This document discusses various syndromes that can result from strokes in different areas of the brainstem. It begins with an overview of brainstem anatomy and blood supply. It then describes in detail the clinical presentations of medial and lateral midbrain syndromes, various pontine syndromes including medial and lateral inferior pontine syndromes, and medial and lateral medullary syndromes. Case examples are provided to illustrate the different neurological deficits that can occur based on the location of the brainstem stroke.

1. BRAINSTEM STROKE
SYNDROMES

2. Discussion will contain
• Basic neuro-anatomy of the brainstem from a
clinician’s perspective
• Details of the blood supply of the brainstem
• Various syndromes caused by stroke involving the
brainstem vessels
• RULE OF FOUR = a very simple way to
remember various brainstem lesions.
• Clinical case examples

3. Brainstem
Located between the cerebrum
and the spinal cord Midbrain
Provides a pathway for tracts running
between higher and lower neural centers.
Pons
Consists of the midbrain, pons,
and medulla oblongata.
Medulla
obongata

4. Ventral surface of brain stem
Midbrain
Pons
Medulla
oblongata

5. Ventral – Lateral View
Midbrain
Cerebral
peduncles
Pons
Basis pontis
Medulla

7. Posterior circulation
Vertebral artery branches
Posterior inferior cerebellar Medulla, lower cerebellum
Basilar artery branches
Anterior inferior cerebellar Lower and middle pons, anterior
cerebellum
Superior cerebellar Upper pons, lower midbrain, upper
cerebellum
Posterior cerebral Medial occipital and temporal
cortex and subjacent white matter,
posterior corpus callosum, upper
midbrain
Thalamoperforate branches Thalamus
Thalamogeniculate branches Thalamus

8. • Brain stem arteries - anterior view
1. Posterior cerebral artery
2. Superior cerebellar artery
3. Pontine branches of the basilar artery
4. Anterior inferior cerebellar artery
5. Internal auditory artery
6. Vertebral artery
7. Posterior inferior cerebellar a.
8. Anterior spinal artery
• 9. Basilar artery
8

12. MID-BRAIN STOKE SYNDROMES

13. Midbrain

14. Midbrain
Crus cerebri
Shortest brain stem,not more than
2cm in length,lies in the posterior cranial
Fossa.
For descriptive purpose,divided into
Dorsal tectum and right and left cerebral
Peduncles.
Each cerebral peduncles divide further
into ventral crus cerebri and a dorsal
Tegmentum by a pigmented lamina
“ Substantia nigra”
Cerebral peduncles contains:
-Descending fibers that go to the
cerebellum via the pons
-Descending pyramidal tracts
Running through the midbrain is the
hollow cerebral aqueduct which
connects the 3rd and 4th ventricles of the
brain.

15. Cerebral aqueduct
Substantia nigra Basis pedunculi
Crus cerebri
(cerebral peduncle)

16. Ventral – Dorsal Organization
Tectum
Basis Tegmentum

17. Superior
colliculi
The roof of the aqueduct ( the tectum)
Inferior
contains the corpora quadrigemina
2 superior colliculi that control reflex colliculi
movements of the eyes, head and
neck in response to visual stimuli
2 inferior colliculi that control reflex
movements of the head, neck, and
trunk in response to auditory stimuli
Corpora quadregemina
Superior and inferior colliculi
seperated by cruciform sulcus
Superior colliculi larger and darker
than inferior colliculi,the difference
In colour due to superficial neurons in
Superior colliculi

18. Internal structure
Transverse section of midbrain
Common to both at inferior and superior colliculus:
Crus cerebri (or basis pedunculi):
- Consists of fibres descending from cerebral cortex.
- Its medial one-sixth is occupied by coticopontine
fibres from frontal lobe,lateral one-sixth fibres
from temporal,occipital and parietal lobes,the
intermediate two third by corticospinal and cortico-
nuclear fibres.
Substantia nigra :
- Present immediately behind and medial to basis
pedunculi.
- It appears dark as neuron within it contain pigment.
( neuromelanin )

