Where

1
Wheres the Lesion?

• Neuroscience Core Lecture Series
• 23 October 2002
• David Roman Renner, MD
• Department of Neurology

2
Scotts CC

• My balance is off.
• Multiple ER visits for fall-related trauma
• Im losing the fine control of my fingers.
• Loss of manual dexterity
• Ive had pneumonia three times.
• Dysphagia to liquidsgtsolids

3
All of Scotts Complaints Sounded Neurologic in
Origin

• His lesion should lie somewhere in the neuraxis.

4
Divisions of the Neuraxis

• Cortical Brain
• Subcortical Brain
• Brainstem
• Cerebellum
• Spinal Cord
• Root
• Peripheral Nerve

• Neuromuscular Junction
• Muscle

5
Off the Top of my Head . . .

• Imbalance Cerebellum
• Pneumonia Brainstem (related dysphagia)
• Loss of Dexterity Peripheral Nerve

6
Neurologic Examination

• Higher Cortical Function
• Cranial Nerves
• Cerebellar Function
• Motor
• Sensory
• Deep Tendon Reflexes
• Pathologic Reflexes

7
The Neuro Exam Should Evaluate the Entire
Neuraxis

• Higher Cortical Function cortex
• Cranial Nerves subcortex, brainstem
• Cerebellar Function cerebellum
• Motor motor homonculous, subcortical pyramidal
  tracts, BS, cord, radicle, PN, muscle
• Sensory ascending tracts, thalamus, subcortical
  tracts, sensory hononculous
• Deep Tendon Reflexes afferent PN, radicle, cord,
  efferent PN, muscle
• Pathologic Reflexes

8
Scotts Exam Showed

• Higher Cortical Function normal
• Cranial Nerves oropharyngeal dysarthria
• Cerebellar Function hypotonia, assynergy,
  dysmetria, staccato dysarthria, intention tremor,
  appendicular ataxia
• Motor hypotonia, normal strength
• Sensory decreased vibration and temperature
• Deep Tendon Reflexes areflexia
• Pathologic Reflexes plantar flexing

9
So Wheres the Lesion?
10
Divisions of the Neuraxis

• Cortical Brain
• Subcortical Brain
• Brainstem
• Cerebellum
• Spinal Cord
• Root
• Peripheral Nerve

• Neuromuscular Junction
• Muscle

11
Cortical Brain

• Depends upon hemispheric dominance
• Non-neurologists generalize
• right visual/spatial, perception and memory
• left language and language dependent memory
• Look for aphasias, apraxias, and agnosias

12
Neurologic Examination when Cortical Brain is
Lesioned

• Higher Cortical Function aphasia, apraxia,
  agnosia
• Cranial Nerves normal
• Cerebellar Function normal
• Motor weakness if you hit the motor homonculous
• Sensory sensory abnormalities if you hit the
  sensory homonculous
• Deep Tendon Reflexes hemi-hyper-reflexia
• Pathologic Reflexes possibly Babinskis reflex
  or frontal release signs

13
Divisions of the Neuraxis

• Cortical Brain
• Subcortical Brain
• Brainstem
• Cerebellum
• Spinal Cord
• Root
• Peripheral Nerve

• Neuromuscular Junction
• Muscle

14
Subcortical Brain

• Deep white radiating fibers produce equal
  involvement of face/arm/leg
• weakness
• sensory abnormalities
• Visual radiating fibers are interrupted
• deep parietal pie on the floor
• deep temporal pie in the sky

15
Neurologic Examination when Subcortical Brain is
Lesioned

• Higher Cortical Function normal
• Cranial Nerves visual field cuts
• Cerebellar Function usually normal
• Motor weakness in facearmleg, UMN
• Sensory sensory abnormalities in facearmleg
• Deep Tendon Reflexes hemi-hyper-reflexia
• Pathologic Reflexes Babinskis reflex and
  possibly frontal release signs

16
Divisions of the Neuraxis

• Cortical Brain
• Subcortical Brain
• Brainstem
• Cerebellum
• Spinal Cord
• Root
• Peripheral Nerve

• Neuromuscular Junction
• Muscle

17
Brainstem

• The Brainstem is basically spinal cord with
  embedded cranial nerves, producing the following
  abnormalities
• cranial nerve abnormalities
• classic spinal cord complaints
• bowel and bladder problems
• long tract signs (bilateral and crossed)
• corticospinal (pyramidal) motor
• spinothalamic pain/temp to the thalamus
• dorsal columns prioprioception/vibration to
  thal.

