Neurology: Clinical Skills - Cranial Nerve Exam #neurology #cranialnerveexam #ubcmedicine

Summary

This video walks through a detailed cranial nerve examination, showcasing how doctors assess the function of all 12 cranial nerves. The exam includes testing the sense of smell, visual acuity, eye movements, facial sensation, hearing, and strength in neck and tongue muscles. Key techniques like the pupillary light reflex, swinging light test, and corneal reflex are demonstrated, with the physician also evaluating balance and coordination through specific maneuvers. Throughout the exam, patient responses are carefully noted to identify any abnormalities in cranial nerve function.

Takeaways

• 😀 The cranial nerve exam assesses the function of the 12 cranial nerves, which control various facial functions and sensations.
• 😀 The olfactory nerve is usually tested only when an altered sense of smell is suspected, using familiar scents like citrus or coffee.
• 😀 The optic nerve is assessed through various tests such as the pupillary light reflex, swinging light test, funduscopy, and visual acuity.
• 😀 Smooth pursuit, reflexive saccade, and volitional saccade tests evaluate the oculomotor, trochlear, and abducens nerves, which control eye movements.
• 😀 The trigeminal nerve is tested for sensation through light touch, pinprick, and the corneal reflex, along with evaluating the strength of chewing muscles.
• 😀 The facial nerve is tested by inspecting facial asymmetry and evaluating facial expressions such as scrunching the forehead and puffing the cheeks.
• 😀 The vestibulocochlear nerve is screened for hearing loss using tuning forks (Weber and Rinne tests) and by checking for balance and spatial orientation.
• 😀 The glossopharyngeal and vagus nerves are assessed by inspecting the back of the throat and testing the gag reflex and phonation.
• 😀 The accessory nerve is tested by evaluating the strength of the sternocleidomastoid and trapezius muscles, which control head turning and shoulder shrugging.
• 😀 The hypoglossal nerve is assessed by inspecting the tongue for strength, symmetry, and fasciculations, as well as checking its movement and bulk.

Q & A

What is the purpose of the cranial nerve exam?

The cranial nerve exam is designed to assess the function of the 12 cranial nerves, evaluating sensations and motor functions affecting the face and other regions of the body.

Why is the olfactory nerve often not tested during routine exams?

The olfactory nerve is usually not tested unless there is suspicion of an altered sense of smell based on patient history.

What sensory stimuli are typically used to test the olfactory nerve?

Familiar scents such as citrus fruit or coffee are often used, as well as scratchcards. Noxious smells like ammonia are avoided because they can irritate the nasal mucosa and stimulate the trigeminal nerve.

What does the swinging light test assess?

The swinging light test assesses the relative strength of sensory signals sent through each optic nerve. It checks for afferent pupillary defects, which may indicate optic nerve damage.

What is the purpose of the fundus examination in the optic nerve test?

The fundus examination allows the clinician to inspect the retina, blood vessels, and optic disc for abnormalities such as bulging, blurred margins, or pallor, which may indicate damage to the optic nerve or other conditions.

How is visual acuity typically assessed in a cranial nerve exam?

Visual acuity is assessed using a Snellen chart or a handheld chart. The patient is asked to identify the smallest row of numbers they can read, and this helps determine if their vision is normal or if there is any impairment.

What does the oculocephalic maneuver test?

The oculocephalic maneuver tests the function of the cranial nerves and nuclei responsible for controlling the extraocular muscles. It is particularly useful for assessing comatose patients who cannot voluntarily move their eyes.

How are the sensory and motor components of the trigeminal nerve assessed?

The sensory function is tested through light touch, pinprick, and the corneal reflex. The motor function is tested by assessing the strength of the muscles of mastication (e.g., masseter and temporalis muscles).

What does the corneal reflex test for?

The corneal reflex tests the sensory function of the trigeminal nerve and the motor function of the facial nerve. It involves lightly touching the cornea to see if the patient blinks involuntarily.

What role do the glossopharyngeal and vagus nerves play in the cranial nerve exam?

The glossopharyngeal and vagus nerves are tested for their involvement in the motor control of the soft palate and the uvula. This is assessed by observing the symmetry of the uvula and performing the gag reflex. They are also involved in phonation.