Cranial Nerve Exam

Introduction to cranial nerves

The cranial nerves test is a critical aspect of neurological assessment, providing key insights into the functioning of the twelve cranial nerves. Each cranial nerve has a specific role, ranging from sensory functions like smell and vision to motor functions like facial and eye movements. The cranial nerves are traditionally numbered I through XII and named based on their primary function or the area they affect. Here's an overview of the cranial nerves and their purposes:

• Cranial nerve i — olfactory: Cranial nerve I is pivotal for the sense of smell.
• Cranial nerve ii — optic: Cranial Nerve II is essential for normal vision.
• Cranial nerves iii, iv, and vi — oculomotor, trochlear, abducens: These three nerves control eye movements.
• Cranial nerve vii — facial: This nerve is responsible for facial expression, speech articulation, and lip movement and tone.
• Cranial nerve viii — vestibulocochlear: This nerve is involved in hearing and balance.
• Cranial nerve ix,x — glossopharyngeal, vagus nerve: The glossopharyngeal and vagus nerves are essential for swallowing, taste, and the gag reflex.
• Cranial nerve xi — spinal accessory: The spinal accessory nerve controls the sternocleidomastoid and trapezius muscles.
• Cranial nerve xii—hypoglossal: The hypoglossal nerve controls tongue movements.

In clinical practice, cranial nerve testing is crucial for diagnosing conditions like stroke, multiple sclerosis, and tumors. Therefore, a comprehensive examination of the cranial nerves is an indispensable tool in neurological assessment, aiding in accurately diagnosing and managing various neurological disorders.

What is a Cranial Nerve Assessment?

The Cranial Nerves Assessment forms an important part of the complete neurological examination and involves examining the functioning of the cranial nerves. It is a structured examination designed to check each cranial nerve using various methods that can usually be completed with equipment readily available in a hospital environment (Reese, 2023). Its broader purpose is to localize neuropathology as part of a complete neurological exam. 

Clinical indications for a cranial nerve examination include (Reese, 2023):

• Trauma or traumatic brain injury (TBI)
• Unconsciousness or coma
• Intracranial hemorrhage
• Stroke
• Cerebral aneurysm

Although this exam can be completed relatively quickly without specialized equipment, it has many different parts that must be completed in succession to assess each cranial nerve thoroughly – and that's where our template can help. Just keep reading to find out how!

How to do a cranial nerve examination?

Need a quick memory refresh on how to examine each cranial nerve? Here's a concise cranial nerve exam how-to based on the Oxford Medical Education Cranial Nerve Examination guidelines (Oxford Medical Education, 2015). Once you have a copy of our Cranial Nerve Assessment template, follow the order of cranial nerve testing below:

Step 1: Assess the olfactory nerve (CN I)

Question the patient on any recent change in sense of taste or smell, or formally assess using smelling bottles, e.g. coffee or peppermint occluding one nostril at a time.

Step 2: Assess the optic nerve (CN II)

Assess the optic nerve through vision tests. Test visual acuity using a Snellen chart at 6m covering one eye in turn. Test peripheral fields by confrontation and check visual neglect.

Step 3: Assess the oculomotor nerve (CN III), trochlear nerve (CN IV), and abducens nerve (CN VI)

These cranial nerve iii, cranial nerve iv, and cranial nerve vi are tested simultaneously. Check primary position, diplopia (double vision), smooth pursuit, and saccadic eye movements. Consider a PERRLA test for testing the pupillary light reflex.

Step 4: Assess the trigeminal nerve (CN V)

For the trigeminal nerve tests, assess ophthalmic, maxillary, and mandibular sensory branches with a piece of cotton wool. Inspect for wasting of the masseter and temporalis muscles and check for jaw resistance strength. Check corneal reflex and jaw-jerk reflexes.

Step 5: Assess the facial nerve (CN VII)

To assess the functioning of the facial nerve, ask the patient to scrunch up their eyes, look upwards and raise their eyebrows, puff out their cheeks, show their teeth, and inspect for facial asymmetry.

Step 6: Assess the vestibulocochlear nerve (CN VIII)

Perform gross hearing assessment followed by a Rinne test, Weber's test, otoscopy, and audiometry if hearing loss is detected.

Step 7: Assess the glossopharyngeal nerve (CN IX) and vagus nerve (CN X)

The glossopharyngeal nerve test and vagus nerve test involve assessment for dysarthria or dysphonia. Ask the patient to say “aah” and inspect the soft palate and uvula. Perform a swallow assessment or assessment of the gag reflex.

Step 8: Assess the spinal accessory nerve (CN XI)

Ask the patient to raise their shoulders, turn their head, and keep them there while you provide resistance.

Step 9: Assess the hypoglossal nerve (CN XII)

To test the hypoglossal nerve, inspect the tongue for wasting and fasciculations, ask the patient to protract their tongue and inspect for deviation, and test the tongue strength against each cheek.

Once you have completed the testing for each cranial nerve, the next steps will depend on your clinical findings and the results of any further testing or imaging they have undertaken. Ensure you securely store your patient's Cranial Nerve Exam notes in their medical record.

Benefits of using our Cranial Nerve Assessment template

Although one can conduct the assessment without the need for an examination template, there are an array of benefits to using our cranial nerve assessment, such as:

• Better structure your exam: This template serves as a pre-formatted record for your clinical findings and as a structure for the exam itself, which can help keep you on track and ensure you don't accidentally skip any during the examination.
• Keep your findings organized: Our Cranial Nerve Exam template will help you keep your notes from the cranial nerve exam clearly laid out and understandable. 
• Easily share results with other practitioners: Your colleagues will thank you for using a clearly formatted Cranial Nerve Exam template, as they can quickly understand your findings and move on to making informed treatment decisions.
• Standardize your Cranial Nerve Exams: Using the same template for each exam, you can demonstrate your efforts to standardize your practice and deliver the same high-quality examination to every patient. 
• Go fully digital: This exam template can be filled out and shared entirely digitally, which saves time and improves your information security.

References

Reese, V., Das, J. M., Al Khalili, Y. (2023, May 6). Cranial nerve testing. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK585066/

Oxford Medical Education. (2015). Cranial nerve examination. https://oxfordmedicaleducation.com/clinical-examinations/cranial-nerve-examination