18
Neurologic Examination when Brainstem is Lesioned

• Higher Cortical Function normal
• Cranial Nerves
• III, IV, VI diplopia
• V decreased facial sensation
• VII drooping
• VIII deaf and dizzy
• IX, X, XII dysarthria and dysphagia
• XI decreased strength in neck and shoulders
• Cerebellar Function normal
• Motor hemi-paresis, UMN
• Sensory hemi-dysesthesias
• Deep Tendon Reflexes hemi-hyper-reflexia
• Pathologic Reflexes Babinskis reflex

19
Divisions of the Neuraxis

• Cortical Brain
• Subcortical Brain
• Brainstem
• Cerebellum
• Spinal Cord
• Root
• Peripheral Nerve

• Neuromuscular Junction
• Muscle

20
Cerebellar Function

• Some people believe that one can not test
  specifically for cerebellar abnormalities
• no one test on examination reliably evaluates the
  cerebellum
• H hypotonia
• A assynergy of (ant)agonist muscles
• N nystagmus
• D dysmetria, dysarthria
• S stance and gait
• T tremor

21
Neurologic Examination when the Cerebellum is
Lesioned

• Higher Cortical Function normal
• Cranial Nerves normal
• Cerebellar Function
• nystagmus
• staccato dysarthria (abnormality of prosody)
• Motor
• hemi-hypotonia
• intention gt positional tremor
• axial instability with dysmetria
• Sensory normal
• Deep Tendon Reflexes normal
• Pathologic Reflexes none

22
Divisions of the Neuraxis

• Cortical Brain
• Subcortical Brain
• Brainstem
• Cerebellum
• Spinal Cord
• Root
• Peripheral Nerve

• Neuromuscular Junction
• Muscle

23
Spinal Cord

• Sensory level (horizontal)
• Weakness below the lesion (paraparesis)
• UMN signs below the lesion
• Bowel and bladder incontinence

24
Neurologic Examination when the Spinal Cord is
Lesioned

• Higher Cortical Function normal
• Cranial Nerves normal
• Cerebellar Function normal
• Motor weakness below the lesion
• Sensory horizontal level
• Deep Tendon Reflexes hyper-reflexia below the
  lesion
• Pathologic Reflexes Babinskis reflex

25
Divisions of the Neuraxis

• Cortical Brain
• Subcortical Brain
• Brainstem
• Cerebellum
• Spinal Cord
• Root
• Peripheral Nerve

• Neuromuscular Junction
• Muscle

26
Root/Radiculopathy

• Pain is the hallmark of a radiculopathy
• Sensory abnormalities in a dermatome
• provocative maneuvres exacerbate the pain
• Weakness in a myotome (assymetric)
• LMN findings

27
Neurologic Examination when a Root is Lesioned

• Higher Cortical Function normal
• Cranial Nerves normal
• Cerebellar Function normal
• Motor assymetric weakness in a myotome
• Sensory pain and dysesthesia confined to a
  dermatome
• Deep Tendon Reflexes hypo- to a-reflexia if the
  root carries a reflex
• Pathologic Reflexes none

28
Divisions of the Neuraxis

• Cortical Brain
• Subcortical Brain
• Brainstem
• Cerebellum
• Spinal Cord
• Root
• Peripheral Nerve

• Neuromuscular Junction
• Muscle

29
Peripheral Nerve(presuming nonfocality)

• Weakness distal predominant
• Sensory Dysesthesias distal predominant

30
Neurologic Examination with Diffuse PN Lesioning

• Higher Cortical Function normal
• Cranial Nerves normal
• Cerebellar Function normal
• Motor weakness is distal predominant
• Sensory dysesthesias are distal predominant
• Deep Tendon Reflexes loss of distal reflexes
• Pathologic Reflexes mute responses to plantar
  stimulation

31
Divisions of the Neuraxis

• Cortical Brain
• Subcortical Brain
• Brainstem
• Cerebellum
• Spinal Cord
• Root
• Peripheral Nerve

• Neuromuscular Junction
• Muscle

32
Neuromuscular Junction

• Fatiguability is the hallmark
• Weakness proximal and symmetric
• exacerbated with use, recovers with rest
• often affects facial muscles (ptosis,
  dysconjugate gaze, slack jaw)
• Sensation preserved

33
Neurologic Examination in Disorders of the NMJ

• Higher Cortical Function normal
• Cranial Nerves fatiguabile ptosis, dysconjugate
  gaze, slack jaw
• Cerebellar Function normal
• Motor fatiguable proximal weakness in both UEs
  and LEs
• Sensory normal
• Deep Tendon Reflexes normal
• Pathologic Reflexes none

34
Divisions of the Neuraxis

• Cortical Brain
• Subcortical Brain
• Brainstem
• Cerebellum
• Spinal Cord
• Root
• Peripheral Nerve

• Neuromuscular Junction
• Muscle

35
Muscle

• Weakness of proximal arm and leg muscles
• symmetric
• Sensation is normal
• though patients complain of cramping and aching

36
Neurologic Examination in Disorders of Muscle

• Higher Cortical Function normal
• Cranial Nerves ptosis, dysconjugate gaze,
  dysphagia, dysphonia, (dysarthria)
• Cerebellar Function normal
• Motor proximal weakness in both UEs and LEs,
  atrophy and fasiculations, hypotonia
• Sensory normal
• Deep Tendon Reflexes preserved until late in the
  disease
• Pathologic Reflexes none

37
Scotts Lesion Localizes to

• Almost exclusively the Cerebellum, though to a
  minor degree the BS and PN are involved.
• Isolated heritable cerebellar dysfunction is
  rare, so we would expect to see other parts of
  the CNS involved.

38
SpinoCerebellar Ataxia (SCA4)

• Prior to Scotts diagnosis, his cousin was the
  proband for this entity.
• Scott has a 38-family member, 5 generation
  pedigree of this disorder
• His family entered into a study, and his family
  led to the classification of SCA4
• ataxia with axonal sensory neuropathy