Transcript The Spinothalamic System - Academy of Neurologic Physical Therapy

The Spinothalamic System
Learning Module
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Used with permission of the
Academy of Neurologic
Physical Therapy
of the APTA
Do not duplicate without
acknowledging Learning
Activity author
Michael McKeough, PT, EdD
Contents
Overview
Introduction
Learning Objectives
Instructions
Legend
Read these Instructions!
Review of the Lateral Spinothalamic Tract
Lesion lessons
Lateral spinothalamic tract lesion
Internal capsule lesion
Lateral medulla lesion
Patient Cases
Case 1
Case 2
Case 3
Case 4
Contents LSTT Lesions Patient Cases Exit
Overview
Introduction
Learning Objectives
Instructions
Legend
Contents LSTT Lesions Patient Cases Exit
Introduction
• This module reviews the Spinothalamic System.
• Module organization consists of three components. Review of the
lateral spinothalamic tract, lesion lessons (3 interactive lesions with
feedback), and patient cases (4 interactive cases with feedback).
• At the bottom of each screen a navigation bar contains options to
move throughout the module.
• Material is presented at both the behavioral level and the
neuroanatomical level.
• The behavioral level is presented first and depicts a patient’s clinical
presentation.
• The neuroanatomical level depicts the detailed anatomy of firstorder, second-order and third-order neurons.
• The neuroanatomical level accounts for the patient’s behavioral
presentation on examination under normal and lesioned conditions.
Contents LSTT Lesions Patient Cases Exit
Learning Objectives
After completing this module you should be able to:
1. describe, in detail, the structure and function of the
lateral spinothalamic system.
2. given a lesion, identify the signs and symptoms that
would be expected.
3. given a patient case (examination results and chief
complaint), identify the location of the lesion
causing the signs and symptoms .
4. correlate neurology information between the
behavioral and neuroanatomical levels.
Contents LSTT Lesions Patient Cases Exit
Instructions
• This module contains 3 interactive lesion lessons with animation.
• Lesson lessons begin with a question about the symptoms
produced by that particular lesion.
• Clicking the answer button will reveal the answer to the question.
• Clicking the explanation button will lead to both behavioral and
neuroanatomical explanations of the lesion.
• Each presentation is launched by clicking the animation button.
The same button serves to replay the animation if desired.
• Any of the lessons may be accessed by simply clicking on the
lesion title on the Contents page.
• Please refer to the Legend that defines the symbols used
throughout the module.
Contents LSTT Lesions Patient Cases Exit
Legend
Mechanism of injury
First-order neuron
Lesion
Second-order neuron
Pain stimulus
Sensory stimulus
Function intact
Function lost
Contents LSTT Lesions Patient Cases Exit
Third-order neuron
Sensory impairment
The Lateral Spinothalamic
Tract: Behavioral Description
Information about pain and
temperature from the body is
conveyed via several spinal
tracts collectively known as the
anterolateral system. The
lateral spinothalamic tract
(LSTT) is the most prominent
among these. The LSTT is a
crossed system. It originates
from nociceptors (free nerve
endings and chemo-receptors)
and projects to the opposite
(contralateral) cerebral
hemisphere via a three neuron
projection system.
Click to animate
Primary sensory cortex
Thalamus
Lateral spinothalamic
tract
Stimulus
Neuroanatomical Explanation
Contents LSTT Lesions Patient Cases Exit
First-order neuron
Second-order neuron
Third-order neuron
The Lateral Spinothalamic
Tract: Neuroanatomical
Description
First-order neurons
Cell body: dorsal root ganglion
(DRG)
Distal axon: innervates nociceptors
via peripheral nerves
Proximal axon: enter the spinal cord,
diverge 1-3 levels and terminate on
second-order neurons in the dorsal
horn
Second-order neurons
Cell body: dorsal horn
Axon: decussates at or about the
level of entry and projects to the
contralateral thalamus (ventral
posterior lateral nucleus, VPL) via
the lateral spinothalamic tract
Third-order neurons
Cell body: VPL of thalamus
Axon: ascends via the posterior limb
of the internal capsule and
terminates in the primary
somatosensory cortex
Behavioral Explanation
DRG
Click to animate
Contents LSTT Lesions Patient Cases Exit
Lateral spinothalamic tract
Lesion Lessons
Lateral spinothalamic tract lesion
Internal capsule lesion
Lateral medulla lesion
Contents LSTT Lesions Patient Cases Exit
Lesion of the right lateral
spinothalamic tract at T7 would
produce what impairment?
