Sports + Occupations

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NEUROMUSCULAR DISORDERS: Sports & Occupations

Sports/Occupation
Backpacking
Baseball
Bicycle
Bodybuilding
Bowling
Football
Mountain climbing
Musicians
Running
Surfing
Volleyball

Occupations
Batteries: Lead
Cabinet maker: Hexacarbon
Copper smelting: Arsenic
Demolition: Lead
Dentist: Nitrous oxide
Dry cleaner: Trichloroethylene
Epoxy resin: Allyl chloride
Farmers: Organophosphates
Glass & Ceramics: Tellurium
Mining: Arsenic
Painter: Hexacarbon
Plastic industry: Acrylamide
Rayon industry: Carbon disulfide
Rubber industry: Trichloroethylene
Tool use: Vibration syndrome

BASEBALL

Local Nerve Lesions

Ulnar nerve lesion at elbow
- Rupture of ligaments holding nerve
- Inflammation of collateral ligament
- Nerve traction
- Inflammation at entrance to cubital tunnel
- Anomalous epitrochleoanconeus
Median nerve
- Pronator syndrome
  - ? Related to throwing fastball: Hypertrophy of pronator teres
  - Entrapment by fibrous bands: Pronator teres; Flexor digitorum superficialis
- Carpal tunnel syndrome
- Ulnar digital nerve of thumb
  - Batters
  - Traumatic neuroma
  - See: Bowler's thumb
Suprascapular neuropathy
- Location: Suprascapular notch underneath superior transverse scapular ligament
  - Shoulder symptoms: Weakness; Posterior pain
  - Muscle involvement: Infraspinatus & Supraspinatus
- Location: Spinoglenoid notch; Distal
  - Overhead throwing athletes
  - Causes: Injury; Ganglion cyst
  - Muscle involvement: Isolated infraspinatus atrophy
  - No pain
Axillary nerve ± Posterior humeral circumflex artery
- Quadrilateral space syndrome
- Glenoid fossa osteophyte
"Pitcher's Arm": Asymptomatic
- Location: Throwing arm
- Biceps reflex: Reduced
- Sensory nerve action potential amplitudes: Reduced
Musculocutaneous nerve
- Nerve lesion
  - Onset
    - Rapid
    - Pain in the pitching arm
  - Clinical
    - Weakness & Atrophy: Biceps & Coracobrachialis
    - Sensory loss: Lateral antebrachial nerve territory
- Bassett's Lesion: Lateral antebrachial cutaneous nerve
  - Throwing athletes: During throwing movement
  - Parathesias down forearm with forced pronation
  - Lesion: Lateral edge of biceps, above elbow
Other
- Thoracic outlet syndrome
- Hamstring strain
- Radial neuropathy: Softball pitchers

Other Disorders

Shoulder injury
Subclavian artery lesions

BODYBUILDERS¹

Local Nerve Lesions

Entrapments:
- Acute or subacute onset
- May be related to strenuous training
- Often with anabolic steroids
Specific mononeuropathies
- Carpal tunnel syndrome
- Musculocutaneous
- Long thoracic nerve
- Medial pectoral
- Thoracodorsal
- Dorsoscapular
- Suprascapular: Distal inferior branch in bodybuilders & Volleyball
- Femoral: Distal
Prognosis: Improvement over time

Muscle

Abdominal rhabdomyolysis
Electrolyte disorders:
- K⁺: Reduced
- PO₄: Reduced
Tear & Trauma
Hypertrophy

Joint disorders

BOWLING

Neuroma of digital nerve to thumb ("Bowler's thumb")

Nerve: Palmar digital
Sensory loss: Medial thumb
Nerve: May be thickened & painful to palpation
Pain: Local over lesion
Time course: Chronic
Pathology: Perineurial fibrosis
Other types of causative injuries
- Baseball
- Jewelers
- Cherry pitting
- Repetitive use
- Finger surgery
- Snow blowing
- Cysts & Neoplasms
- Mononeuritis multiplex

