Lessons on Brainstem

LesionsDr. Dennis Bravo

CaseA 58 y/o was referred to you because of recent

onset of left hemiparesis, left-sided loss of propioception and right-sided tongue

deviation. What CNS structures are affected? Explain the symptoms with regards to

structures affected. Where is the lesion?

review of

Brainstem Structure

Brainstem Anatomy

MidbrainPons

Medulla

Brainstem Anatomy

MidbrainPons

Medulla

Rules of 4*

1. 4 structures in ‘midline’ and begin with ‘M’2. 4 motor nuclei in midline and are those that are divisors of 12 (3,4,6,12)3. 4 structures to the ‘side’ (lateral) and begin with ‘S’4. 4 CN in medulla, 4 in pons and 4 above pons

*Gates, P. The rule of 4 of the brainstem: a simplified method for understanding brainstem anatomy and brainstem vascular syndromes for the non-neurologist. Internal Medicine Journal 2005; 35: 263-266

4 Structures in midline and begin with ‘M’

4 Motor nuclei in midline and are divisors

of 12( 3, 4, 6, 12)

4 Structures to the side and begin with ‘S’

4 CN in medulla4 CN in pons

4 CN above pons

*Gates, P. The rule of 4 of the brainstem: a simplified method for understanding brainstem anatomy and brainstem vascular syndromes for the non-neurologist. Internal Medicine Journal 2005; 35: 263-266

231

4RULE of FOUR*

4 Structures in midline and begin with ‘M’

4 Motor nuclei in midline and are divisors

of 12( 3, 4, 6, 12)

4 Structures to the side and begin with ‘S’

4 CN in medulla4 CN in pons

4 CN above pons

*Gates, P. The rule of 4 of the brainstem: a simplified method for understanding brainstem anatomy and brainstem vascular syndromes for the non-neurologist. Internal Medicine Journal 2005; 35: 263-266

23 4

4 Structures in midline and begin with ‘M’

4 Motor nuclei in midline and are divisors

of 12( 3, 4, 6, 12)

4 Structures to the side and begin with ‘S’

4 CN in medulla4 CN in pons

4 CN above pons

*Gates, P. The rule of 4 of the brainstem: a simplified method for understanding brainstem anatomy and brainstem vascular syndromes for the non-neurologist. Internal Medicine Journal 2005; 35: 263-266

3 4

4 Structures in midline and begin with ‘M’

4 Motor nuclei in midline and are divisors

of 12( 3, 4, 6, 12)

4 Structures to the side and begin with ‘S’

4 CN in medulla4 CN in pons

4 CN above pons

*Gates, P. The rule of 4 of the brainstem: a simplified method for understanding brainstem anatomy and brainstem vascular syndromes for the non-neurologist. Internal Medicine Journal 2005; 35: 263-266

4

4 Structures in midline and begin with ‘M’

4 Motor nuclei in midline and are divisors

of 12( 3, 4, 6, 12)

4 Structures to the side and begin with ‘S’

4 CN in medulla4 CN in pons

4 CN above pons

*Gates, P. The rule of 4 of the brainstem: a simplified method for understanding brainstem anatomy and brainstem vascular syndromes for the non-neurologist. Internal Medicine Journal 2005; 35: 263-266

4 Medial Structures

•Motor pathway•Medial leminiscus•Medial longitudinal fasciculus•Motor nucleus and nerve

RULE #1

4 Medial Motor Nucleus

•CN divides number 12•CN 3, 4, 6, 12 are midline•3, 4, 6, 12 nucleus are midline•5, 7, 9, 11 lateral

RULE #2

4 Side Structures

•Spinocerebellar pathway•Spinothalamic pathway•Sensory nucleus of CN5•Sympathetic pathway

RULE #3

4 Medulla Cranial Nerves

•Glossopharyngeal (CN9)•Vagus (CN10)•Spinal accessory (CN11)•Hypoglossal (CN12)

RULE #4

4 Pons Cranial Nerves

•Trigeminal (CN5)•Abducent (CN6)•Facial (CN7)•Auditory (CN8)

RULE #4

4 Cranial Nerves Above Pons

•Olfactory (CN1)•Optic (CN2)•Occulomotor (CN3)•Trochlear (CN4)

RULE #4

Motor pathway(Corticospinal tract)

