Blink Reflex

Original Editor - Arnold Fredrick D'Souza

Top Contributors - Arnold Fredrick D'Souza

Introduction

It is an electrodiagnostic test that evokes the corneal reflex.[1] It evaluates the integrity of the trigeminal and facial nerve.[1][2]

Neuroanatomy

The supraorbital branch of the ophthalmic division of the trigeminal nerve constitutes the afferent arm, while the motor fibers of the facial nerve form the efferent arm of this reflex.[1][2] The diagram below depicts the pathway of the blink reflex.

Pathway of the Blink Reflex

Technique

The subject is supine and asked to stay relaxed with their eyes open or gently closed. The active electrode is placed over the inferior aspect of the orbicularis oculus while the reference electrode is placed either over the bony prominence of the zygomatic arch or the nose. The ground electrode can be placed over the forehead or under the chin. Using a prong stimulator, each supraorbital nerve is stimulated and the response from the orbicularis oculus is recorded bilaterally. Habituation is prevented by allowing a rest period of a few seconds between successive stimuli.[1][2]

Electrode placement for Blink Reflex
[3]

Interpretation

Normally, as with the corneal reflex, the ipsilateral electrical stimulation of the trigeminal nerve will produce an eye blink bilaterally.[2]

Indications

It is indicated in facial palsies (especially Bell's palsy), acoustic neuromas, brain stem lesions such as stroke or tumors, multiple sclerosis, and polyneuropathies like Guillain-Barre syndrome.[1]

Contraindications

There are no absolute contraindications, but an uncooperative patient or post-operative wounds or dressings can hamper the test procedure.[1]

Advantages

No effort is needed on the patient's end. Unlike traditional tests like the nerve conduction study, this test evaluates both the intracranial and extracranial sections of the trigeminal and facial nerve.[1]

Disadvantages

For better accuracy, the patient must be completely relaxed and extend full co-operation. Stimulation of the supraorbital nerve can be quite painful for some.[1]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Hartmann J.E. (2013) Blink Reflex. In: Kountakis S.E. (eds) Encyclopedia of Otolaryngology, Head and Neck Surgery. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-23499-6_904
  2. 2.0 2.1 2.2 2.3 Kimura J (2001) The blink reflex. In: Electrodiagnosis in diseases of nerve and muscle: principles and practice. Oxford University Press, New York
  3. NEUROWERK by SIGMA Medizin-Technik (2014) Reflexes - Blink Reflex. Available at: https://www.youtube.com/watch?v=_LTEdal_wWA (Accessed 29 August 2020)