Acute sensory neuropathy of thumb

Onset: Rapid; During bowling activity
Sensory loss: Medial thumb
Pain & Paresthesias: Medial thumb
Time course: Monophasic; Resolution over 2 months
Electrophysiology: Reduced medial SNAP stimulating from thumb

SURFING

Saphenous nerve lesion at knee

BICYCLING⁶

Injury frequency: Non-traumatic injuries common
Syndromes
- Ulnar nerve
  - Nosology: "Handlebar palsy"
  - Location: Distal; At wrist or palm
  - Frequency: 10% to 30%
- Median nerve
  - Carpal tunnel syndrome
  - Activity: Riding on the 'hoods' (Where brake lever attaches to handlebars)
- Sciatic nerve
- Buttock: Ischial tuberosity pain
- Perineum
  - Numbness: Penis
  - Erectile dysfunction
  - Mechanism: Pressure on
    - Dorsal branch of pudendal nerve
    - Perineal artery either at symphysis pubis or Alcock’s canal
- Orthopedic: Knee; Neck; Shoulder; Back; Hip; Foot

FOOTBALL

Stinger
- Sudden burning in arm after tackle
- Lasts 3 to 10 seconds
- Weakness
  - Initially lasts 1 to 2 minutes
  - May be more persistent with repeated episodes
- ? Brachial plexopathy or radiculopathy
Cervical spine lesion
Hamstring strain

MOUNTAIN CLIMBING & BACKPACKING

Backpack paralysis: Mononeuropathies
- Brachial plexus
- Axillary nerve
- Suprascapular nerve
- Accessory nerve
- Long thoracic nerve
- Radial nerve
Tarsal tunnel syndrome

TENNIS

Pain
- Lateral epicondyle of elbow: Ground strokes, especially backhand
- Medial elbow pain: Serving
Cubital tunnel: Spin serve
Posterior interosseus nerve entrapment
- Arcade of Frohse
- Pain with resistance to passive arm pronation or wrist flexion

RUNNING

Neuropathy
- Reduction in vibration threshold: Subclinical
- Peroneal neuropathy
- Tarsal tunnel syndrome
- Morton's neuroma
Muscle
- Rhabdomyolysis: Sickle cell trait at thigh altitude
- Compartment syndrome: Exertional
- Hamstring strain: Especially sprinting

SKIING

Ski Boot neuropathies

Superficial peroneal nerve
- Branches: Medial & Intermediate Dorsal cutaneous branches
- Clinical
  - Sensory loss: Medial dorsal foot to ankle

MUSICIANS, INSTRUMENTAL⁴

Playing-related disorders: General

Epidemiology
- Sex: Famale 60%, except focal dystonia (Male > Female)
- Age: Mean 4th decade
Common complaint: Pain
Lateralization
- Left > Right: Strings & Brass
- Right > Left: Keyboards & Woodwind
- Bilateral: Most percussionists (47%); Least bowed string instruments (17%)
- Oboists & Clarinetists: Weight-bearing thumb
Syndromes
- Musculoskeletal disorders: 64%
  - Regional muscle pain syndromes
  - Local disorders
    - Tendinitis
    - Ligament sprain
    - Shoulder disorders: Rotator cuff...
- Peripheral nerve disorders: 20%
- Focal dystonia: 8%
Electrodiagnostic studies
- Often normal: Especially early in course, with intermittent symptoms, regional pain syndromes
- Useful to test for nerve entrapment