Medial lemniscus

Medial longditudinal fasciculus

Motor nucleus and nerve

Contalateral weakness

DEFICITMidline

Structu

res

More Info

Motor pathway(Corticospinal tract)

Medial lemniscus

Medial longditudinal fasciculus

Motor nucleus and nerve

Contalateral weakness

Contralateral propioception/ vibration loss

DEFICITMidline

Structu

res

More Info

Motor pathway(Corticospinal tract)

Medial lemniscus

Medial longditudinal fasciculus

Motor nucleus and nerve

Contalateral weakness

Contralateral propioception/ vibration

loss

Ipsilateral internuclear ophthalmoplegia

DEFICITMidline

Structu

res

More Info

Motor pathway(Corticospinal tract)

Medial lemniscus

Medial longditudinal fasciculus

Motor nucleus and nerve

Contalateral weakness

Contralateral propioception/ vibration

loss

Ipsilateral internuclear ophthalmoplegia

Ipsilateral CN function loss

DEFICITMidline

Structu

res

Spinocerebellar pathway

Spinothalamic

Sensory nucleus of CN5

Sympathetic pathway

Ipsilateral ataxia

DEFICITLateral

Structu

res

More Info

Spinocerebellar pathway

Spinothalamic

Sensory nucleus of CN5

Sympathetic pathway

Ipsilateral ataxia

Contralateral pain/temp sensory loss

DEFICITLateral

Structu

res

More Info

Spinocerebellar pathway

Spinothalamic

Sensory nucleus of CN5

Sympathetic pathway

Ipsilateral ataxia

Contralateral pain/temp sensory loss

Ipsilateral pain/ temp loss in face

DEFICITLateral

Structu

res

More Info

Spinocerebellar pathway

Spinothalamic

Sensory nucleus of CN5

Sympathetic pathway

Ipsilateral ataxia

Contralateral pain/temp sensory loss

Ipsilateral pain/ temp loss in face

Ipsilateral Horner’s syndrome

DEFICITLateral

Structu

res

More Info

Glossopharyngeal CN9

Vagus CN10

Spinal accessory CN11

Hypoglossal CN12

Ipsilateral pharyngeal sensory loss

DEFICIT4 CN

Medulla

Glossopharyngeal CN9

Vagus CN10

Spinal accessory CN11

Hypoglossal CN12

Ipsilateral pharyngeal sensory loss

Ipsilateral palatal weakness

DEFICIT4 CN

Medulla

More Info

Glossopharyngeal CN9

Vagus CN10

Spinal accessory CN11

Hypoglossal CN12

Ipsilateral pharyngeal sensory loss

Ipsilateral palatal weakness

Ipsilateral shoulder weakness

DEFICIT4 CN

Medulla

Glossopharyngeal CN9

Vagus CN10

Spinal accessory CN11

Hypoglossal CN12

Ipsilateral pharyngeal sensory loss

Ipsilateral palatal weakness

Ipsilateral shoulder weakness

Ipsilateral weakness of tongue

DEFICIT4 CN

Medulla

More Info

Trigeminal CN5

Abducent CN6

Facial CN7

Auditory CN8

Ipsilateral facial sensory loss

DEFICIT4 CN

Pons

More Info

Trigeminal CN5

Abducent CN6

Facial CN7

Auditory CN8

Ipsilateral facial sensory loss

Ipsilateral eye abduction weakness

DEFICIT4 CN

Pons

More Info

Trigeminal CN5

Abducent CN6

Facial CN7

Auditory CN8

Ipsilateral facial sensory loss

Ipsilateral eye abduction weakness

Ipsilateral facial weakness

DEFICIT4 CN

Pons

More Info

Trigeminal CN5

Abducent CN6

Facial CN7

Auditory CN8

Ipsilateral facial sensory loss

Ipsilateral eye abduction weakness

Ipsilateral facial weakness

Ipsilateral deafness

DEFICIT4 CN

Pons

Olfactory CN1

Optic CN2

Occulomotor CN3

Trochlear CN4

Not in midbrain

Not in midbrain

Eye turned out and down

DEFICIT4 CN

Above Pons

More Info

Olfactory CN1

Optic CN2

Occulomotor CN3

Trochlear CN4

Not in midbrain

Not in midbrain

Eye turned out and down

Eye unable to look down when looking towards nose

DEFICIT4 CN

Above Pons

More Info

Let’s put your knowledge to use...

