1. Syndromes and Lesions of Brainstem Nuclei
Sudeep Bhabad, MD
Vrushali Bacchav, MD
Daniel L’Heureux, MD
Miral Jhaveri, MD

2. Rule of 4 4 structures in the ‘midline’ beginning with M.
4 structures to the side beginning with S.
4 cranial nerves in the medulla, 4 in the pons and 4 above the pons (2 in the midbrain).
4 motor nuclei that are in the midline are those that divide equally into 12 except for 1 and 2, that is 3, 4, 6 and 12 (5, 7, 9 and 11 are in the lateral brainstem).

3. 4 midline “M” nuclei 4 lateral “S” tracts
Motor Pathway
(Pyramidal tract)
Medial Lemniscus
Medial Longitudinal fasciculus
Motor Nucleus of CN - XII
Spinothalamic
Spinocerebellar
Sympathatic
(rubrospinal)
Spinal nucleus of CN - V ML ST SC
MLF
Sym Sv M 12

4. MIDLINE MOTOR NUCLEI CN - III Nc & N CN - IV Nc & N CN - VI Nc & N
CN - XII Nc.
MOTOR

5. BRAINSTEM NUCLEI Edinger Westphal Nc. CN - III Nc & N CN - IV Nc & N
Sensory Nc. of CN – V & N.
Motor Nc. Of CN - V & N
Ant. & Post. Cochlear N.
CN - VI & Nc
CN – Vll & Nc
Vestibular N & Nc.
Sup. & Inf. Salivary Nc.
Solitary Nc.
Nucleus Ambiguus
Dorsal Motor Nc. Of CN - X
Hypoglossal Nc.
Spinal Nc. & tract of CN - V
Spinal accessory Nc.
MOTOR
SENSORY

6. Involement of Midline ‘M’otor pathways and Lateral ‘S’ tracts is “Meridian of Longitude”.
The cranial nerve “the parallels of latitude” indicates whether the lesion is in the medulla (12th), pons (6th) or midbrain (3rd).

7. Brainstem Syndrome 1
34 yo male with diplopia, progressively worsening nausea and vomiting, headaches and ataxia with paralysis of upward gaze.

8. Diagnosis : Pineal Germinoma
What is the Clinical Syndrome caused by Pineal Germinoma in this patient?

9. Parinaud syndrome
Caused by direct compression of the quadrigeminal plate, which interrupts the neurons that link the cerebral cortex, the superior calculi, and the occulomotor nuclei.
It is characterised by:
Upward-gaze Palsy
Pseudo-Argyll Robertson pupils – Paralysis of accomodation and large pupils
Convergence-retraction nystagmus
Eyelid retraction (Collier's sign)
Conjugate down gaze in the primary position: "setting-sun sign".

10. Brainstem Syndrome 2
50 year old Male with diplopia and right sided ataxia and Chorea.
FLAIR hyperintense peripherally enhancing lesion involving the left paramedian Midbrain.

11. Midbrain at Superior ColliculusRN RN 3 3 SC SC

12. Diagnosis: Neurocysticercosis of midbrain
Location and presentation of this lesion mimics which midbrain infarction Syndrome?
Answer : BENEDIKT SYNDROME
Diplopia – Cochlear Nucleus
right sided ataxia and Chorea – Red Nucleus

13. Brainstem Syndrome 3 3 3 SC SC RN RN
Images used courtesy of Dr. Frank Gaillard at Radiopaedia. org (

14. WEBER’s SYNDROME Structure damaged Effect Substantia nigra
contralateral parkinsonism because its dopaminergic projections to the basal ganglia innervate the ipsilateral hemisphere motor field, leading to a movement disorder of the contralateral body.
Corticospinal fibers
contralateral hemiparesis and typical upper motor neuron findings. It is contralateral because it occurs before the decussation in the medulla.
Corticobulbar tract
difficulty with contralateral lower facial muscles and hypoglossal nerve functions
Oculomotor nerve fibers
ipsilateral oculomotor nerve palsy with a drooping eyelid and fixed wide pupil pointed down and out. This leads to diplopia.

