Imaging of the peripheral nerves

PERIPHERAL NERVES
IMAGING
Jef Huyskens, MD
Jan L Gielen, MD PhD
CONTENT
•
Anatomy
•
Pathophysiology
•
Ultrasound
•
MRI
•
Cases
CONTENT
•
Anatomy
•
Pathophysiology
•
Ultrasound
•
MRI
•
Cases
ANATOMY
CONTENT
•
Anatomy
•
Pathophysiology
•
Ultrasound
•
MRI
•
Cases
PATHOPHYSIOLOGY
•
Compressive:
• Entrapment
• Nerve Instability
•
Non-compressive:
• Traumatic
• Tumors and tumor like conditions
• Inflammation
• Infection: leprosy
• Miscellaneous
MECHANISMS OF PERIPHERAL NERVE INJURIES
•
•
Mechanical-acute disruption of continuity
•
Laceration
•
Stretch
•
Intraneural injection
Arterial vascular occlusion
•
•
•
Acute ischemia: vasa nervora
Pressure
•
Extraneural: entrapment neuropathy, fibrosis
•
Intraneural: injection ischemia, hemorrhage in nerve sheath, fibrosis
•
Compartment syndrome
Chemical
•
Injection of neurotoxic solutions
CLASSIFICATION
Seddon
Sunderland
Structural and functional
processes
Recovery
Neurapraxia
1
Myelin damage, conduction
slowing, and blocking
Blunt trauma: 6 months
2
Loss of axonal continuity,
endoneurium intact, no conduction
Interruption axons, intact nerve
sheath: axonal regeneration 1
mm/day
3
Loss of axonal and endoneurial
continuity, perineurium intact, no
conduction
Interruption fascicles and sheath:
Wallerian degeneration, axonal
regeneration or neuroma formation
4
Loss of axonal, endoneurial, and
perineurial continuity; epineurium
intact; no conduction
5
Entire nerve trunk separated; no
conduction
Axonotmesis
Neurotmesis
Based on data from Seddon, Sunderland, and Lundborg
CLASSIFICATION
Seddon
Sunderland
Structural and functional
processes
Recovery
Neurapraxia
1
Myelin damage, conduction
slowing, and blocking
Blunt trauma: 6 months
2
Loss of axonal continuity,
endoneurium intact, no conduction
Interruption axons, intact nerve
sheath: axonal regeneration 1
mm/day
3
Loss of axonal and endoneurial
continuity, perineurium intact, no
conduction
Interruption fascicles and sheath:
Wallerian degeneration, axonal
regeneration or neuroma formation
4
Loss of axonal, endoneurial, and
perineurial continuity; epineurium
intact; no conduction
5
Entire nerve trunk separated; no
conduction
Axonotmesis
Neurotmesis
Based on data from Seddon, Sunderland, and Lundborg
CLASSIFICATION
Seddon
Sunderland
Structural and functional
processes
Recovery
Neurapraxia
1
Myelin damage, conduction
slowing, and blocking
Blunt trauma: 6 months
2
Loss of axonal continuity,
endoneurium intact, no conduction
Interruption axons, intact nerve
sheath: axonal regeneration 1
mm/day
3
Loss of axonal and endoneurial
continuity, perineurium intact, no
conduction
Interruption fascicles and sheath:
Wallerian degeneration, axonal
regeneration or neuroma formation
4
Loss of axonal, endoneurial, and
perineurial continuity; epineurium
intact; no conduction
5
Entire nerve trunk separated; no
conduction
Axonotmesis
Neurotmesis
Based on data from Seddon, Sunderland, and Lundborg
CLASSIFICATION
Seddon
Sunderland
Structural and functional
processes
Recovery
Neurapraxia
1
Myelin damage, conduction
slowing, and blocking
Blunt trauma: 6 months
2
Loss of axonal continuity,
endoneurium intact, no conduction
Interruption axons, intact nerve
sheath: axonal regeneration 1
mm/day
3
Loss of axonal and endoneurial
continuity, perineurium intact, no
conduction
Interruption fascicles and sheath:
Wallerian degeneration, axonal
