Spinal Cord Pathology

• PNS can regenerate

  CNS cannot -> due to environment of the CNS that prevents growth
• What is varicella zoster?


  Virus

  Causes chickenpox & shingles
• Motor pathways

  Vestibulospinal

  Tectospinal

  Reticulospinal

  Corticobulbar

  Lateral corticospinal
• Somatosensory pathways

  DCML

  Spinothalamic
• Central Cord Syndrome

  Lesions damage central area of spinal cord

  Can interrupt pain/temp info from levels of lesion, but can preserve ascending pain/temp from lower body intact (due to anatomy of tracts in the spinal cord)
• Anterior spinal artery syndrome

  Artery damaged by bone or cartilage spicules

  Bilateral loss of motor function & pain sensation below injured segment

  Position sense preserved
• Brown-Séquard syndrome

  One side of spinal cord affected

  Loss of motor function & position sense on same side & of pain sensation on opposite side
• Posterior column syndrome

  Position sense lost below lesion

  Motor function & pain sensation preserved
• While pain generally ascends through the anterolateral system, there is a dorsal column pain pathway for visceral (ie GI tract) pain.
• What is Bell's palsy?


  Common condition that results from damage to the facial motor nerve (LMN)
• How can Bell's Palsy be differentiated from UMN lesions?


  Bell's palsy - no forehead sparing

  UMN - forehead sparing
• What happens in reactivated varicella zoster?

  Shingles

  Produces haemorrhagic lesions of dorsal root ganglia
• Do peripheral nerves regenerate?

  Yes
• Do central nerves regenerate?

  No
• Is it only adults who get shingles?

  No, children can get shingles
• What is diabetic neuropathy?

  Progressive distal sensorimotor polyneuropathy

  Loss of myelinated fibres -> due to interruption of blood supply to nerves
• What happens to muscle fibres when they lose their LMN innervation?

  Atrophy
• What is myasthenia gravis?

  Autoimmune condition

  Antibodies against neuromuscular junction (AChR, anti0-MuSK & anti-LRP4 antibodies) -> malfunction of junction -> muscle weakness
• What are the antibodies found in myasthenia gravis?

  Anti-AChR

  Anti-MuSK

  Anti-LRP4
• Dorsal column

  Proprioception
• Lateral funiculus

  Lateral corticospinal

  Anterolateral system (pain)

  Spinocerebellar (tension)
• Ventral funiculus

  Ventral corticospinal

  Extrapyramidal tracts
• Visceral pain

  Goes via dorsal column pain pathway (rather than the normal anterolateral system)

  Pain can be treated by dorsal column lesion at the midline (e.g. in severe GI cancer pain)
• Bell's palsy vs stroke

  Bell's = LMN lesion, loss of 1 side of face (no forehead sparing)

  Stroke = UMN lesion, forehead sparing
• How can we tell a 'fake' smile?

  Lack of input from orbicularis oculi muscles
• What is the role of the anterior cingulate motor area?

  Emotional processing of experience

  Motor functions (facial expression)
• How will this present?

  A pt with lesion in right motor cortex-derived pyramidal fibres

  Unable to voluntary smile (due to L side paralysis)

  Able to smile in response to humour (anterior cingulate motor area intact)
• How will this present?

  A pt with lesion in left medical forebrain affecting non-pyramidal fibres

  Able to voluntary smile (UMNs intact)

  Unable to smile in response to humour (on R side, due to damage to anterior cingulate motor area)