Bulbar and Pseudobulbar

1
Bulbar and Pseudobulbar
2
Terminology Pathways

• UMN
• Includes corticospinal corticobulbar tracts
• Corticospinal terminates at spinal motor nuclei
• Most provide contralateral influence
• Corticobulbar terminates at brainstem motor
  nuclei
• Most corticobulbar tracts provide some bilateral
  influence

3
Corticobulbar and Corticospinal Pathways
4
Terminology Pathways

• Upper Motor Neurons (UMN)
• Direct activation pathway (conscious, skilled
  behaviors)
• Pyramidal (pyramid shape) pathway
• Mostly crossingdirect activation pathway

5
Terminology Pathways

• Upper Motor Neurons (UMN)
• Indirect activation pathway (subconscious,
  automatic)
• Extra-pyramidal pathway
• Intermingled with pyramidal
• Contralateral predominanceindirect activation
  pathway

6
Direct and Indirect Activation
7
Terminology Pathways

• LMNlower motor neuron
• final common pathway
• In both CNS and PNS
• Cell bodies in CNS
• Cranial and spinal nerves in PNS
• Motor unit LMN muscle fibers innervated by it

8
Motor Unit
9
Terminology LMN

• Alpha motor neurons
• Innervate extrafusal muscle fiberscontractile
  element of muscle (from brainstem or spinal cord)
• ? motor neurons activated by direct activation
  pathways
• Gamma motor neurons
• Innervate intrafusal muscle fibers (muscle
  spindles)
• Intrafusal fibers parallel to extrafusal fibers
• Regulate reflexes and maintain muscle tone
  posture
• ? motor neurons activated by indirect activation
  pathways

10
Terminology of Impairment

• Bulbar
• Unilateral or bilateral LMN and/or sensory
• Dysarthria, dysphagia, possible
  respiratory/cardiac changes
• Flaccid, loss of reflexes
• Atrophy, fasciculations

11
Terminology of Impairment

• Pseudobulbar
• Bilateral UMN
• Dysarthria, dysphagia, emotional lability,
  cognitive changes/higher level function
  impairments
• Spastic, hyperactive reflexes, pathologic
  reflexes
• Tightness, slowness, contracture

12
Supratentorium Cortical Forebrain Supranuclear
Bulbar Brainstem Hindbrain Nuclear
13
UMN and LMN Influence
14
Critical Points

• Know the difference between UMNs and LMNs
• Know the 2 pathways of the UMN system
• Know the 2 types of LMNs
• Know the various terms that apply to brain
  regions
• Differentiate bulbar from pseudobulbar by
  characteristics of the impairments