Acute Upper Extremity Pain/Weakness

Kevin R. Moore, MD

DIFFERENTIAL DIAGNOSIS

Common

Intervertebral Disc Herniation
- Intervertebral Disc Herniation, Cervical
- Intervertebral Disc Herniation, Traumatic
Cervical Fracture with Nerve Compression
- Burst Fracture, Cervical
- Hyperflexion Injury, Cervical
- Lateral Flexion Injury, Cervical
- Hyperflexion-Rotation Injury, Cervical
- Pathologic Vertebral Fracture

Less Common

Syringomyelia
Traumatic Dural AV Fistula
Peripheral Neuropathy
- Brachial Plexus Traction Injury
- Radial Neuropathy
- Ulnar Neuropathy
- Median Nerve Entrapment
- Suprascapular Nerve Entrapment
Infection
- Abscess, Paraspinal
- Abscess, Epidural
- Osteomyelitis, Granulomatous
- Osteomyelitis, Pyogenic

Rare but Important

Idiopathic Brachial Plexus Neuritis
Acute Transverse Myelitis, Idiopathic
Secondary Acute Transverse Myelitis
ADEM, Spinal Cord

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Careful clinical exam distinguishes radiculopathy from mechanical back pain or myelopathy, limiting pertinent differential diagnosis list

Helpful Clues for Common Diagnoses

Intervertebral Disc Herniation
- Intervertebral Disc Herniation, Cervical
  - Localized (< 50% of disc circumference) displacement of disc material beyond edges of vertebral ring apophyses
  - Clinical symptoms affected by level, location, herniation size
- Intervertebral Disc Herniation, Traumatic
  - Disc herniation following trauma
  - Muscle, ligamentous injuries suggest etiology
Cervical Fracture with Nerve Compression
- Burst Fracture, Cervical
  - Typically mid- or lower cervical spine
  - Axial compression → comminuted fracture extending through both endplates
- Hyperflexion Injury, Cervical
  - Typically mid or lower cervical spine
  - Flexion force disrupts capsular & posterior ligaments → anterior vertebral displacement/angulation, focal kyphosis, ↑ space between spinous processes
- Lateral Flexion Injury, Cervical
  - Typically mid or lower cervical spine
  - Articular mass fracture ± fractures of transverse and uncinate processes, vertebral body
- Hyperflexion-Rotation Injury, Cervical
  - Typically mid or lower cervical spine
  - Traumatic disruption of cervical spine (ligaments ± bony elements) → facet subluxation, focal vertebral angulation, rotation
- Pathologic Vertebral Fracture
  - Fracture through abnormal bone weakened by tumor or infection
  - Search for trabecular and cortical bone destruction, spinal cord &/or nerve root compression

Helpful Clues for Less Common Diagnoses

Syringomyelia
- Expanded spinal cord with central dilated, beaded, or sacculated cystic cavity
Traumatic Dural AV Fistula
- AVF nidus with enlarged draining veins
- Radiculopathy 2° to nerve compression by enlarged epidural veins
Peripheral Neuropathy
- Brachial Plexus Traction Injury
  - Stretch injury or avulsion of ≥ 1 cervical roots, brachial plexus elements
  - Denervation changes in dorsal paraspinal muscles, arm and forearm muscles innervated by terminal peripheral nerve branches
- Radial Neuropathy
  - Focal radial nerve enlargement, abnormal T2 hyperintensity
  - Characteristic entrapment locations include mid humeral shaft or fibrous arch of Frohse
- Ulnar Neuropathy
  - Focal ulnar nerve enlargement, abnormal T2 hyperintensity
  - Most common in cubital tunnel (elbow); uncommon in Guyon tunnel (wrist) or brachial plexus
- Median Nerve Entrapment
  - Focal median nerve enlargement, abnormal T2 hyperintensity
  - Entrapment most common at carpal tunnel or pronator teres muscle
- Suprascapular Nerve Entrapment
  - Mass impinges nerve at spinoglenoid or suprascapular notch
  - Abnormal T2 hyperintensity in denervated muscles
Infection
- Abscess, Paraspinal
  - Paravertebral enhancing phlegmon or peripherally enhancing liquified pus collection
- Abscess, Epidural
  - Spondylodiscitis with adjacent enhancing epidural phlegmon ± peripherally enhancing fluid collection
  - May extend over many vertebral segments
- Osteomyelitis, Granulomatous
  - Tuberculosis or brucellosis most common
  - May produce spinal cord, nerve compression
- Osteomyelitis, Pyogenic
  - Ill-defined abnormal vertebral marrow signal centered at disc with loss of adjacent endplate definition
  - May produce spinal cord, nerve compression

Helpful Clues for Rare Diagnoses

Idiopathic Brachial Plexus Neuritis
- Parsonage-Turner syndrome
- Immune-mediated neuropathy of brachial plexus
- Smooth enlargement of brachial plexus elements, mild diffuse nerve and muscle enhancement
Acute Transverse Myelitis, Idiopathic
- Inflammatory lesion involving both spinal hemicords → bilateral motor, sensory, and autonomic dysfunction
- Lesion extent > 2 vertebral segments + eccentric enhancement
Secondary Acute Transverse Myelitis
- Inflammatory disorder of spinal cord associated with many etiologies
- T2 hyperintense lesion with mild cord expansion, minimal to no enhancement
ADEM, Spinal Cord
- Para/postinfectious immune-mediated inflammatory disorder of spinal cord white matter
- Multiple sclerosis mimic

Image Gallery

Sagittal T2WI MR demonstrates a C4-5 cervical disc herniation with spinal cord deformation. Location corresponds with left arm pain.

Axial T2* GRE MR shows a large left C6-7 cervical disc herniation with deformation of the spinal cord concordant with clinical localization of left arm pain.