15. Weber’s Vs Benedict’s Syndrome
Main difference between the two being involement of red nucleus in Benedikt Syndrome.
Weber's is more associated with hemiplegia, and Benedikt's with hemiataxia.

16. Brainstem syndrome 4
39 yo male who presented with vertical diplopia, torsional nystagmus and right leg ataxia with poor gait.

17. Midbrain at Inferior Colliculus
MLF IV IC IC

18. Claude Syndrome
Infarct within the paramedian midbrain tegmentum, with extension from the Sylvian aqueduct.
This patient presented with vertical diplopia, torsional nystagmus and right leg ataxia with poor gait.
The visual disturbance is related to the involvement of the trochlear nerve nucleus and fascicles.
Injury to the dentato-rubro fibers and/or red nucleus resulted in ataxia.

19. Hypertrophic olivary degeneration

20. Triangle of Guillain and Mollaret
Red Nucleus
dentatorubral fibres
central tegmental tract
Dentate nucleus
olivocerebellar fibres
Inferior Olivary nucleus

21. Hypertrophic right olivary degeneration.
57/M Post transplant lymphoproliferative disorder. A B
Enhancing lesion involving the left dentate nucleus (A) with surrounding vasogenic edema. Subtle T2 signal change in the right inferior olivary nucleus due to hypertrophy olivary degeneration secondary to the left dentate nucleus lesion.

22. Brainstem syndrome 5
Enhancing lesion involving dorsal aspect of rostral Pons Involving the MEDIAL LONGITUDINAL FASCIUCLUS.
What is the Clinical Syndrome associated with this lesion?

23. Rostral PONS PT PT ML ML V
MCP V S
MLF S M M
SCP

24. Internuclear Ophthalmoplegia
Involvement of MLF results in an ipsilateral internuclear
Ophthalmoplegia (INO).
INO is characterized by failure of adduction (movement towards the nose) of the ipsilateral eye and contralateral eye (leading eye) nystagmus on looking laterally to the opposite side of the lesion.
e.g. If the patient had involvement of the left MLF then, on being asked to look to the left, the eye movements would be normal, but on looking to the right the left eye would not go past the midline, while there would be nystagmus in the right eye as it looked to the right.
P. GATES, Internal Medicine Journal 2005; 35: 263–266

25. Medial longitudinal fasciculus (MLF)
MLF is heavily myelinated tract in the brain stem that connects the nuclei of the 3rd, 4th, 6th and 8th cranial nerves.
This pathway provides a neural mechanism for simultaneous contraction of the lateral rectus muscle on the one side and the medial rectus muscle on the opposite side, required for conjugate lateral gaze.
The vertical gaze center is at the rostral interstitial nucleus (riMLF).
The MLF ascends to the interstitial nucleus of Cajal, which lies in the lateral wall of the third ventricle, just above the cerebral aqueduct.
MLF is the main central connection for the oculomotor nerve,trochlear nerve, and abducens nerve.

26. MLF Pathway
Axons from the canal project to the ipsilateral vestibular nuclei and then decussate to innervate the contralateral inferior rectus subnucleus of the oculomotor complex of cranial nerve III and the trochlear nucleus. The trochlear neurons then exit the brainstem posteriorly and decussate back to the left side innervating the superior oblique muscle. Activation of both canals (as with pitching the head upward and attempting straight ahead fixation) will result in cancellation of the torsional vector components, but addition of the vertical vector components resulting in downward movement of the eyes.
Vestibular Nystagnus
COWS: Cold Opposite, Warm Same
Cold water = FAST phase of nystagmus to the side Opposite from the cold water filled ear Warm water = FAST phase of nystagmus to the Same side as the warm water filled ear
In other words: Contralateral when cold is applied and ipsilateral when warm is applied

27. Trigeminal nucleus lesions
32/F with left tongue and peri -oral numbness. PT PT ML ML V V S
MLF S M M
Subtle enhancing FLAIR hyperintense demyelinating lesions in the region of the right facial colliculus and left trigeminal nucleus.

