Spinal Cord Anatomy and Injuries Quiz

Spinal Cord Anatomy

• The spinal cord is an extension of the brain running through the spinal canal, ending at the lower border of the 1st lumbar vertebra.
• It connects to the medulla oblongata above and the filum terminale below.
• It's divided into 31 segments.
• Each segment has four roots: a ventral and a dorsal root for each half.
• The dorsal root has an oval swelling called the dorsal root ganglion.
• Three meningeal layers surround the spinal cord: Dura mater (superficial), arachnoid mater, and pia mater (deep).
• The spinal cord consists of gray matter surrounded by white matter.
• The gray matter resembles the letter "H" in a transverse section, with two anterior and two posterior horns.
• The white matter contains ascending and descending nerve fibers arranged into tracts.

Causes of Spinal Cord Injuries

• Non-traumatic (16%): secondary to disease, infection, and congenital defects.
• Trauma (84%): most common causes include motor vehicle and motorbike accidents, falls, sports (water-based activities), and work-related injuries.

Mechanisms of Spinal Cord Injury

• Distraction: occurs when the bony spine is hyperextended due to rapid acceleration and deceleration injuries.
• Compression: results from axial loading, compromising the spinal cord due to encroachment of vertebral body fragments or intravertebral discs.
• Torsional injuries: result from high-impact collisions that twist and tear spinal cord tissue.
• Penetrating trauma: directly damages the spinal cord, particularly vulnerable in the lower cervical or upper lumbar regions.

Classification of Spinal Cord Injuries

• Level (site) of lesion:
  • Cervical: Tetraplegia (Quadriplegia)
  • Below cervical: Paraplegia
• Cause:
  • Traumatic
  • Non-traumatic: congenital, infection, vascular, neoplastic, etc.
• Injury (Impairment):
  • Complete lesion: No motor or sensory function in the S4-S5 area of the spinal cord.
    • Motor Function: Inability to voluntarily contract the anal sphincter.
    • Sensory Function: Loss of deep anal pressure or light touch/pinprick sensation in the perianal area.
  • Incomplete lesion: Some preservation of sensory and/or motor function in the S4-S5 area of the spinal cord.
    • Types: central cord, Brown-Sequard, anterior cord, posterior cord, conus medullaris, and epiconus.

Clinical Picture

• Local Manifestations: Pain, local tenderness, swelling, or deformity at the site of the lesion.
• Lower Motor Neuron Signs:
  • Motor: Muscle weakness or paralysis.
  • Sensory: Hyposthesia (decreased sensation) or anesthesia (loss of sensation).
  • Sphincters: Retention of urine and stool in S3-5 lesions.
• Upper Motor Neuron Signs:
  • Paralysis: Impaired muscle power below the neurological level of the lesion.
    • Stages:
      • Flaccid Stage: Initial stage lasting from several hours to weeks, characterized by complete loss of tone and reflexes.
      • Spastic Stage: On recovery from the shock stage, hypertonia, hyperreflexia, positive Babinski sign, and clonus develop.
  • Sensory Loss: Impaired superficial and deep sensations below the neurological level of the lesion.
  • Loss of Bladder and Bowel Control: Retention of urine in the flaccid stage followed by incontinence (reflex emptying) in the spastic stage.
  • Sexual Dysfunction: Linked to bladder involvement.
  • Impaired Sympathetic Outflow: More severe in cervical than thoracic level lesions, leading to impaired temperature control, hypertension, and bradycardia.
  • Respiratory Problems: Lesions above C4 cause diaphragm paralysis, lower cervical lesions cause intercostal muscle and abdominal paralysis, reducing vital capacity.

Complete Lesion at C5 Segment

• Weakness and Atrophy: Deltoids, supraspinatous, infraspinatous, and rhomboids (LMNL).
• Biceps Reflex: Present.
• Hyposthesia or Anesthesia: Lateral aspect of the shoulder.
• UMNL: Motor and sensory below C5, including sphincters.

Incomplete Spinal Cord Injury Patterns

• Central Cord Syndrome:
  • Commonly Occurred: Hyperextension injuries of the cervical spine in older people with cervical spondylosis.
  • Symptoms: More severe paralysis of the upper limbs than the lower limbs.
• Brown-Sequard Syndrome:
  • Caused: Damage to one side of the spinal cord due to penetrating injuries.
  • Symptoms: Ipsilateral motor and proprioception loss, contralateral pain and temperature loss.
• Anterior Cord Syndrome:
  • Caused: Flexion injury damaging the anterior two-thirds of the spinal cord, often due to vascular insult to the anterior vertebral artery.
  • Symptoms: Preservation of light touch and proprioception, but loss of motor function, pain, and temperature sensation.
• Posterior Cord Syndrome:
  • Caused: Damage to the back of the spinal cord.
  • Symptoms: Loss of proprioception below the level of injury, but motor function, pain, temperature, and light touch sensations are usually intact.
• Conus Medullaris Syndrome:
  • Caused: S3,4,5 segment lesion.
  • Symptoms: Early urinary and faecal incontinence, impotence, impaired sensation in the saddle-shaped area, no motor or sensory disability in the lower limbs.
• Epiconus Lesion:
  • Caused: L4,5 S1,2 segment lesion.
  • Symptoms: Weakness or paralysis in the lower limbs, absent ankle reflex, intact knee reflex, sensory loss from L4-S2, and potential bladder precipitancy.
• Cauda Equina Syndrome:
  • Caused: Injury to the cauda equina, lumbar and sacral nerve roots.
  • Symptoms: Motor weakness of LMN nature in one or both lower limbs, sensory loss, and bladder and bowel dysfunction.