Musculoskeletal disorders: 64%

Specific disorders
- Tendinitis
- Ligament sprain
- Shoulder disorders: Rotator cuff; Shoulder impingement
Regional muscle pain syndromes
- "Overuse"
- Upper limb, upper trunk & neck
- Discomfort
  - Pain or Tenderness
  - Elicited by stretching or activating affected region against resistance
- Distribution
  - Uni- or multifocal
  - Localized to muscle or muscle-tendon junctions
- Symptoms: Tightness, stiffness, cramping, fatigue, swelling, numbness
- Strength: Normal; May be limited by pain
- Electrodiagnostic studies: Usually normal
- Course: 50% with reduction insymptoms over years
- Treatment: Initial rest or abstinence from offending activity; Identify technical flaws

Peripheral nerve disorders: 20%

Thoracic outlet syndrome
- Type: Symptomatic; No neurogenic forms
- Epidemiology
  - Male:Female = 1:3
  - Onset age: Mean 26 years
- Sensory symptoms
  - Pain
  - Other: Numbness, Tingling, Burning, Swelling
  - Distribution: Forearm & Hand; Ulnar > Radial
  - No sensory loss on exam
- No weakness
- Provocation
  - Specific positions or activities
  - Arm Maneuvers: Hyperabduction; Abduction & extension; Downward traction with internal rotation at shoulder
- Droopy shoulder configuration: 50%
- Otherwise normal neurologic examination
Mononeuropathies
- Ulnar neuropathy
  - Most common at elbow
  - Pain: Elbow; Ulnar arm
  - Paresthesias
  - Sensory loss: Ulnar hand & fingers
  - Weakness: Occasional; May be painless
  - Male = Female
  - Age: Mean = 39 years
  - Laterality: String, all on left; Keyboard, left > right
  - Other ulnar: Wrist; Forearm (trauma)
- Median
  - Most common: Carpal tunnel syndrome
  - Pain: Proximal & Distal; May occur at night, especially in bow string players
  - Paresthesais
  - Laterality: Bilateral in 50%; Right common in bow string players
  - Course: 50% improve with non-operative management
  - Surgery: Open or Endoscopic; 90% cure rate
  - Other median: Trauma (66%); Anterior interosseus (? Brachial plexopathy); Pronator syndrome
- Cervical radiculopathy
  - Especially string & keyboard players
  - Age: Mean 50 years; Range 29 to 90 years
  - Male: Female = 3:1
  - Levels: C6 > C7 > C8
- Digital neuropathy
  - Playing related: 60%
  - Flautists: Left index finger
  - Guitarists & violinist: Radial digital branch of index finger, 2° pressure on the neck of instrument
  - Marimba player (four-mallet technique): Digital branch to middle finger
- Other
  - Radial
  - Posterior cutaneous nerve to forearm
  - Branches to lip: Brass & woodwind
    - Sensory loss ± Weakness
    - Upper or lower lip
    - Improves with change of technique

Focal dystonia: 8%

Distribution
- Most distal arm: Loss of control, speed, or dexterity
- Brass & wind involve embouchure: Difficulty in tone production
Often task specific to playing instrument
Sex: Male > Female
Onset: Mean in mid 30's
Progression: Slow; Over years
Physiology
- Excessive motor cortical excitability with abnormal cortical sensory processing
- ? Mediated by basal ganglia

Hand-Arm Vibration syndrome³

Exposure
- Regular use of vibratory tools: Risk proportional to
  - Magnitude & duration of vibration exposure
  - Vibration frequency: Harmful frequencies 8 to 1,000 Hz
- Professions
  - Lumberjacks: Chainsaw
  - Drilling
  - Metal working: Fettling tools
- Association with tobacco use (7x risk) & cold
Clinical
- Onset
  - Paresthesias, continuous or relapsing
  - Latency: Mean 6 years; Range 1 to 17 years
- Sensory loss
  - Panmodal
  - Arms
  - During & after exposure: Especially during night-time
- Pain: Wrist, palm, or fingers; Often worse at night
- Motor: Weakness; Reduced manual dexterity
- Vascular: Raynaud's like symptoms; Vibration white finger
- Joint: Dupytron's contracture (Ring finger)
NCV
- Abnormal motor & sensory potentials in arms
- Multifocal pattern: Ulnar, Median, Radial, or Digital
  - Multiple-site lesions in segments of nerves
  - Lesions especially common distal to wrist
Vascular pathology: Thickened walls of digital vessels
Associated disorders
- Rotator cuff tendinitis
- Carpal tunnel syndrome
- Epicondylitis
External link: Ergonext

