where’s the lesion? neuroscience core lecture series 23 october 2002 david roman renner, md...
TRANSCRIPT
Where’s the Lesion?
Neuroscience Core Lecture Series23 October 2002
David Roman Renner, MDDepartment of Neurology
Scott’s CC:
“My balance is off.” Multiple ER visits for fall-related trauma
“I’m losing the fine control of my fingers.” Loss of manual dexterity
“I’ve had pneumonia three times.” Dysphagia to liquids>solids
All of Scott’s Complaints Sounded Neurologic in Origin
His lesion should lie somewhere in the
neuraxis.
Divisions of the Neuraxis
Cortical BrainSubcortical
BrainBrainstemCerebellumSpinal CordRootPeripheral
Nerve
Neuromuscular Junction
Muscle
Off the Top of my Head . . .
Imbalance = Cerebellum
Pneumonia = Brainstem (related dysphagia)
Loss of Dexterity = Peripheral Nerve
Neurologic Examination
Higher Cortical FunctionCranial NervesCerebellar Function MotorSensoryDeep Tendon ReflexesPathologic Reflexes
The Neuro Exam Should Evaluate the Entire Neuraxis
Higher Cortical Function: cortexCranial Nerves: subcortex, brainstemCerebellar Function: cerebellumMotor: motor homonculous, subcortical
pyramidal tracts, BS, cord, radicle, PN, muscleSensory: ascending tracts, thalamus,
subcortical tracts, sensory hononculousDeep Tendon Reflexes: afferent PN, radicle,
cord, efferent PN, musclePathologic Reflexes:
Scott’s Exam Showed:
Higher Cortical Function: normalCranial Nerves: oropharyngeal dysarthriaCerebellar Function: hypotonia, assynergy,
dysmetria, staccato dysarthria, intention tremor, appendicular ataxia
Motor: hypotonia, normal strengthSensory: decreased vibration and temperatureDeep Tendon Reflexes: areflexiaPathologic Reflexes: plantar flexing
Divisions of the Neuraxis
Cortical BrainSubcortical
BrainBrainstemCerebellumSpinal CordRootPeripheral
Nerve
Neuromuscular Junction
Muscle
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
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 Babinski’s reflex or
frontal release signs
Divisions of the Neuraxis
Cortical BrainSubcortical
BrainBrainstemCerebellumSpinal CordRootPeripheral
Nerve
Neuromuscular Junction
Muscle
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
Neurologic Examination when Subcortical Brain is
Lesioned
Higher Cortical Function: normal Cranial Nerves: visual field cuts Cerebellar Function: usually normal Motor: weakness in face=arm=leg, UMN Sensory: sensory abnormalities in face=arm=leg Deep Tendon Reflexes: hemi-hyper-reflexia Pathologic Reflexes: Babinski’s reflex and
possibly frontal release signs
Divisions of the Neuraxis
Cortical BrainSubcortical
BrainBrainstemCerebellumSpinal CordRootPeripheral
Nerve
Neuromuscular Junction
Muscle
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): motorspinothalamic: pain/temp to the thalamusdorsal columns: prioprioception/vibration to
thal.
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: Babinski’s reflex
Divisions of the Neuraxis
Cortical BrainSubcortical
BrainBrainstemCerebellumSpinal CordRootPeripheral
Nerve
Neuromuscular Junction
Muscle
Cerebellar Function
Some people believe that one can not test specifically for cerebellar abnormalities no one test on examination reliably evaluates the cerebellum
H: hypotoniaA: assynergy of (ant)agonist musclesN: nystagmusD: dysmetria, dysarthriaS: stance and gaitT: tremor
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 > positional tremor axial instability with dysmetria
Sensory: normal Deep Tendon Reflexes: normal Pathologic Reflexes: none
Divisions of the Neuraxis
Cortical BrainSubcortical
BrainBrainstemCerebellumSpinal CordRootPeripheral
Nerve
Neuromuscular Junction
Muscle
Spinal Cord
Sensory level (horizontal)Weakness below the lesion
(paraparesis)UMN signs below the lesion Bowel and bladder incontinence
Neurologic Examination when the Spinal Cord is
Lesioned
Higher Cortical Function: normalCranial Nerves: normalCerebellar Function: normalMotor: weakness below the lesionSensory: horizontal levelDeep Tendon Reflexes: hyper-reflexia
below the lesionPathologic Reflexes: Babinski’s reflex
Divisions of the Neuraxis
Cortical BrainSubcortical
BrainBrainstemCerebellumSpinal CordRootPeripheral
Nerve
Neuromuscular Junction
Muscle
Root/Radiculopathy
Pain is the hallmark of a radiculopathySensory abnormalities in a dermatome
provocative maneuvres exacerbate the pain
Weakness in a myotome (assymetric)LMN findings
Neurologic Examination when a Root is Lesioned
Higher Cortical Function: normalCranial Nerves: normalCerebellar Function: normalMotor: assymetric weakness in a
myotomeSensory: pain and dysesthesia confined to
a dermatomeDeep Tendon Reflexes: hypo- to a-reflexia
if the root carries a reflexPathologic Reflexes: none
Divisions of the Neuraxis
Cortical BrainSubcortical
BrainBrainstemCerebellumSpinal CordRootPeripheral
Nerve
Neuromuscular Junction
Muscle
Peripheral Nerve(presuming nonfocality)
Weakness: distal predominantSensory Dysesthesias: distal
predominant
Neurologic Examination with Diffuse PN Lesioning
Higher Cortical Function: normalCranial Nerves: normalCerebellar Function: normalMotor: weakness is distal predominant Sensory: dysesthesias are distal
predominantDeep Tendon Reflexes: loss of distal
reflexesPathologic Reflexes: mute responses to
plantar stimulation
Divisions of the Neuraxis
Cortical BrainSubcortical
BrainBrainstemCerebellumSpinal CordRootPeripheral
Nerve
Neuromuscular Junction
Muscle
Neuromuscular Junction
Fatiguability is the hallmarkWeakness: proximal and symmetric
exacerbated with use, recovers with rest
often affects facial muscles (ptosis, dysconjugate gaze, slack jaw)
Sensation: preserved
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 UE’s
and LE’s Sensory: normal Deep Tendon Reflexes: normal Pathologic Reflexes: none
Divisions of the Neuraxis
Cortical BrainSubcortical
BrainBrainstemCerebellumSpinal CordRootPeripheral
Nerve
Neuromuscular Junction
Muscle
Muscle
Weakness of proximal arm and leg muscles symmetric
Sensation is normal though patients complain of cramping
and aching
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 UE’s and LE’s,
atrophy and fasiculations, hypotonia Sensory: normal Deep Tendon Reflexes: preserved until late in the
disease Pathologic Reflexes: none
Scott’s 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.