coma, CNs

Question 1

are there brainstem reflexes in coma?

Answer 1

yes

Question 2

persistent vegetative state

Answer 2

eyes periodically open
movement
pain responsive

but no meaningful interaction

Question 3

a solitary, unilateral cerebral lesion does not produce coma unless it …

Answer 3

adversely affects the opposite hemisphere via brain edema or herniation.

Question 4

decorticate posturing is lesion in

Answer 4

cerebral cortex, hemisphere

Question 5

decerebrate posturing is lesion in

Answer 5

midbrain (red nucleus)

Question 6

what situations is cheyne-stokes breathing seen in comatose patients?

Answer 6

bilateral cortical involvement due to:

• metabolic encephalopathy, such as renal failure,
• a unilateral lesion with severe brain edema,
• bilateral structural lesions in cerebral cortex.

Question 7

central neurogenic hyperventilation may result from a lesion or edema in the

Answer 7

low midbrain, upper pons

Question 8

are there pupillary light reflexes in coma from metabolic cause?

Answer 8

surprisingly yes!

Question 9

relative afferent pupillary defect (RAPD)

Answer 9

Both pupils may initially constrict to light, but after moving the light source from the normal to the abnormal eye (“swinging flashlight test”), pupillary dilatation occurs because of relatively reduced afferent input at the affected eye.

Question 10

relative afferent pupillary defect (RAPD) occurs due to

Answer 10

• partial optic nerve lesion

- retinal lesion

Question 11

near reflex

Answer 11

when viewing a nearby object:

• pupil constricts
• lens accommodates
• eyes converge

Question 12

dissociation of light and near reflexes (light-near dissociation) presentation

Answer 12

disruption of the pupillary light reflex pathway at the pretectal area, but connections for the near reflex are preserved.

–>pupils only constrict during the near reflex, but not to a light stimulus.

Question 13

dissociation of light and near reflexes (light-near dissociation) causes

Answer 13

• argylle robertson pupils (syphilis)

- dorsal midbrain syndrome (parinaud’s syndrome)

Question 14

Dorsal midbrain syndrome (parinaud’s syndrome)

Answer 14

pineal tumor or infarct compressing the dorsal midbrain

light-near dissociation of the pupils + impairment of upward gaze

Question 15

3 levels of Horner’s syndrome causes

Answer 15

1. lateral medulla infarct- wallenberg syn
2. spinal cord C8-T2 - lung tumor
3. neck trauma affects superior cervical sympathetic ganglion

Question 16

A V-1 territory sensory impairment plus ipsilateral involvement of cranial nerves III, IV and VI may occur from a lesion at

Answer 16

• superior orbital fissure

- cavernous sinus

Question 17

which trigeminal regions does trigeminal neuralgia occur in?

Answer 17

V2, V3

Question 18

uvula deviates which way in CN X LMN lesion?

Answer 18

toward unaffected side

Question 19

right pontine lesion presentation

Answer 19

right facial nucleus –> right LMN facial paralysis

right CST –> UMN left hemiparesis

Question 20

medial midbrain syndrome (Weber syndrome) is due to occlusion of…

Answer 20

PCA

Question 21

medial midbrain syndrome (Weber syndrome) presentation

Answer 21

CN 3 —> ipsilateral oculomotor nerve lesion

cerebral peduncle (CST and CBT) –> weakness of the contralateral face and limbs