regeneration or neuroma formation
4
Loss of axonal, endoneurial, and
perineurial continuity; epineurium
intact; no conduction
5
Entire nerve trunk separated; no
conduction
Axonotmesis
Neurotmesis
Based on data from Seddon, Sunderland, and Lundborg
CONTENT
•
Anatomy
•
Pathophysiology
•
Ultrasound
•
MRI
•
Cases
ULTRASOUND
•
•
Identifying and localisation of morphologic changes in peripheral nerves:
•
nerve rupture
•
inflammatory processes
•
compressive syndromes
•
tumoral lesions
Testing of motor nerve function: muscle contraction
•
Alternative to EMG
•
Does not test for the functional (sensorial) capacity of the nerve: combined with nerve
conduction study
•
Muscle morphology: volume reduction and increased reflectivity
•
Initial imaging of a suspected peripheral nerve injury or for follow-up imaging for
superficial nerves (< 2cm)
CONTENT
•
Anatomy
•
Pathophysiology
•
Ultrasound
•
MRI
•
Cases
MRI
•
•
Nerve: acute axonal disease
•
T2: High SI
•
Increased cross section distal to compression
Muscle denervation mapping on axial images: nerve identification and location
•
•
T2-WI (FS) - STIR
•
Acute and subacute: >24h -< 3 weeks
•
Muscle edema
T1 WI:
•
•
involution
•
> 3 weeks
•
Lipomatous infiltration
•
Volume reduction
Gadolinium enhancement
•
24h after injury
CONTENT
•
Anatomy
•
Pathophysiology
•
Ultrasound
•
MRI
•
Cases
Zenuw
Wortel
Spieren
n. dorsalis scapulae
C5
mm. rhomboideus en m. levator scapulae
n. thoracicus longus
C5-C7
m. serratus anterior
n. subclavius
C5-C6
m. subclavius
n. suprascapularis
C5-C6
m. supraspinatus en m. infraspinatus
n. pectoralis lateralis
C5-C7
m. pectoralis major (door contact met n. pectoralis medialis)
n. musculocutaneus
C5-C7
m. coracobrachialis, m. brachialis en m. biceps brachii
laterale wortel van de n. medialis
C5-C7
vezels naar de n. medialis
n. subscapularis superior
C5-C6
bovenste deel m. subscapularis
n. thoracodorsalis
C6-C8
m. latissimus dorsi
n. subscapularis inferior
C5-C6
Onderste deel m. subscapularis en m. teres major
nervus axillaris
C5-C6
voorste tak: m. deltoideus en een smal gebied van de overliggende huid.
achterste tak: m. teres minor and m. deltoideus
n. radialis
C5-T1
m. triceps brachii, m. supinator, m. anconeus, de extensoren van de onderarm en m. brachioradialis
n. pectoralis medialis
C8-T1
m. pectoralis major en pectoralis minor
middelste wortel van de n. medialis
C8-T1
vezels naar de n. medialis
n. cutaneus brachii medialis
C8-T1
-
n. cutaneus antibrachii medialis
C8-T1
-
n. ulnaris
C8-T1
m. flexor carpi ulnaris, de 2 mediale buiken van de m. flexor digitorum profundus, groot gedeelte van de kleine handspieren
Zenuw
Wortel
Spieren
n. dorsalis scapulae
C5
mm. rhomboideus en m. levator scapulae
n. thoracicus longus
C5-C7
m. serratus anterior
n. subclavius
C5-C6
m. subclavius
n. suprascapularis
C5-C6
m. supraspinatus en m. infraspinatus
n. pectoralis lateralis
C5-C7
m. pectoralis major (door contact met n. pectoralis medialis)
n. musculocutaneus
C5-C7
m. coracobrachialis, m. brachialis en m. biceps brachii
laterale wortel van de n. medialis
C5-C7
vezels naar de n. medialis
n. subscapularis superior
C5-C6
bovenste deel m. subscapularis
n. thoracodorsalis
C6-C8
m. latissimus dorsi
n. subscapularis inferior
C5-C6
Onderste deel m. subscapularis en m. teres major
nervus axillaris
C5-C6
voorste tak: m. deltoideus en een smal gebied van de overliggende huid.