19. Medial midbrain syndrome (paramedian
branches of upper basilar and proximal posterior cerebral arteries)
• ON SIDE OF LESION
Eye "down and out"
secondary to unopposed
action of fourth and sixth
cranial nerves, with
dilated and unresponsive
pupil: Third nerve fibers
ON OPPOSITE SIDE
• Paralysis of face, arm, and
leg: Corticobulbar and
corticospinal tract
descending in crus cerebri

21. Lateral midbrain syndrome (syndrome of small
penetrating arteries arising from posterior cerebral artery)
On side of lesion
• Eye "down and out"
secondary to unopposed
action of fourth and sixth
cranial nerves, with
dilated and unresponsive
pupil: Third nerve fibers
and/or third nerve
nucleus
On side opposite lesion
• Hemiataxia,
hyperkinesias, tremor:
Red nucleus,
dentatorubrothalamic
pathway

22. Mid brain syndromes

23. Medial midbrain syndrome (paramedian
branches of upper basilar and proximal posterior cerebral arteries)
• ON SIDE OF LESION
Eye "down and out"
secondary to unopposed
action of fourth and sixth
cranial nerves, with
dilated and unresponsive
pupil: Third nerve fibers
ON OPPOSITE SIDE
• Paralysis of face, arm, and
leg: Corticobulbar and
corticospinal tract
descending in crus cerebri

24. Pontine syndromes

25. Pons

26. Pons
The pons shows a convex anterior surface
with prominent transversely running fibres.
These fibres collect to form bundles,the
middle cerebellar peduncles.
Pons
The anterior surface of pons is marked in the
midline by a shallow groove,the sulcus
basilaris which lodges the basilar artery.
s
Sulcus basilaris

27. Subdivided into ventral and dorsal part
Ventral part of the pons contains
Pontine nuclei:
•Recieves corticopontine fibres from frontal,
temporal,parietal and occipital lobes of
cerebrum
•The efferent fibres form the transverse fibres
of pons.
Pontine nuclei
Vertically running corticospinal and
corticopontine fibres.
Transversely running fibres arising in
pontine nuclei

28. Dorsal part of pons Midpons
The dorsal part of the pons may be regarded as
continuation of the part of the medulla behind the
pyramids.
Superiorly continous with the tegmentum of the
midbrain.
DORSAL PART
Occupied predominately by reticular formation
Posterior surface help to form floor of fourth
ventricle
The dorsal part is bounded laterally by inferior
cerebellar peduncle in the lower part of the pons
and superior cerebellar peduncle in upper part.
Upper pons

29. Medial inferior pontine syndrome
(occlusion of paramedian branch of basilar artery)
On side of lesion
• Paralysis of conjugate gaze to
side of lesion (preservation of
convergence): Center for
conjugate lateral gaze(PPRF)
• Nystagmus: Vestibular nucleus
• Ataxia of limbs and gait: Likely
middle cerebellar peduncle
• Diplopia on lateral gaze:
Abducens nerve
On side opposite lesion
• Paralysis of face, arm, and leg:
Corticobulbar and corticospinal
tract in lower pons
• Impaired tactile and
proprioceptive sense over one-
half of the body: Medial
lemniscus

30. Lateral inferior pontine syndrome
(occlusion of anterior inferior cerebellar artery)
• On side of lesion
• Horizontal and vertical nystagmus, vertigo,
nausea, vomiting, oscillopsia: Vestibular
nerve or nucleus
• Facial paralysis: Seventh nerve
• Paralysis of conjugate gaze to side of
lesion: Center for conjugate lateral gaze
• Deafness, tinnitus: Auditory nerve or
cochlear nucleus
• Ataxia: Middle cerebellar peduncle and
cerebellar hemisphere
• Impaired sensation over face: Descending
tract and nucleus fifth nerve
• On side opposite lesion
• Impaired pain and thermal sense over
one-half the body (may include face):
Spinothalamic tract

31. Medial midpontine syndrome
(paramedian branch of midbasilar artery)
• On side of lesion
• Ataxia of limbs and gait
(more prominent in bilateral
involvement): Pontine nuclei
• On side opposite lesion
• Paralysis of face, arm, and
leg: Corticobulbar and
corticospinal tract
• Variable impaired touch and
proprioception when lesion
extends posteriorly: Medial
lemniscus

