From the Guidelines
A cranial nerve exam should be conducted by systematically testing all 12 cranial nerves to assess their function, starting with the olfactory nerve (CN I) and proceeding to the optic nerve (CN II), oculomotor, trochlear, and abducens nerves (CN III, IV, VI), trigeminal nerve (CN V), facial nerve (CN VII), vestibulocochlear nerve (CN VIII), glossopharyngeal and vagus nerves (CN IX, X), spinal accessory nerve (CN XI), and hypoglossal nerve (CN XII), as recommended by recent guidelines 1.
Key Components of the Exam
- Begin by examining the olfactory nerve (CN I) by having the patient identify common scents with each nostril.
- Test the optic nerve (CN II) by checking visual acuity and visual fields.
- For oculomotor, trochlear, and abducens nerves (CN III, IV, VI), assess pupillary responses to light and accommodation, and evaluate extraocular movements in all directions.
- Examine the trigeminal nerve (CN V) by testing facial sensation in all three divisions and jaw strength.
- For the facial nerve (CN VII), observe facial symmetry and have the patient perform facial movements.
- Test the vestibulocochlear nerve (CN VIII) by checking hearing with whispered words or a tuning fork.
- Evaluate the glossopharyngeal and vagus nerves (CN IX, X) by assessing the gag reflex, palate elevation, and voice quality.
- For the spinal accessory nerve (CN XI), test shoulder shrug and neck rotation strength.
- Finally, examine the hypoglossal nerve (CN XII) by observing tongue movement and strength.
Imaging Recommendations
According to the American College of Radiology 1, MRI with and without intravenous contrast is often the modality of choice for imaging cranial neuropathy, and specific protocols may vary depending on the affected nerve and institutional protocols.
Documentation and Follow-up
Document any abnormalities observed during each component of the exam for accurate diagnosis and follow-up, as this systematic approach allows for comprehensive assessment of all cranial nerve functions, helping to localize neurological deficits to specific nerves or brain regions.
From the Research
Cranial Nerve Exam Overview
- The examination of cranial nerves is a crucial part of a complete neurological examination 2
- Historically, these skills were essential for diagnosing specific lesions, but with the development of modern imaging modalities, the significance of clinical examination techniques may have been undermined 2
- Cranial nerve testing is also important in musculoskeletal practice, particularly for clinicians who treat patients with neck, head, or orofacial pain and associated symptoms 3
Conducting the Exam
- A concise summary of examination techniques for each cranial nerve can be found in the literature 2
- The exam should be based on the function of the nerves, and should include an assessment of potential impairments and associated conditions 3
- Basic skills involved in cranial nerve examination can be summarized and used to facilitate clinicians in understanding neural function and impairment 3
- Cranial nerve testing can be performed quickly and efficiently without the need for complicated or specialized equipment 3
Key Considerations
- Clinicians should have an index of suspicion for cranial nerve dysfunction and be able to examine and determine if dysfunction is present 3
- An understanding of the cranial nerves' function and potential reasons for impairment can increase the frequency of cranial nerve testing in orthopedic clinical practice 3
- Positive findings should be referred appropriately 3