This document provides information about the brainstem, including its parts (midbrain, pons, and medulla), functions, internal structures, blood supply, and various clinical case scenarios involving lesions or syndromes associated with the brainstem. It describes key features of the midbrain, pons, and medulla such as their locations, surfaces, and structures. It also summarizes several important brainstem syndromes and lesions, outlining the sites and clinical signs involved. Diagrams are included to illustrate anatomical structures and lesions.

1. BRAINSTEM
Presented by: Dr. Md. Nazmus sadat
Resident (Phase-B)Neurology
Mymensingh Medical College
Hospital,
Bangladesh.

2. BRAINSTEM
PARTS:
1.Midbrain
2.Pons
3.Medulla.
FUNCTION:
1.Serves as a conduit for the ascending & descending tracts connecting
the spinal cord to higher centres in the forebrain.
2.Contains important reflex centres associated with the control of
respiration,cardiovascular system & consciousness.
3.Contains important cranial nerve nuclei from 3rd to 12th .

3. MIDBRAIN
• Connects the pons and cerebellum with the forebrain.
• Traversed by a narrow channel ,the cerebral aqueduct which connects
the 3rd and 4th ventricle.
• Four colliculi (corpura quadrigemina) are present on the posterior
surface- 2 superior & 2 inferior.
• Two cranial nerves emerges from midbrain- 3rd and 4th cranial nerve.

4. INTERNAL STRUCTURES OF MIDBRAIN
• 1.Cerebral peduncle:
a.Crus cerebri
b.Tegmentum
• 2. Tectum

6. TRANSVERSE SECTION OF MIDBRAIN AT THE LEVEL OF
SUPERIOR COLLICULUS

7. TRANSVERSE SECTION OF MIDBRAIN AT THE LEVEL OF
INFERIOR COLLICULUS

9. PONS
• Anterior to cerebellum & connects medulla oblongata to midbrain.
• Two surfaces:
1.Anterior: a.Convex from side to side.
b.Basilar grove lodges basilar artery.
c.Trigeminal nerve emerges from anterolateral surface.
d. Abducens,Facial & Vestibulocochlear nerve arises from
pontomedullary junction from medial to lateral.
2.Posterior:Forms the upper half of the floor of the 4th ventricle.

12. INTERNAL STRUCTURE OF PONS
• Two parts: 1. Tegmentum
2.Basal part
• Two important transverse section:
1.Through caudal part at the level of facial colliculus.
2.Through cranial part at the level of trigeminal nuclei.

16. MEDULLA OBLONGATA
• Connects the pons superiorly with the spinal cord inferiorly.
• Four lower cranial nerves emerges from medulla.
• Connects with cerebellum through inferior cerebellar peduncle.
• Posterior surface forms the lower half of floor of 4th ventricle

18. TRANSVERSE SECTION OF MEDULLA AT THE LEVEL OF
DECUSSATION OF PYRAMID

19. TRANSVERSE SECTION OF MEDULLA AT THE LEVEL OF
DECUSSATION OF THE MEDIAL LEMINISCI

21. BLOOD SUPPLY OF
BRAINSTEM

25. CASE SCENERIO-01
• Mr. Ibrahim mollah 50 years old person ,non-
diabetic,normotensive,smoker admitted to hospital with the
complaints of sudden onset dysphagia,dysarthria with nasal voice and
gait ataxia.On examination patient was conscious,well
oriented,speech is dysarthric with nasal voice.Patient also had right
sided Horner’s syndrome,loss of pain and temperature sensation on
right side of face,9th & 10th cranial nerve palsy on right side with
presence of cerebellar signs on the same side.There was also loss of
pain & temperature sensation on left side of the body.All deep
tendon reflexes and planter reflexes were normal.Vitals are within
normal limit.

27. WALLENBERG’S SYNDROME
Site of the lesion: Lateral part of medulla
Vessel involved: Posterior inferior cerebellar artery/vertebral artery/
superior ,middle or inferior lateral medullary artery.
Clinical features:
Contralateral-Impaired pain and thermal sensation over half of the
body(spinothalamic tract)

28. Ipsilateral:
1.Impaired sensation over half of face- descending tract and nucleus
of trigeminal nerve.
2.Ataxia-spinocerebellar tract
3.Dysphagia,hoarseness,paralysis of palate,paralysis of vocal
cord,diminished gag reflex- fibres of 9th and 10th nerve.
4.Horner’s syndrome-descending sympathetic tract.