32. Lateral midpontine syndrome
(short circumferential artery)
On side of lesion
• Ataxia of limbs: Middle
cerebellar peduncle
• Paralysis of muscles of
mastication: Motor fibers or
nucleus of fifth nerve
• Impaired sensation over
side of face: Sensory fibers
or nucleus of fifth nerve
On side opposite lesion
• Impaired pain and thermal
sense on limbs and trunk:
Spinothalamic tract

33. Medial superior pontine syndrome
(paramedian branches of upper basilar artery)
On side of lesion
• Cerebellar ataxia (probably):
Superior and/or middle
cerebellar peduncle
• Internuclear ophthalmoplegia:
Medial longitudinal fasciculus
• Myoclonic syndrome, of palate,
pharynx, vocal cords,
respiratory apparatus, face,
oculomotor apparatus, etc.: —
central tegmental bundle.
On side opposite lesion
• Paralysis of face, arm, and leg:
Corticobulbar and corticospinal
tract
• Rarely touch, vibration, and
position are affected(arm>leg):
Medial lemniscus

35. Rt internuclear ophthalmoplegia

36. One and a half syndrome
RT LT

37. Lateral superior pontine syndrome
(syndrome of superior cerebellar artery)
On side of lesion
• Ataxia of limbs and gait, falling to side of
lesion: Middle and superior cerebellar
peduncles, superior surface of
cerebellum, dentate nucleus
• Dizziness, nausea, vomiting; horizontal
nystagmus: Vestibular nucleus
• Paresis of conjugate gaze (ipsilateral):
Pontine contralateral gaze
• Miosis, ptosis, decreased sweating over
face (Horner's syndrome): Descending
sympathetic fibers
On side opposite lesion
• Impaired pain and thermal sense on
face, limbs, and trunk: Spinothalamic
tract
• Impaired touch, vibration, and position
sense, more in leg than arm : Medial
lemniscus (lateral portion)

38. MEDULLA
OBLONGATA

39. External structure of medulla
Most inferior region of the brain stem.
Becomes the spinal cord at the level of
the foramen magnum.
Medulla is broad above ,joins with pons
narrow below, continous with spinal cord
Length is about 3cm, width is about 2cm
at its upper end
Surfaces shows series of fissures
Anterior median fissure Medulla oblongata
Posterior median fissure

40. External surface of medulla
Ventral surface of medulla oblongata contains
Pyramid
•elevation between anterior median
and anterolateral sulcus
•Formed due to decussation of corticospinal
fibres. Olive
•Oval swelling between anterolateral
posterolateral sulcus,half an inch
long
•Produced by large mass of gray
matter called inferior olivary
nucleus
Olive
Pyramid

41. Pyramid
Olive
Anterolateral fissure
Anterior median fissure

42. Medial medullary syndrome
(occlusion of vertebral artery or of branch of vertebral or lower basilar artery)
On side of lesion
• Paralysis with atrophy of
one-half half the tongue:
Ipsilateral twelfth nerve
On side opposite lesion
• Paralysis of arm and leg,
sparing face; impaired
tactile and proprioceptive
sense over one-half the
body: Contralateral
pyramidal tract and
medial lemniscus

43. Lateral medullary syndrome
(occlusion of any of five vessels may be responsible—vertebral, posterior inferior
cerebellar, superior, middle, or inferior lateral medullary arteries)
On side of lesion
• Pain, numbness, impaired sensation over one-
half the face: Descending tract and nucleus fifth
nerve
• Ataxia of limbs, falling to side of lesion:
Uncertain—restiform body, cerebellar
hemisphere, cerebellar fibers, spinocerebellar
tract (?)
• Nystagmus, diplopia, oscillopsia, vertigo,
nausea, vomiting: Vestibular nucleus
• Horner's syndrome (miosis, ptosis, decreased
sweating): Descending sympathetic tract
• Dysphagia, hoarseness, paralysis of palate,
paralysis of vocal cord, diminished gag reflex:
Issuing fibers ninth and tenth nerves
• Loss of taste: Nucleus and tractus solitarius
• Numbness of ipsilateral arm, trunk, or leg:
Cuneate and gracile nuclei
• Weakness of lower face: Genuflected upper
motor neuron fibers to ipsilateral facial nucleus
On side opposite lesion
• Impaired pain and thermal sense over half the
body, sometimes face: Spinothalamic tract