Suprascapular nerve
Spinoglenoid notch	Suprascapular notch
Spinoglenoid notch

SUPRASCAPULAR NEUROPATHY

Anatomy
- Roots: C5-6
- Brachial plexus: Upper trunk
- Muscles innervated: Supraspinatus; Infraspinatus
- Sensory cutaneous innervation: None
Entrapment & Lesions
- Weakness: Arm abduction & External rotation
- Locations
  - Suprascapular notch
    - Weakness: Supraspinatus & Infraspinatus
  - Spinoglenoid notch
    - Ligament over notch: Male > Female
    - Weakness: Isolated infraspinatus
- Causes
  - Ganglion
    - Diagnosis: MRI or Ultrasound
    - Location
      - Spinoglenoid notch 75%
      - Suprascapular notch 20%
  - Nerve stretch: Overhead sports
  - Repeated trauma in notch
  - Shoulder trauma or damage
  - Surgery
    - Arthroscopy
    - Posterior shoulder approach
  - Familial calcification of superior transverse scapular ligament
Differential diagnosis
- Rotator cuff tear
- Quadrilateral space syndrome
- Frozen shoulder
- Brachial plexopathy
- C5 root lesion
Sports
- Backpacking
- Volleyball
- Baseball
- Fencing
- Weightlifting
- Skeet shootong
- Dancing
Clinical
- Pain
  - Shoulder (Posterior & Lateral)
  - Less & more inferior with spinoglenoid lesions
  - Exacerbated by: Adduction of extended arm
- Tenderness: Suprscapular notch; Over infraspinatus fossa
- Weakness & wasting
  - Infraspinatus > Supraspinatus
  - Reduced arm abduction & external rotation
Laboratory
- Electrodiagnostic
  - Nerve conduction: Prolonged distal latency to infraspinatus in most
  - EMG: Denervation in Infraspinatus > Supraspinatus
- MRI or ultrasound: May localize ganglion
Treatment
- Modalities
  - Rest
  - Nerve decompression
- Outcomes
  - Reduces pain
  - ± Improvement in strength

Gowers

Deltoid weakness
Shoulder is elevated by trapezius.
Slight abduction by supraspinatus.

AXILLARY NERVE

Anatomy
- Origin: C5-6
- Brachial plexus: Posterior cord
- Innervation
  - Motor: Deltoid; Teres minor
  - Sensory: Skin over lateral shoulder
Lesions: Weak arm abduction & external rotation
- Trauma: Shoulder dislocation (anterior); Humerus fracture
- Compression: Sleeping prone with arms over head
- Penetrating injury: Injection; Bullet; Rotator cuff surgery
- Quadrilateral (quadrangular) space syndrome
- Brachial neuritis

Quadrilateral (quadrangular) space syndrome

Pathology: Nerve & vessel damaged or occluded in quadrangular space
- Distal branch of axillary nerve
- ± Posterior humeral circumflex artery
Clinical
- Age: Young adults; 22 to 35 years
- Pain
  - Shoulder; Poorly localized
  - Increased by: Abduction & external rotation of arm
- Tenderness
  - Quadrilateral space
  - Near insertion of teres minor muscle
- Paresthesias: Lateral shoulder; Upper posterior arm
- Weakness
  - Muscles: Teres minor ± Deltoid
  - External rotation ± Abduction of arm
  - Dominant extremity
Sports
- Baseball
Differential diagnosis
- Other axillary nerve change
  - Anterior shoulder dislocation
  - Humeral neck fracture
  - Brachial plexus stretch injury
- Shoulder injury
- Subclavian artery stenosis
Lab
- EMG: Denervation of teres minor
- MRI: Selective atrophy of teres minor ± deltoid muscle with normal tendon
- Subclavian arteriography
  - Posterior humeral circumflex artery
    - Occluded with abduction & external rotation of arm
    - ? Non-specific: Occlusion may also occur in normals

