Electrically Induced Blink Reflex and Facial Motor Nerve Stimulation in Beagles

Abstract

Electrophysiologic assessment of the blink reflex test and the muscle-evoked potentials evoked by stimulation of the facial nerve were performed in 15 healthy adult Beagles before and after supraorbital (trigeminal) and facial anesthetic nerve blocks performed by lidocaine injections. Unilateral electrical stimulation of the supraorbital nerve elicited 2 ipsilateral (R1 and R2) and a contralateral (Rc) reflex muscle potential in orbicularis oculi muscles. Electrical stimulation of the facial nerve elicited 2 muscle potentials (a direct response [D] and a reflex faciofacial response [RF]) in the ipsilateral orbicularis oculi muscle. Anesthetic block of the left supraorbital nerve resulted in bilateral lack of responses upon left supraorbital nerve stimulation, but normal responses in right and left orbicularis oculi muscles upon right supraorbital stimulation. Right facial anesthetic block produced lack of responses in the right orbicularis oculi muscle regardless the side of supraorbital nerve stimulation. Results of this study demonstrate that the blink reflex can be electrically elicited and assessed in dogs. Reference values for the blink reflex responses and for the muscle potentials evoked by direct facial nerve stimulation in dogs are provided. The potential usefulness of the electrically elicited blink reflex test in the diagnosis of peripheral facial and trigeminal dysfunction in dogs was demonstrated.

Resistance of the Peripheral Nervous System to the Effects of Chronic Canine Hypothyroidism

“…For recording of the blink reflex and facial motor nerve stimulation procedures, dogs were sedated with meperidine (5 mg/kg SC or IM), and recordings made in sternal recumbency using previously described techniques. 7 The 2nd late ipsilateral (R3) response was not consistently evoked in test dogs, and therefore this variable was not included in statistical analyses. Onset latencies were measured from the stimulus artifact to the initial deflection of the reflexinduced muscle potential.…”

Hemifacial spasm associated with an intracranial mass in two dogs

“…In these patients, the palpebral reflex may even be hyperactive characterised by a spasm or repetitively blinking of the eyelids (Ö ge and others 2005). Other criteria to differentiate UMN from LMN dysfunction are the presence of other signs of cerebral dysfunction and electrophysiological assessment of the facial nerve (Añor andothers 2000, Lorenz andKornegay 2004). In the second case of this report, a lesion, seemingly arising from the cranial middle fossa and extending 3 cm rostrally, was noticed with no involvement of the facial nucleus or facial nerve.…”