In-Depth Notes on Neurologic Disorders: SCIs, CP & CVAs

Spinal Cord Injuries (SCIs)

  • Demographics: SCIs most commonly affect young individuals aged 16-30.
  • Causes:
    • Non-traumatic:
    • Disc herniation
    • Spondylosis (degenerative vertebral disease)
    • Osteoporosis-related fractures
    • Metastatic cancer-related fractures
    • Traumatic:
    • Motor vehicle accidents (around 50%)
    • Falls
    • Sports accidents
    • Penetrating injuries (e.g., firearms)
  • Pathologies from SCIs may include:
    • Concussion
    • Contusion
    • Compression
    • Laceration
    • Complete/incomplete transection
  • Haemorrhages and oedema may reduce blood supply and worsen ischemic injuries.

Common Locations for Traumatic SCIs

  • Regions: Cervical region, lower thoracic, and upper lumbar vertebrae (most mobile).
  • Mechanisms of injury:
    • Hyperextension
    • Hyperflexion
    • Extreme rotation
    • Vertical compression

Functional Impairments due to SCIs

  • Segmental function:
    • Involves spinal neurons in specific spinal segments.
  • Vertical tract function:
    • Involves ascending and descending tracts.
    • Dysfunction can result in loss of sensory/motor function below the level of the lesion.
  • Dysfunction consequences:
    • Impaired sensation in dermatomal distributions.
    • Lower motor neuron lesion signs in myotomal distributions.

Key Terms

  • Spinal Segment: Origin of one pair of spinal nerves.
  • Dermatome: Skin area serves by a single spinal segment.
  • Myotome: Muscle group innervated by a single spinal segment.

Motor Manifestations of SCIs

  • Motor Tracts:
    • Corticospinal tract:
    • Originates in cerebral cortex, terminates in spinal cord's anterior horns.
      • Divided into lateral (90%) and anterior (10%) tracts.
      • Lateral tract: voluntary control of limb muscles, fine movements (crosses over).
      • Anterior tract: controls some neck, shoulder, and trunk muscles (some cross, some do not).

Manifestations of Lower Motor Neuron Lesions

  • Signs:
    • Paresis/paralysis
    • Hypotonia (flaccidity)
    • Loss of muscle stretch reflexes
    • Muscle atrophy (neurogenic atrophy)

Upper Motor Neuron Lesion Signs

  • Signs:
    • Paresis/paralysis (typically paresis)
    • Hypertonia (spasticity)
    • Hyperactive muscle stretch reflexes
    • Positive Babinski reflex
    • Muscle atrophy minimal or absent

Types of Muscle Weakness/Paresis

  • Monoplegia/monoparesis: Affects one limb only.
  • Hemiplegia/hemiparesis: Affects one side of the body.
  • Paraplegia/paraparesis: Affects the body below the arms.
  • Tetraplegia/quadriplegia: Affects all limbs and trunk.

Sensory Manifestations of SCIs

  • Tract Functions:
    • Spinothalamic tracts: pain, temperature, crude touch (contralateral).
    • Dorsal column-medial lemniscus pathway: discriminative touch and proprioception (ipsilateral).
  • Total transection leads to loss of all sensation below the lesion, often with paraplegia.

Respiratory Function in SCIs

  • Main inspiratory muscle: Diaphragm (C3-C5).
  • Function loss varies based on injury location:
    • Above C3: Total loss of respiratory function.
    • C3-C5: Diaphragm works, shallow breathing.
    • C6-C8: Diaphragm works but shallow breaths, coughing impaired.
    • T1-T5: Diaphragm and intercostals work, cough impaired.
    • T6-T12: Diaphragm and intercostals work well; some abdominal muscle weakness.

Bladder Function in SCIs

  • Bladder function is influenced by reflex pathways from S2-S4.
  • Neurogenic bladder types:
    • Above T12: Hypertonic, hyper-reflexive bladder with uncontrolled emptying.
    • S2-S4 injuries: No sensation/control, leading to a flaccid bladder.

Bowel Function in SCIs

  • Neurogenic bowel syndrome:
    • Above sacral cord: No awareness/control; risk of constipation/incontinence.
    • S2-S4 lesions: Loss of bowel reflexes leading to hypotonic bowel and incontinence.

Sexual Function in SCIs

  • Affects both genders, related to injury level:
    • L2-S1: Preserved reflexogenic arousal; incomplete psychogenic arousal.
    • Above T11: Total loss of psychogenic arousal.
    • S2-S4 lesions: Loss of reflexogenic arousal but preserved psychogenic arousal.

Cerebral Palsy (CP)

  • Definition: Non-progressive chronic conditions affecting movement, coordination due to brain damage (e.g., UMNs, basal nuclei).
  • Causes:
    • Prenatal developmental issues
    • Birth trauma (hypoxia)
    • Postnatal injuries (e.g., choking).
  • Types of CP:
    • Spastic CP: Most common, muscle stiffness and weakness.
    • Dyskinetic CP: Involuntary movements, affects posture.
    • Ataxic CP: Impaired balance/coordinated movements.
    • Mixed CP: Symptoms from multiple types.

Cerebrovascular Accident (CVA)

  • Definition: Damage to brain tissue from cerebral infarction (85%) or intracranial hemorrhage (15%).
  • Causes of Ischemic stroke:
    • Thrombosis due to atherosclerosis.
    • Embolic strokes from heart.
  • Symptoms of Ischemic Stroke:
    • Hemiparesis/hemiplegia
    • Aphasia
    • Dysarthria
    • Visual deficits.

Diagnosis and Treatment of Stroke

  • Imaging:
    • CT for hemorrhagic stroke detection
    • MRI for ischemic detection.
  • Treatment:
    • Ischemic strokes: Reperfusion therapy.
    • Hemorrhagic strokes: Surgical repair needed immediately.

Mortality and Recovery Rates for Stroke

  • 10% recover completely; 25% with minor impairments; 40% moderate to severe impairments.
  • 10% require long-term nursing care; often no significant improvement after 1 year.