A 62-year-old man presented with sudden onset of unsteadiness, tendency to fall to the right side, loss of sensation in the right half of the face and left side of the torso, and dysphagia. On examination, he had partial ptosis, enophthalmos, miosis of the right eye, and cerebellar signs. Localizing the lesion based on associated neurological deficits suggests a lesion in the pons, as the patient has crossed sensory loss of the face indicative of a lower motor neuron lesion of the trigeminal nerve, as well as unilateral facial numbness and potential unilateral deafness. Lesions in specific areas of the brainstem can be localized based on the cranial nerves

1. HOW TO
LOCALISE
BRAIN STEM
LESIONS WITH
SENSORY
SYMPTOMS????

2. THE CURIOUS CASE OF A
62 YEAR OLD DRIVER…
H/o sudden onset of
unsteadiness of gait,tendency to fall
to right side
C/o loss of sensation in the rt half
of face & left hemitorso,dysphagia.
O/e partial
ptosis,enophthalmos, miosis of right
eye.
Cerebellar signs present

3. ANATOMY OF BRAIN STEM

7. LOCALISATION
OF THE LESION
IS BY
OBSERVING THE
COMPANY THEY
KEEP…

10. A midbrain
lesion
: CN III
: ptosis, dilated
pupil, eye down and
out

11. A lesion of the pons
: CN 6 or 7
(this is a LOWER motor neurone type
lesion)
: Horizontal gaze palsy
: Unilateral facial numbness from CN 5
(results in CROSSED SENSORY
LOSS)
: Unilateral deafness

12. A lesion of the
medulla
: bulbar palsy
: Unilateral facial numbness from
CN V
Nystagmus :
(Descending spinal tract and
nucleus)
medullo-pontine
junction.

13. MEDIAL LESIONS
Medial Lemniscus:
contralateral loss of vibration and
proprioception in the arm and leg
Medial longitudinal fasciculus:
ipsilateral inter-nuclear
ophthalmoplegia
Motor cranial nerve nuclei

15. LATERAL LESIONS
Sensory pathways.
Motor cranial nerve nuclei.
Cerebellar peduncles.
superior • Ataxic tremor
middle • General clumsiness
inferior • Motor adaptation impaired.

16. BACK TO THE CASE…
ptosis

19. Cross section of

20. WALLENBERGS
SYNDROME/ LATERAL
MEDULLARY SYNDROME

21. VENTRAL LESIONS
Descending corticospinal
pathways
LOW MEDULLARY LESIONS
Bilaterl or ipsilateral
weakness/sensory disturbance.
Main pathways decussate at this
level.

22. BALACLAVA HELMET DISTRIBUTION
Trigeminal sensory
fibres
Back of face-descend
more
More forward areas
of face- descend
shorter distance

23. MULTIPLE SCLEROSIS
Resemble trigeminal neuralgia
CEREBELLAR INVOLVEMENT
Unsteadiness of gait
Intention tremor
Nystagmus on attempted
lateral gaze

24. FALSE LOCALISATION SIGNS
Increased ICT – 6th CN palsy
Third nerve palsy
Tentorial herniation.
Posterior communicating
artery aneurysm

25. Thank you!!!