Clinical Skills; Neuro

Name the 12 cranial nerves

1. olfactory

2. optic

3. oculomotor

4. trochlear

5. trigeminal

6. abducens

7. facial

8. vestibulochochlear

9. glossopharyngeal

10. vagus

11. accessory

12. hypoglossal

Name some causes of cranial nerve disorders

Cranial nerve disorders have many causes, including:

-Head injuries

-Tumors

-Infections

-An inadequate blood supply (CVA, DM)

-Pressure on a nerve (e.g. aneurysm, arteriovenous malformation, tumor)

- Disorders that cause nerve cells to degenerate (ALS, multiple sclerosis)

- Disorders that cause inflammation of blood vessels (vasculitis, GCA)

- Some toxins and medications

What is the function of cranial nerve I? How would you check it on exam?

CN I = Olfactory nerve

Sense of smell

Occlude one nostril, place a non noxious substance near the open nostril, have patient identify the smell

What are some differentials if a patient has an abnormal cranial nerve I exam?

CN I = Olfactory nerve

Loss of smell is anosmia. The most common cause is a cold or nasal allergies. Other causes include trauma or a meningioma affecting the olfactory tracts. Anosmia is also seen in Kallman syndrome because of agenesis of the olfactory bulbs

What is the function of cranial nerve II? How would you check for it on exam?

CN II = Optic nerve

1. Visual acuity with Snellen

2. Visual fields by confrontation

3. Fundoscopy to look for papilledema

4. (CN II+III) Pupillary reflex

While using a Snellen chart, you note decreased visual acuity in one eye. What are some differentials?

CN II = Visual acuity, visual fields

Loss of visual acuity can be due to the eye itself (corneal damage such as abrasions/lacerations/infections, vitreal damage such as vitreous hemorrhages, retinal damage such as detachment, glaucoma) OR neurologic due to Optic nerve damage (optic neuritis, GCA, trauma, stroke, CRAO, IIH or other elevated ICP, toxins such as ethambutol or methanol)

When testing the pupillary reflexes in a person with left eye pain, you note that they have worsening left eye pain when you shined a light into the opposite (unaffected) eye. What is this response and what does it suggest?

This person is exhibiting pain when light is shined in the unaffected eye, called "consensual photophobia". This is often seen in anterior uveitis.

How do you do visual fields by direct confrontation?

Patients covers one eye, you cover an eye on the same same (their left, your right) - hold up fingers halfway between yourselves in the peripheral vision, and have them tell you how many fingers you are holding up in each quadrant of their vision

Define: Quadrantanopia

Lesion (stroke) that takes out one quadrant of the vision

While testing a patients visual fields you note a right sided visual field deficit for both eyes. How do you document this?

Right hemianopia

Right hemianopsias occur due to lesions behind the optic chiasm involving the left optic tract, radiation or striate cortex.

While testing a patients visual fields you note a bitemporal visual field deficit. What are you concerned about and what are your next steps?

Bitemporal hemianopia suggests a lesion/mass at the optic chiasm/pituitary mass and requires imaging.

You are evaluating a patient who is 20 years old, obese, and complaining of daily headaches unrelieved with OTC medications and occasional double vision. What is the purpose of performing a fundoscopy examination on this patient?

Papilledema: This is the swelling of the optic nerve head, visible during an eye exam. It is the hallmark sign of IIH and occurs due to the increased pressure exerted on the optic nerve.

What is the swinging flashlight test?

The swinging flashlight test is used to show a relative afferent pupillary defect or a Marcus Gunn pupil.

Which cranial nerves control our extraocular eye movements?

Cranial nerve III, IV, VI

You make a large "H" in the air and have the patient track the movement of your finger with their eyes. There is no abnormality detected; they are able to track easily without double vision. How do you document this finding?

EOMI (extraocular movements intact)

CN III palsy affected eye is...

down and out ** most common

In CN IV palsy, the eye appears....

upward and medial

In CN VI palsy, the affected eye is...

medially deviated

During ocular examination, the patient is noted to have unilateral ptosis, dilated pupil, limited adduction, elevation, and depression of the eye. Which nerve is affected?

Cranial nerve III (Patient has a 3rd nerve palsy)

What is the function of cranial nerve V and how do you test it?

CN V = Trigeminal nerve

1. Sensory: Check for light touch sensation in V1, V2, V3 bilaterally

2. Motor: Check for temporal and masseter strength

3. Corneal reflex

A patient who is unconscious is having their corneal reflex tested. Which cranial nerves are involved, and what are the implications if no reflex is elicited?

A patient with an absent corneal reflex either has a CN 5 sensory deficit or a CN 7 motor deficit. An absent corneal reflex in this setting would indicate brainstem dysfunction.

What is cranial nerve VII and how do you test it?

CN VII = Facial nerve

1. Test for expressions of the face: raise your eyebrows, close eyes shut tightly, smile showing teeth, optional: puff out your cheeks , frown

2. Taste/Sensory: Anterior two thirds of the tongue, test both sides

What is the most common cause for a Bell's palsy?

*viral infections - herpes, varicella

idiopathic

lyme dz

meningitis

tumors

diabetes

During a neurology exam, you note weakness of the lower half of a patients left face including the orbicularis oculi muscle but sparing the forehead. What is this concerning for?

This is consistent with a central 7th or upper motor neuron lesion (concerning for stroke).

