Chapter 13: palsies and pupils

Question 1

1) Define diplopia
2) Name some of its numerous causes

Answer 1

1) Double vision
2) -Orbital fracture causing muscle entrapment
-Inflammatory disorders of the EOM or thyroid disease
-Disorders of the neuromuscular junction such as myasthenia gravis
-Disorders of CN III, IV, or VI or their brainstem nuclei
-Toxins and alcohol.

Question 2

1) What should you ask if a patient tells you they have diplopia?
2) What does it mean if they answer “yes”?
3) What does it mean if they answer “no”?

Answer 2

1) Does symptom resolve when one eye is closed?
2) If yes, then due to eye muscles.
3) If no, then due to more centralized lesion.

Question 3

1) What does CN III Palsy cause? (3 things)
2) What can cause this? (4 things)

Answer 3

1)
-Eye will only move in abduction, depression and intorsion.
-Eye may be in “down and out” position at rest.
-Pupil is dilated and unresponsive to light
2) Diabetic neuropathy, HTN, head trauma, intracranial aneurysms

Question 4

1) What does a CN IV (4, trochlear) Palsy cause? Why?
2) What does its morphology cause?

Answer 4

1) A palsy here would produce a vertical diplopia since the trochlear nerve produces depression and intorsion of the eye.
2) Because it’s long and thin and susceptible to shearing, it’s the most commonly affected CN in head trauma

Question 5

What is the most commonly affected CN in head trauma?

Answer 5

Trochlear Nerve (CN4)

Question 6

1) What does CN 6 (Abducens) Palsy cause?
2) What can cause this? What can it be a warning sign of?

Answer 6

1) Produces horizontal diplopia, worse when viewing far objects
2) Susceptible to injury from elevated intracranial pressure, therefore, can be an early warning sign of elevated ICP

Question 7

1) What pathways control the pupils?
2) What would parasympathetic innervation cause?

Answer 7

1) Both parasympathetic and sympathetic pathways
2) Constriction

Question 8

1) What should you see if you shine a light in the eye?
2) What would a lesion of CNIII cause?

Answer 8

1) A direct response in that eye and a consensual response in the opposite eye.
2) Impaired pupillary constriction resulting in a dilated pupils or “blown pupils”

Question 9

1) What structure is affected to cause Horner’s syndrome?
2) What are the potential causes of that?

Answer 9

1) Lesions in the sympathetic pathway
2) Brainstem damage, spinal cord trauma, infection, tumor, aneurysm, thrombus

Question 10

What are the 3 symptoms of Horner’s syndrome? Define each

Answer 10

1) Ptosis: drooping upper eyelid
2) Miosis: decreased pupillary size
3) Anhidrosis: decreased sweating in the face and neck of the ipsilateral side

Question 11

1) Define Pontine Pupil
2) What can cause it?

Answer 11

1) Small pupils, but reactive to light
2) Caused by large lesions of the pons

Question 12

What is pharmacological miosis? Give an example

Answer 12

Many meds can affect pupil size (like opiates) can cause bilateral pinpoint pupils

Question 13

Brainstem lesions need to be worked up emergently, which should include what two things?

Answer 13

Medication history and toxicology screen