Brainstem Lesions

Question 1

Lesion of spinal lemniscus in brainstem would result in?

What tract is involved?

Answer 1

Pain/temp hemianesthesia contralaterally in body

Spinothalamic tract- Lateral brainstem

Question 2

Lesion of medial lemniscus in brainstem would result in?

What tract is involved?

Answer 2

Proprioception/2-pt tactile contralateral hemianesthesia in body. Posterior column/medial lemniscal system- Medial brainstem

Question 3

Lesion of trigeminal lemniscus would result in?

Answer 3

Loss of pain/temp from opposite side of face

Question 4

Lesion of medial longitudinal fasciculus?

Answer 4

Ipsilateral intranuclear opthalmaplegia

Question 5

Lesions of lateral lemniscus result in?

Answer 5

B/L hearing loss, most prominent in contralateral ear

Question 6

What 4 cranial nerves exit the brainstem near the corticospinal tract and can cause alternating hemiplegia?

Answer 6

CN 5,6,3,12

Question 7

What is alternating hemiplegia?

Answer 7

Loss of a cranial nerve plus corticospinal tract-> ipsilateral crainial nerve deficit, contralateral motor paralysis/paresis.

Question 8

What would a lesion of uncrossed corticobulbar fibers cause?

Answer 8

Affect contralateral crainial nerves below the lesion

Question 9

Unilateral lesions of corticobulbar tract above the level of the decussation cause what?

Answer 9

Supranuclear facial palsy (contralateral paralysis of lower half of face) from uncrossed fibers (also CN4, 12, 10)

Question 10

What would a lesion of the descending tract of V cause?

Answer 10

Ipsilateral pain/temp analgesia in face

Question 11

What cranial nerves are at the level of the pontomedullary sulcus?

Answer 11

6.7.8

Question 12

What characteristic features does the medulla have on an MRI?

Answer 12

4th ventricle, ION, Pyramids (CST)

Question 13

What usually causes thalamic syndrome and what is a classic sign?

Answer 13

Thrombosis of posterior choroidal or thalamogenticulate branches of PCA branches. May have contralateral hemihypalgesia (“crawling ant” sensation)

Question 14

What causes Parinaud’s syndrome and what are the sx?

Answer 14

Lesion of the superior colliculus, may be d/t pineal tumor or Great vein of galen varix. Causes paralysis of upward gaze. May also destroy posterior commissure and lose consensual light reflex.

Question 15

What is alternating hemianalgesia?

Answer 15

Ipsilateral loss of pain/temp from face (descending tract of 5) and contralateral loss of pain/temp from body. (spinal lemniscus)

Question 16

A lesion of the Nucleus Ambiguous would result in what?

Answer 16

Dysphagia, dysarthria, hoarseness

Deviation of uvula away from affected side

Question 17

What does the trigeminal lemniscus convey?

Answer 17

Pain/temp/crude tactile sensations from opposite side of face

Question 18

A dorsal extension of alternating hemiplegia results in compromise of what?

Answer 18

Medial lemniscus- contralateral propriocepion/2 pt tactile loss

Question 19

External strabismus, complete ptosis, and dilated pupil indicate what cranial nerve lesion? Where is it in the brainstem?

Answer 19

CN3 palsy on ipsilateral side, in the midbrain (mesencephalon)

Question 20

What are charactaristics of Lateral medullary syndrome?

Answer 20

Alternating hemianalgesia, destruction of nucleus ambiguous, vestibular nuclei, solitary nucleus, CN9 and CN10, destruction of spinal lemniscus and descending tract of 5..

Question 21

What syndrome involves CN3, the CST, and the CBT? Sx?

Answer 21

Weber’s syndrome (A3H).

Oculomotor palsy, contralateral spastic hemiplegia, contralateral palsy of CN4, 5, 12, 10