29. Medial medullary syndrome
• Vessel involved: Vertebral artery or branch of vertebral artery or
anterior spinal artery.
• Features:
On the side of the lesion: Paralysis & atrophy of tongue due to
ipsilateral 12th nerve involvement
Opposite to the lesion: paralysis of arm and leg sparing face-
contralateral pyramidal tract.
Proprioceptive sense over half of the body- medial leminiscus.

31. Total unilateral medullary syndrome:
Vessel involved: Occlusion of vertebral artery.
Features: Combination of medial and lateral syndromes.

32. CASE SCENERIO: 02
• A 10 year old girl is taken to a physician because her mother has
noticed that the right half of her face was weak and does not
appear to react to emotional changes.Her mouth is pulled over
slightly to the left,especially when she is tired.On questioning,the
patient admits food tends to stick inside her right cheek and that
the right side of her face “felt funny”.The mother had first
noticed the facial changes 3 months previously,and the condition
has progressively worsened.

33. • On examination,definite weakness of facial muscles on the right side
is noted;the facial muscles on the left side are normal.Skin sensation
on stimulation of face is normal.On testing of the ocular
movements,slight weakness on the lateral rectus muscle is evident on
the right side.Examination of the movements of the arm and leg
shows slight weakness on the left side.
What is the diagnosis?

35. Millard-Gubler syndrome
• Site of lesion: Ventral pons
• Clinical features: Ipsilateral 6th nerve palsy
Ipsilateral 7th nerve palsy
Contralateral hemiplegia

36. Inferior medial pontine syndrome/Foville syndrome
• Veesel involved: Paramedian branch of basilar artery
• Clinical signs:
Ipsilateral- Paresis of conjugate gaze
INO or One and a half syndrome
LMN type facial palsy
Contralateral- Hemiplegia
Impaired tactile & proprioceptive sense
Other- Nystagmus

37. Internuclear ophthalmoplegia
Site of lesion: Medial longitudinal fasciculus
Clinical features:
1. Adduction failure on affected side
2. Nystagmus in opposite side

38. • Common causes:
1.Multiple sclerosis-usually bilateral.
2.Brainstem infarction/haemorrhage
3.Brainstem encephalitis
4. Intrinsic tumor-primary or metastatic
5.Drugs-anticonvulsants,phenothiazine,TCA, Lithium.

39. One and a half
syndrome
Site of lesion: Damage in the
dorsal pons involving –
1.PPRF/6th nerve nucleus.
2.MLF lesion on the same side

40. • Clinical features:
1.Horizontal gaze palsy on the affected side- due to same sided
PPRF/6th nerve lesion.
2.INO-due to lesion in same sided MLF
3.Only intact horizontal eye movement is abduction in the eye
opposite to the site of lesion

41. Lateral inferior pontine syndrome/AICA syndrome:
• Vessel involved: Anterior inferior cerebellar artery
• Clinical signs:
Contralateral- Impaired pain & thermal sense
Ipsilateral-Deafness(8th nerve)
Facial paralysis(7th nerve)
Ataxia(Middle cerebellar peduncle)
Impaired sensation over face(Descending tract & nucleus
of 5th nerve)
Other: Nystagmus

42. Raymond syndrome/Ventromedial pontine syndrome:
• Ipsilateral 6th nerve palsy
• Contralateral hemiparesis

43. CASE SCENERIO 03
• A 31 years old normotensive, previously fit & well man suddenly felt
unwell after getting up from bed.Subsequently, he collapsed on the
floor.He did not lose consciousness but was making grunting noises
and could not move.An ambulance was called,and he was taken to
the hospital.On arrival in the hospital ,he was unable to speak but
could fully understand the verbal commands by moving eyes up &
down.

44. • He had no horizontal eye movements.His pupil & optic fundi were
normal.The facial movements were limited.He was unable to
speak.The only appreciable movements were some flickers in the
fingers.His muscle tone & deep tendon reflexes were normal &
planters were extensor bilaterally.He was able to appreciate
touch.Rest of the systemic examination was normal.
• What is the diagnosis?