Click for answer
Absence of pain and temperature sensation on the
left side of the body generalized below T7.
Click for explanation
Contents LSTT Lesions Patient Cases Exit
Primary sensory cortex
Thalamus
Lesions of the lateral
spinothalamic tract on the
right : Behavioral
explanation
T7
Lateral spinothalamic
tract
Sensory impairment:
absence of pain and
temperature sensation on
the left side of the body,
below the lesion level.
Click to animate
Sensory impairment:
left body, below the
lesion level.
Stimulus
Neuroanatomical Explanation
Contents LSTT Lesions Patient Cases Exit
First-order neuron
Second-order neuron
Third-order neuron
Lesions of the
lateral spinothalamic
tract on the right:
Neuroanatomical
explanation
Because the lesion
involves second-order
neurons that have already
decussated, impairment is
contralateral to the
lesion. Interruption of the
right LSTT causes
absence of pain and
temperature sensation on
the left side of the body,
below the lesion level.
Click to animate
Behavioral Explanation
Contents LSTT Lesions Patient Cases Exit
Lesion of the right internal capsule
or primary somatosensory cortex
would produce what impairment?
Click for answer
Absence of pain and temp. sensation on the entire
left body, including the face.
Click for explanation
Contents LSTT Lesions Patient Cases Exit
Primary sensory cortex
Thalamus
Lesion of the internal
capsule or primary
somatosensory cortex
on the right: Behavioral
explanation
Sensory impairment:
absence of pain and
temperature sensation
on the entire left body,
including the face.
Click to animate
Neuroanatomical Explanation
Contents LSTT Lesions Patient Cases Exit
Lateral spinothalamic
tract
Sensory impairment:
the entire left side of
the body, including
the face.
Lesion
Lost function
Impairment
Lesion of the internal
capsule or primary
somatosensory cortex
on the right:
Neuroanatomical
explanation
Because the lesion involves
third-order neurons that
have decussated,
impairment is contralateral
to the lesion. Lesion of the
right internal capsule or
primary sensory cortex
causes absence of pain and
temperature sensation on
the entire left body,
including the face.
Behavioral Explanation
Click to animate
Contents LSTT Lesions Patient Cases Exit
Lesion of the right lateral medulla would
produce what impairment?
Click for answer
Absence of pain and temperature sensation on the
ipsilateral face and contralateral body.
Click for explanation
Contents LSTT Lesions Patient Cases Exit
Primary sensory cortex
Thalamus
Lesion of the lateral
medulla on the right
(Wallenberg syndrome):
Behavioral explanation
Sensory impairment:
absence of pain and
temp. sensation on the
ipsilateral face and
contralateral body.
Lateral spinothalamic
tract
Sensory impairment:
ipsilateral face and
contralateral body.
Click to animate
Neuroanatomical Explanation
Contents LSTT Lesions Patient Cases Exit
Lesion
Lost function
Impairment
Lateral Medullary (Wallenberg) Syndrome
Because the lesion
involves first-order
neurons in the
trigeminal system
before decussation,
facial impairment is
ipsilateral to the
lesion. Because the
lesion involves
second-order
neurons in the
LSTT after
decussation, body
impairment is
contralateral to the
lesion. The lesion
impairs the
sensation of pain
and temperature.
Click to animate
Behavioral Explanation
Contents LSTT Lesions Patient Cases Exit
Patient Cases
Read these instructions!
Patient Case 1
Patient Case 2
Patient Case 3
Patient Case 4
Contents LSTT Lesions Patient Cases Exit
Case Instructions
• These patient cases are intended to facilitate the integration and
clinical application of information about the spinothalamic tract
by coupling the findings on examination and patient interview
with their neuroanatomical correlates.
