Untitled Quiz

Spinal Cord Anatomy

• 31 pairs of spinal nerves, each with a specific path and function
• Cervical nerves exit above their corresponding vertebrae, expect for C8 nerve which exits below C7
• Thoracic, lumbar, and sacral nerves exit below their corresponding vertebrae
• The spinal cord ends between L1 and L2 in adults
• Lumbar and sacral roots descend caudally forming the cauda equina

Terminology

• Dermatome: the specific area of skin innervated by a single spinal nerve root
• Myotome: a group of muscles primarily innervated by a single nerve root
• Paresthesia: Subjective tingling sensation caused by nerve or nerve pathway pathology
• Radiculopathy: Pathology affecting a nerve root, often caused by compression

Causes of Radiculopathy

• Spondylosis: Degenerative spinal changes, often leading to stenosis but not always interchangeable
• Disc Herniation: Protrusion of the nucleus pulposus through the annulus, often caused by degeneration and pressure

Risk factors for developing radiculopathy:

• Manual labor involving heavy lifting, driving, or operating vibrating equipment
• History of chronic smoking

Cervical Spine

• The spinal canal is widest in the upper cervical spine (C1-C3)
• Canal narrows significantly with neck extension
• Spondylotic disease most commonly occurs in the lower cervical spine

Lumbar Spine

• Most susceptible to disc herniations due to flexion, extension, and torsion movements
• L4-L5 and L5-S1 are most vulnerable to injury, accounting for 90-95% of compressive radiculopathies

Nerve Root Compression Symptoms

• Acute onset with herniated disc
• Slower onset with spondylosis
• Pain typically radiates in a dermatomal pattern
• Sensory loss may be mild or absent due to overlapping dermatomes

Common Symptoms:

• Paresthesia or numbness in a root distribution (80% of cases)
• Subjective weakness is less common
• Symptoms exacerbated by Valsalva maneuvers (cough, sneeze, strain)

Cervical Radiculopathy Statistics:

• C7 is the most frequently affected nerve root (approx. 70% of cases)
• C6 root involvement occurs in approximately 20% cases

Physical Exam:

• Spurling test: compression of the affected nerve root
• Shoulder abduction test: tests C5-C7 nerve root compression, relief of symptoms is a postive test
• Valsalva maneuver
• Neck distraction test: traction on the neck

Reflexes:

• C5 - biceps and brachioradialis
• C6 - brachioradialis
• C7 - triceps
• L4 - quadriceps
• S1 - Achilles

Lower Extremity Examination:

• Straight leg test: assesses lower lumbar nerve root involvement (L4 to S1)
• Reverse straight leg: assesses L2 to L4 nerve roots
• Slump test: can reproduce radicular symptoms

Bowstring sign:

• Relief of radicular pain when the knee is flexed during a positive straight leg raise

Key Points to Remember:

• Cervical radiculopathy is usually unilateral
• Comparing reflexes side to side is vital
• Reduced strength of muscles innervated by the affected nerve is a significant finding

L1 Radiculopathy:

• Uncommon
• Symptoms: pain, paresthesia, sensory loss in the inguinal region
• Rare: minor hip flexion weakness

L2/L3/L4 Radiculopathy

• Difficult to differentiate due to overlapping innervation
• Commonly involved in older patients with spinal stenosis symptoms

L5 Radiculopathy:

• Most common lumbosacral radiculopathy
• Symptoms: back pain radiating down the lateral leg into the foot
• Weakness: foot dorsiflexion, toe extension, foot inversion/eversion, and sometimes leg abduction

S1 Radiculopathy

• Pain radiates down the posterior leg into the foot
• Weakness: plantar flexion (gastrocnemius muscle), leg extension, and knee flexion

S2/S3/S4 Radiculopathy:

• Less common
• Symptoms: sacral or buttock pain radiating down the posterior leg or into the perineum
• Minimal weakness but urinary and fecal incontinence and sexual dysfunction may be present

Diagnostic Evaluation:

• Plain x-rays
• CT scan
• MRI
• EMG/NCS
• Myelogram

Treatment:

• Pain control
• Muscle relaxants
• Physical therapy
• Epidural steroid injections
• Surgical intervention

Non-Degenerative Radiculopathies

• Often affect the ventral and dorsal roots more diffusely
• May also affect the dorsal root ganglion
• Deficits may span multiple myotomes and dermatomes

Non-Degenerative Causes of Radiculopathy:

• Diabetes mellitus
• Nerve root trauma
• Nerve root infarction
• Nerve root avulsion
• Infectious or granulomatous conditions:
  • Herpes zoster
  • Lyme disease
  • Tuberculosis
  • HIV
  • Syphilis
  • Brucellosis
  • Cytomegalovirus
  • Histiocytosis X
• Sarcoid
• Infiltrative conditions:
  • Lymphoma
  • Carcinomatous meningitis
• Inflammatory conditions:
  • Guillain-Barré syndrome
  • Chronic inflammatory demyelinating polyneuropathy
  • Vasculitis with nerve root infarction

Herpes Zoster

• Caused by varicella zoster virus
• Symptoms:
  • Erythematous vesicular maculopapular rash
  • Sensory changes: burning or tingling pain
• Most commonly affects thoracic dermatomes and face

Herpes Zoster Risk Factors:

• Age > 60 years
• Underlying malignancy
• Immunosuppression
• Diabetes
• Surgical trauma
• UV light

Herpes Zoster Disease Course:

• 80-90% resolve spontaneously within 6 months
• Chronic pain (Post-Herpetic Neuralgia):
  • Pain lasting greater than 2-3 months after rash
  • Occurs in about 5% of cases
  • Severity correlates with the severity of the rash and acute pain

Herpes Zoster Treatment:

• Prevention with the Shingrix vaccine
• Antiviral medication started