MUSCULOCUTANEOUS NERVE

Anatomy
- Origin
  - Roots: C5-7
  - Brachial plexus: Lateral cord
- Innervation
  - Motor: Biceps; Brachialis; Coracobrachialis
  - Sensory: Forearm (Lateral antebrachial cutaneous nerve), Radial side from elbow to wrist
  - Anomalous branch: To median nerve in arm
Lesions
- Signs
  - Weakness: Weak elbow flexion & supination
  - Sensory loss & Dysesthesias: Lateral forearm; Not hand
  - Tendon reflex: Biceps reflex absent
- Causes
  - Injuries
    - Direct trauma: Most common, especially proximal humerus fracture
    - Rapid extension of forearm
    - Strenuous exercise
      - Lesion between Erbs point & Axilla
      - Entrapment: Passing through coracobrachialis
    - During anesthesia
    - Shoulder dislocation
    - Rotator cuff tear: Less common than axillary & suprascapular damage
  - Brachial neuritis
- Sport associations
  - Weightlifters
  - Baseball pitchers: Reduced biceps reflex
  - Tennis: Elbow hyper-extension
Differential diagnosis
- Ruptured biceps tendon
- C6 radiculopathy
Diagnosis: EMG
Variant: Lateral antebrachial cutaneous nerve lesion
- Location
  - Elbow
  - Nerve entrapped between: Biceps tendon & Brachialis muscle
- Causes
  - Strap of heavy bag across elbow crease
  - Venipuncture
  - Throwing athletes
  - Elbow hyperextension
- Pain
  - Location: Lateral elbow
  - Worsened by: Arm pronation & extension
- Sensory loss: Lateral distal forearm

MEDIAL PECTORAL NERVE²

Cause: ? Entrapment in hypertrophied pectoralis minor muscles
Clinical
- Inferior sternal portion of pectoralis major: Wasting & weakness
- Painless
- May be bilateral
- Compensatory hypertrophy of other chest muscles may occur
? Recovery with resting of affected region

HAMSTRING STRAIN⁵

Sports involved
- Sprinting: Running; Baseball; Football; Cricket (Fast bowlers)
- Kicking a ball
Specific muscle activity
- Eccentric contraction (Contracting muscle is lengthened)
- Injury more likely when muscle is already in lengthened position
Frequency
- Very common
- Reinjury rate: 34%
Predisposition
- Previously injured muscles: Shortened range of motion
- Unaccustomed eccentric exercise
Prevention
- Eccentric exercise
  - Repetitive mild
  - Mechanism: During 1 week after exercise muscle fibers produce additional sarcomeres
- After injury
  - Muscle stretching exercise: Increase range of motion
  - Agility & trunk stabilization exercises: Icing
MRI of injury
- Tendon damage: 12%
  - Proximal: Common (80%)
  - Distal: Occasional
  - Requires surgical intervention
- Muscle injury
  - Biceps femoris: 81%
  - Semimembranosus: 14%
  - Semitendinosus rare: 5%
  - May respond to conservative management

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References
1. Muscle & Nerve 1998;21:809-812
2. Muscle & Nerve 1999;22:1597-1599
3. Clin Neurophysiol 1999;110:1276-1283, Int Arch Occup Environ Health 2006;79:665–671
4. Muscle & Nerve 2003;27:549-561, Neurologist 2002;8:163-174
5. Clinical Experimental Pharmacol Physiol 2004;31:546–550, Med Sci Sports Exerc 2004;36:756-759.
6. Sports Med 2006;36:7-18

8/12/2008