• Each case begins with the patient’s chief complaint and
significant examination findings. Then, the question is asked,
Damage to what system(s) is causing this patient’s problems?
Clicking the Answer button will reveal the answer and clicking
the Show lesion button will reveal the neuroanatomic lesion
along with the patient’s behavioral impairments.
• Cases are presented from two perspectives. What lesion would
account for a given set of examination results and patient
history? For a given lesion, what signs and symptoms would be
expected on examination?
• Click on a Case number to begin the exercise.
Contents LSTT Lesions Patient Cases Exit
Review Questions: Case 1
The 73 year old African-American woman complains of a sudden onset left
sided weakness, loss of balance, and left sided numbness. Her face is
asymmetric with drooping of the mouth and loss of the nasal-labial fold on the
left. Her left arm is flaccid with no voluntary movement. Her left leg is weak
and she requires assistance to stand. Deep tendon reflexes are hyperactive
on the left. Sensation of light touch and sharp/dull are absent in the left arm
and impaired in the left face and leg. Strength and sensation are WNL in the
right trunk, arm and leg.
Lesion of the right internal capsule or cerebral cortex.
Damage to what system(s) is causing this patient’s problems?
Answer
Corticospinal tracts are impaired on the right and intact on the left: her left arm is flaccid with no voluntary
movement. Her left leg is weak and she requires assistance to stand. Deep tendon reflexes are
hyperactive on the left. Strength is WNL in the right trunk, arm and leg.
Corticobulbar tract impaired on the right: her face is asymmetric with drooping of the mouth and loss of
the nasal-labial fold on the left.
Lateral spinothalamic tracts are impaired on the right and intact on the left. Sensation of light touch and
sharp/dull are absent in the left arm and impaired in the left face and leg. Sensation is WNL in the right
trunk, arm and leg.
Dorsal columns are impaired on the right and intact on the left: sensation of light touch is absent in the left
arm and impaired in the left face and leg. But intact on the right trunk, arm and leg.
Lesion type: stroke, distribution of signs and symptoms are hemi (left) body.
Lesion location: the right middle cerebral artery supplies the internal capsule and primary cortical areas
for the motor and sensory systems.
Contents LSTT Lesions Patient Cases Exit
Show lesion
Primary sensory cortex
Thalamus
Lesion of the internal
capsule or primary
somatosensory cortex
on the right: Behavioral
explanation
Sensory impairment:
absence of pain and
temperature sensation
on the entire left body,
including the face.
Click to animate
Neuroanatomical Explanation
Contents LSTT Lesions Patient Cases Exit
Lateral spinothalamic
tract
Sensory impairment:
the entire left side of
the body, including
the face.
Lesion
Lost function
Impairment
Lesion of the internal
capsule or primary
somatosensory cortex
on the right:
Neuroanatomical
explanation
Because the lesion involves
third-order neurons that
have decussated,
impairment is contralateral
to the lesion. Lesion of the
right internal capsule or
primary sensory cortex
causes absence of pain and
temperature sensation on
the entire left body,
including the face.
Behavioral Explanation
Click to animate
Contents LSTT Lesions Patient Cases Exit
Review Questions: Case 2
Following a gun shot wound to the abdomen, the patient complains of inability to
feel or move the right leg. Light touch, position, and vibration sensation are
intact in the left lower extremity but absent in the right below the L1 dermatome.
Strength is 5/5 for all motions at the hip, knee and ankle of the left lower
extremity, 0/5 for the right. Sharp/dull and temperature sensation are intact in
the right lower extremity but absent in the left below the L1 dermatome.
Damage to what system(s) is causing this patient’s problems?
Answer
Right hemicord lesion (Brown-Sequard Syndrome) at L1
Dorsal column (fasciculus gracilis) is intact on the left but absent on the right: light
touch, position, and vibration sensation are intact in the left lower extremity but
absent in the right below L1.
Lateral corticospinal tract is intact on the left but absent on the right : strength is 5/5
for all motions at the hip, knee and ankle of the left lower extremity, 0/5 for the right.
Lateral spinothalamic tract is intact on the left but absent on the right : sharp/ dull and
temperature sensation are intact in the right lower extremity but absent in the left
below L1.
