Evaluation of the Cranial Nerves

  • George Sachs


Electrophysiological testing of the cranial nerves remains an important and perhaps under utilized area of neurophysiological evaluation. Motor responses from individual branches of the facial nerve can be obtained to assist in the diagnosis and prognosis of facial neuropathies. In blink reflex testing, the first division of the trigeminal nerve is stimulated and responses from the orbicularis oculi are obtained. This form of testing can be used for a variety of purposes including helping to localize disorders of the Vth and VIIth cranial nerves, assisting in the evaluation of Guillain-Barré syndrome, and even in the assessment of brainstem disorders. It is also useful in the assessment of hemifacial spasm. The masseter reflex and master silent period can also be assessed when clinically indicated. Although less commonly pursued, other cranial nerves can also be evaluated electrophysiologically, including the XIth and XIIth cranial nerves. Assessment of these cranial nerves can be important in assessing other diseases, including amyotrophic lateral sclerosis.

Key Words

Bell’s palsy blink reflex facial neuropathy hemifacial spasm trigeminal neuropathy 


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Suggested Reading

  1. Ongerboer de Visser BW, Cruccu G. Chapter 3: Neurophysiologic examination of the trigeminal, facial, hypoglossal, and spinal accessory nerves in cranial neuropathies and brain stem disorders. In: Clinical Electromyography, 2nd ed. (Brown WF, Bolton CF, eds.). Butterworth Heinemann, Boston, MA, 1993, pp. 63–64.Google Scholar
  2. Kimura J. Chapter 16: The blink reflex. In: Electrodiagnosis in Diseases of Nerve and Muscle: Principles and Practice, 2nd ed. FA Davis, Philadelphia, PA, 1989, pp. 307–331.Google Scholar
  3. Preston DC, Shapiro BE. Chapter 5: The blink reflex. In: Electromyography and Neuromuscular Disorders: Clinical-Electrophysiologic Correlations. Butterworth-Heinemann, Boston, MA, 1998, pp. 57–62.Google Scholar

Copyright information

© Humana Press Inc. 2007

Authors and Affiliations

  • George Sachs
    • 1
  1. 1.Department of Neurology, Rhode Island HospitalBrown UniversityProvidence

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