequently Tested Differential A

key distinguishing factor

Complete differential tables

Prevention

Prevention A

Prevention B

Prevention C

Treatment (for surgical residency sites, e.g., orthobullets, ENT bullets)

Nonoperative

nonoperative treatment A

indications

outcomes

Operative

operative treatment A

indications

indication a

indication b

outcomes

operative treatment B

indications

indication a

indication b

outcomes

Treatment (for medical residency sites and medical student sites, e.g., medbullets, IM bullets)

Lifestyle

lifestyle change A

indications

indication a

outcomes

Pharmacologic

drug A

indications

indication a

outcomes

Operative

operative treatment A

indications

indication a

outcomes

Treatment (for medical residency sites and medical student sites, e.g., medbullets, IM bullets)

Nonoperative

nonoperative treatment A

indications

outcomes

Operative

operative treatment A

indications

indication a

indication b

outcomes

operative treatment B

indications

indication a

indication b

outcomes

Techniques

Techniques

NSAIDs, activity modification, and nighttime elbow extension splinting
- technique
  - night bracing in 45° extension with forearm in neutral rotation
In situ decompression
- releasing the fascial structures superficial to the ulnar nerve along the medial aspect of the elbow
- 4-cm incision midway between the olecranon and medial epicondyle
- distally release Osborne ligament and the superficial and deep fascia of FCU
- proximally release the fascia between the medial triceps and medial intermuscular septum
- avoid circumferential dissection of the nerve to minimize devascularization and to avoid creating hypermobility of the nerve
- endoscopically-assisted cubital tunnel release is an option
  - favorable early results but lacks long-term data
Decompression and transposition (submuscular, intramuscular, or subcutaneous)
- decompress the nerve and circumferentially dissect the nerve to allow for transposition
- excise the medial intermuscular septum
- anteriorly transpose the nerve
  - secured with subcutaneous tissue,
  - placed anterior to a fascial sling,
  - or placed within or beneath the flexor pronator mass
Medial Epicondylectomy
- decompress the nerve and then perform an oblique osteotomy of the medial epicondyle
- preserve the insertion of the MCL + repair the periosteum

Complications

Recurrence
- secondary to inadequate decompression, perineural scarring, or tethering at the intermuscular septum or FCU fascia
- higher rate of recurrence than after carpal tunnel release
Neuroma formation
- iatrogenic injury to a branch of the medial antebrachial cutaneous nerve may cause persistent posteromedial elbow pain