28. Facial colliculus Syndrome
Brainstem syndrome 6
Facial colliculus Syndrome
Same 32 yo Female patient with MS also had diplopia.
Subtle enhancing FLAIR hyperintense demyelinating lesions in the region of the right facial colliculus and left trigeminal nucleus.

29. Facial Colliculus – Caudal PonsPT PT 5 8V 8C

30. Facial Colliculus lesion
61/M Multiple sclerosis with diplopia and paralytic strabismus, left sixth nerve palsy. C A B
Enhancing lesion in the left lateral aspect of the pons near the facial colliculus in the region of the left sixth nerve nucleus.

31. 62 yo male with dizziness with slight anisocoria (L>R) restricted lateral gaze bilaterally, left lower>upper facial weakness, dysarthric speech.
Focal area of restricted diffusion in the dorsal aspect of pons in the region of the facial colliculus.

32. One-and-a-half syndrome
Brainstem syndrome 7
One-and-a-half syndrome
ipsilateral conjugate horizontal gaze palsy (the "one") and
an ipsilateral internuclear ophthalmoplegia (INO) (the "half").
This is caused by
a lesion that affects the ipisilateral paramedian pontine reticular formation (PPRF) or the abducens (CN IV) nucleus (responsible for the horizontal gaze palsy) and
the ipsilateral medial longitudinal fasciculus (MLF) (responsible for the INO - failed adduction of the ipsilateral eye).
The only remaining horizontal movement is contralateral abduction. The apparent adduction deficits can be overcome with convergence.
This patient showed signs of right facial weakness (forehead weakness, orbicularis weakness, ectropion, mouth droop). Along with a right horizontal gaze palsy that was not overcome with vestibulo-ocular reflex and an adduction deficit in the left eye. Adduction was preserved in both eyes with convergence.

33. Eight-and-a-half syndrome
Brainstem syndrome 8
Eight-and-a-half syndrome
One-and-a-half syndrome + 7th nerve palsy = eight-and-a-half syndrome.
When this lesion also affects the fascicle of the the ipsilateral facial nerve (CN VII) in the region of the facial colliculus as it wraps around the CN VI nucleus, it produces a lower motor neuron pattern of ipsilateral facial weakness. When this occurs, a one-and-a-half syndrome plus a 7th nerve palsy, it is termed an eight-and-a-half syndrome.

34. Brainstem Syndrome 9
3 year old male with acute onset ataxia, leading to his left while walking, repeated emesis, Horner’s syndrome.
H/o fall on head an hour before the symptoms started.
H/o recent travel to Puerto Rico
Mother had 2 miscarriages.

35. Lateral Medullary Syndrome (Wallenberg Syndrome)
What is this stroke Syndrome?

36. Rostral MEDULLA Vs Vs PT ION ML ST SC A S X ST ICP VIII XII XII MLF
Rub Vs
ICP Vs
XII
XII S X
VIII

37. Lateral medullary syndrome (Wallenberg syndrome)
ipsilateral
deficits in pain and temperature over face (spinal trigeminal nucleus involvement)
ataxia and in-coordination (inferior cerebellar peduncle)
dysarthria/dysphagia/decreased gag (nucleus ambiguus)
contralateral
deficits in pain and temperature over trunks and limbs
vertigo (vestibular nucleus)

38. 59 / M left sided numbness, fall with right sided weakness.
Brainstem syndrome 10
59 / M left sided numbness, fall with right sided weakness. A B C
Punctate acute infarct in the medial aspect of medulla on the left.

39. Medial medullary syndrome (Dejerine syndrome)
Hypoglossal nerve fibers –
Deviation of the tongue to the side of the infarct on attempted protrusion, caused by ipsilateral muscle weakness.
Medullary pyramid (corticospinal tract)-
Contralateral hemiplegia
Medial leminiscus –
loss of discriminative touch,  proprioception, and vibration sense on the contralateral side of the infarct

40. Thank You