Oculocardiac reflex

Published on 07/02/2015 by admin

Filed under Anesthesiology

Last modified 07/02/2015

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Oculocardiac reflex

Peter Radell, MD, PhD and Sten G.E. Lindahl, MD, PhD, FRCA

The oculocardiac reflex (OCR) was first described by Aschner and Dagnini in 1908. Recently, with the understanding that stimulation of the trigeminal nerve in areas other than the ophthalmic branch (V₁) can occur, a more comprehensive term, trigeminocardiac reflex, has come into use.

Anatomy

The afferent limb of the fifth cranial nerve is trigeminal, and the efferent limb is vagal. Specifically, afferent impulses travel via short and long ciliary nerves to the ciliary ganglion. From there, afferent information is sent to the gasserian ganglion via the ophthalmic branch of the trigeminal nerve (V₁). Efferent impulses leave the brainstem by way of the vagus nerve (X) (Figure 38-1).

Figure 38-1 Trigeminocardiac reflex pathway. Divisions of the trigeminal nerve: V₁, ophthalmic; V₂, maxillary; V₃, mandibular. ICA, Internal carotid artery.

Triggering stimuli

This reflex is triggered most commonly by traction on extraocular muscles (especially the medial rectus), direct pressure on the globe, ocular manipulation, and ocular pain. It may also be elicited by retrobulbar block, ocular trauma, and manipulation of tissue remaining in the orbital apex after enucleation. The reflex arc has even been described originating from other trigeminal afferent branches, for example, during sinus or nasal operations. The OCR seems to fatigue with repeated manipulation.

Manifestations

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