45. T2- weighted axial MRI of
brain showing bilateral
massive pontine infarct

46. Locked in syndrome
• Leison: Bilateral ventral pontine lesion due to basilar artery occlusion.
• Clinical features:
1. Quadriplegia- due to bilateral corticospinal tract involvement
2.Aphonia & anarthria-due to involvement of corticobulbar tracts
3.Bilateral horizontal gaze palsy-due to involvement of 6th nerve
bilaterally.
4.Consciousness,sleep/wake cycle & vertical gaze is intact.

52. CASE SCENERIO 04
• A 67 years old diabetic man was admitted with an abrupt onset of
predominantly right sided weakness.On examination he had a new
left ptosis with eye positioned in downwards and outwards.The left
pupil was dilated and unresponsive to light.Peripheral examination
revealed right hemiparesis.
What is the most likely diagnosis?

54. WEBER SYNDROME
• Site of lesion: Base of midbrain
• Clinical signs:
1.Ipsilateral 3rd nerve palsy
2.Contralateral hemiparesis.
• Common causes:
1.Vascular occlusion
2.Tumor
3.Aneurysm.
• Vessel involved: Perforating branches of posterior cerebral arteries.

55. CLAUDE SYNDROME
• Site of lesion: Tegmentum of midbrain
• Structures involved:
1.3rd cranial nerve
2.Red nucleus
3.Superior cerebellar peduncles after decussation
• Clinical signs:
1.3rd nerve palsy
2.Contralateral cerebellar ataxia
3.Tremor.

56. CLAUDE SYNDROME

57. BENEDIKT SYNDROME
• Site of lesion: Tegmentum of midbrain
• Structures involved:
1.3rd cranial nerve
2.Superior cerebellar peduncles after decussation
3.Corticospinal tract
4.Red nucleus

58. • Clinical signs:
1.Ipsilateral 3rd nerve palsy
2.Contralateral cerebellar ataxia
3.Tremor
4.Contralateral corticospinal signs
5.May have choreoathetosis

60. NOTHNAGEL SYNDROME
• Site of lesion: Tectum of midbrain.
• Structures involved:
1.3rd cranial nerve nucleus
2.Superior cerebellar peduncle
3.Vertical gaze centre.
• Clinical signs:
1.Ipsilateral 3rd nerve palsy
2.Contralateral cerebellar ataxia
3.Vertical gaze palsy.

62. PARINAUD SYNDROME
• Site of lesion: Dorsal midbrain
• Structures involved: Supranuclear mechanism for upward gaze &
other structures in peri-aqueductal grey matter.

63. • Clinical signs:
1.Paralysis of upward gaze
2.Convergence-retraction nystagmus
3.pupillary light-near dissociation.
4.Lid retraction (Collier sign).
• Common cause:
1.Pineal region mass lesion
2.Stroke
3.Trauma
4.Hydrocephalus & shunt malfunction
5.Multiple sclerosis
6.Congenital aqueductal stenosis.

64. PARINAUD SYNDROME(PINEAL TUMOR)

66. SYRINGOBULBIA
• A disorder of the lower brainstem caused by progressive enlargement
of a fluid filled cavity that involves the medulla.
• Invariably associated with syringomyelia.
• Clinical presentation:
1.Dysphagia,dysarthria,hoarseness of voice,palatal palsy,facial
sensory loss,wasting & weakness of tongue.
2.Diplopia,vertigo.
3.Headache,neck pain.
4.Spastic paraparesis.
5.Dissociated ,suspended sensory loss.(If associated with
syringomyelia)

68. CHIARI MALFORMATIONS
• A congenital anomaly in which there is a herniation of the tonsils of
the cerebellum and medulla oblongata through the foramen magnum
into the vertebral canal.
• May be associated with syringomyelia or spinal development
anomaly.
• Types:
1.Chiari 1 malformation:
Most common
Cerebellar tonsilar herniation through foramen magnum into upper
cervical canal.

69. 2. Chiari 2 malformation:
Part of cerebellar vermis,medulla and 4th ventricle extend through
foramen magnum often to the mid-cervical region.
Associated with lumbosacral spinal myelomeningocele.
3. Chiari 3 malformation:
High cervical or occipito-cervical meningomyelocele with cerebellar
herniation.
4.Chiari 4 malformation:
Severe cerebellar hypoplasia without herniation.
Considered as a separate entity.