What is the function of cranial nerve VIII and how can you test it?

CN VIII = Vestibulocochlear which controls hearing, balance, spatial sensation, posture

1. Auditory = test hearing with rubbing fingers and/or whispered numbers test. Further screening for conduction versus neurosensory hearing loss can be accomplished by using the Weber and Rinne tests if indicated.

2. vestibulo-ocular reflex or ice water calorics (not routinely done)

You are evaluating a patient with complaint of dizziness. If a benign peripheral vestibular nerve disease is suspected, and nystagmus is present, describe the type of nystagmus you expect to see.

Nystagmus is the principle finding in vestibular disease. It is horizontal with the slow phase of the nystagmus toward the abnormal side in peripheral vestibular nerve disease.

You are evaluating a patient with complaint of dizziness. How can nystagmus appear if the patient is having a central cause of vertigo (brainstem lesion)?

Nystagmus can be horizontal, upbeat, downbeat, or torsional and is not suppressed by visual fixation in central causes

Inspection of the soft palate an uvula, assessment for cough/swallowing difficulties, and the gag reflex, all assess which cranial nerves?

Glossopharyngeal (CN IX) and vagus (CN X) nerves. The glossopharyngeal and vagus nerves are assessed together because of their closely related functions.

When your patient says "ahh" you note that the palate raises asymmetrically, and the uvula points toward the left. There is no visible PTA. Which cranial nerve do you think is affected?

Cranial nerve IX&X, of the right side. A vagus nerve lesion will cause asymmetrical elevation of the palate and uvula deviation away from the lesion (unless of course there is bilateral involvement)

What is cranial nerve XI and how is it tested?

CN XI = Accessory muscle nerve

CN 11 is tested by asking the patient to shrug their shoulders (trapezius muscles) and turn their head (sternocleidomastoid muscles) against resistance.

What is cranial nerve XII and how is it tested?

CN XII = Hypoglossal nerve

The 12th CN is tested by having the patient stick out their tongue and move it side to side. Further strength testing can be done by having the patient push the tongue against a tongue blade. Inspect the tongue for atrophy and fasciculations. If there is unilateral weakness, the protruded tongue will deviate towards the weak side.

When you ask your patient to stick their tongue out, you notice it deviates to the left, and that the left side appears atrophied. Which nerve is affected?

Left CN XII (hypoglossal nerve). Hypoglossal nerve palsy causes atrophy of the ipsilateral tongue and deviation of the tongue when protruded towards the side of the lesion.

Which neurologic tests check for cerebellar function?

The cerebellum controls coordination, balance and fine motor movement

Rapid alternating hand movements, finger tapping, toe tapping all assess for cerebellar dysfunction

Define dysdiadochokinesia and a task used to assess for it

Inability to perform rapid alternating movements in a rapid and rhythmic fashion (rapid alternating hand, rapid finger tapping, toe tapping)

Define dysmetria and a task used to assess for it

The inability to control the range of a movement and the force of muscular activity during finger-to-nose or heel-to-shin testing

While conducting the Romberg test, the patient starts to fall over when their eyes are closed. This suggests a problem with?

Either the vestibular or propioceptive centers.

Standing still requires input from at least 2/3: visual, vestibular, proprioceptive centers. By choosing to remove vision, we are testing to see if the other two are intact.

Light touch is used as a screening tool to test which nerve systems?

Both the spinothalamic and dorsal column systems serve light touch so it is not specific for either one. A cotton tip applicator or fine hair brush is used. Select areas from different dermatomes and peripheral nerves and compare right versus left.

If a patient has difficulty sensing vibrations on the distal interphalangeal joint of the finger, or of the great toe, what should be done?

Test the next most proximal bony joint

If a patient has a loss of joint position sense (loss of proprioception), this suggests a lesion of what?

Dorsal column

What is the first sensation lost in peripheral neuropathy?

Vibration sense

Define graphesthesia and how you would test for it

Graphesthesia is the ability of the patient to identify characters that are written on the skin using a dull pointed object

Define stereognosis

Stereognosis is the ability to identify objects that are placed in the hand when the eyes are closed. The patient is given common objects and asked to identify them without looking at them. The inability to do this called astereognosis and indicates parietal lobe dysfunction.

Define the following types of muscle tone:

1. Flaccid

2. Rigidity

3. Spasticity

1. Flaccid: Little to no resistance

2. Rigidity: An increase in muscle tone that is constant, regardless of the speed of the movement. Classic finding in Parkinson's

3. Spasticity: A velocity-dependent increase in muscle tone, meaning the resistance to movement increases with the speed of the movement. Commonly seen in: cerebral palsy, stroke, and spinal cord injuries.

State the different grades of muscle strength testing

0 - No contraction

1 - Slight contraction, no movement

2 - Full range of motion without gravity

3 - Full range of motion with gravity

4 - Full range of motion , some resistance

5 - Full range of motion, full resistance

State the different grades for reflex testing

0 - Absent

1 - Decreased but present

2 - Normal

3 - Brisk and excessive

4 - With clonus

How do you check for clonus of the ankle?

Have patient reflexed with knee partially flexed. Gently move the ankle in dorsi and plantarflexion before rapidly dorsiflexing the ankle. Abnormal jerking of the foot is a positive finding.

Hyperreflexia is a sign of an [upper/lower] motor neuron lesion

Upper