Localization skills: impaired consciousness or sleep disorder

Question 1

What sign would be seen due to a lesion in the medulla?

Answer 1

Ataxic respirations (variable breaths at an irregular interval)

Question 2

If you see large, fixed pupils (b/l), where would the lesion be, regionally? (+ parasymp or symp?)

What if it is just 1 unilaterally blown pupil?

Answer 2

Tectal (dorsal) midbrain lesion involving the parasympathetic fibers there

Ipsilateral CN III compression from swollen temporal lobe (*uncal herniation)

Question 3

Where is the lesion, regionally, if the pupils are small and pinpoint? (+ parasymp or symp?)

Answer 3

Pontine lesion involving sympathetic fibers

Question 4

What is the oculocephalic reflex and how is it affected if brainstem is not intact?

Answer 4

Eyes roll in opposite direction of head turn w/ intact brainstem.
- Remain in fixed position despite rolling if brainstem not intact

Question 5

What is the oculovestibular reflex (AKA?) and how is it affected if brainstem is not intact?

Answer 5

• AKA cold caloric

- Eyes should move slowly toward the cold (irrigated) ear. If not present, brainstem compromised.

Question 6

Recognize the symptoms suggestive of sleep apnea.

- What more severe diseases can it lead to, and what is the main reason?

Answer 6

Noticed often by bed partners as heavy snoring with periodic breathing cessation; pt often feels unrefreshed in the morning with potentially dangerous daytime sleepiness.
- Can secondarily → pulmonary HTN or cardiac arrhythmia (d/t nocturnal hypoxemia).

• Dr. Nasir claims that it increases risk of stroke.

Question 7

Define narcolepsy.

Recognize the symptoms suggestive of narcolepsy.

Answer 7

REM sleep occurring at inappropriate times. (extreme tendency to fall asleep in relaxing surroundings)
Sx:
- Narcoleptic attacks (abrupt, often multiple, intrusions of sleep during daytime activities)
- Cataplexy (periodic loss of muscle tone often provoked by emotional triggers)
- Sleep paralysis (REM hypotonia transiently prevents the pt from getting out of bed upon waking)
- Visual hallucinations when falling asleep or waking up

Question 8

How is sleep apnea dx’d?

How is narcolepsy dx’d?

Answer 8

• Via sleep study
• Via multiple sleep latency tests, where the abnormally early onset of REM is recorded as the pt is allowed to fall asleep several times but not in a state of sleep deprivation