“Pathways and tracts pass through the entire length of the brainstem and can be likened to ‘meridians of longitude‘ whereas the various cranial nerves can be regarded as ‘parallels of latitude‘. If you establish where the meridians of longitude and parallels of latitude intersect then you have established the site of the lesion.”

Always remember

Gates, P. The rule of 4 of the brainstem: a simplified method for understanding brainstem anatomy and brainstem vascular syndromes for the non-neurologist. Internal Medicine Journal 2005; 35: 263-266

58 year old woman•Left hemiparesis•Left-sided loss of propioception•Right-sided tongue deviation

Case

58 year old woman•Left hemiparesis•Left-sided loss of propioception•Right-sided tongue deviation

•Motor (CS tract, R)

•Medial lemniscus, R•CN12, R

Case Structure

•Motor (CS tract, R)

•Medial lemniscus, R•CN12, R

Structure

•Medial•Medial

•Medulla

•Motor (CS tract, R)

•Medial lemniscus, R•CN12, R

Location Structure

•Medial•Medial

•Medulla

•Motor (CS tract, R)

•Medial lemniscus, R•CN12, R

Location

Medial medullary syndrome (R)

Vertebral artery, medullary branch (R)

Structure

58 year old woman•Left-sided meiosis, anhydrosis, ptosis•Left-sided ataxia•Uvula deviated to right

Case

58 year old woman•Left-sided meiosis, anhydrosis, ptosis•Left-sided ataxia•Uvula deviated to right

•Sympathetic tract, Left

•Spinocerebellar•CN10, Left

Case Structure

•Sympathetic tract, Left

•Spinocerebellar•CN10, Left

Structure

•Side, Left

•Side, Left•Medulla

•Sympathetic tract, Left

•Spinocerebellar•CN10, Left

Location Structure

•Side, Left

•Side, Left•Medulla

•Sympathetic tract, Left

•Spinocerebellar•CN10, Left

Lateral medullary syndrome (L)

Posterior inferior cerebellar artery (L)

Location Structure

Assignment

In lateral medullary syndrome (Wallenberg syndrome), there are associated analgesia and thermoanalgesia of the ipsilateral face. Why? What brainstem structure is affected?

10 y/o girl with the ff symptoms

Case

Left-sided weakness

Right eye deviates medially

Righ-sided facial weakness

Structure

10 y/o girl with the ff symptoms

Case

Left-sided weakness

Right eye deviates medially

Righ-sided facial weakness

Motor (CS tract, R)

Structure

10 y/o girl with the ff symptoms

Case

Left-sided weakness

Right eye deviates medially

Righ-sided facial weakness

Motor (CS tract, R)

LR weakness, CN6 Right

Structure

10 y/o girl with the ff symptoms

Case

Left-sided weakness

Right eye deviates medially

Righ-sided facial weakness

Motor (CS tract, R)

LR weakness, CN6 Right

CN7, Right

Structure

Location

Motor (CS tract, R)

LR weakness, CN6 Right

CN7, Right

Structure

Location

Medial structure Motor (CS tract, R)

LR weakness, CN6 Right

CN7, Right

Structure

Location

Medial structure

Pons

Motor (CS tract, R)

LR weakness, CN6 Right

CN7, Right

Structure

Location

Medial structure

Pons

Pons

Motor (CS tract, R)

LR weakness, CN6 Right

CN7, Right

Structure

Location

Medial structure

Pons

Pons

Motor (CS tract, R)

LR weakness, CN6 Right

CN7, Right

Medial Pons Pons tumor

Structure

Location

Medial structure

Pons

Pons

Motor (CS tract, R)

LR weakness, CN6 Right

CN7, Right

Medial Pons Pons tumorMillard-Gubler Syndrome

Structure

Assignment

What is astrocytoma?Where is it usually located?Who are most often affected?

