BLINK REFLEXDr.Sujin Koshy

Neuro PG

The blink reflex is essentially the electrical correlate to corneal reflex

It is useful in finding defect anywhere in the reflex arc.

Afferent: supraorbital branch of the opthalmic division of Trigeminal nerve.

Efferent: Motor fibers of facial nerve.

Blink reflex anatomy

Two response: Early R1(ipsilateral) and

Late R2 response(bilateral).

R1: disynaptic- Biphasic

R2: multisynaptic- Polyphasic

Procedure Patient lie relaxed Two channel recording Electrodes: Inferior

orbicularis oculi Active electrode G1-lateral

and inferior to pupil. Reference electrode G2

placed lateral to lateral canthus bilaterally.

Ground electrode: mid forehead

Sweep speed: 5-10ms/divisionSensitivity:100 or 200 micro volt/divMotor filter: 10 Hz-10Khz

G1

G2

Electrode is placed on the supra orbital fissure over

medial supra orbital ridge (depression over bony ridge

over eye brow) to stimulate supra orbital nerve branch of

opthalmic disvision of trigeminal nerve.

Electrical stimulus of 100 micro seconds duration used.

The current is increased in small increments 3-5 milli ampere

Until supra maximal stimulation is reached.

Typically no more than 15-25 milli ampere

Four to six trials are obtained on rastered tracing and superimposed

R1 and R2 latency are measured

Blink reflex is elicited by stimulation of supraorbital nerve or

infra orbital nerve or by glabellar tap using special reflex

hammer that automatically triggers the oscilloscope sweep

In normal response electrical stimulation elicits R1 response

on the side ipsilateral to stimulation and R2 responses

bilaterally.

R 2 latency is the measure of conduction time along the

fastest fibers of afferent pathway of ipsilateral trigeminal

nerve to nucleus of the spinal tract of fifth across multiple

synapses in pons and lateral medulla to both ipsilateral and

contralateral facial n nuclei.

INCOMPLETE RIGHT TRIGEMINAL NERVE LEISION

COMPLETE TRIGEMINAL LEISION

R1

INCOMPLETE FACIAL

R2

COPLETE FACIAL N LEISION

IPSILATERAL R1 AND R2

RIGHT MIDPONTINE LEISION

RIGHT MEDULLARY

DEMYLINATING PERIPHERAL NEUROPATHY

Blink reflex R2 changes and localisation of lesionsin the lower brainstem (Wallenberg’s syndrome):an electrophysiological and MRI study

J Neurol Neurosurg Psychiatry 1999;67:630–636 S Fitzek, C Fitzek, J Marx, H Speckter, P P Urban, F

Thömke, P Stoeter, H C Hopf

Modified Rankin scale 0=no symptoms at all; 1=no significant disability despite symptoms; 2=slight disability; unable to carry out all previous activities but able to look after own affairs

without assistance; 3=moderate disability; requiring some help; but able to walk without assistance; 4=moderately severe disability; unable to walk without assistance; and unable

to attend to own bodily needs without assistance; 5=severe disability; bedridden; incontinent; and requiring constant nursing care and attention; 6=death; x=no acute infarction

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