achterste tak: m. teres minor and m. deltoideus
n. radialis
C5-T1
m. triceps brachii, m. supinator, m.
n. pectoralis medialis
C8-T1
m. pectoralis major en pectoralis minor
middelste wortel van de n. medialis
C8-T1
vezels naar de n. medialis flexoren, pronator
n. cutaneus brachii medialis
C8-T1
-
n. cutaneus antibrachii medialis
C8-T1
-
n. ulnaris
C8-T1
m. flexor
anconeus, de extensoren van de onderarm en m. brachioradialis
carpi ulnaris, de 2 mediale buiken van de m. flexor digitorum profundus, groot gedeelte van de kleine handspieren
CASES UPPER LIMB
•
Brachial plexus
•
Suprascapular nerve
•
Radial nerve
•
Median nerve
•
Ulnar nerve
SUPRASCAPULAR NERVE
•
C5-C6
•
Superior trunk brachial plexus
•
Transverse scapular ligament
•
Suprascapular foramen
•
Supraspinatus fossa
•
Inferior transverse ligament
•
Infraspinatus muscle
RADIAL NERVE
•
N. Radialis:
•
Precubital
• Humerus fracture mid diaphysis
•
Cubital: vague forearm pain, no muscle dysfunction
• Radial tunnel syndrome (RTS)
•
N. Interosseus posterior (PIN):
•
Postcubital compression
• Arcade Frohse, tumor, bursa, cyst, fibrosis (radial head FX)
•
N. Radialis, superficial sensory branch
•
Wrist: Wartenberg syndrome
ULNAR NERVE
•
Cubital Tunnel Syndrome (2nd most frequent compressive neuropathy)
•
Ulnar nerve impingement at cubital tunnel
•
Activity – mechanism
• baseball, jackhammer, boxers, javelin throwers
•
Imaging findings
• US and MRI: detect anomalies at the cubital tunnel: ganglia, bone spurs and
musculus anconeus accessorius
• Position of the ulnar nerve relative to the medial epicondyle is evaluatied during
flexion and extention movement on US
MEDIAN NERVE
•
Elbow:
• Struthers Ligament
• Pronator teres syndrome
• AINS (Kiloh nevin)
• Lacertus fibrosus
• Supracondylar humerus fracture
•
Carpal Tunnel Syndrome
• >20mm: pathologic, 10-20mm?, < 10mm: normal
• Caliber jump
•
Persistent median artery
•
Accessory muscle belly
CASES LOWER LIMB
•
Lumbar plexus
• Femoral nerve
•
Sacral plexus
• Sciatic nerve
LOWER LIMBS
•
N. Ischiadicus
• Hematoma
• Lipoma
•
N. Peroneus communis
• Fibula compression
• (Intraneural) Cyst, fracture, dislocation, cast
•
N. Suralis
•
N. Tibialis, N. plantaris medialis et lateralis
•
N. Interdigitalis
• Bursa, fibrosis: Morton neuroma
TAKE HOME MESSAGES
•
What do I want to see?
•
Ultrasound: entrapment, nerve thickening
•
MRI: denervation edema – mapping
•
MRI spine
•
Several entrapment syndromes
•
Cubital tunnel U
•
Ulnar nerve dislocation U
•
Guyon tunnel U
•
PIN – Frohse arcade R
•
Pronator M
•
Carpal tunnel M
•
Tarsal tunnel T