70 y/o male hypertensive suddenly developed

Case

Left-sided ipsilateral ophthalmoplegia

Loss of pupilary light reflex, left eye

Paralysis of right arm and leg

Structure

70 y/o male hypertensive suddenly developed

Case

Left-sided ipsilateral ophthalmoplegia

Loss of pupilary light reflex, left eye

Paralysis of right arm and leg

CN3, Left

Structure

70 y/o male hypertensive suddenly developed

Case

Left-sided ipsilateral ophthalmoplegia

Loss of pupilary light reflex, left eye

Paralysis of right arm and leg

CN3, Left

CN3, Left

Structure

70 y/o male hypertensive suddenly developed

Case

Left-sided ipsilateral ophthalmoplegia

Loss of pupilary light reflex, left eye

Paralysis of right arm and leg

CN3, Left

Motor, CS tract, Left

CN3, Left

Structure

Location

CN3, Left

Motor, CS tract, Left

CN3, Left

Structure

Location

Midbrain CN3, Left

Motor, CS tract, Left

CN3, Left

Structure

Location

Midbrain

Midbrain

CN3, Left

Motor, CS tract, Left

CN3, Left

Structure

Location

Midbrain

Midbrain

Medial, Left

CN3, Left

Motor, CS tract, Left

CN3, Left

Structure

Location

Midbrain

Midbrain

Medial, Left

CN3, Left

Motor, CS tract, Left

CN3, Left

Medial Midbrain Weber’s Syndrome

Structure

70 y/o male hypertensive suddenly developed

Case

Left-sided ipsilateral ophthalmoplegia

Right-sided propioception loss

Involuntary movement

Structure

70 y/o male hypertensive suddenly developed

Case

Left-sided ipsilateral ophthalmoplegia

Right-sided propioception loss

Involuntary movement

CN3, Left

Structure

70 y/o male hypertensive suddenly developed

Case

Left-sided ipsilateral ophthalmoplegia

Right-sided propioception loss

Involuntary movement

CN3, Left

Medial Lemniscus, Left

Structure

70 y/o male hypertensive suddenly developed

Case

Left-sided ipsilateral ophthalmoplegia

Right-sided propioception loss

Involuntary movement

CN3, Left

Medial Lemniscus, Left

Red nucleus, Left

Structure

CN3, Left

Medial Lemniscus, Left

Red nucleus, Left

StructureLocation

Midbrain, Left CN3, Left

Medial Lemniscus, Left

Red nucleus, Left

StructureLocation

Midbrain, Left

Medial, Left

CN3, Left

Medial Lemniscus, Left

Red nucleus, Left

StructureLocation

Midbrain, Left

Medial, Left

Medial, Left

CN3, Left

Medial Lemniscus, Left

Red nucleus, Left

StructureLocation

Midbrain, Left

Medial, Left

Medial, Left

CN3, Left

Medial Lemniscus, Left

Red nucleus, Left

Medial Midbrain Benedikt’s Syndrome

StructureLocation

Weber’s Syndrome Benedikt’s Syndrome

CN3

Medial Lemniscus

Red nucleus

CN3

Motor, CS tract

Corticobulbar tract

Medial midbrain Medial midbrain

Benedikt’sWeber’s

Parinaud’s syndrome•Posterior midbrain•Superior colliculi•Center for upward gaze•Inability to look up (Doll’s eye)•Argylle-Robertson pupil

Any questions?The End

Brain stem

90%10%

RETURN

Brain stem

90%10%

LESION

RETURN

Brain stem

90%10%

LESION

Contralateral paralysis

RETURN

Return

LESION

Return

LESION

Contralateral sensory loss

Return

Return

Return

Return

Return

LESION

Return

LESION

Ipsilateral ataxia

Brain Stem

Pain &

temperature

LESION

Contralateral sensory loss

Return

Return

LESION

Return

LESION

Ipsilateral facial sensory loss

Return

MeiosisPtosis

Anhydrosis

Horner’s Syndrome

Return

Deviated to the right

Return

Levator uvalaeVagusVagus

Return

Deviated to the right

Levator uvalaeVagusVagus

Lesion

Return

Deviated to the right

Levator uvalaeVagusVagus

Lesion

Uvula deviates OPPOSITEthe lesion

Return

Deviated to the LEFT

Tongue deviates

OPPOSITE the lesion

Return

Return

Return

Facial weakness

Return

Return

Cranial Nerve 3•EOM except lateral rectus & superior oblique•Down and out•Ptosis•Absent pupillary light reflex

Return