Lesion level: L1
.
Contents LSTT Lesions Patient Cases Exit
Show lesion
Hemicord Lesion (Brown-Sequard Syndrome)
UMN
DRG
R
L
DRG
L1
Dorsal column lesion
Ipsilateral loss of light touch,
vibration, and position sense
Lateral corticospinal tract lesion
Ipsilateral upper motor neurons signs
Click to animate
Lateral spinothalamic tract lesion
Contralateral loss of pain and
temperature sense
Contents LSTT Lesions Patient Cases Exit
Hemicord lesion
Review Questions: Case 3
A 24 year-old cocaine addict has reported to the emergency room
complaining of headache, vertigo, nausea, and vomiting. Cerebral angiogram
reveals spontaneous dissection and hemorrhaging of the right posterior
inferior cerebellar artery.
What signs and symptoms would be expected from this lesion?
Answer
Lesion of the posterior inferior cerebellar artery (PICA) produces lateral medullary
(Wallenberg) syndrome. Common signs and symptoms include:
1. Ipsilateral facial hypalgasia (diminished sensation of pain) and thermoanaesthesia
(diminished sensation of temperature) (due to involvement of the trigeminal system).
2. Contralateral trunk and extremity hypalgasia and thermoanaesthesia (due to
involvement of the spinothalamic tract).
3. Dysarthria (hoarse speech) and dysphagia (difficulty swallowing) due to ipsilateral
palatal, pharyngeal and vocal cord paralysis (due to involvement of the nucleus
ambiguous).
4. Ipsilateral ptosis (eyelid drooping), miosis (excessive constriction of the pupil) and
anhidrosis (absence of sweating) Horner’s syndrome (due to sympathetic denervation).
5. Ipsilateral cerebellar signs, vertigo, nausea, and vomiting (due to involvement of the
cerebellum).
Contents LSTT Lesions Patient Cases Exit
Show lesion
Primary sensory cortex
Thalamus
Lesion of the lateral
medulla on the right
(Wallenberg syndrome):
Behavioral explanation
Lateral spinothalamic
tract
Sensory impairment:
absence of pain and
temp. sensation on the
ipsilateral face and
contralateral body.
Click to animate
Neuroanatomical Explanation
Contents LSTT Lesions Patient Cases Exit
Sensory impairment:
ipsilateral face and
contralateral body.
Lesion
Lost function
Impairment
Lateral Medullary (Wallenberg) Syndrome
Because the lesion
involves first-order
neurons in the
trigeminal system
before decussation,
facial impairment is
ipsilateral to the
lesion. Because the
lesion involves
second-order
neurons in the
LSTT after
decussation, body
impairment is
contralateral to the
lesion. The lesion
impairs the
sensation of pain
and temperature.
Behavioral Explanation
Click to animate
Contents LSTT Lesions Patient Cases Exit
Review Questions: Case 4
The patient complains of a progressive loss of the ability to sense hot or cold or
pain in both arms and hands. The condition started in the shoulders and
progressed down both arms. The sensation of pain and temperature in the trunk
and legs is intact. The sensation of light touch, position, and vibration is intact
throughout including the affected dermatomes. Strength is 5/5 throughout
including the affected dermatomes.
Damage to what system(s) is causing this patient’s problems?
Answer
The anterior gray and white commissures, in the cervical region of the spinal cord.
Lateral spinothalamic tracts are intact bilaterally: the sensation of pain and
temperature in the trunk and legs is intact, bilaterally.
Dorsal columns are intact bilaterally: the sensation of light touch, position, and
vibration is intact throughout including the affected dermatomes.
Lateral corticospinal tracts are intact bilaterally: strength is 5/5 throughout including
the affected dermatomes.
Lesion level: cervical region of the spinal cord
.
Contents LSTT Lesions Patient Cases Exit
Show lesion
Syringomyelia
Click to animate
DRG
R
L
DRG
Syrinx
Second-order neuron lesion
Loss of pain and temperature
sensation
Contents LSTT Lesions Patient Cases Exit
The End
D. Michael McKeough, PT, EdD
 2015